Difference between revisions of "Paper - The development of the arteries of the human lower extremity"

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{| class="wikitable mw-collapsible mw-collapsed"
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! Online Editor 
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|-
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| [[File:Mark_Hill.jpg|90px|left]] This historic 1919 paper by Senior described development of the arteries in the lower limbs. Note the later correction published in 1920 paper. {{Ref-Senior1920}}
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<br>
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'''Modern Notes''' [[Musculoskeletal System - Limb Development|Limb Development]] | [[Cardiovascular System Development]]
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{{Musculoskeletal Links}}
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[https://www.ncbi.nlm.nih.gov/pubmed/?term=Femoral+Artery+development Search PubMed Femoral Artery development]
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{{Historic Disclaimer}}
 
{{Historic Disclaimer}}
 
=The Development of the Arteries of the Human Lower Extremity=
 
=The Development of the Arteries of the Human Lower Extremity=
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==I. Introduction==
 
==I. Introduction==
  
===a. General considerations===
+
===a. General Considerations===
 
+
It is well known that considerable differences exist between the various types of arterial distribution which are nor encountered in the pelvic limb of the different representatives of the mammalian series. In all mammals in which the developmental history of the arteries of the limb has been investigated, however, it has been found that the adult arterial system of the part results from the elaboration of two embryonic vessels. Both of the embryonic arteries in question take origin from the dorsal (secondaiy) root of the a, umbilicalis. One of them, the primitive artery of the limb, traverses the axis of the thigh and leg and divides into a number of branches for the supply of the foot. This vessel is present before the limb forms a distinct prominence upon the surface of the body and is known as the axial or ischiadic artery.
It is well known that considerable differences exist between the various types of arterial distribution which are nor encountered in the pelvic limb of the different representatives of the mammalian series. In all mammals in which the developmental history of the arteries of the limb has been investigated, however, it has been found that the adult arterial system of the part results from the elaboration of two embryonic vessels. Both of the embryonic arteries in question take origin from the dorsal (secondaiy) root of the a, umbilicalis. One of them, the primitive artery of the limb, traverses the axis of the thigh and leg and divides into a number of branches for the supply of the foot. This vessel is present before the limb forms a distinct prominence upon the surface of the body and is known as the axial or ischiadic artery.  
 
  
  
The other is an artery of later development which traverse the pelvis and the ventral region of the thigh. It joins the axial artery a short distance above the knee and gives rise to the a. iliaca externa, the a. femoralis, and the a. epigastrica inferior and to the branches which arise from these vessels. All other arteries of the limb arise from the axial artery itself or from the branches to which it gives origin.  
+
The other is an artery of later development which traverse the pelvis and the ventral region of the thigh. It joins the axial artery a short distance above the knee and gives rise to the a. iliaca externa, the a. femoralis, and the a. epigastrica inferior and to the branches which arise from these vessels. All other arteries of the limb arise from the axial artery itself or from the branches to which it gives origin.
  
  
Whether the relations of the embryonic axial artery to the other constituents of the limb are identical in the embryos of all mammalian forms is a question to Avhich direct observation of the vessel has not yet furnished an answer. Much indirect evidence bearing upon this subject is furnished by Zuckerkandl's comparative study of the arteries of the leg which appeared in 1895.  
+
Whether the relations of the embryonic axial artery to the other constituents of the limb are identical in the embryos of all mammalian forms is a question to Avhich direct observation of the vessel has not yet furnished an answer. Much indirect evidence bearing upon this subject is furnished by Zuckerkandl's comparative study of the arteries of the leg which appeared in 1895.
  
  
The study in question, although it is mainly concerned with the relations of the adult arteries, is influenced throughout by embryological considerations. It includes, in fact, a study of the arteries in a series of vertebrate embryos in which the mammalia are represented by the rabbit and cat. Zuckerkandl's work is obviously based upon the conception of the identity of the course of the axial artery throughout the mammalian series. It may be said that the general results of the investigation are greatly in favor of the correctness of the author's  
+
The study in question, although it is mainly concerned with the relations of the adult arteries, is influenced throughout by embryological considerations. It includes, in fact, a study of the arteries in a series of vertebrate embryos in which the mammalia are represented by the rabbit and cat. Zuckerkandl's work is obviously based upon the conception of the identity of the course of the axial artery throughout the mammalian series. It may be said that the general results of the investigation are greatly in favor of the correctness of the author's conception.
conception.  
 
  
  
The principal relations of the axial artery of the embryo have been established by the present study. An adequate account of the relations of this and other arteries of the developing limb of one of the quadruped mammals would be of great value for purposes of comparison.  
+
The principal relations of the axial artery of the embryo have been established by the present study. An adequate account of the relations of this and other arteries of the developing limb of one of the quadruped mammals would be of great value for purposes of comparison.
  
only consecutive account which has been given of the development of the arteries of the pelvic limb in any mammalian form is that of DeVriese, which appeared in 1902. It deals with the human embryo. The other papers contained in the literature of the subject are concerned with isolated stages in the development of one or more forms rather than with a complete history of the arteries of any particular mammal.  
+
only consecutive account which has been given of the development of the arteries of the pelvic limb in any mammalian form is that of DeVriese, which appeared in 1902. It deals with the human embryo. The other papers contained in the literature of the subject are concerned with isolated stages in the development of one or more forms rather than with a complete history of the arteries of any particular mammal.
  
  
Hochstetter showed for the first time, in 1890, that the primitive artery of the mammalian thigh, which he termed the a. ischiadica, follows the course of the n. ischiadicus in the embryos of both the cat and the rabbit. He also described the development of the a. femoralis, which, appearing at a later stage, supersedes the proximal part of the a. ischiadica as the artery of the thigh. The secondary assumption of the original function of the a. ischiadica by the a. femoralis was shown to occur in man by DeVriese in 1902.  
+
Hochstetter showed for the first time, in 1890, that the primitive artery of the mammalian thigh, which he termed the a. ischiadica, follows the course of the n. ischiadicus in the embryos of both the cat and the rabbit. He also described the development of the a. femoralis, which, appearing at a later stage, supersedes the proximal part of the a. ischiadica as the artery of the thigh. The secondary assumption of the original function of the a. ischiadica by the a. femoralis was shown to occur in man by DeVriese in 1902.
  
  
Hochstetter did not succeed in following the continuation of the a, ischiadiea through the leg. Leboucq, however, described it in 1893, as pursuing, in the human embryo, an axial course between the tibia and fibula and finally perforating the tarsus to reach the dorsum of the foot.  
+
Hochstetter did not succeed in following the continuation of the a, ischiadiea through the leg. Leboucq, however, described it in 1893, as pursuing, in the human embryo, an axial course between the tibia and fibula and finally perforating the tarsus to reach the dorsum of the foot.
  
In 1894, Zuckerkandl described the continuation of the a. ischiadiea of the rabbit as traversing the flexor region of the leg and dividhig into a number of branches for the supply of the sole. He also described two branches of the artery which supply the extensor aspects of the leg and foot, respectively. In 1895 the same author described the perforating artery of the tarsus in rabbit embryos and made considerable progress in the nomenclature to the primitive artery of the limb.  
+
In 1894, Zuckerkandl described the continuation of the a. ischiadiea of the rabbit as traversing the flexor region of the leg and dividhig into a number of branches for the supply of the sole. He also described two branches of the artery which supply the extensor aspects of the leg and foot, respectively. In 1895 the same author described the perforating artery of the tarsus in rabbit embryos and made considerable progress in the nomenclature to the primitive artery of the limb.
  
  
 
In Zuckerkandrs second paper a distinction was made between the terms axial and ischiadic which formerlv had been used more or less interchangeably to denote the primitive artery of the
 
In Zuckerkandrs second paper a distinction was made between the terms axial and ischiadic which formerlv had been used more or less interchangeably to denote the primitive artery of the
  
For the entire artery Zuckerkandl employed the name He restricted the use of the term ischiadic to the part of  
+
For the entire artery Zuckerkandl employed the name He restricted the use of the term ischiadic to the part of it which traverses the thiah and used the term a. interossea for the remainder of the vessel. The same paper contained the first accurate description which had been given of the distal part of the axial artery of any mammal. The a. interossea was described in the rabbit as lying between the interosseous membrane and m. tibialis posterior.
it which traverses the thiah and used the term a. interossea for the remainder of the vessel. The same paper contained the  
 
first accurate description which had been given of the distal part  
 
of the axial artery of any mammal. The a. interossea was described in the rabbit as lying between the interosseous membrane  
 
and m. tibialis posterior.  
 
  
  
Grosser, in 1901, and DcYriese, in 1902, described the a. interossea (the a. nervi interossei cruris of the latter in bat and human embryos, respectively, as pursuing the course it had been described b}^ Zuckerkandl as following in the rabbit.  
+
Grosser, in 1901, and DcYriese, in 1902, described the a. interossea (the a. nervi interossei cruris of the latter in bat and human embryos, respectively, as pursuing the course it had been described b}^ Zuckerkandl as following in the rabbit.
  
  
Both of these observers also recorded the presence, in subjects of their respective studies, of the r. perforans tarsi.  
+
Both of these observers also recorded the presence, in subjects of their respective studies, of the r. perforans tarsi.
  
During the course of the present investigation it has become apparent that the existing literature contains no definite statement regarding the course taken by the part of the axial artery which traverses the popliteal fossa. It is questionable whether the popliteal section of the axial artery has been tacitly included as a part of the a. ischiadiea or not, since the distal limit of the latter artery does not appear to have been definitely fixed. In the following description the term a. ischiadica has been restricted to the part of the axial artery proximal to the site at which it is subsequently joined by the a, femoralis. restriction has necessitated the use of a new term for the part of the axial artery which extends from the hiatus tendineus (the approximate site of the femoro-ischiadic junction) to the  
+
During the course of the present investigation it has become apparent that the existing literature contains no definite statement regarding the course taken by the part of the axial artery which traverses the popliteal fossa. It is questionable whether the popliteal section of the axial artery has been tacitly included as a part of the a. ischiadiea or not, since the distal limit of the latter artery does not appear to have been definitely fixed. In the following description the term a. ischiadica has been restricted to the part of the axial artery proximal to the site at which it is subsequently joined by the a, femoralis. restriction has necessitated the use of a new term for the part of the axial artery which extends from the hiatus tendineus (the approximate site of the femoro-ischiadic junction) to the point (in the neighborhood of the distal border of the m. popliteus) at which the a. mterossea begins.
point (in the neighborhood of the distal border of the m. popliteus) at which the a. mterossea begins.  
 
  
  
An examination of the popliteal portion of the human axial artery shows that its distal part does not lie upon the posterior surface of the m. popliteus as does the distal part of the adult a, popliteal but upon the anterior surface of that muscle. It seems clear, therefore, that the distal part of the a. poplitea of the majority of adult mammals, which lies upon the anterior surface of the m. popliteus represents a persisting portion of the embryonic axial artery. On this account the name a. poplitea has been used in the following pages to designate  
+
An examination of the popliteal portion of the human axial artery shows that its distal part does not lie upon the posterior surface of the m. popliteus as does the distal part of the adult a, popliteal but upon the anterior surface of that muscle. It seems clear, therefore, that the distal part of the a. poplitea of the majority of adult mammals, which lies upon the anterior surface of the m. popliteus represents a persisting portion of the embryonic axial artery. On this account the name a. poplitea has been used in the following pages to designate entire popliteal section of the human axial artery.
entire popliteal section of the human axial artery.  
 
  
  
The solution of Zuckerkandl's difficulty regarding the difference of the mutual relations between the a. poplitea and the m. popliteus in man on the one hand and in the majority of other mammals upon the other has thus been furnished by determining the course of the popliteal portion of the axial artery of the human embryo.<ref>Arteria poplitea. Ein Stiick dieser Arterie lagert bei denHalbaflfen und den Primaten auf der freien (dorsalcn) Flachc des Musculus popliteus, bei den librigen Saugetieren auf der Gelenkskapsel, bedekt von dcm oben erwahntcn Muskel. Diese Verschiedenheit im Verlaufe der Poplitea kann nur auf die weise erklart werden, dass entweder die den Muskel querenden Sttieke der Poplitea nicht homolog oder die beiden AIu:skeln nicht dieselben sind. Nach meinen bisherigen Erfahrungen scheint ersteres wahrscheinlicher zu sein. (Zuekerkandl ('95), p. 255.)</ref>
+
The solution of Zuckerkandl's difficulty regarding the difference of the mutual relations between the a. poplitea and the m. popliteus in man on the one hand and in the majority of other mammals upon the other has thus been furnished by determining the course of the popliteal portion of the axial artery of the human embryo.[1]
  
  
The part of the adult human a. poplitea which extends from the hiatus tendineus to the origin of the a. genu inferior medialis is a direct survival of the embryonic a. poplitea profunda. The part of that artery which lies upon the posterior surface of the m. popliteus is derived from an embryonic vessel of later formation referred to in the following pages as the a. poplitea superficialis.  
+
The part of the adult human a. poplitea which extends from the hiatus tendineus to the origin of the a. genu inferior medialis is a direct survival of the embryonic a. poplitea profunda. The part of that artery which lies upon the posterior surface of the m. popliteus is derived from an embryonic vessel of later formation referred to in the following pages as the a. poplitea superficialis.
  
  
The literature dealine; with the arteries of the mammalian pelvic limb shows a tendency towards the perpetuation of a conception regarding the relation of the adult human a. peronaea to the embryonic a. interossea which Zuckerkandl has already shown to be erroneous. Stieda stated, in 1893, that the study of the variations of the arteries of the human leg had led him to the conclusion that the a. peronaea represents a persisting portion of the embryonic axial artery. A similar opinion regarding the between these two arteries was expressed by Zuckerkandl in 1894. In 1895 the recognition of the course of the a. interossea led Zuckerkandl to a modification of the views he had previously expressed upon the subject. He drew attention to the fact that it would be impossible for the part of the a. peronaea which is separated from the interosseous membrane by the m. tibialis posterior to be a derivative of the part of the a. interossea which lies between the membrane and the muscle. In 1902 DeVriese revived the conception of the identity of the  
+
The literature dealine; with the arteries of the mammalian pelvic limb shows a tendency towards the perpetuation of a conception regarding the relation of the adult human a. peronaea to the embryonic a. interossea which Zuckerkandl has already shown to be erroneous. Stieda stated, in 1893, that the study of the variations of the arteries of the human leg had led him to the conclusion that the a. peronaea represents a persisting portion of the embryonic axial artery. A similar opinion regarding the between these two arteries was expressed by Zuckerkandl in 1894. In 1895 the recognition of the course of the a. interossea led Zuckerkandl to a modification of the views he had previously expressed upon the subject. He drew attention to the fact that it would be impossible for the part of the a. peronaea which is separated from the interosseous membrane by the m. tibialis posterior to be a derivative of the part of the a. interossea which lies between the membrane and the muscle. In 1902 DeVriese revived the conception of the identity of the aa. interossea and peronaea, notwithstanding the obvious justice of ZuckerkandUs contention.
aa. interossea and peronaea, notwithstanding the obvious justice of ZuckerkandUs contention.  
 
  
  
A careful examination of the embryos which form the basis of the present study and of a large number of others belonging to the collection of the Carnegie Institution has been made in the search for a r. saphenus of the a. femoralis comparable in extent to that of the a. saphena which occurs very rarely in adult man and invariably in most of the other mammals. The result has been entirely negative.  
+
A careful examination of the embryos which form the basis of the present study and of a large number of others belonging to the collection of the Carnegie Institution has been made in the search for a r. saphenus of the a. femoralis comparable in extent to that of the a. saphena which occurs very rarely in adult man and invariably in most of the other mammals. The result has been entirely negative.
  
  
That the a. saphena occurs occasionally in the huinan embryo is indicated by the fact that its presence has been noted at least five times in the adult. In the embryos examined in connection with the present study, however, the r. saphenus has not been found to extend in a single instance beyond the middle of the leg.  
+
That the a. saphena occurs occasionally in the huinan embryo is indicated by the fact that its presence has been noted at least five times in the adult. In the embryos examined in connection with the present study, however, the r. saphenus has not been found to extend in a single instance beyond the middle of the leg.
  
 
I take this opportunity of expressing my gratitude to Professor Thyng for the trouble he has taken in the revision of manuscript.
 
I take this opportunity of expressing my gratitude to Professor Thyng for the trouble he has taken in the revision of manuscript.
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* 6.0 mm+  Carnegie Institution, Embryological Collection (C.T.E.C.) No. 1075.
+
{{Senior1919 table1}}
* 8.5 mm+ Cornell University, Embryological Collection (C.E.C.) No. 9.
 
* 12.0 mm+ Cornell University, Embryological Collection (C.E.C.) No. 3.
 
* 12.0 mm+ Minnesota, Embryological Collection (M.E.C.) No. H. 16.
 
* 14.0 mm Cornell University, Embryological Collection (C.E.C.) No. 5.
 
* 17. 5 (?) Harvard University, Embryological Collection (H.E.C.) No. 839.
 
* 18.0 mm Carnegie Institution, Embryological Collection (C.I.E.C.) No. 409.
 
* 22.0 mm Cornell University, Embryological Collection (C.E.C.) No. 1.
 
  
 +
{{Senior1919 collapse table1}}
  
For their generosity in placing their material at my disposal, I wish to express my great obligation to Profs. C. M. Jackson, F. T. Lewis, F. P. Mall, C, R. Stockard, and G. L, Streeter.  
+
For their generosity in placing their material at my disposal, I wish to express my great obligation to Profs. C. M. Jackson, F. T. Lewis, F. P. Mall, C, R. Stockard, and G. L, Streeter.
  
  
Toward the end of the investigation, there were a number of difficulties, for the solution of which the examination of rather close intermediate stages was required. Such stages were found in the collection of the Carnegie Institution at Baltimore.  
+
Toward the end of the investigation, there were a number of difficulties, for the solution of which the examination of rather close intermediate stages was required. Such stages were found in the collection of the Carnegie Institution at Baltimore.
  
  
In the formation of this valuable collection, so ably cared for and sympathetically administered. Professor Mall has  
+
In the formation of this valuable collection, so ably cared for and sympathetically administered. Professor Mall has available to his fellow workers a wealth of material adequate for the solution of any ordinary problem in human embryology.
available to his fellow workers a wealth of material adequate for the solution of any ordinary problem in human embryology.  
 
  
  
The reconstruction of vascular plexuses in wax, using every second or fourth section as the case may be, is somewhat difficult.  
+
The reconstruction of vascular plexuses in wax, using every second or fourth section as the case may be, is somewhat difficult. The practice followed has been to unite the parts of the adjacent plates which fit after careful adjustment and to remove those which do not join. In this way the plexus represented in the reconstruction is probably less dense than that occurring in the embryo. The reconstruction in fact, reproduces the spirit rather than the letter of the original.
The practice followed has been to unite the parts of the adjacent plates which fit after careful adjustment and to remove those  
 
which do not join. In this way the plexus represented in the reconstruction is probably less dense than that occurring in the embryo. The reconstruction in fact, reproduces the spirit rather than the letter of the original.
 
  
  
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==II. The Arterial System Of The Lower Limb In Progressive Stages Of Development==
 
==II. The Arterial System Of The Lower Limb In Progressive Stages Of Development==
  
:''a. Stage of 6 mm. C. I. E. C, no. 1075, figs, 1 and 9 A''.
+
===a. Stage of 6 mm===
 +
C. I. E. C, no. 1075, figs, 1 and 9 A
  
 
In the lumbar region the nerve roots are not recognizable. The ganglia of the lumbar and sacral regions appear as segmentally disposed swellings upon the continuous neural crest. Distal to the second lumbar segment the postcardinal vein becomes plexiform. The medial part of the plexus receives the segmental veins, the lateral part represents the still indefinite marginal vein.  
 
In the lumbar region the nerve roots are not recognizable. The ganglia of the lumbar and sacral regions appear as segmentally disposed swellings upon the continuous neural crest. Distal to the second lumbar segment the postcardinal vein becomes plexiform. The medial part of the plexus receives the segmental veins, the lateral part represents the still indefinite marginal vein.  
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The axial artery, takes an almost transverse, slightly recurrent, course towards the surface. It ends by dividing into two branches, each of which breaks up into a plexus which passes over into the postcardinal venous plexus. The a. pudenda interna follows the dorsolateral surface of the Wolffian duct towards the urogenital sinus and enters the pelvic arterial plexus.  
 
The axial artery, takes an almost transverse, slightly recurrent, course towards the surface. It ends by dividing into two branches, each of which breaks up into a plexus which passes over into the postcardinal venous plexus. The a. pudenda interna follows the dorsolateral surface of the Wolffian duct towards the urogenital sinus and enters the pelvic arterial plexus.  
  
 +
 +
[[File:Senior1919 fig01.jpg|600px]]
  
 
'''Fig. 1.''' Reconstruction showing the distal end of the aorta; also the arteries of the right lower extremity and neighboring parts in a human embryo of 6 mm. C.I. E.G., 1075). Medial aspect. X 40 diams.  
 
'''Fig. 1.''' Reconstruction showing the distal end of the aorta; also the arteries of the right lower extremity and neighboring parts in a human embryo of 6 mm. C.I. E.G., 1075). Medial aspect. X 40 diams.  
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:''b. Stuge of 8.5 mm., C. U. C., no. 9, figs. 2 and 9 B
+
===b. Stuge of 8.5 mm===
  
 +
C. U. C., no. 9, figs. 2 and 9 B
  
 
The femoral, obturator, genitofemoral, and peroneal nerves are readily recognized as short relatively unbranched trunks. The extremity of the tibial is divided into what appear to be the medial and lateral plantar nerves.  
 
The femoral, obturator, genitofemoral, and peroneal nerves are readily recognized as short relatively unbranched trunks. The extremity of the tibial is divided into what appear to be the medial and lateral plantar nerves.  
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The axial artery passes distally into the lower Umb, crossing the n. tibialis posteriorly from the medial to the lateral side. It then follows the posterior aspect of the skeletal mesenchyme throughout the leg into the sole. In the latter situation it breaks up into a flattened plexus which extends somewhat beyond the extremities of the plantar nerves. Just as it is breaking up axial which pierce  
 
The axial artery passes distally into the lower Umb, crossing the n. tibialis posteriorly from the medial to the lateral side. It then follows the posterior aspect of the skeletal mesenchyme throughout the leg into the sole. In the latter situation it breaks up into a flattened plexus which extends somewhat beyond the extremities of the plantar nerves. Just as it is breaking up axial which pierce  
  
 +
[[File:Senior1919 fig02.jpg|600px]]
  
 
'''Fig. 2.''' Reconstruction showing the arteries of the right lower extremity in a human embryo of 8.5 mm. (C.E.C.; 9). Medial aspect. X 20 diams.  
 
'''Fig. 2.''' Reconstruction showing the arteries of the right lower extremity in a human embryo of 8.5 mm. (C.E.C.; 9). Medial aspect. X 20 diams.  
  
'''Fig. 3.''' Reconstruction showing the arteries of the right side of the pelvis, right thigh, leg, and dorsum of the foot in a human embr)'o of 12 mm. (M.E. C.,H. 14). Medial aspect. X 20 diams,
+
[[File:Senior1919 fig03.jpg|600px]]
 
 
  
 +
'''Fig. 3.''' Reconstruction showing the arteries of the right side of the pelvis, right thigh, leg, and dorsum of the foot in a human embryo of 12 mm. (M.E. C.,H. 14). Medial aspect. X 20 diams,
  
 
mesenchymal  
 
mesenchymal  
 
+
foot reach  
foot  
 
 
 
 
 
 
 
reach  
 
 
 
 
 
  
 
Up  
 
Up  
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perforating branches prod  
 
perforating branches prod  
  
 
+
another flattened plexus- The two plexuses (or retia) of the foot are separated from one another by the mesenchymal skeleton of the foot, the plantar rete lying between the latter and the plantar nerves.  
 
 
another flattened plexus- The two plexuses (or retia) of the foot are separated from one another  
 
by the mesenchymal skeleton of the foot, the plantar rete lying  
 
between the latter and the plantar nerves.  
 
  
  
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aspect of the concavity of the umbilical  
+
aspect of the concavity of the umbilical artery, some distance proximal to the origin of the axial artery,  
artery, some distance proximal to the origin of the axial artery,  
 
 
there now arises a new vessel, the a. iliaca externa. This vessel  
 
there now arises a new vessel, the a. iliaca externa. This vessel  
 
takes a cephalic direction, nearly parallel to the aorta, coursing  
 
takes a cephalic direction, nearly parallel to the aorta, coursing  
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tortuous. The artery is not connected with the dorsal segmental arterial series or with any other artery. The further history of  
 
tortuous. The artery is not connected with the dorsal segmental arterial series or with any other artery. The further history of  
 
the external iliac is rather remarkable. It soon becomes quite  
 
the external iliac is rather remarkable. It soon becomes quite  
straight and acquires a w^all of great thickness, but remains unbranched until a stage of (approximately) 12 mm.  
+
straight and acquires a wall of great thickness, but remains unbranched until a stage of (approximately) 12 mm.  
externa appears as a thick-walled straight artery in the well-  
+
externa appears as a thick-walled straight artery in the well- known pig embryo of 12 mm.  
known pig embryo of 12 mm.  
 
  
  
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part becomes the adult a. iliaca communis while the distal part represents the a. hyjDogastrica and a short proximal section of its  
 
part becomes the adult a. iliaca communis while the distal part represents the a. hyjDogastrica and a short proximal section of its  
  
al branch. At  
+
al branch. At marginal vein is fully formed; its caudal  
 
 
marginal vein is fully formed; its caudal  
 
  
 
root, represented by the v. ischiadica, runs in close contact with the proximal of the corresponding artery  
 
root, represented by the v. ischiadica, runs in close contact with the proximal of the corresponding artery  
  
  
c.  
+
===c. of 12 mm===
 
+
M. E. C, no. H. 16, figs. 3 and 9 C  
of 12 mm. M. E. C, no. H. 16, figs. 3 and 9 C  
 
 
 
Condensation of the mesenchymal
 
 
 
 
 
eton is now well
 
 
 
  
vanced. It is not sufficiently definite in the tarsal region, however, for the determination of the course taken by the connection  
+
Condensation of the mesenchymal skeleton is now well advanced. It is not sufficiently definite in the tarsal region, however, for the determination of the course taken by the connection  
 
between the axial artery and the dorsal rete of the foot,  
 
between the axial artery and the dorsal rete of the foot,  
 
surfaces of the growing nerves are considerably roughened by the beginning outgrowth of numerous branches^ many of which  
 
surfaces of the growing nerves are considerably roughened by the beginning outgrowth of numerous branches^ many of which  
 
can be identified.  
 
can be identified.  
 +
  
 
The course of the axial artery is somewhat less straight than  
 
The course of the axial artery is somewhat less straight than  
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the femoral is later to unite with  
 
the femoral is later to unite with  
 
 
  
 
Although the axial artery is straighter in the  
 
Although the axial artery is straighter in the  
  
 
than at the stage of 12 mm., an irregularity is  
 
than at the stage of 12 mm., an irregularity is  
 
  
 
preceding stage  
 
preceding stage  
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at the  
 
at the  
  
ge of 8.5 mm. in a similar situation. It seems to represent  
+
stage of 8.5 mm. in a similar situation. It seems to represent  
  
  
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is so pronounced at  
 
is so pronounced at  
 
  
 
artery lies in the narrow interval  
 
artery lies in the narrow interval  
 
The interosseous membrane and  
 
The interosseous membrane and  
 
  
 
muscles are still unrecognizable, but, although the  
 
muscles are still unrecognizable, but, although the  
ges toward the extensor region, its  
+
ges toward the extensor region, its course
  
  
course
+
artery
  
 +
clearly indicates that it does not leave the flexor aspect of the
  
 +
Ipcr
  
artery
 
 
clearly indicates that it does not leave the flexor aspect of the
 
 
 
 
Ipcr
 
 
 
 
proximal
 
 
 
 
econd bend
 
  
 +
proximal
  
 +
econd bend
  
 
This bend is so pronounced as to practically amount to the bud  
 
This bend is so pronounced as to practically amount to the bud  
Line 340: Line 302:
  
 
The a.  
 
The a.  
 
 
 
  
 
externa has  
 
externa has  
 
 
  
  
Line 364: Line 321:
  
  
^ That the a. epigastrica inferior is an indejiendent branch of the a. iliaca externa, which considerably antedates it and the a. femoralis in  
+
* That the a. epigastrica inferior is an indejiendent branch of the a. iliaca externa, which considerably antedates it and the a. femoralis in has already been pointed out by the writer (Senior, '17).  
has already been pointed out by the writer (Senior, '17).  
 
 
 
  
  
 
ment,  
 
ment,  
 
 
  
 
ramus commumcans superius  
 
ramus commumcans superius  
  
 +
The latter is
  
 +
er
  
The latter is
+
and
  
 +
IS
  
 +
recognizable as the ramus saphenus of the a. genu suprema.
  
 +
The difficulty in finding developmental stages in which the a. femoralis is present, but not yet united with the axial artery, coupled with the thinness of the wall of the femoral artery at this stage, indicates that the artery is one of extremely rapid growth. In a 12-mm. embryo slightly younger than the specimen described (C. E. C, No. 3), reconstruction was begun under the impression that the femoral was absent. After more thorough study the artery was identified, bifurcated as in IVI. E. C, No. H 16, but much shorter. At this stage the a. femoralis has no branches, other than the terminal bifurcation already referred to.
  
 +
m
  
er
+
===d. Stage of I4 mm===
 +
C E. C, no. 5, figs. 4 o.nd 9 D
  
 +
the a. femoralis in the blood
  
 +
of the leg and by the
  
and
+
the two
  
 +
appearance of three branches of the axial artery.
  
 +
The r, communicans superius of the a, femoralis has joined
 +
axial artery at the more proximal
 +
noticed in the preceding stage.
  
IS
+
can be traced to the level of
 +
t the more distal bend of tl
  
 +
bend
  
  
recognizable as the ramus saphenus of the a. genu suprema.
 
  
The difficulty in finding developmental stages in which the a. femoralis is present, but not yet united with the axial artery, coupled with the thinness of the wall of the femoral artery at this stage, indicates that the artery is one of extremely rapid growth. In a 12-mm. embryo slightly younger than the specimen described (C. E. C, No. 3), reconstruction was begun under the impression that the femoral was absent. After more thorough study the artery was identified, bifurcated as in IVI. E. C, No. H 16, but much shorter. At this stage the a. femoralis has no branches, other than the terminal bifurcation already referred to.  
+
The r. sa
  
 +
remam
  
 +
branch
  
m
+
proximal end
  
d. Stage of I4 "rnm. C E. C, no. 5, figs. 4 o.nd 9 D
+
space and takes a recurrent course toward
  
  
 +
The
  
ed b^^
+
proxim
  
 +
formation
  
 +
a. tibialis anterior.
  
the a. femoralis in the blood
+
may be referred to as the ramus
 +
cruris. The recurrent vessel continuing from the r.
 +
perforans cruris is the arteria recurrens tibialis anterior of the  
  
  
 +
The
  
  
of the leg and by the
+
k.
  
  
 +
upon the axial artery by means of the r.
 +
and by the origin of the r. perforans
  
the two
+
cruris, respectively, may be used tor tlie convenient subdivision
 +
of the vessel into three parts. The part upon the proximal side
  
  
  
appearance of three branches of the axial artery.  
+
of the r. communicans superius w
  
The r, communicans superius of the a, femoralis has joined
+
be
axial artery at the more proximal
 
noticed in the preceding stage.
 
  
can be traced to the level of
+
to as
t the more distal bend of tl
 
  
 +
a.
  
 +
ischiadica and that upon the distal side of the r. perforans cruris
  
bend
+
[[File:Senior1919 fig04.jpg|600px]]
  
 +
'''Fig. 4.''' Reconstruction showing the arteries of the right side of the pelvis and right thigh and leg in a human embyro, of 14 mm. (C.E.C., 5). X 20 diams.
  
 +
[[File:Senior1919 fig05.jpg|600px]]
  
The r. sa
+
'''Fig. 5.''' Reconstruction showing the arteries of the right side of the pelvis and right lower extremity in a human embryo of 17.6 mm. (H.E.C., 839). aspect. X 20 diams.  
  
 +
[[File:Senior1919 fig06.jpg|600px]]
  
 +
'''Fig. 6.''' Reconstruction showing the arteries of the right side of the pelvis and right lower extremity in a human embryo of 18 mm. (C.E.LC, 409) X 20 diams.
  
  
remam
+
as the a. interossea- The intervening jDart will be called the a. poplitea profunda.
  
 +
At this stage the a. poplitea profunda has two branches which course longitudinally through the posterior crural region. One of these resembles, in a general way, the a. tibialis posterior of the adult, it may be called the a. tibialis posterior superficialis.
  
 +
The slightly more
  
  
branch
+
in its place of
  
  
  
 +
origin is the a, peronaea posterior superficialis (of HyrtVjJ The
 +
relations borne by these arteries to the n. tibialis remain constant
 +
throughout a prolonged period of development.
  
proximal end
+
The a* tibialis posterior superficialis passes at first backward
  
 +
side of the n. tibialis to reach its posterior
 +
aspect. Running upon the posterior aspect of the n. tibialis in
 +
the leg, it passes into the sole upon the inferior aspect of the n.
  
  
space and takes a recurrent course toward
 
  
 +
plantaris
  
  
  
 +
t of the artery which enters the sole becomes the a. plantaris medialis of the adult.
  
The  
+
The a. peronaea posterior superficialis passes from the
 +
to the lateral aspect of the n. tibialis by skirting around
  
  
 +
proximal and
  
proxim
 
  
 +
s of a large muscular ramus of the
  
  
formation
+
nerve. It follows the anterior and lateral aspect of the n.
 +
tibialis as far as the place of origin of the nn. plantares. In this
 +
situation the artery bifurcates into a lateral and a medial
 +
The branches are both short and end blindly.
  
  
  
 +
Two branches now spring from the lateral side of the a.
  
a. tibialis anterior.  
+
One of these is situated upon the proximal side of
 +
the r. saphenus and represents the r. musculo-articularis of the
 +
.adult a. genu suprema. The other is the a. circumflexa femoris
 +
lateralis of the adult a. profunda femoris.  
  
 +
The branches arising from the medial side of the a. femoralis
 +
which will be discussed under stages E and F.
  
 +
The a. glutaea superior is present and takes origin from the
  
may be referred to as the ramus
+
root of the a. ischiadica.
 
 
  
  
 +
^ According to the system of nomenclature in use at the present time, the
 +
iective 'posterior' as used by Hyrtl is redundant. In view of the essentially
  
cruris. The recurrent vessel continuing from the r.
 
perforans cruris is the arteria recurrens tibialis anterior of the
 
  
  
 +
fugitive nature of anatomical terminology it has seemed unnecessary to modify
 +
Hyrtl's original term, which adequately meets the requirements of the case.
  
 +
i musculares for the mm. popliteus,
  
The
 
  
  
 +
s This is resolved later into the
 +
tibialis posterior, flexor digitorum longus, and flexor longus hallucis.
  
  
 +
===e. Stage of 17.8 mm===
 +
H. E. C.^ no. 839,^ figs. 5 and 9 E
  
 
+
During the iDreceding stages of develoi3ment the arterial retia
k.  
+
of the foot have received their blood supplj^ exclusively through
 +
the a. interossea; the reta plantare directly, and the rete dorsale
 +
by means of the r. perforans tarsi. The mesenchymal skeleton
 +
of the foot is now definitely circumscribed, and it is plain that
 +
the latter vessel reaches the dorsum by way of the tarsal sinus.
 +
The arterial retia of the foot lie in close contact with the tarsus
 +
and metatarsus and represent the following vessels of the adult
 +
circulation — the arcus plantaris and its articular branches, the
 +
aa. tarseae mediales and laterales, the a. arcuata, the aa. metatarseae and digitales (both dorsal and plantar), and the rami
 +
perforantes (including the ramus plantaris profundus).  
  
  
 +
The present stage is characterized by the presence of four
 +
arteries which traverse the leg for the supply of the sole. The
 +
a. interossea is still present, the aa. tibialis posterior superficialis
 +
and peronaea posterior superficialis have formed their definitive
 +
connections, and a new vessel, the a. tibialis anterior, pars
 +
distalis, has arisen.
  
  
upon the axial artery by means of the r.
 
and by the origin of the r. perforans
 
  
 +
The a. tibialis posterior superficialis and the a. peronaea
 +
posterior superficialis preserve in the leg the same relations to
 +
the n. tibialis as obtained in the preceding stage. At the ankle the medial terminal branch of the a. peronaea posterior super-
 +
ficialis has traversed the fork formed by the diverging plantar
 +
nerves to join the a. tibialis posterior superficialis. The lateral
 +
terminal branch of the same artery has reached the lateral side
 +
of the sole to join the plantar arterial rete. The connection thus
 +
formed between the a.
 +
rete plantare becomes the a. plantaris lateralis of the adult foot.
 +
At the present stage of development it receives blood from two
  
cruris, respectively, may be used tor tlie convenient subdivision
 
of the vessel into three parts. The part upon the proximal side
 
  
 +
* The greatest total length of this embryo, measured in formalin, was 17.8 mm.  In 80 per cent alcohol it measured 13.6 mm. It has been described by Thyng as a 17.8 mm. embryo (Am. Jour. Anat., vol, 17, p. 31), and referred to by Thyng  (Am. Jour. Anat., vol. 7, p. 489) and hy Thyng and Lewis (Am. Jour. Anat., vol. 7,  p. 505) as an embrj^o of 13.6 mm. The distribution of the arteries of the lower  extremity resembles that of other embryos of about 15 or 16 mm.
  
  
of the r. communicans superius w
 
  
 +
The part of the a. tibiaus posterior superncialis distal to the origin of the a. plant aris lateraUs now
 +
the a. plantaris mediahs. The portion of the remainder of that,
 +
vessel which is not concerned in the formation of the a. poplitea.
 +
becomes the a. tibialis posterior.
  
  
 
+
The branches of the medial plantar artery anastomose, upon
be
+
the lateral side of the foot, with the plantar rete, thus consti-
 +
tuting a (transitory) superficial plantar arch.
  
  
 +
The a. tibialis anterior, pars distalis, extends from the part of
 +
r. perforans cruris which lies in the extensor region of the leg to
 +
the rete dorsale. The portion of the r. perforans which now lies
 +
beyond the proximal end of the pars distalis corresponds to the adult a. recurrens tibialis anterior. The portion which extends,
 +
from the a. poplitea profunda to the pars distalis enters into
 +
the composition of the adult a. tibialis anterior. The a. recurrens.
 +
tibialis anterior is connected by means of a plexiform anastomosis,
 +
with the r. saphenus of the a. femoralis.
  
  
to as
 
  
 +
Upon the medial side of the a. femoralis there are at this,
 +
stage three branches exclusive of the r. saphenus. Of these the
 +
most distal, which has a longer individual course than the others, takes a recurrent direction. The three branches break up to
 +
form an extensive plexus (not indicated in the figures) which
 +
ramifies throughout the thigh and is particularly rich around,
 +
the perichondrium. It is probable that this plexus is eventually
 +
taken over by the adult a. profunda femoris and its branches.
 +
Two branches arise from the lateral side of the a. femoralis as.
 +
in the preceding stage.
  
 +
The a. glutaea superior now takes du-ect origin from the a. hypogastrica upon the proximal side of the origin of the a. ischiadica.
  
  
a.
 
  
 +
===Stage of 18 mm===
 +
C. I. E. C, no. 409, figs. 6 and 9 F
  
 +
From the time of the junction between the r, communicans
  
ischiadica and that upon the distal side of the r. perforans cruris
+
superius and the axial artery the caHber of the a. femoralis has
  
 +
exceeded that of the a. ischiadica^ which has now become exceedingly slender. After having traversed the lower of the sacropudendal plexuS; the a. ischiadica passes.
  
Fig. 4 Reconstruction showing the arteries of the right side of the pelvis and right thigh and leg in a human embyro, of 14 mm. (C.E.C., 5). X 20 diams.  
+
to the region of the hiatus tendineus upon the lateral side of the  
 +
n. tibiaUs. The n. peronaeus lies immediately upon its lateral
  
  
Fig. 5 Reconstruction showing the arteries of the right side of the pelvis and right lower extremity in a human embryo of 17.6 mm. (H.E.C., 839). aspect. ' X 20 diams.  
+
In a general way the aa. poplitea profunda and interossea  and their branches have the same arrangement as in the preceding stage. The exact course taken by these vessels can now
  
Fig. 6 Reconstruction showing the arteries of the right side of the pelvis and right lower extremity in a human embryo of 18 mm. (C.E.LC, 409) X 20 diams.
 
  
 +
ed, since it is possible to identifv the individual
  
as the a. interossea- The intervening jDart will be called the a.
 
poplitea profunda.
 
  
At this stage the a. poplitea profunda has two branches which
+
muscles of the limb.  
course longitudinally through the posterior crural region. One
 
 
 
 
 
 
 
of these
 
  
 +
The a. poplitea profunda runs between the m. popliteus and
  
 +
. At the proximal border of the muscle the artery
 +
gives off the a. genu media and a short trunk which is being
 +
formed by the progressive union of the proximal ends of the aa.
 +
tibialis posterior superficialis and the a. peronaea posterior super-
 +
ficialis. This short trunk, which lies upon the posterior surface
 +
of the m. popliteus, may now be called the a. poplitea super-
 +
ficialis. It forms the distal part of the a. poplitea of the adult.
 +
A short distance below the origin of the a, poplitea superficialis
 +
there arises the a. genu inferior medialis.
  
 +
The a. interossea passes down the leg between the m. tibialis posterior and the interosseous membrane. Just above
 +
medial malleolus it gives off a branch which passes around the
 +
posterior to the medial side of the tibia, the ramus coronarius
 +
of the medial malleolus (Hyrtl).^^ At the malleolus the a.
  
resembles, in a general way, the a. tibialis  
+
* In this vessel lies, according to Hyrtl, the key to the deep supramalleolar
 +
anastomosis (i.e., the r. communicans) between the a. perong^ea and the a.
 +
tibialis posterior. The r. coronarius is regarded by Hyrtl as primarily passing
 +
from the a* peronaea around the medial side of the tibia to unite with the a.
 +
tibialis anterior. By means of a secondary connection occurring between the r.
 +
coronarius and the a. tibialis posterior, the former vessel eventually becomes
 +
converted into an anastomosing chain in which the aa. malleolaris anterior
 +
medialis, malleolaris posterior medialis and r. communicans are the named
 +
components. At the stage of 18 mm. of this series the r. coronarius arises from the
 +
part of the a. interossea which persists to take part in the formation of the adult
 +
a. peronaea. It runs, at this stage, as at the stage of 22 mm,, toward the a. tibialis
 +
anterior as described by Hyrtl, and would, no doubt, eventually join it. Since
 +
in both these stages the a. tibialis posterior is situated upon a plane superficial
 +
to that occupied by the r. coronarius, no junction of the vessels in question has
 +
occurred. There can be little doubt, however, that Hyrtl has interpreted the
 +
nature of the r. coronarius correctly. His views upon this subject, which were
 +
derived from an extensive study of the normal and abnormal conditions found
 +
in adult legs, have been of the greatest assistance in the interpretation of the
 +
conditions obtaining during development.
  
  
 +
interossea lies upon the lateral side of the tendon of the m.
 +
tibialis posterior (i.e., between tendon and malleolus) and then
 +
passes across the plantar end of the sinus tarsi to join the plantar
  
posterior of the adult, it may be called the a. tibialis posterior
+
rete.  
  
 +
The a. peronaea posi^erior superficialis is placed anteriorly and  laterally to the n. tibialis and lies upon the posterior surface of
 +
the m. flexor hallucis longus. At the distal border of the muscle
 +
the artery lies near the a. interossea and interosseous membrane.
 +
In this situation it gives off a very large r. calcaneus lateralis
 +
which runs upon the lateral side of the tuber calcanei. This
 +
branch eventually forms the termination of the a. peronaea.
  
  
superficialis.  
+
The a. tibialis posterior superficialis follows the posterior
 +
surface of the n. tibialis until the latter bifurcates in the neighborhood of the medial malleolus. Here the artery is placed  between the n. tibialis and the tendon of the flexor hallucis longus. The a. tibialis anterior, pars distalis, has relations
 +
identical with those of the adult.  
  
  
 +
The relations existing between the various structures of the
 +
leg were ascertained by making a reconstruction which, from
 +
the fact that it yields but little information when entirely built
  
The
 
  
  
 +
up, IS uns
  
  
slightly more
 
  
  
 +
The data gained from an examination of its separate parts are embodied in two diagrams
 +
(fig 7, A and B) which may serve as a rough guide to the inter-
 +
pretation of anomalies. These diagrams show, approximately,
 +
the course taken by the embryonic aa. poplitea profunda,
  
  
in its place of
 
  
 +
interossea, and peronaea posterior superficialis.
  
 +
The order in which the various structures passing from the
 +
leg to foot are arranged in the hollow between the medial mal-
 +
leolus and tuber calcanei is as follows: m. tibialis anterior and
 +
a. interosseus together: m. flexor digitorum longus; a. peronaea
  
origin is the a, peronaea posterior superficialis (of HyrtVjJ The
 
relations borne by these arteries to the n. tibialis remain constant
 
throughout a prolonged period of development.
 
  
The a* tibialis posterior superficialis passes at first backward
 
  
side of the n. tibialis to reach its posterior
+
posterior superficialis; n. tibialis, a. tibialis posterior super-
aspect. Running upon the posterior aspect of the n. tibialis in
+
ficialis, and m. flexor hallucis longus.  
the leg, it passes into the sole upon the inferior aspect of the n.  
 
  
 +
Embryos of about this age are instructive mainly by reason
 +
of the fortunate circumstance that the individual muscles are
  
  
  
 +
differentiated before the continuity of the axial artery has
 +
been broken. Only one important change has occurred at this
 +
stage of development; this consists in the appearance of a communicating branch which foreshadows the development of the
  
 +
^e a. peronaea.
  
plantaris
+
. The communicating branch in question leaves the a, peronaea
 +
posterior superficialis at the proximal border of the m. flexor
  
 +
gus. It passes distally between the mm. flexor
 +
hallucis longus and tibialis posterior to join the a. interossea, as that artery lies upon the interosseous membrane. It may be
 +
called the r. communicans inferius.
  
  
 +
[[File:Senior1919 fig07.jpg|600px]]
  
 +
Fig, 7. Indicates the course of three arteries of the embryonic lower extremity, represented diagrammatically as they would appear if persisting in the adult. The vessels which normally persist are indicated by shading. A, A. poplitea profunda and a. interossea. B. A. peronaea posterior superficialis. d. L m. flexor digitorum longus; h, L, m. flexor hallucis longus; L p., m. tibialis posterior.
  
  
t of the artery which enters the
 
  
  
  
sole becomes the a. plantaris medialis of the adult.  
+
The entire r. communicans inferius persists in the adult as
 +
the portion of the a, peronaea which lies between the mm. flexor
 +
hallucis longus and tibialis posterior. The portions of the aa.  
 +
peronaea posterior superficialis and interossea with which the
  
The a. peronaea posterior superficialis passes from the
 
to the lateral aspect of the n. tibialis by skirting around
 
  
 +
and distal ends of the r. communicans inferior are
  
  
  
 +
connected
  
proximal and
 
  
  
 +
a* peronaea.
  
  
  
s of a large muscular ramus of the  
+
Of the branches of the a* femorahs^ those arising from the  
  
 +
lateral side are identical with the branches of the preceding
 +
stage. There are three branches upon the medial side,
 +
recurrent branch {R in figures) seems to be identical with the
  
  
nerve. It follows the anterior and lateral aspect of the n.
 
tibialis as far as the place of origin of the nn. plantares. In this
 
situation the artery bifurcates into a lateral and a medial
 
The branches are both short and end blindly.
 
  
  
 +
similar branch of the preceding stage. It is doubtful whether
 +
the two other medial branches correspond to those observed in
 +
the preceding stage or not.
  
  
  
Two branches now spring from the lateral side of the a.  
+
*
 +
===g. Stage of 22 mm===
 +
C /. C no. 1, figs. 8 and 9 G
  
. One of these is situated upon the proximal side of
 
the r. saphenus and represents the r. musculo-articularis of the
 
.adult a. genu suprema. The other is the a. circumflexa femoris
 
lateralis of the adult a. profunda femoris.
 
  
The branches arising from the medial side of the a. femoralis
 
which will be discussed under stages E and F.
 
  
The a. glutaea sui^erior is present and takes origin from the  
+
At this stage of development the continuity of the a. ischiadica has been interrupted and the a. femoralis alone conveys blood
 +
to the region beyond the knee.
  
 +
The femoral artery pursues a more direct course than before
 +
and gives origin to most of its important branches. In addition
 +
to the a. circumflexa lateralis which appeared at the stage of
 +
14 mm., it gives origin to the a. pudenda externa and the a.
 +
profunda. The r. musculo-articularis has migrated to the em-
  
  
root of the a. ischiadica.
 
  
  
  
  
^ According to the system of nomenclature in use at the present time, the
 
iective 'posterior' as used by Hyrtl is redundant. In view of the essentially
 
  
 +
nic r. saphenus. The root of the latter branch,
 +
now appears as the a. genu suprema and gives origin to the r.
 +
saphenus and the rr. muscularis and articulares of the adult.
  
 +
The a. profunda arises from the a. femoralis quite close to the
 +
origin of the a. circumflexa lateralis. It seems probable that
  
fugitive nature of anatomical terminology it has seemed unnecessary to modify
+
onic a. profunda sometimes arises from the root of
Hyrtl's original term, which adequately meets the requirements of the case.  
+
the latter artery and sometimes directly from the femoral. In
 
+
the former case the adult a. circumflexa lateralis would
i musculares for the mm. popliteus,
+
appear to arise from the a. profunda and in the latter from the
 +
femoral. The great variation in the site of the origin of the
 +
vessel is well known.
 +
 
 +
The a. profunda femoris gives origin to one perforating artery
 +
y since it pierces the adductores brevis and magus, repre-
 +
sents the first or second of the adult series. The single a. per-
 +
forans is connected, by means of an extensive plexus, with the
 +
more distal section of the now interrupted a. ischiadica.  
  
  
  
s This is resolved later into the  
+
The a. ischiadica passes through the sacropudendal j^lexus as
tibialis posterior, flexor digitorum longus, and flexor longus hallucis.  
+
before and reaches the lateral side of the a. tibialis, which is now
 +
contained in the same sheath as the n. peronaeus. After its
 +
exit from the pelvis the artery gives origin to a few gluteral
 +
branches and leaves the n. tibialis with the n. cutaneus femoris
 +
posterior. In company with the latter nerve and the v. ischiadica,  
 +
it passes to the posterior surface of the thigh and ends
 +
dividing into several cutaneous branches. This part of the a.
 +
ischiadica persists as the a. glutaea inferior.  
  
 +
The more distal portion of the a. ischiadica is traceable as a
 +
definite path through a plexus upon the posterior surface of the
 +
m. adductor magnus, but has lost its continuity wdth the a.
  
e. Stage of 17.8 mm. H. E. C.^ no. 839,^ figs. 5 and 9 E
 
  
  
  
During the iDreceding stages of develoi3ment the arterial retia
+
pophtea. The other vessel participating in the  
of the foot have received their blood supplj^ exclusively through
 
the a. interossea; the reta plantare directly, and the rete dorsale
 
by means of the r. perforans tarsi. The mesenchymal skeleton
 
of the foot is now definitely circumscribed, and it is plain that
 
the latter vessel reaches the dorsum by way of the tarsal sinus.
 
The arterial retia of the foot lie in close contact with the tarsus
 
and metatarsus and represent the following vessels of the adult
 
circulation — the arcus plantaris and its articular branches, the
 
aa. tarseae mediales and laterales, the a. arcuata, the aa. meta-
 
  
  
 +
of
  
tarseae and digitales (both dorsal and plantar), and the rami
 
perforantes (including the ramus plantaris profundus).
 
  
The present stage is characterized by the presence of four
+
the plexus is the perforating branch of the a. profunda femoris.
arteries which traverse the leg for the supply of the sole. The  
+
This plexus evidently represents the terminal anastomosis
a. interossea is still present, the aa. tibialis posterior superficialis
+
between the perforating arteries of the adult. It probably takes
and peronaea posterior superficialis have formed their definitive
+
a large share in the formation of the perforating arteries
connections, and a new vessel, the a. tibialis anterior, pars
+
themselves.  
distalis, has arisen.
+
 
 +
The distal part of the anterior tibial artery has received blood
 +
since the time of its first appearance by way of the a. poplitea
 +
profunda and r. perforans cruris. An alternative path has now
 +
 
 +
by the appearance of a vessel which, passing
  
 +
of the m. popliteus, connects the
  
 +
around
  
The a. tibialis posterior superficialis and the a. peronaea
+
distal
  
 +
developing a. peronaea with a more distal part of the a. poplitea
 +
profunda. It is the r. communicans medius which will later become
 +
the definitive proximal end of the a. tibialis anterior. The
 +
significance of this vessel in relation to the formation of the
 +
adult aa. profunda and tibialis anterior will be dealt with in the
 +
succeeding section.
  
 +
The principal changes which have occurred in the embryonic
 +
arteries of the posterior crural region since the preceding stage
  
posterior superficialis preserve in the leg the same relations to
+
participate in the  
the n. tibialis as obtained in the preceding stage. At the ankle
 
  
ti
+
of development involve the vessels
  
the medial terminal branch of the a. peronaea posterior super-  
+
formation of the adult a, peronaea- These changes cons' st in
ficialis has traversed the fork formed by the diverging plantar
+
the disappearance of considerable parts of the aa, interossea and
nerves to join the a. tibialis posterior superficialis. The lateral
+
peronaea posterior superficialis.  
terminal branch of the same artery has reached the lateral side
 
of the sole to join the plantar arterial rete. The connection thus
 
formed between the a.
 
rete plantare becomes the a. plantaris lateralis of the adult foot.
 
At the present stage of development it receives blood from two
 
  
 +
The portion of the a. interossea which formerly extended from
 +
the r. perforans cruris. to the distal end of the r. communicans
  
 +
[[File:Senior1919 fig07.jpg|600px]]
  
 +
Fig. 8. Reconstruction showing the arteries of the right side of the pelvis and right lower extremity in a human embryo of 22 mm. (C.E.I.C, 1.). Medial aspect. X 20 diams.
  
 +
inferius has practically disappeared. The portion immediately
 +
beyond the distal end of the latter vessel lies upon the posterior
 +
surface of the interosseus membrane and gives origin to two
 +
branches. The remainder of the vessel is involved in the meshes
 +
of the rete calcaneum.
  
^ The greatest total length of this embryo, measured in formalin, was 17.8 mm.  
+
The portion of the a. peronaea posterior superficialis which
In 80 per cent alcohol it measured 13.6 mm. It has been described by Thyng as a
+
extends from the present termination of the a. popUtea super-
 +
ficialis to the proximal end of the r.  
  
-ft
 
  
17.8 mm. embryo (Am. Jour. Anat., vol, 17, p. 31), and referred to by Thyng
+
commumcan
(Am. Jour. Anat., vol. 7, p. 489) and hy Thyng and Lewis (Am. Jour. Anat., vol. 7,
 
p. 505) as an embrj^o of 13.6 mm. The distribution of the arteries of the lower
 
extremity resembles that of other embryos of about 15 or 16 mm.
 
  
 +
sists
 +
the re
  
  
The part of the a. tibiaus posterior superncialis distal to the  
+
of the  
  
 +
become a part of the adult a. peronaea.
 +
ainder of the artery has been lost, but th
 +
essel can still be recognized as forming a
  
 +
aspect of the rete calcaneum. Thi
  
 +
A large part of artery can be traced through the meshes of the rete as far as
  
 +
the a.
  
 +
The rete calcaneum is very
  
origin of the a. plant aris lateraUs now
+
ive at this stage of develop
the a. plantaris mediahs. The portion of the remainder of that,
 
vessel which is not concerned in the formation of the a. poplitea.
 
becomes the a. tibialis posterior.
 
  
The branches of the medial plantar artery anastomose, upon  
+
ment and occuT^ies the concavity upon the medial side of the  
the lateral side of the foot, with the plantar rete, thus consti-
 
tuting a (transitory) superficial plantar arch.
 
  
The a. tibialis anterior, pars distalis, extends from the part of
+
surrounds the  
r. perforans cruris which lies in the extensor region of the leg to
 
the rete dorsale. The portion of the r. perforans which now lies
 
beyond the proximal end of the pars distalis corresponds to the  
 
  
 +
m
  
  
adult a. recurrens tibialis anterior. The portion which extends,
 
from the a. poplitea profunda to the pars distalis enters into
 
the composition of the adult a. tibialis anterior. The a. recurrens.
 
tibialis anterior is connected by means of a plexiform anastomosis,
 
with the r. saphenus of the a. femoralis.
 
  
 +
the
  
  
Upon the medial side of the a. femoralis there are at this,
+
malleolar region of the leg.  
stage three branches exclusive of the r. saphenus. Of these the
 
most distal, which has a longer individual course than the others,
 
  
m
+
The component parts of the a. peronaea are now recognizable.
 +
The proximal part is derived from the a. peronaea posterior super-
  
takes a recurrent direction. The three branches break up to
+
hallucis longiis and  
form an extensive plexus (not indicated in the figures) which
 
ramifies throughout the thigh and is particularly rich around,
 
the perichondrium. It is probable that this plexus is eventually
 
taken over by the adult a. profunda femoris and its branches.
 
Two branches arise from the lateral side of the a. femoralis as.
 
in the preceding stage.
 
  
The a. glutaea superior now takes du-ect origin from the a. hy-
+
The  
pogastrica upon the proximal side of the origin of the a. ischiadica.
 
  
 +
between tibialis posterior represents the entire r. communicans inferius.
 +
The immediately succeeding part, which rests upon the mem-
 +
brana interossea, is derived from the a. interossea. The terminal part of the artery consists i
 +
the a. peronaea posterior su
 +
of the r. calcaneus lateraUs of
 +
. The connection between
  
 +
the a. interossea and the part of the latter artery which gives
 +
origin to the calcanean branch is effected through the agency of
  
/. Stage of 18 mm. C. I. E. C, no. 409, figs. 6 and 9 F
 
  
  
 +
the plexus calcaneum.
  
From the time of the junction between the r, communicans
+
The part of the a. interossea which takes part in the formation
 +
of the a. peronaea has been noted as giving rise to a branch, the  
 +
r. coronarius, at the stage of 18 mm. At the present stage
 +
another branch arises from it, namely, the r. perforans. Both
  
â– I
 
  
siiperius and the axial artery the caHber of the a. femoralis has
 
  
 +
of them become branches of the adult artery. At the stage of
 +
22 mm. the r. coronarius can be traced around the posterior
 +
and medial aspects of the tibia almost as far as the a^ tibialis
 +
anterior. The views expressed by Hyrtl upon the conversion
  
  
  
exceeded that of the a. ischiadica^ which has now
+
Fig. 9 Reconstructions showing the arteries of the right lower extremity in the seven human embryos shown in the preceding figures. Tlie cephalic (embryonic pre-axial, adult medial) aspect is shown in all cases. A, X 40, the others X 20 diams. The skeleton is shown, in part, in E, F and G. Parts of the tibia
  
  
  
become exceedingly slender. After having traversed the lower of the sacropudendal plexuS; the a. ischiadica passes.  
+
a femon
 +
a. eplgast. inf.  
  
  
  
to the region of the hiatus tendineus upon the lateral side of the
+
r. SQphtn.  
n. tibiaUs. The n. peronaeus lies immediately upon its lateral
 
  
  
  
 +
n SGphen,
  
In a general way the aa. poplitea profunda and interossea
 
and their branches have the same arrangement as in the pre-
 
ceding stage. The exact course taken by these vessels can now
 
  
 +
I: com. sup.
 +
n. obtur.
  
 +
r. perf, tarsj
 +
retc
  
b
 
  
  
 +
a pudend int
  
 +
n, tiblol
  
ed, since it is possible to identifv the individual
 
  
  
 +
C /2 n7An.
  
  
 +
and tarsus are omitted in E, the tibia in F and the tibia and medial femoral
 +
condyle in G. The fibula is omitted in all. The medial plantar artery has
 +
been almost entirely removed from E and F. In C, a. femor. should read a.
 +
iliaca ext.
  
muscles of the limb.
 
  
The a. poplitea profunda runs between the m. popliteus and
+
of the r. coronarius into the communicating branch and medial
 +
malleolar arteries of the adult have been noted above (footnote 10, p. 73).
 +
A small
  
. At the proximal border of the muscle the artery
 
gives off the a. genu media and a short trunk which is being
 
formed by the progressive union of the proximal ends of the aa.
 
tibialis posterior superficialis and the a. peronaea posterior super-
 
ficialis. This short trunk, which lies upon the posterior surface
 
of the m. popliteus, may now be called the a. poplitea super-
 
ficialis. It forms the distal part of the a. poplitea of the adult.
 
A short distance below the origin of the a, poplitea superficialis
 
there arises the a. genu inferior medialis.
 
  
The a. interossea passes down the leg between the m. tibialis
 
  
 +
of
  
 +
a. peronaea posterior super
  
  
posterior and the interosseous membrane. Just above
 
medial malleolus it gives off a branch which passes around the
 
posterior to the medial side of the tibia, the ramus coronarius
 
of the medial malleolus (Hyrtl).^^ At the malleolus the a.
 
  
^^ In this vessel lies, according to Hyrtl, the key to the deep supramalleolar
 
anastomosis (i.e., the r. communicans) between the a. perong^ea and the a.
 
tibialis posterior. The r. coronarius is regarded by Hyrtl as primarily passing
 
from the a* peronaea around the medial side of the tibia to unite with the a.
 
tibialis anterior. By means of a secondary connection occurring between the r.
 
coronarius and the a. tibialis posterior, the former vessel eventually becomes
 
converted into an anastomosing chain in which the aa. malleolaris anterior
 
medialis, malleolaris posterior medialis and r. communicans are the named
 
components. At the stage of 18 mm. of this series the r. coronarius arises from the
 
part of the a. interossea which persists to take part in the formation of the adult
 
a. peronaea. It runs, at this stage, as at the stage of 22 mm,, toward the a. tibialis
 
anterior as described by Hyrtl, and would, no doubt, eventually join it. Since
 
in both these stages the a. tibialis posterior is situated upon a plane superficial
 
to that occupied by the r. coronarius, no junction of the vessels in question has
 
occurred. There can be little doubt, however, that Hyrtl has interpreted the
 
nature of the r. coronarius correctly. His views upon this subject, which were
 
derived from an extensive study of the normal and abnormal conditions found
 
in adult legs, have been of the greatest assistance in the interpretation of the
 
conditions obtaining during development.
 
  
 +
I
  
interossea lies upon the lateral side of the tendon of the m.  
+
appears at the present stage as a branch of the a. peronaea. It
tibialis posterior (i.e., between tendon and malleolus) and then
+
runs upon the posterior surface of the m. flexor hallucis longus.  
passes across the plantar end of the sinus tarsi to join the plantar
+
The disintegrating a. interossea has left a similar vestige of its
  
rete.
 
  
The a. peronaea posi^erior superficialis is placed anteriorly and
+
'osseous
  
laterally to the n. tibialis and lies upon the posterior surface of
 
the m. flexor hallucis longus. At the distal border of the muscle
 
the artery lies near the a. interossea and interosseous membrane.
 
In this situation it gives off a very large r. calcaneus lateralis
 
which runs upon the lateral side of the tuber calcanei. This
 
branch eventually forms the termination of the a. peronaea.
 
  
The a. tibialis posterior superficialis follows the posterior
 
surface of the n. tibialis until the latter bifurcates in the neigh-
 
  
 +
proximal end upon the posterior surface of its
 +
membrane. This vestigial branch occasionally persists as a
 +
branch of the adult a. tibialis anterior.^^ The terminal part of
 +
the main trunk of the a. peronaea posterior superficialis is now
 +
involved in the rete calcaneum. It usually leaves its mark in
 +
the adult as a recurrent element among the leash of
 +
known as the r. calcaneus medialis of the a. plantaris
  
  
borhood of the medial malleolus. Here the artery is placed
+
The aa. iliolumbalis
  
 +
sacralis lateralis now arise from
  
  
between the n. tibialis and the tendon of the flexor hallucis
 
  
  
 +
a. elutaea
  
longus. The a. tibialis anterior, pars distalis, has relations
 
identical with those of the adult.
 
  
  
The relations existing between the various structures of the
 
leg were ascertained by making a reconstruction which, from
 
the fact that it yields but little information when entirely built
 
  
  
 +
The root of the latter artery has conse-
  
up, IS uns
 
  
  
 +
quently become the
  
  
The data gained from an
 
examination of its separate parts are embodied in two diagrams
 
(fig 7, A and B) which may serve as a rough guide to the inter-
 
pretation of anomalies. These diagrams show, approximately,
 
the course taken by the embryonic aa. poplitea profunda,
 
  
  
 +
division of the
  
interossea, and peronaea posterior superficialis.
 
  
The order in which the various structures passing from the
 
leg to foot are arranged in the hollow between the medial mal-
 
leolus and tuber calcanei is as follows: m. tibialis anterior and
 
a. interosseus together: m. flexor digitorum longus; a. peronaea
 
  
  
 +
a. hypo-
  
posterior superficialis; n. tibialis, a. tibialis posterior super-
 
ficialis, and m. flexor hallucis longus.
 
  
Embryos of about this age are instructive mainly by reason
 
of the fortunate circumstance that the individual muscles are
 
  
 +
gastrica. All the visceral arteries of the pelvis, with the
  
 +
their
  
differentiated before the continuity of the axial artery has
 
been broken. Only one important change has occurred at this
 
stage of development; this consists in the appearance of a communicating branch which foreshadows the development of the
 
  
^e a. peronaea.
 
  
. The communicating branch in question leaves the a, peronaea
 
posterior superficialis at the proximal border of the m. flexor
 
  
gus. It passes distally between the mm. flexor
+
of the a. vesicalis superior, have
hallucis longus and tibialis posterior to join the a. interossea,  
 
  
  
  
  
Fig, 7 Indicates the course of three arteries of the embryonic lower extremity, represented diagrammatically as they would appear if persisting in the adult. The vessels which normally persist are indicated by shading. A, A. poplitea profunda and a. interossea. B. A. peronaea posterior superficialis. d. L m. flexor digitorum longus; h, L, m. flexor hallucis longus; L p., m. tibialis posterior.
 
  
 +
relations
  
  
as that artery lies upon the interosseous membrane. It may be
 
called the r. communicans inferius.
 
  
The entire r. communicans inferius persists in the adult as
+
h. Changes occurring in the principal arteries subsequent to stage of 22 mm .  
the portion of the a, peronaea which lies between the mm. flexor
 
hallucis longus and tibialis posterior. The portions of the aa.
 
peronaea posterior superficialis and interossea with which the
 
  
  
and distal ends of the r. communicans inferior are
+
A. Formation of the adult a. poplitea and a. tibialis anterior.  
  
  
 +
Fig. 10, A, C. I. E. C, 22; B, C E. C, 1; C, C. I. E. C, 840.
  
connected
+
The r. communicans medius, the presence of which was noted at the stage of 22 mm., seems to arise at about that stage of
  
 +
In C. E. C, no 1, it is larger upon the right side than upon the left and in C. E. C , no. 6, which also measures 22 mm., it is absent altogether.
  
  
a* peronaea.
 
  
  
  
Of the branches of the a* femorahs^ those arising from the  
+
*^ Mr. Kimbrig has kindly dissected six adult legs for evidence of persistence
 +
of this vessel. In two instances he found a branch accompanying the n. interos-
 +
seus cruris for a short distance. In both cases the branch arose from the root of
 +
the ramus fibularis.
  
lateral side are identical with the branches of the preceding
+
It is very questionable whether the B. N. A. is correct in classifying the r.
stage. There are three branches upon the medial side,  
+
fibularis as belonging to the a. tibialis posterior. It has usually been regarded,  
recurrent branch {R in figures) seems to be identical with the  
+
in English-speaking countries at all events, as a branch of the a. tibialis anterior.
  
  
  
 +
At the stage of 20 mm. (fig. 10, A) blood traverses the popliteal region to reach the r. perforans cruris through the original
 +
channel, namely the a. poplitea profunda. The a. poplitea is longer than at the stage of 18 mm., having increased in length at the expense of the aa. tibialis posterior and peronaea posterior superficialis.
 +
At the stage of 22 mm. (fig. 10, B), a junction between the developing a. peronaea and the distal part of the a. poplitea
  
similar branch of the preceding stage. It is doubtful whether
 
the two other medial branches correspond to those observed in
 
the preceding stage or not.
 
  
 +
[[File:Senior1919 fig10.jpg|600px]]
  
 +
'''Fig. 10.''' Three reconstructions, each showing a sagittal segment (0.25 mm. thick) from the left leg of an embryo of the length indicated. Lateral aspect. X 19. A, 20 mm. ; B, 22 mm. ; C, 24.8 mm. The tibia appears in all cases. P. indicates the position of the m. popliteus. c. m., a. communicans media; g, i. m., a. genu inferior medialis; g, m., a. genu media; i., a. interossea; {. m., interosseous
 +
membrane; p., a. poplitea; p. c, a. perforans cruris; p- d.^ a. tibialis anterior, pars distalis; p. p., a. poplitea profunda; p. s., a. poplitea superficialis; per., a. peronaea; r. a,, a. recurrens tibialis anterior; r. p., a. recurrens tibialis posterior; t, a., a. tibialis anterior; t, p. s., a. tibialis posterior superficialis.
  
*
 
g. Stage of 22 mm C /. C no. 1, figs. 8 and 9 G
 
  
  
 +
profunda has been effected by the development of the r. com
 +
municans medius. Blood may now pass from the proximal par
 +
of the a. poplitea profunda to the a. tibialis anterior, pars distalis by
 +
super
  
At this stage of development the continuity of the a. ischiadica
 
  
  
  
 +
routes: 1) anterior to the m. popliteus, by way of the a. poplitea profunda and r. perforans cru
 +
or to the m. popliteus, by way of the a. poph
 +
developing a. peronaea, r. communicans medius
  
as been interrupted and the a. femoralis alone conveys blood
 
to the region beyond the knee.
 
  
The femoral artery pursues a more direct course than before
 
and gives origin to most of its important branches. In addition
 
to the a. circumflexa lateralis which appeared at the stage of
 
14 mm., it gives origin to the a. pudenda externa and the a.
 
profunda. The r. musculo-articularis has migrated to the em-
 
  
 +
poplitea profunda, and r. perforans cruris.
  
  
 +
At the stage of 24.5 mm. (fig. 10, C) upon the anterior surface of the m.
  
  
  
 +
ect
  
nic r. saphenus. The root of the latter branch,
+
s
now appears as the a. genu suprema and gives origin to the r.
+
 
saphenus and the rr. muscularis and articulares of the adult.
+
route
  
The a. profunda arises from the a. femoralis quite close to the
+
to  
origin of the a. circumflexa lateralis. It seems probable that
 
  
onic a. profunda sometimes arises from the root of  
+
exist. The part of the a, pophtea profunda not incorporated in  
the latter artery and sometimes directly from the femoral. In
 
the former case the adult a. circumflexa lateralis would
 
appear to arise from the a. profunda and in the latter from the
 
femoral. The great variation in the site of the origin of the
 
vessel is well known.
 
  
The a. profunda femoris gives origin to one perforating artery
+
the definitive a, poplitea or  
y since it pierces the adductores brevis and magus, repre-
 
sents the first or second of the adult series. The single a. per-
 
forans is connected, by means of an extensive plexus, with the
 
more distal section of the now interrupted a. ischiadica.
 
  
  
 +
anterior is represented :
  
The a. ischiadica passes through the sacropudendal j^lexus as
+
1) by the root and a small branch of the a. genu inferior medialis of the former and 2) by the a. recurrens tibialis posterior of the latter. The main arterial channel through the popliteal region has thus been transferred from the anterior to the posterior surface of the popliteus muscle. Both the a. poplitea and the a. tibialis anterior have assumed their adult arrangement.  
before and reaches the lateral side of the a. tibialis, which is now
 
contained in the same sheath as the n. peronaeus. After its
 
exit from the pelvis the artery gives origin to a few gluteral
 
branches and leaves the n. tibialis with the n. cutaneus femoris
 
posterior. In company with the latter nerve and the v. ischiadica,
 
it passes to the posterior surface of the thigh and ends
 
dividing into several cutaneous branches. This part of the a.  
 
ischiadica persists as the a. glutaea inferior.  
 
  
The more distal portion of the a. ischiadica is traceable as a  
+
The formation of the adult a. poplitea results from the combination of two embryonic elements. The part of the vessel which extends from the hiatus tendineus to the origin of the a. genu inferior medialis is derived from the embryonic a. poplitea profunda. The remainder of the artery corresponds to the embryonic a poplitea superficialis.  
definite path through a plexus upon the posterior surface of the  
 
m. adductor magnus, but has lost its continuity wdth the a.  
 
  
 +
The embryonic components of the a. tibialis anterior consist of the r. communicans medius, a short section of the distal end of the a. poplitea profunda, the proximal part of the r. perforans cruris, and the entire tibialis anterior, pars distalis.
  
 +
The a. poplitea superficialis reaches' completion at the stage of 24.5 mm. by extending as far as the r. communicans medius becomes one of branches.
  
  
pophtea. The other vessel participating in the  
+
means the a. peronaea rehnquishes its temporary
 +
in the formation of the a. tibialis anterior.
  
  
of
+
this
  
  
the plexus is the perforating branch of the a. profunda femoris.
+
ion
This plexus evidently represents the terminal anastomosis
 
between the perforating arteries of the adult. It probably takes
 
a large share in the formation of the perforating arteries
 
themselves.
 
  
The distal part of the anterior tibial artery has received blood
+
B. The conversion of the  
since the time of its first appearance by way of the a. poplitea
 
profunda and r. perforans cruris. An alternative path has now
 
  
by the appearance of a vessel which, passing
+
yonic a.
  
of the m. popliteus, connects the
+
s posterior super
  
 +
ficiahs into the adult a. tibialis posterior.
 +
 +
 +
a. tibialis posterior superficialis is originally a branch of
 +
the a. poplitea profunda and extends into the sole. The distal
 +
portion of the artery, marked off from the remainder of the
 +
vessel upon the development of the a. plantaris lateralis, becomes
 +
the a. plantaris medialis. The proximal portion of the a. tibialis
 +
posterior superficialis has blended with the corresponding section
 +
of the a. peronaea posterior superficialis at the stage of 24.5 mm.
 +
as far as the termination of the popliteal artery. The further
 +
blending between these two arteries which is to occur during
 +
the later stages of development will cause the migration of the
  
  
  
around
+
origin of the a. peroiiaea from the termination of the a. poplitea
 
 
 
 
 
 
  
distal
+
tibiali;
  
  
  
 +
com
  
developing a. peronaea with a more distal part of the a. poplitea
 
profunda. It is the r. communicans medius which will later become
 
the definitive proximal end of the a. tibialis anterior. The
 
significance of this vessel in relation to the formation of the
 
adult aa. profunda and tibialis anterior will be dealt with in the
 
succeeding section.
 
  
The principal changes which have occurred in the embryonic
 
arteries of the posterior crural region since the preceding stage
 
  
I
+
pleted by the occurrence of these changes the vessel still retains
 +
its orig
  
participate in th,e
+
to
  
  
  
of development involve the vessels w
+
n.
 +
The relations between
  
  
  
 +
the
  
formation of the adult a, peronaea- These changes cons' st in
 
the disappearance of considerable parts of the aa, interossea and
 
peronaea posterior superficialis.
 
  
The portion of the a. interossea which formerly extended from
+
The  
the r. perforans cruris. to the distal end of the r. communicans
 
  
  
  
Fig. 8 Reconstruction showing the arteries of the right side of the pelvis
 
and right lower extremity in a human embryo of 22 mm. (C.E.I.C, 1.). Medial
 
aspect. X 20 diams.
 
  
inferius has practically disappeared. The portion immediately
+
*
beyond the distal end of the latter vessel lies upon the posterior
 
surface of the interosseus membrane and gives origin to two
 
branches. The remainder of the vessel is involved in the meshes
 
of the rete calcaneum.
 
  
The portion of the a. peronaea posterior superficialis which
+
a, poplitea lies upon the  
extends from the present termination of the a. popUtea super-
 
ficialis to the proximal end of the r.
 
  
  
 +
side of the n.
 +
side of the
 +
tibialis. The a. tibialis posterior crosses the
  
commumcan
+
nerve to gain its posterior aspect upon which it runs until it
  
sists
+
ends behind the  
the re
 
  
i
+
malleolus. The relations of the aa.
  
of the  
+
itea and tibialis posterior to the n. tibialis have been
  
 +
tudied UD to the stage of 22 mm
  
 +
eem
  
become a part of the adult a. peronaea.
+
remain unaltered m the olde
ainder of the artery has been lost, but th
+
been examined in this regard,  
essel can still be recognized as forming a
+
measures 33.5 nmi.
  
aspect of the rete calcaneum. Thi
+
embryo which has
 +
C no. 1134, Tvhich
  
  
  
A large part of  
+
It is not difficult to see how an agency capable of moving
 +
the termination of the a. poplitea across the anterior aspect of
 +
the n. tibialis from the medial to the lateral side would produce
 +
a condition differing little from that normally encountered in
 +
the adult. Since the knee is flexed throughout intrauterine life
 +
it would seem that the modification of the relative positions of
 +
the arteries and nerve might depend upon the straightening of
 +
the n. tibiahs which occurs at birth. In order to put the matter
 +
to the test, a foetus of 7.9 cm. was dissected. ^^ The relations, however, were found to be identical with those of the adult.
  
 +
Apart from the study of a few special points, this investigation
 +
has not extended beyond the stage of 22 mm. At that period
 +
all the vessels of the adult limb are present with the exception
 +
of two of the three aa. perforantes, which usually arise from the
 +
adult a. profunda femoris, the a. circumflexa femoris medialis,
 +
and the a. obturatoria. At the stage of 22 mm. two obturator
 +
veins are present in C. E. C, no. 1, one of these is tributary
  
 +
V. hypogastrica, the other to the v. femoralis.
  
 +
The leading features in the process of the arterial development of the limb are indicated in figure 11.
  
artery can be traced through the meshes of the rete as far as
+
^2 For this dissection and for many others made upon various mammals, I wish to express my indebtedness to Mr. B. Spector.
  
 +
==III. Brief Developmental History Of The Individual Arteries==
  
 +
A. Axis. This artery is a branch of the dorsal root of the a. umbilicalis, its presence has been noted by Tandler as early as the stage of 5 mm. '03). At the stage of 6 mm. it terminates by giving origin to the r. perforans tarsi and to the rete plantare.
  
the a.
 
  
 +
The axial artery has three rami communicantes, and gives origin to three rami perforantes as follows:
  
 +
The r. communicans superius, from the a. femoralis, joins it near the hiatus tendineus shortly before the stage of 14 mm.
  
 +
The r. communicans medius^ from its own branch the a. peronaea posterior superficiaHs, has joined it near the distal border of the m. popliteus at the stage of 22 mm.
  
 +
The r. communicans inferius^ from the a. peronaea posterior superficialis, joins it, near the distal border of the m. posterior, between the stages of 17 and 18 mm.
  
The rete calcaneum is very
+
The r. perforans cruris arises between the stages of 13 and 14 mm.
  
 +
The r. perforans arteriae peronaea arises between the stages of 18 and 22 mm.
  
 +
The r. perforans tarsio is present at the earliest stages of development at which the axial artery has been observed.
  
ive at this stage of develop
+
Two points have been marked upon the axial artery at the stage of 14 mm. which may be used for the convenient sub- division of the axial artery into three parts. These points correspond to the termination of the r. communicans superius and to the origin of the r. perforans cruris, respectively.
  
 +
The respective parts of the artery are defined and named as follows: The part upon the proximal side of the termination of the r. communicans superius is the a. ischiadica, while that upon the distal side, of the origin of the r. perforans cruris is the a. interossea. That part intervening between the other two is the a. poplitea profunda. Further information regarding the axial artery may be found under the headings devoted to the description of its respective parts.
  
 +
A. dor salts pedis. This artery is a channel through the embryonic rete dorsale. Its importance dates from the appearance
  
ment and occuT^ies the concavity upon the medial side of the
 
  
 +
Fig. 11 Diagram to illustrate the general development of the arteries of the human lower extremity. Adult arteries are stippled and their names underlined. The chief embryonic channels are outlined in black. The black line is continuous only in the case of the axial artery, otherwise it is broken. The letter P indicates the position of the m, popliteus; T, that of the m. tibialis posterior, and H that of the m. flexor hallucis longus.
  
  
 +
of the distal part of the a. tibiahs anterior Which is developed between the stages of 15 and 16 mm.
  
 +
Branches. One of the adult rr. tarseae laterales represents
  
surrounds the  
+
5al end of the r.
 +
from the rete dor,
  
 +
other branches are
  
  
 +
A. femoralis. This artery arises from the a.
  
 +
externa
  
 +
between the stages of 11 and 12 mm. From the time of the first appearance of the femoral artery its growing end is bifurcated into the r. communicans superius and the r. saphenus. The r, communicans superius traverses the hiatus tendineus and joins the a. axis between the stages of 12 and 14 mm., while the r. saphenus terminates below the region of the knee-joint.
  
m
+
Branches. The A. profunda femoris seems to be derived from an arterial plexus which envelops the femur as early as the stage
 
+
of 14 mm. The proximal end of the artery is distinguishable at the stage of 22 mm. The a. circumflexa lateralis arises from the
 +
femoral trunk shortly before the stage of 14 mm.
 +
artery is commonly regarded as a branch of the a. profunda, its
 +
original connection with the a. femoralis is frequently retained
 +
in the adult. The a. circumflexa medialis is not present at the
 +
stage of 22 mm. One of the a. perforantes, the first or second,
 +
is present at the stage of 22 mm., and is involved at that period
  
 +
Although this
  
the  
+
of development in an extensive arterial plexus connected with
 +
the remainder of the distal part of the a. ischiadica. The other perforating arteries are not present, at the stage of 22 mm.
  
 +
The
  
 +
a. pudenda externa is the only superficial inguinal branch present
 +
at the stage of 22 mm. The a. genu suprema corresponds to
  
malleolar region of the leg.
+
a
  
The component parts of the a. peronaea are now recognizable.  
+
the part of the r. saphenus upon the proximal side of the origin
The proximal part is derived from the a. peronaea posterior super-
+
of the rr. musculares and articulares. These branches arise
  
hallucis longiis and
 
  
  
  
 +
from the a. femoralis, but have migrated to the embryonic r. saphenus by the stage of 22 mm. The distal portion
  
The
+
of the
  
 +
xL m
  
  
 +
vessel corresponds to the r. saphenus of the adult.
 +
strica. The main stem of this artery represents the
  
between
+
part of the dorsal root of the a. umbilicalis which lies beyond
 +
the place of origin of the a. iliaca externa.
  
 +
Branches. The
  
  
 +
ior division of the a. hypogastrica is derived from the proximal part of the a. axis, which becomes the
  
 +
denda
  
  
tibialis posterior represents the entire r. communicans inferius.  
+
a. glutaea inferior, from the root of from the part of the a. umbilicalis dorsal root. The portion of the contributes to the formation of the a. hypogastrica is the source, in all probabiHty, of all the visceral branches of the artery. The a. obtoratoria is not present at the stage of 22 mm. In consequence of the transference of the origins of the aa. iliolumbalis and sacralis lateralis to the a. glutaea superior, part of that artery becomes the posterior division hypogastrica.  
The immediately succeeding part, which rests upon the mem-
 
brana interossea, is derived from the a. interossea. The terminal
 
  
 +
4. iliaca communis. This artery is derived from the portion
  
 +
of the dorsal root of the a.
  
part of the artery consists i
+
lies upon.
the a. peronaea posterior su
+
proximal side of the origin of the a. iliaca externa.
  
 +
A. iliaca externa. This artery already springs from the con-
 +
vexity of the a. ihaca communis at the stage of 8.5 mm. Its
 +
termination is unbranched until a period shortly before the stage
 +
of 12 mm., when it divides into the a. epigastrica inferior and
  
of the r. calcaneus lateraUs of
 
. The connection between
 
  
  
 +
the a. femoralis
  
the a. interossea and the part of the latter artery which gives
 
origin to the calcanean branch is effected through the agency of
 
  
  
 +
The a.
  
the plexus calcaneum.
 
  
The part of the a. interossea which takes part in the formation
 
of the a. peronaea has been noted as giving rise to a branch, the
 
r. coronarius, at the stage of 18 mm. At the present stage
 
another branch arises from it, namely, the r. perforans. Both
 
  
 +
arise
  
  
of them become branches of the adult artery. At the stage of
 
22 mm. the r. coronarius can be traced around the posterior
 
and medial aspects of the tibia almost as far as the a^ tibialis
 
anterior. The views expressed by Hyrtl upon the conversion
 
  
 +
from the a. iUaca externa between the stages of 18 and 22 mm.
  
  
Fig. 9 Reconstructions showing the arteries of the right lower extremity in the seven human embryos shown in the preceding figures. Tlie cephalic (embryonic pre-axial, adult medial) aspect is shown in all cases. A, X 40, the others X 20 diams. The skeleton is shown, in part, in E, F and G. Parts of the tibia
 
  
 +
A. interossea. The course of this part of the axial artery is
 +
described on page 73,
  
 +
The a. interossea is joined before the stage of 18 mm. by the
 +
distal end of the r. communicans inferius. The junction occurs
 +
at a point immediately beyond the inferior margin of the m.
  
a femon
+
m
a. eplgast. inf.
 
  
 +
s posterior. This artery has given origin to the r. coronarius at the stage of 18 mm. and to the r. perforans and to branch of communication with the a. peronaea posterior superficialis at the stage of 22 mm.
  
 +
The part of the a. interossea extending from the termination of the a. popUtea profunda to the distal end of the r. communicans disappears between the
  
r. SQphtn.
 
  
 +
ges of 18 and 22 mm. A
  
  
n SGphen,
 
  
 +
vestige of the proximal end of this part of the artery sometimes persists in the form of a small branch of the a. tibialis anterior or of the r. fibularis.
  
 +
The small portion of the a. interossea which extends from the distal end of the r. communicans inferius to that of the membrana interossea persists as the third part of the a. peronaea (p. 79).
  
  
I: com. sup.
 
n. obtur.
 
  
 +
which arise from this portion of the a. interossea
 +
are transferred
  
 +
They are the r. coronarius
  
r. perf, tarsj
+
r. communicans,
retc
 
  
  
 +
and the r. perforans. The remainder of the a, interossea has
 +
lost its identity at the stage of 22 mm. The r. perforans tarsi
 +
disappears at about the same period.
  
a pudend int
 
  
n, tiblol
+
A. ischiadica. The course taken by this part of the artery is described on page 73.
  
 +
The continuity of the a. ischiadica has been broken in the region of the glutaeal fold^ at the stage of 22 mm. The proximal part of the vessel, which has now become the a. glutaea inferior,
  
 +
to the
  
C /2 n7An.
 
  
  
 +
follows the V. ischiadica and the n.
 +
surface of the limb where it ends by dividing into cutaneous
 +
branches. The more distal portion of the artery is involved,
 +
with the single perforating artery present at the stage of 22
 +
mm., in the formation of an extensive plexus upon the posterior
 +
surface of the m. adductor niagnus.
  
 +
A. peronaea. This artery is clearly recognizable at the stage of 22 mm. (p. 79). It may be divided into four parts:
  
and tarsus are omitted in E, the tibia in F and the tibia and medial femoral
+
The first part of the a. peronaea, which extends from the origin of the artery to the proximal margin of the m. flexor hallucis longus, is a persisting portion of the a. peronaea posterior superficialis (p. 74).  
condyle in G. The fibula is omitted in all. The medial plantar artery has
 
been almost entirely removed from E and F. In C, a. femor. should read a.  
 
iliaca ext.  
 
  
 +
The second part, which lies between the m. tibialis posterior and the m. flexor hallucis longus, represents the entire embryonic r. communicans inferius (p. 76).
  
 +
The third part, which is short and rests upon the interosseus membrane near the distal border of the m. tibialis posterior, is R persisting portion of the a. interossea (p. 73).
  
of the r. coronarius into the communicating branch and medial
+
The fourth part, which ramifies upon the fibula and calcaneum in the neighborhood of the lateral malleolus, represents a survival of the short portion of the a. peronaea posterior super-
malleolar arteries of the adult have been noted above (footnote
 
  
 +
and of the entire r. calcaneus lateralis of that vessel
  
 +
(p. 74).
  
10, p. 73).
 
A small
 
  
 +
r, perforans and r. communicans, belong
  
 +
originally to the a. interossea. The rr. calcanei laterales are branches of the r. calcaneus lateralis of the a. peronaea posterior
 +
superficialis.
  
  
of
 
  
 +
A. peronaea posterior
  
  
  
a. peronaea posterior super
 
  
 +
The course of this embryonic artery is described on pages 70 and 74.
  
 +
of the vessel is present at the stage of 14 mm.^ its terminal branches form their definitive connections at a stage of 15 or 16 mm.
  
 +
The proximal part of the a. unites with the a. tibiahs posterior s
  
I
+
pophtea
  
appears at the present stage as a branch of the a. peronaea. It
 
runs upon the posterior surface of the m. flexor hallucis longus.
 
The disintegrating a. interossea has left a similar vestige of its
 
  
 +
and the part of
  
  
 +
erior superficialis
 +
is to form the a.
  
'osseous
+
posterior
  
 +
above the root of the a. peronaea. A more distal portion persists
 +
as the first part of the a. peronaea^ and a still more distal portion
 +
enters slightly into the formation of the fourth part of that
  
 +
vessel.
  
proximal end upon the posterior surface of its
 
membrane. This vestigial branch occasionally persists as a
 
branch of the adult a. tibialis anterior.^^ The terminal part of
 
the main trunk of the a. peronaea posterior superficialis is now
 
involved in the rete calcaneum. It usually leaves its mark in
 
the adult as a recurrent element among the leash of
 
known as the r. calcaneus medialis of the a. plantaris
 
  
  
 +
The terminal of the a. peronaea posterior superficialis form the adult a. plantaris lateralis. The r. calcaneus
 +
medialis of the latter artery represents the end of the stem of
 +
the parent vessel. The r. calcaneus lateralis, which arises from
 +
the a. peronaea posterior superficialis shortly before the stage
 +
of 18 mm., persists to form the major portion of the fourth part
 +
of the a. peronaea (p. 79).
 +
A. plantaris
  
  
 +
The part of this artery represents the medial terminal branch of the a. peronaea pos-
  
The aa. iliolumbalis
+
71), which unites with the a.
 +
posterior superficialis. The distal part represents the lateral
 +
terminal part of the same vessel.  
  
 +
Branches. The r. calcaneus mediahs represents the terminal
 +
portion of the main trunk of the embrj^onic a. peronaea posterior
 +
superficiaHs. The arcus plantaris and all its branches are de-
 +
rived from the embryonic rete plantare.
  
 +
A. plantaris medialis. This artery is the distal portion of the
  
  
sacralis lateralis now arise from
+
'^omc a.
  
 +
posterior
  
 +
It is
  
 +
off
 +
from the remainder of that vessel by the medial terminal branch
 +
of the embryonic a. peronaea posterior superficialis.
  
a. elutaea
+
A. poplitea. The part of this artery above the origin of the a.  
  
 +
genu
  
  
 +
a surviving portion of the
  
 +
embryonic a. poplitea profunda (p. 73). The part Ij^ing upon
 +
the posterior surface of that muscle represents the embryonic a.
  
The root of the latter artery has conse-
+
popHtea
  
  
 +
The proxi
  
quently become the
 
  
 +
of
  
 +
a. genu
  
 +
inferior mediahs is derived from the a. poplitea profunda.
  
division of the  
+
Branches. The a. genu media is present at the stage of 18 mm. The other branches appear at a later stage of the development.
  
 +
. poplitea projimda. The course of this vessel is described
 +
on page 73. The part of the a. pojDhtea i3rofunda which
 +
from the hiatus tendineus to the origin of the a. genu
  
  
 +
me
  
a. hypo-
 
  
 +
the
 +
part of the adult a. poplitea.
  
 +
The remainder of the artery is represented in part by the root
 +
of the a. genu inferior medialis. It is represented also by the a.
 +
recurrens tibialis posterior and by the second part of the a.
 +
tibialis anterior (p. 84).
  
gastrica. All the visceral arteries of the pelvis, with the
+
A. poplitea superficialis . The formation of this artery results
 +
from the gradual union which takes place between the proximal
 +
part of the embryonic a. tibialis posterior superficialis and that
 +
of the a. peronaea posterior superficialis. The vessel lies upon
 +
the posterior surface of the m. popliteus and has nearly reached
 +
completion at the stage of 22 mm. The a. poplitea superficialis
 +
persists as the distal portion of the adult a., poplitea (p. 84).
  
their
 
  
 +
anterior. This vessel may be divided into
  
  
 +
parts which correspond
 +
the adult artery.
  
of the a. vesicalis superior, have
 
  
 +
the four embryonic components of
  
 +
The first part extends from the origin of the vessel to the root
  
 +
of the a. recurrens
  
 +
posterior. It corresponds to the
  
relations
+
whole of the r. communicans medius (p. 84).
  
 +
The second part occupies the immediate neighborhood of the
 +
origin of the a. recurrens tibialis posterior. It represents, like
 +
that artery, a persisting portion of the embryonic a. poplitea
 +
profunda (p. 84).
  
 +
The third part extends from the a. redurrens tibialis posterior
  
h. Changes occurring in the principal arteries subsequent to  
+
to a
  
stage of 22 mm .  
+
beyond the root of the a. recurrens
 +
anterior. It is derived from the proximal portion of
 +
embryonic r. perforans cruris (p. 68). *
  
 +
fourth part of the artery extends from the termination of
 +
the third part to the proximal end of the a. dorsalis pedis. It
  
  
 +
represents
 +
embryo (p. 72).
  
A. Formation of the adult a. poplitea and a. tibialis anterior.  
+
entire a.  
  
 +
anterior, pars distalis, of the
  
Fig. 10, A, C. I. E. C, 22; B, C E. C, 1; C, C. I. E. C, 840.
 
 
The r. communicans medius, the presence of which was noted at the stage of 22 mm., seems to arise at about that stage of
 
  
In C. E. C, no 1, it is larger upon the right side than upon the left and in C. E. C , no. 6, which also measures 22 mm., it is absent altogether.  
+
Branches. The a. recurrens tibialis anterior represents the terminal portion of the a. perforans cruris (p. 68).  
  
 +
The a. malleolaris anterior medialis is derived from the r, coronarius of the a, interossea \Yhich arises shortly before the stage of 18 mm.
  
  
 +
A. tibialis anterior, pars distalis. This embryonic artery arises at about the stage of 15 or 16 mm. Its course is identical with that of the fourth part of the a, tibialis anterior of the
  
 +
A. tibialis posterior. The part of this artery proximal to the origin of the a. peronaea is the product of the union between the
  
*^ Mr. Kimbrig has kindly dissected six adult legs for evidenc^e of persistence
 
of this vessel. In two instances he found a branch accompanying the n. interos-
 
seus cruris for a short distance. In both cases the branch arose from the root of
 
the ramus fibularis.
 
  
It is very questionable whether the B. N. A. is correct in classifying the r.
+
a, tibialis posterior superficiahs and the a. peronaea posterior
fibularis as belonging to the a. tibialis posterior. It has usually been regarded,
 
in English-speaking countries at all events, as a branch of the a. tibialis anterior.
 
  
 +
The remainder of the vessel is a survival of the part of the stem of the a. tibialis posterior superficialis pr to the point at which it is joined by the medial terminal branch of the a. peronaea posterior superficiahs.
  
 +
Branches. The a. peronaea is described on page 90- The
  
At the stage of 20 mm. (fig. 10, A) blood traverses the pop
+
r. communicans are  
 
 
 
 
 
 
 
 
liteal region to reach the r. perforans cruris through the original
 
channel, namely the a. poplitea profunda. The a. poplitea
 
 
 
is longer than at the stage of 18 mm., having in-
 
creased in length at the expense of the aa. tibialis posterior
 
 
 
and peronaea posterior superficialis.
 
At the stage of 22 mm. (fig. 10, B), a junction between the
 
developing a. peronaea and the distal part of the a. poplitea
 
 
 
 
 
 
 
 
 
Fig. 10 Three reconstructions, each showing a sagittal segment (0.25 mm. thick) from the left leg of an embryo of the length indicated. Lateral aspect. X 19. A, 20 mm. ; B, 22 mm. ; C, 24.8 mm. The tibia appears in all cases. P.
 
indicates the position of the m. popliteus. c. m., a. communicans media; g, i. m.,
 
a. genu inferior medialis; g, m., a. genu media; i., a. interossea; {. m., interosseous
 
membrane; p., a. poplitea; p. c, a. perforans cruris; p- d.^ a. tibialis anterior, pars
 
distalis; p. p., a. poplitea profunda; p. s., a. poplitea superficialis; per., a.
 
peronaea; r. a,, a. recurrens tibialis anterior; r. p., a. recurrens tibialis posterior;
 
t, a., a. tibialis anterior; t, p. s., a. tibialis posterior superficialis.
 
 
 
 
 
 
 
profunda has been effected by the development of the r. com
 
municans medius. Blood may now pass from the proximal par
 
of the a. poplitea profunda to the a. tibialis anterior, pars dis
 
 
 
 
 
 
 
talis by
 
 
 
 
 
 
 
super
 
 
 
 
 
 
 
 
 
routes: 1) anterior to the m. popliteus, by waj
 
t of the a. poplitea profunda and r. perforans cru
 
or to the m. popliteus, by way of the a. poph
 
developing a. peronaea, r. communicans medius
 
 
 
 
 
 
 
poplitea profunda, and r. perforans cruris.
 
 
 
 
 
At the stage of 24.5 mm. (fig. 10, C)
 
upon the anterior surface of the m.
 
 
 
 
 
 
 
 
 
 
 
ect
 
 
 
 
 
 
 
 
 
 
 
 
 
s
 
 
 
 
 
 
 
 
 
route
 
 
 
 
 
 
 
to
 
 
 
 
 
 
 
exist. The part of the a, pophtea profunda not incorporated in
 
 
 
 
 
 
 
the definitive a, poplitea or
 
 
 
 
 
 
 
 
 
anterior is represented :
 
 
 
 
 
 
 
1) by the root and a small branch of the a. genu inferior medialis
 
of the former and 2) by the a. recurrens tibialis posterior of the
 
latter. The main arterial channel through the popliteal region
 
has thus been transferred from the anterior to the posterior
 
surface of the popliteus muscle. Both the a. poplitea and the
 
a. tibialis anterior have assumed their adult arrangement.
 
 
 
The formation of the adult a. poplitea results from the com-
 
bination of two embryonic elements. The part of the vessel
 
which extends from the hiatus tendineus to the origin of the a.
 
genu inferior medialis is derived from the embryonic a. poplitea
 
profunda. The remainder of the artery corresponds to the
 
embryonic a poplitea superficialis.
 
 
 
The embryonic components of the a. tibialis anterior consist
 
 
 
 
 
 
 
of the r. communicans medius, a short section of the distal end
 
of the a. poplitea profunda, the proximal part of the r. perforans
 
cruris, and the entire tibialis anterior, pars distalis.
 
 
 
The a. poplitea superficialis reaches' completion at the stage
 
of 24.5 mm. by extending as far as the r. communicans medius
 
 
 
 
 
 
 
 
 
becomes one of
 
 
 
 
 
 
 
 
 
 
 
branches.
 
 
 
 
 
 
 
means the a. peronaea rehnquishes its temporary
 
in the formation of the a. tibialis anterior.
 
 
 
 
 
 
 
 
 
this
 
 
 
 
 
 
 
ion
 
 
 
 
 
 
 
B. The conversion of the
 
 
 
 
 
 
 
 
 
yonic a.
 
 
 
 
 
 
 
 
 
s posterior super
 
 
 
 
 
 
 
ficiahs into the adult a. tibialis posterior.
 
 
 
 
 
 
 
 
 
a. tibialis posterior superficialis is originally a branch of
 
the a. poplitea profunda and extends into the sole. The distal
 
portion of the artery, marked off from the remainder of the
 
vessel upon the development of the a. plantaris lateralis, becomes
 
the a. plantaris medialis. The proximal portion of the a. tibialis
 
posterior superficialis has blended with the corresponding section
 
of the a. peronaea posterior superficialis at the stage of 24.5 mm.
 
as far as the termination of the popliteal artery. The further
 
blending between these two arteries which is to occur during
 
the later stages of development will cause the migration of the
 
 
 
 
 
 
 
origin of the a. peroiiaea from the termination of the a. popUtea
 
 
 
 
 
 
 
tibiali;
 
 
 
 
 
 
 
com
 
 
 
 
 
 
 
pleted by the occurrence of these changes the vessel still retains
 
its orig
 
 
 
 
 
 
 
 
 
 
 
to
 
 
 
 
 
 
 
 
 
n.
 
 
 
 
 
 
 
 
 
The relations between
 
 
 
 
 
 
 
the
 
 
 
 
 
 
 
 
 
The
 
 
 
 
 
 
 
 
 
*
 
 
 
a, poplitea lies upon the
 
 
 
 
 
 
 
 
 
 
 
side of the n.
 
side of the
 
 
 
 
 
 
 
tibialis. The a. tibialis posterior crosses the
 
 
 
nerve to gain its posterior aspect upon which it runs until it
 
 
 
 
 
 
 
ends behind the
 
 
 
 
 
 
 
 
 
malleolus. The relations of the aa.
 
 
 
 
 
 
 
 
 
itea and tibialis posterior to the n. tibialis have been
 
 
 
 
 
 
 
tudied UD to the stage of 22 mm
 
 
 
 
 
 
 
 
 
 
 
eem
 
 
 
 
 
 
 
remain unaltered m the olde
 
been examined in this regard,
 
measures 33.5 nmi.
 
 
 
 
 
 
 
embryo which has
 
C no. 1134, Tvhich
 
 
 
 
 
 
 
It is not difficult to see how an agency capable of moving
 
the termination of the a. poplitea across the anterior aspect of
 
the n. tibialis from the medial to the lateral side would produce
 
a condition differing little from that normally encountered in
 
the adult. Since the knee is flexed throughout intrauterine life
 
it would seem that the modification of the relative positions of
 
the arteries and nerve might depend upon the straightening of
 
the n. tibiahs which occurs at birth. In order to put the matter
 
to the test, a foetus of 7.9 cm. was dissected. ^^ The relations,
 
however, were found to be identical with those of the adult.
 
 
 
Apart from the study of a few special points, this investigation
 
has not extended beyond the stage of 22 mm. At that period
 
all the vessels of the adult limb are present with the exception
 
of two of the three aa. perforantes, which usually arise from the
 
adult a. profunda femoris, the a. circumflexa femoris medialis,
 
and the a. obturatoria. At the stage of 22 mm. two obturator
 
veins are present in C. E. C, no. 1, one of these is tributary
 
 
 
V. hypogastrica, the other to the v. femorali^.
 
 
 
The leading features in the process of the arterial development of the limb are indicated in figure 11.
 
 
 
^2 For this dissection and for many others made upon various mammals, I wish to express my indebtedness to Mr. B. Spector.
 
 
 
==III. Brief Developmental History Of The Individual Arteries==
 
 
 
A. Axis. This artery is a branch of the dorsal root of the a.
 
umbilicaUs, its presence has been noted by Tandler as early as
 
the stage of 5 mm. '03). At the stage of 6 mm. it terminates by
 
giving origin to the r. perforans tarsi and to the rete plantare.
 
 
 
 
 
 
 
The axial artery has three rami communicantes, and gives
 
origin to three rami perforantes as follows:
 
 
 
The r. communicans superius, from the a. femoralis, joins it
 
near the hiatus tendineus shortly before the stage of 14 mm.
 
 
 
The r. communicans medius^ from its own branch the a.
 
peronaea posterior superficiaHs, has joined it near the distal
 
 
 
 
 
 
 
 
 
border of the m. popliteus at the stage of 22 mm.
 
' The r. communicans inferius^ from the a. peronaea posterior
 
superficialis, joins it, near the distal border of the m.
 
posterior, between the stages of 17 and 18 mm.
 
 
 
The r. perforans cruris arises between the stages of 13 and
 
 
 
14 mm.
 
 
 
The r. perforans arteriae peronaea arises between the stages
 
of 18 and 22 mm.
 
 
 
The r. perforans tarsio is present at the earliest stages of de-
 
velopment at which the axial artery has been observed.
 
 
 
Tw^o points have been marked upon the axial artery at the
 
stage of 14 mm. which may be used for the convenient sub-
 
 
 
 
 
 
 
division of the axial artery into three parts. These points
 
correspond to the termination of the r. communicans superius
 
and to the origin of the r. perforans cruris, respectively.
 
 
 
The respective parts of the artery are defined and named as
 
follows: The part upon the proximal side of the termination of
 
 
 
 
 
 
 
the r. communicans superius is the a. ischiadica, while that
 
upon the distal side, of the origin of the r. perforans cruris is
 
the a. interossea. That part intervening between the other two
 
 
 
 
 
 
 
is the a. poplitea profunda. Further information regarding the
 
axial artery may be found under the headings devoted to the
 
description of its respective parts.
 
 
 
A. dor salts pedis. This artery is a channel through the em-
 
bryonic rete dorsale. Its importance dates from the appearance
 
 
 
 
 
 
 
Fig. 11 Diagram to illustrate the general development of the arteries of the
 
human lower extremity. Adult arteries are stippled and their names underlined.
 
The chief embryonic channels are outlined in black. The black line is
 
continuous only in the case of the axial artery, otherwise it is broken. The
 
letter P indicates the position of the m, popliteus; T, that of the m. tibialis
 
posterior, and H that of the m. flexor hallucis longus.
 
 
 
 
 
of the distal part of the a. tibiahs anterior \Yhich is developed
 
between the stages of 15 and 16 mm.
 
 
 
Branches. One of the adult rr. tarseae laterales represents
 
 
 
 
 
 
 
5al end of the r.
 
from the rete dor,
 
 
 
 
 
 
 
other branches are
 
 
 
 
 
 
 
W
 
 
 
A. femoralis. This artery arises from the a.
 
 
 
 
 
 
 
 
 
externa
 
 
 
 
 
 
 
between the stages of 11 and 12 mm. From the time of the
 
first appearance of the femoral artery its growing end is bifur-
 
cated into the r. communicans superius and the r. saphenus.
 
The r, communicans superius traverses the hiatus tendineus and
 
joins the a. axis between the stages of 12 and 14 mm., while the
 
r. saphenus terminates below the region of the knee-joint.
 
 
 
Branches. The A. profunda femoris seems to be derived from
 
an arterial plexus which envelops the femur as early as the stage
 
of 14 mm. The proximal end of the artery is distinguishable at
 
the stage of 22 mm. The a. circumflexa lateralis arises from the
 
femoral trunk shortly before the stage of 14 mm.
 
artery is commonly regarded as a branch of the a. profunda, its
 
original connection with the a. femoralis is frequently retained
 
in the adult. The a. circumflexa medialis is not present at the
 
stage of 22 mm. One of the a. perforantes, the first or second,
 
is present at the stage of 22 mm., and is involved at that period
 
 
 
 
 
 
 
Although this
 
 
 
 
 
 
 
of development in an extensive arterial plexus connected with
 
the remainder of the distal part of the a. ischiadica. The other
 
 
 
 
 
 
 
perforating arteries are not present, at the stage of 22 mm.
 
 
 
 
 
 
 
The
 
 
 
 
 
 
 
a. pudenda externa is the only superficial inguinal branch present
 
at the stage of 22 mm. The a. genu suprema corresponds to
 
 
 
a
 
 
 
the part of the r. saphenus upon the proximal side of the origin
 
of the rr. musculares and articulares. These branches arise
 
 
 
 
 
 
 
 
 
from the a. femoralis, but have migrated to the em-
 
 
 
 
 
 
 
bryonic r. saphenus by the stage of 22 mm. The distal portion
 
 
 
 
 
 
 
of the
 
 
 
xL m
 
 
 
 
 
 
 
 
 
 
 
vessel corresponds to the r. saphenus of the adult.
 
strica. The main stem of this artery represents the
 
 
 
 
 
 
 
part of the dorsal root of the a. umbilicalis which lies beyond
 
the place of origin of the a. iliaca externa.
 
 
 
 
 
 
 
Branches. The
 
 
 
 
 
 
 
 
 
ior division of the a. hypogastrica is de-
 
 
 
 
 
 
 
rived from the proximal part of the a. axis, which becomes the
 
 
 
 
 
 
 
 
 
ARTERIES OF HUMAN LOWER EXTREMITY
 
 
 
 
 
 
 
89
 
 
 
 
 
 
 
denda
 
 
 
 
 
 
 
ond
 
 
 
 
 
 
 
 
 
Qj.
 
 
 
 
 
 
 
 
 
Vi
 
 
 
 
 
 
 
 
 
a. glutaea inferior, from the root of
 
from the part of the a. umbilicalis
 
dorsal root. The portion of the
 
contributes to the formation of the a. hypogastrica is the source,
 
in all probabiHty, of all the visceral branches of the artery. The
 
a. obtoratoria is not present at the stage of 22 mm. In conse-
 
quence of the transference of the origins of the aa. iliolumbalis
 
and sacralis lateralis to the a. glutaea superior,
 
part of that artery becomes the posterior division
 
hypogastrica.
 
 
 
.4. iliaca communis. This artery is derived from the portion
 
 
 
 
 
 
 
 
 
of the dorsal root of the a.
 
 
 
 
 
 
 
 
 
w
 
 
 
 
 
 
 
 
 
lies upon.
 
 
 
 
 
 
 
 
 
proximal side of the origin of the a. iliaca externa.
 
 
 
A. iliaca externa. This artery already springs from the con-
 
vexity of the a. ihaca communis at the stage of 8.5 mm. Its
 
termination is unbranched until a period shortly before the stage
 
of 12 mm., when it divides into the a. epigastrica inferior and
 
 
 
 
 
 
 
the a. femoralis
 
 
 
 
 
 
 
The a.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
arise
 
 
 
 
 
 
 
from the a. iUaca externa between the stages of 18 and 22 mm.
 
 
 
 
 
 
 
A. interossea. The course of this part of the axial artery is
 
described on page 73,
 
 
 
The a. interossea is joined before the stage of 18 mm. by the
 
distal end of the r. communicans inferius. The junction occurs
 
at a point immediately beyond the inferior margin of the m.
 
 
 
m
 
 
 
s posterior. This artery has given origin to the r. coro-
 
narius at the stage of 18 mm. and to the r. perforans and to
 
 
 
branch of communication with the a. peronaea posterior
 
superficialis at the stage of 22 mm.
 
 
 
The part of the a. interossea extending from the termination
 
of the a. popUtea profunda to the distal end of the r. communicans
 
 
 
 
 
 
 
 
 
 
 
 
 
disappears between the
 
 
 
 
 
 
 
 
 
ges of 18 and 22 mm. A
 
 
 
 
 
 
 
vestige of the proximal end of this part of the artery sometimes
 
persists in the form of a small branch of the a. tibialis anterior
 
or of the r. fibularis.
 
 
 
The small portion of the a. interossea which extends from the
 
distal end of the r. communicans inferius to that of the membrana
 
interossea persists as the third part of the a. peronaea (p. 79).
 
 
 
 
 
 
 
which arise from this portion of the a. interossea
 
 
 
 
 
 
 
are transferred
 
 
 
 
 
 
 
 
 
 
 
They are the r. coronarius
 
 
 
r. communicans,
 
 
 
 
 
 
 
 
 
 
 
and the r. perforans. The remainder of the a, interossea has
 
lost its identity at the stage of 22 mm. The r. perforans tarsi
 
disappears at about the same period.
 
 
 
 
 
 
 
 
 
A. ischiadica. The course taken by this part of the
 
artery is described on page 73.
 
 
 
The continuity of the a. ischiadica has been broken in the
 
region of the glutaeal fold^ at the stage of 22 mm. The proximal
 
part of the vessel, which has now become the a. glutaea inferior,
 
 
 
to the
 
 
 
 
 
 
 
 
 
 
 
follows the V. ischiadica and the n.
 
surface of the limb where it ends by dividing into cutaneous
 
branches. The more distal portion of the artery is involved,
 
with the single perforating artery present at the stage of 22
 
mm., in the formation of an extensive plexus upon the posterior
 
surface of the m. adductor niagnus.
 
 
 
A. peronaea. This artery is clearly recognizable at the stage
 
of 22 mm. (p. 79). It may be divided into four parts:
 
 
 
 
 
 
 
The first part of the a. peronaea, which extends from the
 
origin of the artery to the proximal margin of the m. flexor
 
hallucis longus, is a persisting portion of the a. peronaea posterior
 
superficialis (p. 74).
 
 
 
The second part, which lies between the m. tibialis posterior
 
and the m. flexor hallucis longus, represents the entire embryonic
 
r. communicans inferius (p. 76).
 
 
 
The third part, which is short and rests upon the interosseus
 
membrane near the distal border of the m. tibialis posterior, is
 
R persisting portion of the a. interossea (p. 73).
 
 
 
The fourth part, which ramifies upon the fibula and calcaneum
 
in the neighborhood of the lateral malleolus, represents a sur-
 
 
 
 
 
 
 
vival of the short portion of the a. peronaea posterior super-
 
 
 
and of the entire r. calcaneus lateralis of that vessel
 
 
 
 
 
 
 
 
 
(p. 74).
 
 
 
 
 
 
 
 
 
 
 
r, perforans and r. communicans, belong
 
 
 
 
 
 
 
orig'nally to the a. interossea. The rr. calcanei laterales are .
 
branches of the r. calcaneus lateralis of the a. peronaea posterior
 
superficialis.
 
 
 
 
 
 
 
A. peronaea posterior
 
 
 
 
 
 
 
 
 
The course of this em-
 
 
 
 
 
 
 
 
 
mam
 
 
 
 
 
 
 
 
 
bryonic artery is described on pages 70 and 74.
 
 
 
of the vessel is present at the stage of 14 mm.^ its terminal
 
 
 
branches form their definitive connections at a stage of 15 or 16
 
 
 
 
 
 
 
mm.
 
 
 
 
 
 
 
The proximal part of the a.
 
unites with the a. tibiahs posterior s
 
 
 
 
 
 
 
pophtea
 
 
 
 
 
 
 
 
 
and the part of
 
 
 
 
 
 
 
 
 
erior superficialis
 
is to form the a.
 
 
 
posterior
 
 
 
 
 
 
 
 
 
above the root of the a. peronaea. A more distal portion persists
 
as the first part of the a. peronaea^ and a still more distal portion
 
enters slightly into the formation of the fourth part of that
 
 
 
 
 
 
 
vessel.
 
 
 
 
 
 
 
The terminal
 
 
 
 
 
 
 
 
 
of the a. peronaea posterior super-
 
 
 
 
 
 
 
ficialis form the adult a. plantaris lateralis. The r. calcaneus
 
medialis of the latter artery represents the end of the stem of
 
the parent vessel. The r. calcaneus lateralis, which arises from
 
the a. peronaea posterior superficialis shortly before the stage
 
of 18 mm., persists to form the major portion of the fourth part
 
 
 
 
 
 
 
of the a. peronaea (p. 79).
 
A. plantaris
 
 
 
 
 
 
 
 
 
The
 
 
 
 
 
 
 
 
 
part of this artery
 
 
 
 
 
 
 
 
 
 
 
 
 
represents the medial terminal branch of the a. peronaea pos-
 
 
 
71), which unites with the a.
 
posterior superficialis. The distal part represents the lateral
 
terminal part of the same vessel.
 
 
 
Branches. The r. calcaneus mediahs represents the terminal
 
portion of the main trunk of the embrj^onic a. peronaea posterior
 
superficiaHs. The arcus plantaris and all its branches are de-
 
rived from the embryonic rete plantare.
 
 
 
A. plantaris medialis. This artery is the distal portion of the
 
 
 
 
 
 
 
e
 
 
 
 
 
 
 
 
 
'^omc a.
 
 
 
 
 
 
 
 
 
posterior
 
 
 
 
 
 
 
 
 
It is
 
 
 
 
 
 
 
 
 
off
 
 
 
 
 
 
 
from the remainder of that vessel by the medial terminal branch
 
of the embryonic a. peronaea posterior superficialis.
 
 
 
A. poplitea. The part of this artery above the origin of the a.
 
 
 
 
 
 
 
genu
 
 
 
 
 
 
 
 
 
 
 
 
 
a surviving portion of the
 
 
 
 
 
 
 
embryonic a. poplitea profunda (p. 73). The part Ij^ing upon
 
the posterior surface of that muscle represents the embryonic a.
 
 
 
 
 
 
 
popHtea
 
 
 
 
 
 
 
 
 
The proxi
 
 
 
 
 
 
 
 
 
 
 
of
 
 
 
 
 
 
 
 
 
a. genu
 
 
 
 
 
 
 
inferior mediahs is derived from the a. poplitea profunda.
 
 
 
 
 
 
 
Branches. The a. genu media is present at the stage of 18
 
mm. The other branches appear at a later stage of the
 
development.
 
 
 
. poplitea projimda. The course of this vessel is described
 
on page 73. The part of the a. pojDhtea i3rofunda which
 
from the hiatus tendineus to the origin of the a. genu
 
 
 
 
 
 
 
 
 
 
 
 
 
me
 
 
 
 
 
 
 
 
 
 
 
the
 
 
 
 
 
 
 
 
 
part of the adult a. poplitea.
 
 
 
 
 
 
 
The remainder of the artery is represented in part by the root
 
of the a. genu inferior medialis. It is represented also by the a.
 
recurrens tibialis posterior and by the second part of the a.
 
tibialis anterior (p. 84).
 
 
 
A. poplitea superficialis . The formation of this artery results
 
from the gradual union which takes place between the proximal
 
part of the embryonic a. tibialis posterior superficialis and that
 
of the a. peronaea posterior superficialis. The vessel lies upon
 
the posterior surface of the m. popliteus and has nearly reached
 
completion at the stage of 22 mm. The a. poplitea superficialis
 
persists as the distal portion of the adult a., poplitea (p. 84).
 
 
 
 
 
 
 
 
 
anterior. This vessel may be divided into
 
 
 
 
 
 
 
 
 
parts which correspond
 
the adult artery.
 
 
 
 
 
 
 
 
 
the four embryonic components of
 
 
 
 
 
 
 
The first part extends from the origin of the vessel to the root
 
 
 
 
 
 
 
of the a. recurrens
 
 
 
 
 
 
 
 
 
posterior. It corresponds to the
 
 
 
 
 
 
 
whole of the r. communicans medius (p. 84).
 
 
 
The second part occupies the immediate neighborhood of the
 
origin of the a. recurrens tibialis posterior. It represents, like
 
that artery, a persisting portion of the embryonic a. poplitea
 
profunda (p. 84).
 
 
 
The third part extends from the a. redurrens tibialis posterior
 
 
 
 
 
 
 
to a
 
 
 
 
 
 
 
 
 
 
 
 
 
beyond the root of the a. recurrens
 
anterior. It is derived from the proximal portion of
 
embryonic r. perforans cruris (p. 68). *
 
 
 
fourth part of the artery extends from the termination of
 
the third part to the proximal end of the a. dorsalis pedis. It
 
 
 
 
 
 
 
 
 
 
 
represents
 
embryo (p. 72).
 
 
 
 
 
 
 
entire a.
 
 
 
 
 
 
 
 
 
anterior, pars distalis, of the
 
 
 
 
 
 
 
I
 
 
 
ARTERIES OF HUMAN LOWER EXTREMITY 93
 
 
 
 
 
 
 
Branches. The a. recurrens tibialis anterior represents the
 
terminal portion of the a. perforans cruris (p. 68).
 
 
 
The a. malleolaris anterior medialis is derived from the r,
 
coronarius of the a, interossea \Yhich arises shortly before the
 
stage of 18 mm.
 
 
 
 
 
 
 
A. tibialis anterior, pars distalis. This embryonic a^rtery
 
arises at about the stage of 15 or 16 mm. Its course is identical
 
with that of the fourth part of the a, tibialis anterior of the
 
 
 
 
 
 
 
 
 
A. tibialis posterior. The part of this artery proximal to the
 
origin of the a. peronaea is the product of the union between the
 
 
 
 
 
 
 
 
 
 
 
a, tibialis posterior superficiahs and the a. peronaea posterior
 
 
 
The remainder of the vessel is a survival of the
 
part of the stem of the a. tibialis posterior superficiahs pr
 
to the point at which it is joined by the medial terminal branch
 
of the a. peronaea posterior superficiahs.
 
 
 
Branches. The a. peronaea is described on page 90- The
 
 
 
r. communicans are
 
 
 
 
 
 
 
 
 
 
 
a. malleolaris posterior
 
 
 
 
 
 
 
derived from the embryonic r. coronarius malleolaris medialis of
 
the a. interossea (p. 73).
 
 
 
 
 
 
 
A. tibialis posterior super ficialis . The course of this artery,
 
 
 
 
 
 
 
which arises shortly before the stage of 14 mm., is described on
 
page 70.
 
 
 
The whole of the a. tibialis posterior superficiahs persists in
 
the adult hfe. In combination with the a. peronaea posterior
 
superficiahs, the more proximal part of the artery forms the
 
part of the a. poplitea in contact with the m. popliteus and the
 
part of the a. tibialis posterior proximal to the origin of the a.
 
peronaea.* The more* distal part of the artery persists as the
 
portion of the a. tibialis posterior beyond the origin of the a.
 
peronaea and as the a. plant aria medialis.
 
 
 
The relation of the part of the a. tibialis posterior super-
 
ficiahs which forms the a. tibialis posterior of the adult to the
 
n. tibialis is discussed on page 84.
 
 
 
Rete dorsale. The dorsal rete of the embryonic arises from
 
the r. perforans tarsi. It forms all the arteries which are
 
distributed upon the dorsum of the adult foot.
 
 
 
 
 
 
 
94 H. D. SENIOR
 
 
 
 
 
 
 
Rete plantare. This embryonic plexus arises from the terminal
 
branches of the a. interossea. It furnishes the arcus plantaris and all the other arteries of the adult sole excepting the aa plantares.
 
 
 
==Bibliography==
 
 
 
 
 
 
 
Caillard 1832 Proportions de ^led. et de la Chir. These inaug., Paris.
 
 
 
Cruveilhier, J. 1843 Traite d'Anotomie descriptive. Paris.
 
 
 
DeVriese, Bertha 1902 Recherches sur I'evolution des vaisseux sanguins chez I'homme. Archiv. de Biologie, T. 18, p. 665.
 
 
 
DuBRUEiL, J. M. 1847 Des anomalies arterielles, Paris.
 
 
 
Ellis, G. V. 1853 An account of an instance of remarkable deformity of the lower limbs. Medico-Chir. Trans., vol. 36, p. 439,
 
 
 
Fagge, C. H. 1864 Case of aneurism seated on an abnormal main artery of the lower limb. Guy's Hosp. Rep., vol. 10, p. 15.
 
 
 
Froriep, L. Fr. V. 1832. Notizen aus dem Gebiete der Natur u. Heilkunde,.
 
 
 
B. 34, S. 45.
 
Green, P. H. 1832 On a new variety of the femoral artery, with observations.
 
 
 
Lancet for 1831, vol. 1, p. 731.
 
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Chiropteren. Anat. Hefte, B. 17, H. 2, S. 203.
 
HocHSTETTER, F. 1890 tjber die urspilingliche hauptschlagader der hinteren
 
 
 
Gliedmasse des Menschen, u.s.w. Morph. Jahrb., B. 16, S. 300.
 
Hyrtl, J. 1864 tJber normal u. abnorme Verhaltnisse der Schlagadern des
 
 
 
Unterschenkels. Wien.
 
Leboucq 1893 Verhandl. d. Anatom. Gesellsch., auf. d. siebenten Versamml.
 
 
 
Anat. Anz., Erganzungsh. zum. B. 8.
 
 
 
 
 
 
 
 
 
Levy, G. 1902 Morphologia delle arteriae iliache, Parte 2. Archiv. Ital. di
 
 
 
Anat. e di EmbrioL, V. 295.
 
 
 
]\lcI\IuRRiCH, J. P. 1904 The development of the human body, 2nd ed., Phila-
 
delphia.
 
 
 
PoPOWSKi, J. 1893 Uberbleibsel der Arteria saphena beim Menschen. Anat.
 
 
 
Anz., B. 8, S. 580. .
 
1894 Das Artcriensystem der unteren Extremitaten bei den Primaten.
 
 
 
Anat. Anz., B. 10, S. 55 u. 99. ' •
 
 
 
QuAiN, R. 1844 The anatomy of the arteries of the human body. London.
 
 
 
 
 
 
 
Rug, C. 1863 Anomalie der Arteria cruralis. Wlirzb. mediz. Zeits., B. 4,.
 
 
 
S. 344.
 
RuGE, G. 1894 Varietaten im Gebiete der Arteria femoralis des Menschen.
 
 
 
Morph. Jahrb., B. 22, S. 161.
 
Salyi 1898 Arteria dorsalis pedis, Pisa.
 
 
 
 
 
 
 
Senior, H. D. 1917 The development of the external iliac artery in man.
 
 
 
Ann. N. Y. Acad. Sci., vol. 27.
 
Stieda, H. 1893 Verhandl d. Anatom. Gesellsch., auf d. siebenten VersammL
 
 
 
Anat., Anz., Erganzungsh. zum B. 8.
 
 
 
 
 
 
 
ARTERIES OF HUMAN LOWER EXTREMITY
 
 
 
 
 
 
 
95
 
 
 
 
 
 
 
SuESSDORF, M. 1895 Lehrbuch der vergleichenden Anatomie der Haustiere.
 
 
 
Stuttgart.
 
Tandler, J. 1903 Zur Entwickelungsges. der menschlichen Darmarterien.
 
 
 
Anat. Hefte, B. 23, H. 1, S. 187.
 
Velpeau 1839 filements de Medicine Operatoire.
 
Zagorski 1809 Mem. de rAcadem. des Sci. de Petersb.
 
 
 
 
 
 
 
ZUCKERKANDL 1894
 
 
 
 
 
 
 
Anat
 
 
 
 
 
 
 
Arterien des Vor-
 
 
 
 
 
 
 
derarms (1. theil). Anat. Hefte, B. 4, H. 1, S. 1.
 
 
 
1895 Zur Anat. u. Entwickelungsges. der Ai^terien des Unterschenkels
 
 
 
u, des Fusses. Anat. Hefte, B. 5, H. 2, S. 207.
 
 
 
 
 
 
 
THE AMERICAN JOT7EXAL OF ANATOMY, VOL. 25, NO. 1
 
 
 
 
 
THE DEVELOPMENT OF THE ARTERIES OF THE
 
HUMAN LOWER EXTREAIITY
 
 
 
H. D. SENIOR
 
 
 
Deparlment of Anatomy, New York University
 
 
 
ELEVEN FIGURES
 
 
 
I. INTRODUCTION
 
 
 
a. General considerations
 
 
 
It is weii known tiiat considerabie differences exist between
 
tlie various types of arterial distribution whicli are normally
 
encountered in the pelvic limb of the different representatives
 
of the mammalian series. In all mammals in which the de-
 
velopmental history of the arteries of the limb has been investi-
 
gated, however, it has been found that the adult arterial system
 
of the part results from the elaboration of two embryonic vessels.
 
 
 
Both of the embryonic arteries in question take origin from
 
the dorsal (secondary) root of the a. umbilicalis. One of them,
 
 
 
 
 
 
 
the primitive artery of tine limb, traverses tine axis of the thigh
 
and leg and divides into a number of branches for the supply
 
of the foot. This vessel is present before the limb forms a
 
distinct prominence upon the surface of the body and is known
 
as the axial or ischiadic artery.
 
 
 
The other is an artery of later development which traverses
 
the pelvis and the ventral region of the thigh. It joins the
 
axial artery a short distance above the knee and gives rise to the
 
a. iliaca externa, the a. femoralis, and the a. epigastrica inferior
 
and to the branches which arise from these vessels. All other
 
arteries of the limb arise from the axial artery itself or from the
 
branches to which it gives origin.
 
 
 
Whether the relations of the embryonic axial artery to the
 
other constituents of the limb are identical in the embryos of
 
 
 
 
 
all mammalian forms is a question to which direct observation
 
of the vessel has not yet furnished an answer. Much indirect
 
evidence bearing upon this subject is furnished by Zuckerkandl's
 
comparative study of the arteries of the leg which appeared in 1895.
 
 
 
 
 
 
 
The study in question, altliougli it is mainly concerned witii
 
tine relations of the adult arteries, is influenced throughout b'^
 
embryological considerations. It includes, in fact, a study of
 
the arteries in a series of vertebrate embryos in which the
 
mammalia are represented by the rabbit and cat. Zucker-
 
kandl's work is obviously based upon the conception of the
 
identity of the course of the axial artery throughout the mamma-
 
lian series. It may be said that the general results of the
 
investigation are greatly in favor of the correctness of the author's
 
conception.
 
 
 
The principal relations of the axial artery of the human
 
embryo have been established by the present study. An ade-
 
quate account of the relations of this and other arteries of the
 
developing limb of one of the quadruped mammals would be of
 
great value for purposes of comparison.
 
 
 
The only consecutive account which has been given of the
 
development of the arteries of the pelvic limb in any mamma-
 
lian form is that of DeVriese, which appeared in 1 902. It deals
 
with the human embryo. The other papers contained in the
 
literature of the subject are concerned with isolated stages in the
 
development of one or more forms rather than with a complete
 
history of the arteries of any particular mammal.
 
 
 
Hochstetter showed for the first time, in 1890, that the primitive artery of the mammalian thigh, which he termed the a.
 
ischiadica, foiiows the course of the n. ischiadicus in the embryos
 
of both the cat and the rabbit. He aiso described the develop-
 
ment of the a. femoraiis, which, appearing at a later stage,
 
supersedes the proximal part of the a. ischiadica as the chief
 
artery of the thigh. The secondary assumption of the original
 
function of the a. ischiadica by the a. femoraiis was shown to
 
occur in man by DeVriese in 1902.
 
 
 
 
 
Hochstetter did not succeed in following the continuation of
 
the a. ischiadica through the leg. Leboucq, however, described
 
it in 1893, as pursuing, in the human embryo, an axial course
 
between the tibia and fibula and finally perforating the tarsus
 
to reach the dorsum of the foot.
 
 
 
In 1894, Zuckerkandl described the continuation of the a.
 
ischiadica of the rabbit as traversing the flexor region of the leg
 
and dividing into a number of branches for the supply of the
 
sole. He also described two branches of the artery which supply
 
the extensor aspects of the leg and foot, respectively. In 1895
 
the same author described the perforating artery of the tarsus in
 
cat and rabbit embryos and made considerable progress in
 
the nomenclature to the primitive artery of the limb.
 
 
 
 
 
 
 
In Zuckerkandl' s second paper a distinction was made between
 
tine terms axial and ischiadic which formerly had been used more
 
or less interchangeably to denote the primitive artery of the
 
limb. For the entire artery Zuckerkandl employed the name
 
axial. He restricted the use of the term ischiadic to the part of
 
it which traverses the thigh and used the term a. interossea for
 
the remainder of the vessel. The same paper contained the
 
first accurate description which had been given of the distal part
 
of the axial artery of any mammal. The a. interossea was described in the rabbit as lying between the interosseous membrane
 
and m. tibialis posterior.
 
 
 
Grosser, in 1901, and DeVriese, in 1902, described the a,
 
interossea (the a. nervi interossei cruris of the latter author)
 
in bat and human embryos, respectively, as pursuing the course
 
it had been described by Zuckerkandl as following in the rabbit.
 
Both of these observers also recorded the presence, in the
 
subjects of their respective studies, of the r. perforans tarsi.
 
 
 
During the course of the present investigation it has become
 
apparent that the existing literature contains no definite statement regarding the course taken by the part of the axial artery
 
which traverses the popliteal fossa. It is questionable whether
 
the popliteal section of the axial arter}'^ has been tacitly included
 
as a part of the a. ischiadica or not, since the distal limit of the
 
latter artery does not appear to have been definitely fixed. In the following description the term a. ischiadica has been re-
 
stricted to the part of the axial artery proximal to the site at
 
which it is subsequently joined by the a. femoralis. This
 
restriction has necessitated the use of a new term for the part
 
of the axial artery which extends from the hiatus tendinous
 
(the approximate site of the femoro-ischiadic junction) to the
 
point (in the neighborhood of the distal border of the m.
 
popliteus) at which the a. interossea begins.
 
 
 
An examination of the popliteal portion of the human axial
 
artery shows that its distal part does not lie upon the posterior
 
surface of the m. popliteus as does the distal part of the adult
 
a. poplitea, but upon the anterior surface of that muscle. It
 
seems clear, therefore, that the distal part of the a. poplitea of
 
the majority of adult mammals, which lies upon the anterior
 
surface of the m. popliteus represents a persisting portion of the
 
embryonic axial artery. On this account the name a. poplitea
 
profunda has been used in the following pages to designate
 
entire popliteal section of the human axial artery.
 
 
 
The solution of Zuckerkandl's difficulty regarding the differ-
 
ence of the mutual relations between the a. poplitea and the m.
 
popliteus in man on the one hand and in the majority of other
 
 
 
 
 
 
 
mammals upon the other has thus been furnished by determining
 
the course of the popiiteai portion of the axiai artery of the
 
human embryo/
 
 
 
The part of the aduit human a. popiitea which extends from
 
the hiatus tendinous to the origin of the a. genu inferior
 
medialis is a direct survival of the embryonic a. popiitea pro-
 
funda. The part of that artery which lies upon the posterior
 
surface of the m. popliteus is derived from an embryonic vessel
 
of later formation referred to in the following pages as the a.
 
popiitea superficialis.
 
 
 
1 Arteria popiitea. Ein Stuck dieser Arterie lagert bei den Halbaffen und den
 
Primaten auf der freien (dorsalen) Flache des Musculus popliteus, bei den iibrigen
 
Saugetieren auf der Gelenkskapsel, bedekt von dem oben erwahnten Muskel.
 
Diese Verschiedenheit im Verlaufe der Popiitea kann nur auf die weise erklart
 
werden, dass entweder die den Muskel querenden Stiicke der Popiitea nieht
 
homolog Oder die beiden Muskein nicht dieselben sind. Nach meinen bisherigen
 
Erfahrungen scheint ersteres wahrscheinlicher zu sein. (Zuckerkandl ('95), p.
 
255.)
 
 
 
 
 
The literature dealing with the arteries of the mammahan
 
pelvic limb shows a tendency towards the perpetuation of a
 
 
 
 
 
 
 
conception regarding tlie reiation of tine aduit liuman a. peronaea
 
to \.he embryonic a. interossea wliicli Zuckerkandi lias aiready
 
sliown to be erroneous. Stieda stated, in 1893, tliat tine study
 
of tine variations of tine arteries of tine liuman leg had led him to
 
the conclusion that the a. peronaea represents a persisting portion
 
of the embryonic axial artery. A similar opinion regarding the
 
relationship between these two arteries was expressed by
 
Zuckerkandi in 1 894. In 1 895 the recognition of the course of
 
the a. interossea led Zuckerkandi to a modification of the views
 
he had previously expressed upon the subject. He drew atten-
 
tion to the fact that it would be impossible for the part of the
 
a. peronaea which is separated from the interosseous membrane
 
by the m. tibialis posterior to be a derivative of the part of the
 
a. interossea which lies between the membrane and the muscle.
 
In 1902 DeVriese revived the conception of the identity of the
 
aa. interossea and peronaea, notwithstanding the obvious justice
 
of Zuckerkandl's contention.
 
 
 
A careful examination of the embryos which form the basis of
 
the present study and of a large number of others belonging to
 
the collection of the Carnegie Institution has been made in the
 
search for a r. saphenus of the a. femoralis comparable in extent
 
to that of the a. saphena w'^hich occurs very rarely in adult man
 
and invariably in most of the other mammals. The result has
 
been entirely negative.
 
 
 
That the a. saphena occurs occasionally in the human embryo
 
is indicated by the fact that its presence has been noted at least
 
five times in the adult. In the embryos examined in connection
 
 
 
 
 
 
 
with the present study, however, the r. saphenus has not been
 
found to extend in a single instance beyond the middle of the
 
leg.
 
 
 
I take this opportunity of expressing my gratitude to Professor
 
Thyng for the trouble he has taken in the revision of this
 
manuscript.
 
 
 
 
 
b. Material
 
 
 
In the present investigation the lower extremities of embryos
 
have been studied in seven stages of developinent, one extremity
 
or both having been reconstructed in wax. The selection of
 
stages depended upon the accessibility of well-preserved material
 
rather than upon a preconceived plan regarding the most in-
 
structive stages to use. 2
 
 
 
The following eknbryos have been studied, the right limb
 
having been reconstructed in all cases. The embryos of which
 
both lower limbs have been reconstructed are marked with an
 
asterisk :
 
 
 
6.0 mm.* Carnegie Institution, Embryolugical Collection (C.I.E.C.) No.
 
 
 
 
 
 
 
1075.
 
 
 
 
 
 
 
8.5 mm.* Cornell University, Embryologlcal Collection (C.E.C.) No. 9.
 
12.0 mm.* Cornell University, Embryologlcal Collection (C.E.C.) No. 3.
 
12.0 mm.* Minnesota, Embryologlcal Collection (M.E.C.) No. H. 16.
 
14.0 mm. Cornell University, Embryologlcal Collection (C.E.C.) No. 5.
 
17.8 (?) Harvard University, Embryologlcal Collection (H.E.C.) No. 839.
 
18.0 mm. Carnegie Institution, Embryologlcal Collection (C.I.E.C.) No. 409.
 
22.0 mm. Cornell University, Embryologlcal Collection (C.E.C.) No. 1.
 
 
 
For their generosity In placing their material at my disposal,
 
I wish to express my great obligation to Profs. C. M. Jackson,
 
F. T. Lewis, F. P. Mall, C. R. Htockard, and G. L. Streeter.
 
 
 
Toward the end of the Investigation, there were a number of
 
difficulties, for the solution of which the examination of rather
 
close Intermediate stages was required. Such stages were found
 
In the collection of the Carnegie Institution at Baltimore.
 
 
 
In the formation of this valuable collection, so ably cared for
 
and sympathetically administered. Professor Mall has made
 
available to his fellow-workers a wealth of material adequate for
 
the solution of any ordinary problem In human embryology.
 
 
 
The reconstruction of vascular plexuses In wax, using every
 
second or fourth section as the case may be. Is somewhat difficult.
 
The practice followed has been to unite the parts of the adjacent
 
 
 
 
 
 
 
* 2 In the case of the embryos from the Carnegie Institution and Minnesota University the measurement is crown-rump. The Harvard and Corneii measurements represent the greatest total length.
 
 
 
 
 
 
 
plates which fit after careful adjustment and to remove those
 
which do not join. In this way the plexus represented in the
 
reconstruction is probably less dense than that occurring in the
 
embryo. The reconstruction, in fact, reproduces the spirit rather
 
than the letter of the original.
 
 
 
In reconstructing the stage of 6 mm. consecutive sections
 
were used, and these were comparatively thick (20 n). In this
 
case the parts usually fitted so accurately that the plexuses,
 
as reproduced, must represent, as nearly as possible, the actual
 
conditions in the original.
 
 
 
c. Nomenclature
 
 
 
As already noted, the term a. poplitea profunda is used in the
 
following account to denote the popliteal section of the em-
 
bryonic axial artery. The term a. ischiadica and a. interossea
 
have been retained for the proximal distal parts of that artery,
 
respectively.
 
 
 
 
 
 
 
To the artery which normally perforates the tarsus of adult
 
ungulates, and which has been recognized in all mammalian
 
embryos hitherto observed, numerous terms have been applied. '^
 
The name ramus perforans tarsi is used here.
 
 
 
For two of the embryonic arteries the names used by HyrtI in
 
1864 have been retained. They are the r. coronarius (of the
 
medial malleolus) and the a. peronaea posterior superficialis.
 
 
 
The description of a number of embryonic vessels, the existence
 
of which has not been noted heretofore, has necessitated the use
 
of several new terms. These conform, as nearly as may be, with
 
current usage.
 
 
 
In referring to the relative positions of the structures of the
 
limb, the adult terms of orientation have been used throughout.
 
This course has been adopted in order to avoid the confusion
 
which might arise from the alternative use of two sets of terms
 
in making comparisons between the relative positions of struc-
 
tures in the adult and embryonic limb, respectively.
 
 
 
* Ramus and sinum tarsi, HyrtI ('64) ; Arteria tarsea perforans, Siissdorf
 
('89); perforans tarsi, DeVriese ('92) Arteria anastomotica tarsi, Salvi ('99).
 
 
 
 
 
 
 
The limb preserves its primitive position which, with the
 
exception of progressively increasing flexion of the knee, remains
 
unchanged throughout the period of development under con-
 
sideration. The flexor aspect of the embryonic thigh and leg
 
and the plantar aspect of the sole are directed medially; the
 
great toe is preaxial or cephalic. The term posterior for the
 
adult has, therefore, the same significance as the term medial for
 
the embryo; so have, respectively, the terms anterior and lateral,
 
medial and pre-axial, lateral, and post-axial. For the parts
 
above the hip-joint there can be no possibility of confusion, since
 
like terms of orientation serve equally well for the postnatal and
 
embryonic periods.
 
 
 
==II. The Arterial System Of The Lower Limb In Progressive Stages Of Development==
 
 
 
a. Stage of 6 mm. C. I. E. C, no. 1075, figs, 1 and 9 A.
 
 
 
In the lumbar region the nerve roots are not recognizable. The
 
ganglia of the lumbar and sacral regions appear as segmentally
 
disposed swellings upon the continuous neural crest. Distal to
 
the second lumbar segment the postcardinal vein becomes plexi-
 
form. The medial part of the plexus receives the segmental
 
veins, the lateral part represents the still indefinite marginal
 
vein.
 
 
 
 
 
 
 
The dorsal segmental arteries, wdth the exception of the fifth
 
lumbar and second sacral, pass directly to the spinal cord with-
 
out branching. The umbilical arteries, the ventral roots of
 
w'^hlch are still very large, arise opposite the Intervals between
 
the third and fourth lumbar segmentals.
 
 
 
The secondary, or dorsal, roots of the umbilical arteries are
 
present, but are smaller than the original or ventral roots of that
 
vessel. Each dorsal root. In the embryo under consideration,
 
arises from the union of two arteries.
 
 
 
The chief share In the formation of the dorsal root of the a.
 
umblllcalls Is taken by a vessel which arises from the fifth
 
lumbar segmental artery a short distance beyond Its root. The
 
vessel In question Is joined almost perpendicularly near Its
 
origin by a smaller one which springs from the aorta In the
 
Interval between the fourth and fifth lumbar segmental arteries.
 
 
 
 
 
The dorsal root of the a. umblhcahs, which may be said -to
 
begin at the junction of the two vessels mentioned above, con-
 
tinues the transverse direction of the larger of the two, until It
 
reaches the dorsal aspect of the Wolffian duct of Its own side. In
 
this situation It turns ventrally, passing upon the lateral side
 
 
 
 
 
 
 
of the duct, which is now enciosed between the two roots of the
 
umbiiicai artery, to join the ventrai root.
 
 
 
As the dorsai root of the a. umbiiicaiis curves around the
 
iaterai side of the Wolffian duct it gives origin to the axial artery
 
of the lower extremity and to the a. pudenda interna.
 
 
 
The axial artery, takes an almost transverse, slightly recurrent,
 
course towards the surface. It ends by dividing into two
 
 
 
 
 
 
 
Fig. 1 Reconstruction showing the distal end of the aorta; also the arteries
 
of the right lower extremity and neighboring parts in a human embryo of 6
 
mm. C.I. E.G., 1075). Medial aspect. X 40 diams.
 
 
 
 
 
 
 
branches, each of which breaks up into a plexus which passes
 
over into the postcardinal venous plexus. The a. pudenda
 
interna follows the dorsolateral surface of the Wolffian duct
 
towards the urogenital sinus and enters the pelvic arterial plexus.
 
In addition to the arteries already described, there are two
 
extensive arterial plexuses, which may be called the abdominal
 
and pelvic plexuses, respectively. Of these the abdominal
 
arises by seven or eight stems from the concavity of the umbilical
 
artery somewhat distal to the junction of its two roots. It
 
invades the flexor region of the thigh, although it is uncertain
 
to what extent, for the lower limb bud is not distinctly circum-
 
scribed at this period.
 
 
 
The abdominal plexus has no connection whatever with the
 
segmental arterial series. It is drained partly by postcardinal
 
plexus, but mainly by the umbiUcal vein. The pelvic plexus arises
 
by two roots from the convexity of the umbilical artery opposite
 
the roots of the abdominal plexus. It covers the cloaca and
 
receives the pudendal artery and a large branch from the second
 
sacral segmental. It is drained by the postcardinal plexus.
 
The abdominal and pelvic plexuses appear to be connected by
 
 
 
 
 
 
 
a few vessels passing lateral to the umbilical artery. It is
 
probable that all the visceral branches of the adult a. hypo-
 
gastrica (excepting the superior vesical) arise out of the primitive
 
pelvic plexus of the original umbilical artery. The parietal
 
branches (as far as they are present before the stage of 22 mm.)
 
arise from, or very near to, the axial artery. They are therefore
 
connected with the dorsal root.'^
 
 
 
This stage agrees in most essentials with the 5-mm. embryo
 
(II) described by Tandler ('03). The inferior mesenteric artery
 
arises opposite the first lumbar segmental.
 
 
 
b. Stnge of 8.5 mm., C. U. C, no. 9, figs. 2 and 9 B
 
 
 
The femoral, obturator, genitofemoral, and peroneal nerves
 
are readily recognized as short relatively unbranched trunks.
 
The extremity of the tibial is divided into what appear to be
 
the medial and lateral plantar nerves.
 
 
 
The aa. umbilicales have lost their original (ventral) roots
 
and now spring from the aorta in the intervals between the
 
fourth and fifth dorsal pairs of lumbar segmental arteries. The
 
 
 
* The distinction between the respective origins of the visceral and parietal
 
branches of the a. hypogastrica has already been pointed out by McMurrich
 
('04).
 
 
 
* It is questionable whether the common iliac artery should be regarded as
 
 
 
 
 
 
 
belonging to the fifth iumbar dorsai segmentai or not. , At the stage of 8.5 mm.
 
of this series the fifth iumbar segmentai has regained its independence, and
 
springs from the aorta (on both sides) between the fourth and fifth. The work
 
of Levy ('02) shows, however, that absence of the a. iumbaiis ima is the ruie
 
rather than the exception. Whether this vessei is frequently retained by the
 
root of the a. iiiaca communis or merely overshadowed (as it were) by it is
 
doubtful.
 
 
 
 
 
Fifth lumbar segmental arteries have thus regained their independence, and, like the other segmental arteries in this region,
 
pass to the spinal cord without branching.
 
 
 
The axial artery passes distally into the lower hmb, crossing the n. tibialis posteriorly from the medial to the lateral side. It then follows the posterior aspect of the skeletal mesenchyme throughout the leg into the sole. In the latter situation it breaks up into a flattened plexus which extends somewhat beyond
 
 
 
 
 
 
 
Fig. 2 Reconstruction showing the arteries of the right lower extremity in a
 
human embryo of 8.5 mm. (C.E.C., 9). Medial aspect. X 20 diams.
 
 
 
Fig. 3 Reconstruction showing the arteries of the right side of the pelvis,
 
right thigh, leg, and dorsum of the foot in a human embrj'o of 12 mm. (M.E.
 
C.,H. 14). Medial aspect. X 20 diams.
 
 
 
 
 
 
 
the extremities of tlie plantar nerves. Just as it is breaking up
 
into tine plantar plexus the axial artery gives origin to two or
 
three branches which pierce the mesenchymal skeleton of the
 
foot to reach the dorsum. Upon the dorsum of the foot the
 
perforating branches produce another flattened plexus. The
 
two plexuses (or retia) of the foot are separated from one another
 
by the mesenchymal skeleton of the foot, the plantar rete lying
 
between the latter and the plantar nerves.
 
 
 
 
 
In passing from the medial to the lateral side of the sacro-
 
pudendal plexus, the axial artery runs between the main plexus
 
and a branch from its lower part. The branch referred to has
 
been removed from the reconstructions illustrated in figures 1
 
to 6, since it partially covers the artery when viewed from the
 
medial side.
 
 
 
From the lateral aspect of the concavity of the umbilical
 
artery, some distance proximal to the origin of the axial artery,
 
there now arises a new vessel, the a. iliaca externa. This vessel
 
takes a cephalic direction, nearly parallel to the aorta, coursing
 
medially to the origin of the obturator nerve. At this stage
 
the wall of the external ihac artery is thin and its course slightly
 
tortuous. The artery is not connected with the dorsal segmental
 
 
 
 
 
 
 
arterial series or witin any otiner artery. Tine further history of
 
the external iliac is rather remarkable. It soon becomes quite
 
straight and acquires a wall of great thickness, but remains un-
 
branched until a stage of (approximately) 12 mm. The a. iliaca
 
externa appears as a thick-walled straight artery in the well-
 
known pig embryo of 12 mm.
 
 
 
The place of origin of the a. iliaca externa marks the permanent
 
subdivision of the dorsal root of the umbilical artery into two
 
parts. The proximal part becomes the adult a. iliaca com-
 
munis while the distal part represents the a. hypogastrica and a
 
short proximal section of its umbilical branch.
 
 
 
At this stage the marginal vein is fully formed; its caudal
 
 
 
root, represented by the v. ischiadica, runs in close contact with
 
 
 
the proximal part of the corresponding artery.
 
 
 
c. Stage of 1 2 mm. M. E. C, no. H. 1 6, figs. 3 and 9 C
 
 
 
Condensation of the mesenchymal skeleton is now well ad-
 
vanced. It is not sufficiently definite in the tarsal region, how-
 
ever, for the determination of the course taken by the connection
 
between the axial artery and the dorsal rete of the foot. The
 
surfaces of the growing nerves are considerably roughened by
 
the beginning outgrowth of numerous branches, many of which
 
can be identified.
 
 
 
The course of the axial artery is somewhat less straight than
 
in the preceding stage. This is due chiefly to a sharp convexity
 
directed toward the growing extremity of the a. femoralis. The
 
convexity is surmounted by a short sprout indicating the point
 
at which the femoral is later to unite with the axial artery.
 
Although the axial artery is straighter in the preceding stage
 
than at the stage of 12 mm., an irreg-ularity is noticeable at the
 
stage of 8.5 mm. in a similar situation. It seems to represent
 
an earlier indication of the convexity which is so pronounced at
 
the present stage of development.
 
 
 
Distal to the knee the axial artery lies in the narrow interval
 
between the tibia and fibula. The interosseous membrane and
 
individual muscles are still unrecognizable, but, although the
 
artery bulges toward the extensor region, its distal course
 
clearly indicates that it does not leave the flexor aspect of the
 
leg.
 
 
 
At what appears to be the proximal end of the very short
 
tibiofibular interspace a second bend occurs in the axial artery.
 
This bend is so pronounced as to practically amount to the bud
 
of the vessel which is shortly to grow into the extensor aspect of
 
the leg from this point.
 
 
 
 
 
 
 
The dorsal and plantar retia of the foot are richer than in the
 
preceding stage. The connection between the axial artery and
 
the dorsal rete is now reduced to a single vessel of large size, the
 
r. perforans tarsi.
 
 
 
The a. iliaca externa has bifurcated into the a. epigastrica
 
inferior and the a. femoralis.'^ The latter is contrasted sharply
 
from the a. iliac externa by the thinness of its walls, which con-
 
sist of endothelium only. Its structure resembles very closely
 
that of the femoral vein which accompanies it. The femoral
 
artery runs parallel with and upon the medial side of the n.
 
saphenus. Its extremity, now about half way along the femur,
 
is bifurcated into a lateral and a medial branch. The former is
 
short and will later join the axial artery; it may be called the
 
 
 
'^ That the a. epigastrica inferior is an indei'^endent branch of the a. iliaca
 
externa, which considerably antedates it and the a. femoralis in development,
 
has already been pointed out by the writer (Senior, '17).
 
 
 
 
 
 
 
ramus communicans superius. The latter is longer and is
 
recognizable as the ramus saphenus of the a. genu suprema.
 
 
 
The difficulty in finding developmental stages in which the a.
 
 
 
 
 
 
 
femoralis is present, but not yet united witli tlie axial artery,
 
coupled with the thinness of the wall of the femoral artery at
 
this stage, indicates that the artery is one of extremely rapid
 
growth. In a 12-mm. embryo slightly younger than the speci-
 
men described (C. E. C, No. 3), reconstruction was begun under
 
the impression that the femoral was absent. After more thorough
 
study the artery was identified, bifurcated as in M. E. C, No.
 
H 16, but much shorter. At this stage the a. femoralis has no
 
branches, other than the terminal bifurcation already referred to.
 
 
 
d. Stage of 14 mm. C. E. C, no. 5, figs. 4 and 9 D
 
 
 
This stage is principally characterized by the participation of
 
the a. femorahs in the blood supply of the leg and by the
 
appearance of three branches of the axial artery.
 
 
 
The r. communicans superius of the a. femoralis has joined the
 
axial artery at the more proximal, of the two angular bends
 
noticed in the preceding stage. The r. saphenus remains free
 
and can be traced to the level of the knee joint.
 
 
 
At the more distal bend of the axial artery there is now a
 
branch, which passes to the extensor surface of the leg. This
 
artery passes through the proximal end of the tibiofibular inter-
 
space and takes a recurrent course toward the knee. The
 
proximal part of the artery takes part in the formation of the
 
adult a. tibialis anterior. It may be referred to as the ramus
 
perforans cruris. The recurrent vessel continuing from the r.
 
 
 
 
 
 
 
perforans cruris is tine arteria recurrens tibiaiis anterior of tine
 
aduit.
 
 
 
Tine points marked upon tine axiai artery by means of tine r.
 
communicans superius and by tine origin of tine r. perforans
 
cruris, respectiveiy, may be used for tine convenient subdivision
 
of tine vessei into tiiree parts. Tine part upon tine proximai side
 
of tine r. communicans superius wiii be referred to as tine a.
 
isclniadica and tliat upon tine distai side of tlie r. perforans cruris
 
 
 
 
 
 
 
Fig. 4 Reconstruction showing the arteries of the right side of the pelvis and
 
right thigh and leg in a human embyro, of 14 mm. (C.E.C., 5). Medial aspect.
 
X20diams.
 
 
 
Fig. 5 Reconstruction showing the arteries of the right side of the pelvis and
 
right lower extremity in a human embryo of 17.6 mm. (H.E.C., 839). Medial
 
aspect. X 20 diams.
 
 
 
Fig. 6 Reconstruction showing the arteries of the right side of the pelvis and
 
right lower extremity in a human embryo of 18 mm. (C.E.I.C, 409) X 20
 
diams.
 
 
 
 
 
 
 
69
 
 
 
 
 
 
 
[Begin Page: Page 70]
 
 
 
70 H. D. SENIOR
 
 
 
as the a. interossea. The intervening part will be called the a.
 
poplitea profunda.
 
 
 
At this stage the a, poplitea profunda has two branches which
 
course longitudinally through the posterior crural region. One
 
of these arteries resembles, in a general way, the a. tibialis
 
posterior of the adult, it may be called the a. tibialis posterior
 
superficialis. The other slightly more distal in its place of
 
origin is the a. peronaea posterior superficialis (of Hyrtl),'^ The
 
relations borne by these arteries to the n. tibialis remain constant
 
throughout a prolonged period of development.
 
 
 
The a. tibialis posterior superficialis passes at first backward
 
Upon the medial side of the n. tibialis to reach its posterior
 
aspect. Running upon the posterior aspect of the n. tibialis in
 
the leg, it passes into the sole upon the inferior aspect of the n.
 
plantaris medialis. The part of the artery which enters the
 
sole becomes the a. plantaris medialis of the adult.
 
 
 
The a. peronaea posterior superficialis passes from the medial
 
 
 
 
 
 
 
to the lateral aspect of the n. tibialis by skirting around the
 
proximal and lateral sides of a large muscular ramus of the
 
nerve. '^ It follows the anterior and lateral aspect of the n.
 
tibialis as far as the place of origin of the nn. plantares. In this
 
situation the artery bifurcates Into a lateral and a medial branch.
 
The branches are both short and end blindly.
 
 
 
Two branches now spring from the lateral side of the a.
 
femoralls. One of these Is situated upon the proximal side of
 
the r. saphenus and represents the r. musculo-artlcularls of the
 
:adult a. genu suprema. The other Is the a. circumflexa femorls
 
lateralis of the adult a. profunda femorls.
 
 
 
The branches arising from the medial side of the a. femoralls
 
which will be discussed under stages E and F.
 
 
 
The a. glutaea superior Is present and takes origin from the
 
root of the a. Ischladlca.
 
 
 
'^ According to the system of nomenclature In use at the present time, the
 
adjective 'posterior' as used by HyrtI Is redundant. In view of the essentially
 
fugitive nature of anatomical terminology It has seemed unnecessary to modify
 
Hyrtl's original term, which adequately meets the requirements of the case.
 
 
 
* This Is resolved later Into the rami musculares for the mm. popllteus,
 
tibialis posterior, flexor digltorum longus, and flexor longus hallucls.
 
 
 
 
 
 
 
e. Stage of 17.8 mm. H. E. C, no. 839,'' figs. 5 and 9 E
 
 
 
During tine preceding stages of development the arterial retia
 
of the foot have received their blood supply exclusively through
 
the a. interossea; the reta plantare directly, and the rete dorsale
 
by means of the r. perforans tarsi. The mesenchymal skeleton
 
of the foot is now definitely circumscribed, and it is plain that
 
the latter vessel reaches the dorsum by way of the tarsal sinus.
 
The arterial retia of the foot lie in close contact with the tarsus
 
and metatarsus and represent the following vessels of the adult
 
circulation — the arcus plantaris and its articular branches, the
 
aa. tarseae mediales and laterales, the a. arcuata, the aa. meta-
 
tarseae and digitales (both dorsal and plantar), and the rami
 
perforantes (including the ramus plantaris profundus).
 
 
 
The present stage is characterized by the presence of four
 
arteries which traverse the leg for the supply of the sole. The
 
a. interossea is still present, the aa. tibialis posterior superficialis
 
and peronaea posterior superficialis have formed their definitive
 
connections, and a new vessel, the a. tibialis anterior, pars
 
distalis, has arisen.
 
 
 
The a. tibialis posterior superficialis and the a. peronaea
 
posterior superficialis preserve in the leg the same relations to
 
 
 
 
 
 
 
the n. tibialis as obtained in tine preceding stage. At tine ankie
 
tlie mediai terminai brancli of tine a. peronaea posterior super-
 
ficiaiis lias traversed tine fork formed by tine diverging piantar
 
nerves to join tlie a. tibialis posterior superficiaiis. Tine lateral
 
terminal branch of the same artery has reached the lateral side
 
of the sole to join the plantar arterial rete. The connection thus
 
formed between the a. tibialis posterior superficiaiis and the
 
rete plantare becomes the a. plantaris lateralis of the adult foot.
 
At the present stage of development it receives blood from two
 
sources.
 
 
 
* 3 The greatest total length of this embryo, measured in formalin, was 1 7.8 mm.
 
In 80 per cent alcohol it measured 13.6 mm. It has been described by Thyng as a
 
17.8 mm. embryo (Am. Jour. Anat., vol. 17, p. 31), and referred to bj'^ Thyng
 
(Am. Jour. Anat., vol. 7, p. 489) and by Thyng and Lewis (Am. Jour. Anat., vol. 7,
 
p. .505) as an embryo of 13.6 mm. The distribution of the arteries of the lower
 
extremity resembles that of other embryos of about 1 5 or 1 6 mm.
 
 
 
 
 
The part of the a. tibiahs posterior superficiaUs distal to the
 
newly formed origin of the a. plantaris lateralis now becomes
 
the a. plantaris medialis. The portion of the remainder of that
 
vessel which is not concerned in the formation of the a. poplitea
 
becomes the a. tibialis posterior.
 
 
 
 
 
 
 
The branches of the medial plantar artery anastomose, upon
 
the lateral side of the foot, with the plantar rete, thus consti-
 
tuting a (transitory) superficial plantar arch.
 
 
 
The a. tibialis anterior, pars distaUs, extends from the part of
 
r. perforans cruris which lies in the extensor region of the leg to
 
the rete dorsale. The portion of the r. perforans which now lies
 
beyond the proximal end of the pars distalis corresponds to the
 
adult a. recurrens tibiahs anterior. The portion which extends
 
from the a. poplitea profunda to the pars distalis enters into
 
the composition of the adult a. tibiahs anterior. The a. recurrens
 
tibialis anterior is connected by means of a plexiform anastomosis,
 
with the r. saphenus of the a. femoralis.
 
 
 
Upon the medial side of the a. femoralis there are at this
 
stage three branches exclusive of the r. saphenus. Of these the
 
most distal, which has a longer individual course than the others,
 
takes a recurrent direction. The three branches break up to
 
form an extensive plexus (not indicated in the figures) which
 
ramifies throughout the thigh and is particularly rich around
 
the perichondrium. It is probable that this plexus is eventually
 
taken over by the adult a. profunda femoris and its branches.
 
Two branches arise from the lateral side of the a. femoralis as.
 
in the preceding stage.
 
 
 
The a. glutaea superior now takes direct origin from the a. hy-
 
pogastrica upon the proximal side of the origin of the a. ischiadica.
 
 
 
 
 
 
 
/. stage of 1 8 mm. C. I. E. C, no. 409, figs. 6 and 9 F
 
 
 
From the time of tine junction between tine r, communicans
 
superius and tine axiai artery tlie caiiber of tlie a. femoraiis lias
 
graduaiiy exceeded tliat of tlie a. iscliiadica, wlnicln Inas now
 
become exceedingiy siender. After iiaving traversed tlie iower
 
portion of tlie sacropudendai piexus, the a. iscliiadica passes.
 
 
 
 
 
 
 
to the region of the hiatus tendinous upon the lateral side of the
 
n. tibialis. The n. peronaeus lies immediately upon its lateral
 
side.
 
 
 
In a general way the aa. poplitea profunda and interossea
 
and their branches have the same arrangement as in the pre-
 
ceding stage. The exact course taken by these vessels can now
 
be clearly recognized, since it is possible to identify the individual
 
muscles of the limb.
 
 
 
The a. poplitea profunda runs between the m. popliteus and
 
the tibia. At the proximal border of the muscle the artery
 
gives off the a. genu media and a short trunk which is being
 
formed by the progressive union of the proximal ends of the aa.
 
tibialis posterior superficialis and the a. peronaea posterior super-
 
 
 
 
 
 
 
ficialis. This short trunk, which lies upon the posterior surface
 
of the m. popliteus, may now be called the a. poplitea super-
 
ficialis. It forms the distal part of the a. poplitea of the adult.
 
A short distance below the origin of the a. poplitea superficialis
 
there arises the a. genu inferior medialis.
 
 
 
The a. interossea passes down the leg between the m. tibialis
 
posterior and the interosseous membrane. Just above the
 
medial malleolus it gives off a branch which passes around the
 
posterior to the medial side of the tibia, the ramus coronarius
 
of the medial malleolus (Hyrtl).'^° At the malleolus the a.
 
 
 
1 ° In this vessel lies, according to HyrtI, the key to the deep supramalleolar
 
anastomosis (i.e., the r. communicans) between the a. peronaea and the a.
 
tibialis posterior. The r. coronarius is regarded by HyrtI as primarily passing
 
from the a. peronaea around the medial side of the tibia to unite with the a.
 
tibialis anterior. By means of a secondary connection occurring between the r.
 
coronarius and the a. tibialis posterior, the former vessel eventually becomes
 
converted into an anastomosing chain in which the aa. malleolaris anterior
 
medialis, malleolaris posterior medialis and r. communicans are the named
 
components. At the stage of 1 8 mm. of this series the r. coronarius arises from the
 
part of the a. interossea which persists to take part in the formation of the adult
 
a. peronaea. It runs, at this stage, as at the stage of 22 mm. , toward the a. tibialis
 
anterior as described by HyrtI, and would, no doubt, eventually join it. Since
 
in both these stages the a. tibialis posterior is situated upon a plane superficial
 
to that occupied by the r. coronarius, no junction of the vessels in question has
 
occurred. There can be little doubt, however, that HyrtI has interpreted the
 
nature of the r. coronarius correctly. His views upon this subject, which were
 
 
 
 
 
 
 
derived from an extensive study of tine normai and abnormai conditions found
 
in aduit iegs, liave been of tlie greatest assistance in tlie interpretation of tine
 
conditions obtaining during development.
 
 
 
 
 
 
 
interossea lies upon the lateral side of the tendon of the m.
 
tibialis posterior (i.e., between tendon and malleolus) and then
 
passes across the plantar end of the sinus tarsi to join the plantar
 
rete.
 
 
 
The a. peronaea posterior superficialis is placed anteriorly and
 
laterally to the n. tibialis and lies upon the posterior surface of
 
the m. flexor hallucis longus. At the distal border of the muscle
 
the artery lies near the a. interossea and interosseous membrane.
 
In this situation it gives off a very large r. calcaneus lateralis
 
which runs upon the lateral side of the tuber calcanei. This
 
branch eventually forms the termination of the a. peronaea.
 
 
 
The a. tibialis posterior superficialis follows the posterior
 
surface of the n. tibialis until the latter bifurcates in the neigh-
 
borhood of the medial malleolus. Here the artery is placed
 
between the n. tibialis and the tendon of the flexor hallucis
 
longus. The a. tibialis anterior, pars distalis, has relations
 
identical with those of the adult.
 
 
 
 
 
 
 
The relations existing between tine various structures of tine
 
leg were ascertained by making a reconstruction which, from
 
the fact that it yields but little information when entirely built
 
up, is unsuitable for reproduction. The data gained from an
 
examination of its separate parts are embodied in two diagrams
 
(fig 7, A and B) which may serve as a rough guide to the inter-
 
pretation of anomalies. These diagrams show, approximately,
 
the course taken by the embryonic aa. poplitea profunda,
 
interossea, and peronaea posterior superficialis.
 
 
 
The order in which the various structures passing from the
 
leg to foot are arranged in the hollow between the medial mal-
 
leolus and tuber calcanei is as follows: m. tibialis anterior and
 
a. interosseus together; m. flexor digitorum longus; a. peronaea
 
posterior superficialis; n. tibialis, a. tibialis posterior super-
 
ficialis, and m. flexor hallucis longus.
 
 
 
Embryos of about this age are instructive mainly by reason
 
of the fortunate circumstance that the individual muscles are
 
differentiated before the continuity of the axial artery has
 
been broken. Only one important change has occurred at this
 
stage of development; this consists in the appearance of a communicating branch which foreshadows the development of the
 
future a. peronaea.
 
 
 
The communicating branch in question ieaves the a. peronaea
 
posterior superficiaiis at the proximai border of the m. fiexor
 
haiiucis iongus. It passes distally between the mm. flexor
 
hallucis Iongus and tibialis posterior to join the a. interossea,
 
 
 
 
 
Fig. 7 Indicates the course of three arteries of the embryonic lower extremity,
 
represented diagrammatically as they would appear if persisting in the adult.
 
The vessels which normally persist are indicated by shading. A, A. poplitea
 
profunda and a. interossea. B. A. peronaea posterior superficiaiis. d. I. m.
 
flexor digitorum Iongus; h. I., m. flexor hallucis Iongus; t. p., m. tibialis posterior.
 
 
 
as that artery lies upon the interosseous membrane. It may be
 
called the r. communicans inferius.
 
 
 
The entire r. communicans inferius persists in the adult as
 
 
 
 
 
 
 
the portion of the a. peronaea which lies between the mm. flexor
 
haUucis longus and tibialis posterior. The portions of the aa.
 
peronaea posterior superficialis and interossea with which the proximal and distal ends of the r. communicans inferior are
 
respectively connected also take part in the formation of the
 
a. peronaea.
 
 
 
Of the branches of the a. femoralis, those arising from the
 
lateral side are identical with the branches of the preceding
 
stage. There are three branches upon the medial side. The
 
recurrent branch {R in figures) seems to be identical with the
 
similar branch of the preceding stage. It is doubtful whether
 
the two other medial branches correspond to those observed in
 
the preceding stage or not.
 
 
 
g. Stage of 22 mm C. I. C no. 1 , figs. 8 and 9 G
 
 
 
At this stage of development the continuity of the a. ischiadica
 
has been interrupted and the a. femoralis alone conveys blood
 
to the region beyond the knee.
 
 
 
The femoral artery pursues a more direct course than before
 
 
 
 
 
 
 
and gives origin to most of its important brandies. In addition
 
to tlie a. circumflexa lateralis which appeared at the stage of
 
14 mm., it gives origin to the a. pudenda externa and the a.
 
profunda. The r. musculo-articularis has migrated to the esm-
 
bryonic r. saphenus. The root of the latter branch, therefore,
 
now appears as the a. genu suprema and gives origin to the r.
 
saphenus and the rr. muscularis and articulares of the adult.
 
 
 
The a. profunda arises from the a. femoralis quite close to the
 
origin of the a. circumflexa lateralis. It seems probable that
 
the embryonic a. profunda sometimes arises from the root of
 
the latter artery and sometimes directly from the femoral. In
 
the former case the adult a. circumflexa lateralis would
 
appear to arise from the a. profunda and in the latter from the
 
femoral. The great variation in the site of the origin of the
 
vessel is well known.
 
 
 
The a. profunda femoris gives origin to one perforating artery
 
which, since it pierces the adductores brevis and magus, repre-
 
sents the first or second of the adult series. The single a. per-
 
forans is connected, by means of an extensive plexus, with the
 
more distal section of the now interrupted a. ischiadica.
 
 
 
 
 
 
 
The a. ischiadica passes through the sacropudendal plexus as
 
before and reaches the lateral side of the a. tibialis, which is now
 
contained in the same sheath as the n. peronaeus. After its
 
exit from the pelvis the artery gives origin to a few gluteral
 
branches and leaves the n. tibialis with the n. cutaneus femoris
 
posterior. In company with the latter nerve and the v. ischiadica,
 
it passes to the posterior surface of the thigh and ends by
 
dividing into several cutaneous branches. This part of the a.
 
ischiadica persists as the a. glutaea inferior.
 
 
 
The more distal portion of the a. ischiadica is traceable as a
 
definite path through a plexus upon the posterior surfa.ce of the
 
m. adductor magnus, but has lost its continuity with the a.
 
popUtea. The other vessel participating in the formation of
 
the plexus is the perforating branch of the a. profunda femoris.
 
This plexus evidently represents the terminal anastomosis
 
between the perforating arteries of the adult. It probably takes
 
a large share in the formation of the perforating arteries
 
themselves.
 
 
 
The distal part of the anterior tibial artery has received blood
 
since the time of its first appearance by way of the a. poplitea
 
profunda and r. perforans cruris. An alternative path has now
 
been provided by the appearance of a vessel which, passing
 
around the distal border of the m. popliteus, connects the
 
developing a. peronaea with a more distal part of the a. poplitea
 
profunda. It is the r. communicans medius which will later become
 
the definitive proximal end of the a. tibialis anterior. The
 
 
 
 
 
 
 
significance of tlnis vessei in reiation to tine formation of tine
 
aduit aa. profunda and tibiaiis anterior wiii be deait witli in tine
 
succeeding section.
 
 
 
Tine principai clianges wliicli iiave occurred in tine embryonic
 
arteries of tine posterior crurai region since tlie preceding stage
 
of deveiopment invoive tine vesseis wliicli participate in the
 
formation of the adult a. peronaea. These changes cons' st in
 
the disappearance of considerable parts of the aa. interossea and
 
peronaea posterior superficialis.
 
 
 
The portion of the a. interossea which formerly extended from
 
the r. perforans cruris, to the distal end of the r. communicans
 
 
 
 
 
Fig. 8 Reconstruction showing the arteries of the right side of the pelvis
 
and right lower extremity in a human embryo of 22 mm. (C.E.I.C, 1 .). Medial
 
aspect. X 20 diams.
 
 
 
 
 
inferius has practically disappeared. The portion immediately
 
beyond the distal end of the latter vessel Ues upon the posterior
 
surface of the interosseus membrane and gives origin to two
 
branches. The remainder of the vessel is involved in the meshes
 
of the rete calcaneum.
 
 
 
The portion of the a. peronaea posterior superficialis which
 
extends from the present termination of the a. poplitea super-
 
ficialis to the proximal end of the r. communicans inferius per-
 
sists to become a part of the adult a. peronaea. A large part of
 
the remainder of the artery has been lost, but the distal portion
 
of the vessel can still be recognized as forming a projection upon
 
the proximal aspect of the rete calcaneum. This portion of the
 
artery can be traced through the meshes of the rete as far as
 
the a. plantaris lateralis.
 
 
 
The rete calcaneum is very extensive at this stage of develop-
 
ment and occupies the concavity upon the medial side" of the
 
calcaneum and surrounds the deep flexor tendons in the
 
malleolar region of the leg.
 
 
 
The component parts of the a. peronaea are now recognizable.
 
The proximal part is derived from the a. peronaea posterior super-
 
ficialis. The part between the aa. flexor hallucis longus and
 
 
 
 
 
 
 
tibialis posterior represents the entire r. communicans inferius.
 
The immediately succeeding part, which rests upon the mem-
 
brana interossea, is derived from the a. interossea. The terminal
 
part of the artery consists mainly of the r. calcaneus laterahs of
 
the a. peronaea posterior superficialis. The connection between
 
the a. interossea and the part of the latter artery which gives
 
origin to the calcanean branch is effected through the agency of
 
the plexus calcaneum.
 
 
 
The part of the a. interossea which takes part in the formation
 
of the a. peronaea has been noted as giving rise to a branch, the
 
r. coronarius, at the stage of 1 8 mm. At the present stage
 
another branch arises from it, namely, the r. perforans. Both
 
of them become branches of the adult artery. At the stage of
 
22 mm. the r. coronarius can be traced around the posterior
 
and medial aspects of the tibia almost as far as the a. tibialis
 
anterior. The views expressed by HyrtI upon the conversion
 
 
 
 
 
Fig. 9 Reconstructions sliowing tine arteries of tine riglit iower extremity in
 
tine seven liuman embryos slnown in tine preceding figures. Tine cepliaiic (em-
 
bryonic pre-axiai, aduit mediai) aspect is sliown in aii cases. A, X 40, tlie otiners
 
X 20 diams. Tine skeieton is sliown, in part, in E, F and G. Parts of the tibia
 
 
 
 
 
0. fervor.
 
 
 
a. ep'igast. inf.
 
r. scphen.
 
n. saphen
 
 
 
f. com. sup.
 
n. obtur.
 
a. axis
 
 
 
 
 
 
 
r. pert, tarsi
 
rete plantar.
 
 
 
n. tibial.
 
 
 
C. II mm.
 
 
 
a. tlloca exT.
 
a epigost inf.
 
a. circ. fern, lot)
 
 
 
a. fern or.
 
a. ischiad.
 
a. Tib. p. superf.
 
a peron. p. superf.
 
a. pop I. prof
 
a. recant, a.
 
r perf crur
 
a. inter OS.
 
r. perf tarsi,
 
rete. plantar.
 
 
 
0. ilioo ext.
 
a. epigost int
 
ore. fern. lot.
 
 
 
a. genu. Inf. med
 
a. recur, t.a.
 
a.tib.ant
 
 
 
 
 
 
 
p.dista/..
 
 
 
\a. pudend inf
 
a. Ischiad.
 
 
 
a. epigast. inf
 
a. circ.fem. ,ht
 
r. muse.-artie.,
 
r. saphen.
 
 
 
fib. p. supprf.
 
 
 
a. peron. p. s uperf.
 
 
 
r. caic. iot.
 
r. com. inf.
 
a. piant, fat
 
r pprf. tarsi,
 
rete piantar.
 
 
 
a. iscliiad.
 
a. popi. prof,
 
a. tib. p-superf
 
a. peron. p. superf.
 
a. piant, med.
 
 
 
piant, iot.
 
 
 
perf. tarsi.
 
 
 
 
 
 
 
rete plantar
 
ir.e mm.
 
 
 
and tarsus are omitted in E, tine tibia in F and tine tibia and mediai femorai
 
condyie in G. Tine fibuia is omitted in aii. Tine mediai piantar artery lias
 
been aimost entirely removed from E and F In C, a. femor. should read a.
 
iliaca ext.
 
 
 
of the r. coronarius into the communicating branch and medial
 
malleolar arteries of the adult have been noted above (footnote
 
10, p. 73).
 
 
 
A small portion of the a. peronaea posterior superficialis
 
appears at the present stage as a branch of the a. peronaea. It
 
runs upon the posterior surface of the m. flexor hallucis longus.
 
The disintegrating a. interossea has left a similar vestige of its
 
proximal end upon the posterior surface of its interosseous
 
membrane. This vestigial branch occasionally persists as a
 
branch of the adult a. tibiaUs anterior. '^'^ The terminal part of
 
the main trunk of the a. peronaea posterior superficialis is now
 
involved in the rete calcaneum. It usually leaves its mark in
 
 
 
 
 
 
 
the adult as a recurrent element among the leash of branches
 
known as the r. calcaneus medialis of the a. plantaris lateralis.
 
 
 
The aa iliolumbaUs and sacralls lateralis now arise from the
 
a. glutaea superior. The root of the latter artery has conse-
 
quently become the posterior division of the adult a. hypo-
 
gastrica. All the visceral arteries of the pelvis, with the excep-
 
tion of the a. vesicalis superior, have assumed their adult
 
relations.
 
 
 
h. Changes occurring in the principal arteries subsequent to the stage of 22 mm.
 
 
 
A. Formation of the adult a. poplitea and a. tibialis anterior.
 
Fig. 10, A, C. I. E. C, 22;B, C E. C, 1;C, C. I. E. C, 840.
 
 
 
The r. communicans medius, the presence of which was noted
 
at the stage of 22 mm., seems to arise at about that stage of
 
development. In C. E. C, no 1 , it is larger upon the right side
 
than upon the left and in C. E. C , no. 6, which also measures
 
22 mm., it is absent altogether.
 
 
 
" Mr. Kimbrig has kindly dissected six adult legs for evidence of persistence
 
of this vessel. In two instances he found a branch accompanying the n. interos-
 
seus cruris for a short distance. In both cases the branch arose from the root of
 
the ramus fibularis.
 
 
 
It is very questionable whether the B. N. A. is correct in classifying the r. fibularis as belonging to the a. tibialis posterior. It has usually been regarded, in English-speaking countries at all events, as a branch of the a. tibialis anterior.
 
 
 
 
 
At the stage of 20 mm. (fig. 10, A) blood traverses the pop-
 
Uteal region to reach the r, perforans cruris through the original
 
channel, namely the a. poplitea profunda. The a. poplitea
 
superficialis is longer than at the stage of 1 8 mm., having in-
 
creased in length at the expense of the aa. tibialis posterior
 
superficialis and peronaea posterior superficialis.
 
 
 
At the stage of 22 mm. (fig. 1 0, B), a junction between the
 
-developing a. peronaea and the distal part of the a. poplitea
 
 
 
Fig. 10 Three reconstructions, each showing a sagittal segment (0.25 mm.
 
thick) from the left leg of an embryo of the length indicated. Lateral aspect.
 
X 19. A, 20 mm.; B, 22 mm.; C, 24.8 mm. The tibia appears in all cases. P.
 
indicates the position of the m. popliteus. c. m., a. communicans media; g. i. m.,
 
a. genu inferior medialis; g. to., a. genu media; i., a. interossea; i. m., interosseous
 
membrane; p., a. poplitea; p. c, a. perforans cruris; p. d., a. tibialis anterior, pars
 
distalis; p. p., a. poplitea profunda; p. s., a. poplitea superficialis; -per., a.
 
peronaea; r. a., a. recurrens tibialis anterior; r. p., a. recurrens tibialis posterior;
 
 
 
 
 
 
 
t. a., a. tibialis anterior; t. p. s., a. tibialis posterior superficialis.
 
 
 
profunda has been effected by the development of the r. com-
 
municans medius. Blood may now pass from the proximal part
 
of the a. poplitea profunda to the a. tibialis anterior, pars dis-
 
talis by two routes: 1 ) anterior to the m. popliteus, by way of
 
the distal part of the a. poplitea profunda and r. perforans cruris,
 
or 2) posterior to the m. popliteus, by way of the a. poplitea
 
superficialis, developing a. peronaea, r. communicans medius, a.
 
poplitea profunda, and r. perforans cruris.
 
 
 
 
 
At the stage of 24.5 mm. (fig. 1 0, C) the direct arterial route
 
upon the anterior surface of the m. popliteus has ceased to
 
exist. The part of the a. pophtea profunda not incorporated in
 
the definitive a. pophtea or tibiahs anterior is represented:
 
1 ) by the root and a small branch of the a. genu inferior medialis
 
of the former and 2) by the a. recurrens tibialis posterior of the
 
latter. The main arterial channel through the popliteal region
 
has thus been transferred from the anterior to the posterior
 
surface of the popliteus muscle. Both the a. pophtea and the
 
a. tibialis anterior have assumed their adult arrangement.
 
 
 
 
 
The formation of the adult a. poplitea results from the combination of two embryonic elements. The part of the vessel
 
which extends from the hiatus tendinous to the origin of the a.
 
genu inferior medialis is derived from the embryonic a. poplitea
 
profunda. The remainder of the artery corresponds to the
 
embryonic a poplitea superficialis.
 
 
 
The embryonic components of the a. tibialis anterior consist
 
of the r. communicans medius, a short section of the distal end
 
of the a. poplitea profunda, the proximal part of the r. perforans
 
cruris, and the entire tibialis anterior, pars distahs.
 
 
 
The a. poplitea superficialis reaches completion at the stage
 
of 24.5 mm. by extending as far as the r. communicans medius
 
which then becomes one of its terminal branches. By this
 
means the a. peronaea rehnquishes its temporary participation
 
in the formation of the a. tibialis anterior.
 
 
 
B. The conversion of the embryonic a. tibialis posterior superficialis into the adult a. tibialis posterior.
 
 
 
The a. tibialis posterior superficialis is originally a branch of
 
the a. poplitea profunda and extends into the sole. The distal
 
portion of the artery, marked off from the remainder of the
 
vessel upon the development of the a. plantaris lateralis, becomes
 
the a. plantaris medialis. The proximal portion of the a. tibialis
 
posterior superficialis has blended with the corresponding section
 
of the a. peronaea posterior superficialis at the stage of 24.5 mm.
 
as far as the termination of the pophteal artery. The further blending between these two arteries wiiicli is to occur during
 
tine iater stages of deveiopment wiii cause tine migration of the origin of the a. peronaea from the terroination of the a. pophtea
 
to a point upon the a. tibialis posterior.
 
 
 
After the formation of the a. tibiahs posterior has been com-
 
pleted by the occurrence of these changes the vessel still retains
 
its original relation to the n. tibiahs. The relations between
 
the a. poplitea and the n. tibialis also differ from those of the
 
adult.
 
 
 
The entire a. pophtea hes upon the medial side of the n.
 
tibialis. The a. tibialis posterior crosses the medial side of the
 
nerve to gain its posterior aspect upon which it runs until it
 
ends behind the medial malleolus. The relations of the aa.
 
poplitea and tibialis posterior to the n. tibialis have been
 
thoroughly studied up to the stage of 22 mm. They seem to
 
remain unaltered in the oldest serially cut embryo which has
 
been examined in this regard. It is C. I, E. C, no. 1 134, which
 
measures 33.5 mm.
 
 
 
It is not difficult to see how an agency capable of moving the termination of tlie a. popiitea across tine anterior aspect of
 
tlie n. tibiaiis from tine mediai to tlie iaterai side wouid produce
 
a condition differing little from that normally encountered in
 
the adult. Since the knee is flexed throughout intrauterine life
 
it would seem that the modification of the relative positions of
 
the arteries and nerve might depend upon the straightening of
 
the n. tibiahs which occurs at birth. In order to put the matter
 
to the test, a foetus of 7.9 cm. was dissected, i- The relaMons,
 
however, were found to be identical with those of the adult.
 
 
 
Apart from the study of a few special points, this investigation
 
has not extended beyond the stage of 22 mm. At that period
 
all the vessels of the adult limb are present wdth the exception
 
of two of the three aa. perforantes, which usually arise from the
 
adult a. profunda femoris, the a. circumflexa femoris medialis,
 
and the a. obturatoria. At the stage of 22 mm. two obturator
 
veins are present in C. E. C, no. 1 , one of these is tributary
 
to the V. hypogastrica, the otiier to the v. femoralis.
 
 
 
The leading features in the process of the arterial development of the limb are indicated in figure 11 .
 
 
 
* 12 For this dissection and for many others made upon various mammals, I wish to express my indebtedness to Mr. B. Specter.
 
 
 
 
 
 
 
==III. Brief Developmental History Of The Individual Arteries==
 
 
 
A. Axis. This artery is a brancln of tine dorsal root of the a.
 
umbiHcaHs, its presence has been noted by Tandler as early as
 
the stage of 5 mm, '03). At the stage of 6 mm. it terminates by
 
giving origin to the r. perforans tarsi and to the rete plantare.
 
 
 
The axial artery has three rami communicantes, and gives
 
origin to three rami perforantes as follows:
 
 
 
The r. communicans superius, from the a. femoralis, joins it
 
near the hiatus tendinous shortly before the stage of 14 mm.
 
 
 
The r. communicans medius'^ from its own branch the a.
 
peronaea posterior superficialis, has joined it near the distal
 
border of the m. popliteus at the stage of 22 mm.
 
 
 
The r. communicans inferius, from the a. peronaea posterior
 
superficialis, joins it, near the distal border of the m. tibialis
 
posterior, between the stages of 1 7 and 1 8 mm.
 
 
 
The r. perforans cruris arises between the stages of 13 and
 
14 mm.
 
 
 
 
 
 
 
The r. perforans arteriae peronaea arises between the stages
 
of 18 and 22 mm.
 
 
 
The r. perforans tarsio is present at the eariiest stages of de-
 
veiopment at which the axiai artery has been observed.
 
 
 
Two points have been marked upon the axiai artery at the
 
stage of 14 mm. which may be used for the convenient sub-
 
division of the axiai artery into three parts. These points
 
correspond to the termination of the r. communicans superius
 
and to the origin of the r. perforans cruris, respectiveiy.
 
 
 
The respective parts of the artery are defined and named as
 
foiiows: The part upon the proximai side of the termination of
 
the r. communicans superius is the a. ischiadica, whiie that
 
upon the distai side, of the origin of the r. perforans cruris is
 
the a. interossea. That part intervening between the other two
 
is the a. popiitea profunda. Further information regarding the
 
axiai artery may be found under the headings devoted to the
 
description of its respective parts.
 
 
 
A. dorsaiis pedis. This artery is a channei through the embryonic rete dorsaie. Its importance dates from the appearance of the distal part of the a. tibiahs anterior which is developed
 
between the stages of 1 5 and 1 6 mm.
 
 
 
 
 
'''Fig. 11''' Diagram to iiiustrate tlie generai deveiopment of tine arteries of tine
 
liuman iower extremity. Aduit arteries are stippied and tlieir names underlined.
 
Tlie cliief embryonic cinanneis are outlined in black. The black line is
 
continuous only in the case of the axial artery, otherwise it is broken. The
 
letter P indicates the position of the m. popliteus; T, that of the m. tibialis
 
posterior, and H that of the m. flexor hallucis longus.
 
 
 
 
Branches. One of the adult rr. tarseae laterales represents
 
the dorsal end of the r. perforans tarsi, all other branches are
 
derived from the rete dorsale.
 
 
 
A. femoralis. This artery arises from the a. iliaca externa
 
 
 
 
 
 
 
between the stages of 1 1 and 12 mm. From the time of the
 
first appearance of the femorai artery its growing end is bifurcated into the r. communicans superius and the r. saphenus.
 
The r. communicans superius traverses the hiatus tendinous and
 
joins the a. axis between the stages of 12 and 14 mm., while the
 
r. saphenus terminates below the region of the knee-joint.
 
 
 
Branches. The A. profunda femoris seems to be derived from
 
an arterial plexus which envelops the femur as early as the stage
 
of 14 mm. The proximal end of the artery is distinguishable at
 
the stage of 22 mm. The a. circumflexa lateralis arises from the
 
femoral trunk shortly before the stage of 14 mm. Although this
 
artery is commonly regarded as a branch of the a. profunda, its
 
original connection with the a. femoralis is frequently retained
 
in the adult. The a. circumflexa medialis is not present at the
 
stage of 22 mm. One of the a. perforantes, the first or second,
 
is present at the stage of 22 mm., and is involved at that period
 
of development in an extensive arterial plexus connected with
 
the remainder of the distal part of the a. ischiadica. The other
 
perforating arteries are not present at the stage of 22 mm. The
 
a. pudenda externa is the only superficial inguinal branch present
 
at the stage of 22 mm. The a. genu suprema corresponds to
 
the part of the r. saphenus upon the proximal side of the origin
 
of the rr. musculares and articulares. These branches arise
 
directly from the a. femoralis, but have migrated to the embryonic r. saphenus by the stage of 22 mm. The distal portion
 
of the latter vessel corresponds to the r. saphenus of the adult.
 
 
 
A. hypogastrica. The main stem of this artery represents the
 
 
 
 
 
 
 
part of the dorsal root of the a. umbilicalis which lies beyond
 
the place of origin of the a. iliaca externa.
 
 
 
Branches. The anterior division of the a. hypogastrica is derived from the proximal part of the a. axis, which becomes the
 
 
 
a. glutaea inferior, from the root of the a. pudenda interna, and
 
from the part of the a. umbilicaHs beyond the distal end of its
 
dorsal root. The portion of the original a. umbihcalis which
 
contributes to the formation of the a. hypogastrica is the source,
 
in all probability, of all the visceral branches of the artery. The
 
a. obtoratoria is not present at the stage of 22 mm. In conse-
 
quence of the transference of the origins of the aa. iliolumbalis
 
and sacrahs lateralis to the a. glutaea superior, the proximal
 
part of that artery becomes the posterior division of the a.
 
hypogastrica.
 
 
 
A. iliaca communis. This artery is derived from the portion
 
of the dorsal root of the a, umbihcalis which lies upon the
 
proximal side of the origin of the a. iliaca externa.
 
 
 
A. iliaca externa. This artery already springs from the convexity of the a. iliaca communis at the stage of 8.5 mm. Its
 
 
 
 
 
 
 
termination is unbranclied until a period sliortly before tine stage
 
of 12 mm., wlien it divides into tine a. epigastrica inferior and
 
tine a. femoralis. Tine a. circumfiexa ileum profunda arise
 
from the a. ihaca externa between the stages of 18 and 22 mm.
 
 
 
A. interossea. The course of this part of the axial artery is described on page 73.
 
 
 
The a. interossea is joined before the stage of 1 8 mm. by the distal end of the r. communicans inferius. The junction occurs
 
at a point immediately beyond the inferior margin of the m. tibialis posterior. This artery has given origin to the r. coronarius at the stage of 18 mm. and to the r. perforans and to
 
the branch of communication with the a. peronaea posterior
 
superficialis at the stage of 22 mm.
 
 
 
The part of the a. interossea extending from the termination
 
of the a. popUtea profunda to the distal end of the r. communicans
 
inferius disappears between the stages of 1 8 and 22 mm. A
 
vestige of the proximal end of this part of the artery sometimes
 
persists in the form of a small branch of the a. tibialis anterior
 
or of the r. fibularis.
 
 
 
The small portion of the a. interossea which extends from the
 
distal end of the r. communicans inferius to that of the membrana
 
interossea persists as the third part of the a. peronaea (p. 79).
 
 
 
 
 
The branches which arise from this portion of the a. interossea
 
are transferred to the a.' peronaea. They are the r. coronarius
 
malleolaris, part of which becomes the adult r. communicans,
 
and the r. perforans. The remainder of the a. interossea has
 
lost its identity at the stage of 22 mm. The r. perforans tarsi
 
disappears at about the same period.
 
 
 
A. ischiadica. The course taken by this part of the axial
 
artery is described on page 73.
 
 
 
The continuity of the a. ischiadica has been broken in the
 
region of the glutaeal fold, at the stage of 22 mm. The proximal
 
part of the vessel, which has now become the a. glutaea inferior,
 
follows the V. ischiadica and the n. cutaneus femoris to the
 
surface of the limb where it ends by dividing into cutaneous
 
branches. The more distal portion of the artery is involved,
 
with the single perforating artery present at the stage of 22
 
mm., in the formation of an extensive plexus upon the posterior
 
surface of the m. adductor magnus.
 
 
 
A. peronaea. This artery is clearly recognizable at the stage
 
of 22 mm. (p. 79). It may be divided into four parts:
 
 
 
The first part of the a. peronaea, which extends from the
 
 
 
 
 
 
 
origin of tine artery to [he proximal margin of the m. flexor
 
hallucis longus, is a persisting portion of the a. peronaea posterior
 
superficialis (p. 74).
 
 
 
The second part, which lies between the m. tibialis posterior
 
and the m. flexor hallucis longus, represents the entire embryonic
 
r. communicans inferius (p. 76).
 
 
 
The third part, which is short and rests upon the interosseus
 
membrane near the distal border of the m. tibialis posterior, is
 
a persisting portion of the a. interossea (p. 73).
 
 
 
The fourth part, which ramifies upon the fibula and calcaneum
 
in the neighborhood of the lateral malleolus, represents a sur-
 
vival of the short portion of the a. peronaea posterior super-
 
ficialis and of the entire r. calcaneus lateralis of that vessel
 
(p. 74).
 
 
 
Branches. The r. perforans and r. communicans, belong
 
orig'nally to the a. interossea. The rr. calcanei laterales are .
 
branches of the r. calcaneus lateralis of the a. peronaea posterior
 
superficialis.
 
 
 
 
 
A. peronaea posterior super ficialis. The course of this em-
 
bryonic artery is described on pages 70 and 74. The main stein
 
of the vessel is present at the stage of 14 mm., its terminal
 
branches form their definitive connections at a stage of 1 5 or 1 6
 
mm.
 
 
 
The proximal part of the a. peronaea posterior superficiahs
 
unites with the a. tibialis posterior superficiahs to form the a.
 
pophtea superficiahs and the part of the a. tibiahs posterior
 
above the root of the a. peronaea. A more distal portion persists
 
as the first part of the a. peronaea, and a still more distal portion
 
enters slightly into the formation of the fourth part of that
 
vessel.
 
 
 
The terminal branches of the a. peronaea posterior super-
 
ficiahs form the adult a. plantaris lateralis. The r. calcaneus
 
medialis of the latter artery represents the end of the stem of
 
the parent vessel. The r. calcaneus laterahs, which arises from
 
the a. peronaea posterior superficiahs shortly before the stage
 
of 18 mm., persists to form the major portion of the fourth part
 
of the a. peronaea (p. 79).
 
 
 
A. plantaris lateralis. The proximal part of this artery
 
represents the medial terminal branch of the a. peronaea pos-
 
terior superficiahs (p. 71), which unites with the a. tibialis
 
posterior superficiahs. The distal part represents the lateral
 
terminal part of the same vessel.
 
 
 
 
 
 
 
Branches. The r. calcaneus medialis represents the terminal
 
portion of the main trunk of the embrj'^onic a. peronaea posterior
 
superficiahs. The arcus plantaris and all its branches are derived from the embryonic rete plantare.
 
 
 
A. plantaris medialis. This artery is the distal portion of the
 
embryonic a. tibialis posterior superficiahs. It is marked off
 
from the remainder of that vessel by the medial terminal branch
 
of the embryonic a. peronaea posterior superficiahs.
 
 
 
A. poplitea. The part of this artery above the origin of the a.
 
genu inferior medialis represents a surviving portion of the
 
embryonic a. poplitea profunda (p. 73). The part lying upon
 
the posterior surface of that muscle represents the embryonic a.
 
poplitea superficiahs. The proximal portion of the a. genu
 
inferior medialis is derived from the a. poplitea profunda.
 
 
 
 
 
Branches. The a. genu media is present at the stage of 18
 
mm. The other branches appear at a later stage of the
 
development.
 
 
 
A. poplitea profunda. The course of this vessel is described
 
on page 73. The part of the a. poplitea profunda which extends
 
 
 
 
 
 
 
from the hiatus tendineus to the origin of the a. genu inferior
 
mediaiis becomes the proximai part of the aduit a. popiitea.
 
The remainder of the artery is represented in part by the root
 
of the a. genu inferior mediaiis. It is represented aiso by the a.
 
recurrens tibialis posterior and by the second part of the a.
 
tibialis anterior (p. 84).
 
 
 
A. popiitea super ficialis. The formation of this artery results
 
from the gradual union which takes place between the proximal
 
part of the embryonic a. tibialis posterior superficialis and that
 
of the a. peronaea posterior superficialis. The vessel lies upon
 
the posterior surface of the m. popliteus and has nearly reached
 
completion at the stage of 22 mm. The a. popiitea superficialis
 
persists as the distal portion of the adult a., popiitea (p. 84).
 
 
 
A. tibialis anterior. This vessel may be divided into four
 
parts which correspond to the four embryonic components of
 
the adult artery.
 
 
 
The first part extends from the origin of the vessel to the root
 
of the a. recurrens tibialis posterior. It corresponds to the
 
whole of the r. communicans medius (p. 84).
 
 
 
The second part occupies the immediate neighborhood of the
 
origin of the a. recurrens tibialis posterior. It represents, like
 
that artery, a persisting portion of the embryonic a. popiitea
 
profunda (p. 84).
 
 
 
The third part extends from the a. redurrens tibialis posterior
 
 
 
 
 
 
 
to a point immediately beyond the root of tlie a. recurrens
 
tibialis anterior. It is derived from the proximal portion of
 
embryonic r. perforans cruris (p. 68).
 
 
 
The fourth part of the artery extends from the termination of
 
the third part to the proximal end of the a. dorsalis pedis. It
 
represents the entire a. tibialis anterior, pars distalis, of the
 
embryo (p. 72).
 
 
 
 
 
Branches. The a. recurrens tibialis anterior represents the
 
terminal portion of the a. perforans cruris (p. 68).
 
 
 
The a. malleolaris anterior medialis is derived from the r.
 
coronarius of the a. interossea which arises shortly before the
 
stage of 18 mm.
 
 
 
A. tibialis anterior, pars distalis. This embryonic artery
 
arises at about the stage of 15 or 16 mm. Its course is identical
 
with that of the fourth part of the a. tibialis anterior of the
 
adult.
 
 
 
A. tibialis posterior. The part of this artery proximal to the
 
origin of the a. peronaea is the product of the union between the
 
 
 
 
 
 
 
a. tibialis posterior superficialis and \he a. peronaea posterior
 
superficialis. Tlie remainder of tine vessel is a survival of the
 
part of the stem of the a. tibialis posterior superficialis proximal
 
to the point at which it is joined by the medial terminal branch
 
of the a. peronaea posterior superficialis.
 
  
Branches. The a. peronaea is described on page 90. The
+
a. malleolaris posterior derived from the embryonic r. coronarius malleolaris medialis of the a. interossea (p. 73).  
a. malleolaris posterior medialis and the r. communicans are
 
derived from the embryonic r. coronarius malleolaris medialis of  
 
the a. interossea (p. 73).  
 
  
A. tibialis posterior superficialis. The course of this artery,  
+
A. tibialis posterior super ficialis . The course of this artery, which arises shortly before the stage of 14 mm., is described on  
which arises shortly before the stage of 14 mm., is described on  
 
 
page 70.  
 
page 70.  
  
The whole of the a. tibialis posterior superficialis persists in  
+
The whole of the a. tibialis posterior superficiahs persists in the adult hfe. In combination with the a. peronaea posterior superficiahs, the more proximal part of the artery forms the part of the a. poplitea in contact with the m. popliteus and the part of the a. tibialis posterior proximal to the origin of the a. peronaea.* The more* distal part of the artery persists as the portion of the a. tibialis posterior beyond the origin of the a. peronaea and as the a. plant aria medialis.  
the adult life. In combination with the a. peronaea posterior  
 
superficialis, the more proximal part of the artery forms the  
 
part of the a. poplitea in contact with the m. popliteus and the  
 
part of the a. tibialis posterior proximal to the origin of the a,
 
peronaea. The more" distal part of the artery persists as the  
 
portion of the a. tibiahs posterior beyond the origin of the a.  
 
peronaea and as the a. plantaria medialis.  
 
  
The relation of the part of the a. tibialis posterior super-
+
The relation of the part of the a. tibialis posterior superficiahs which forms the a. tibialis posterior of the adult to the n. tibialis is discussed on page 84.  
ficialis which forms the a. tibialis posterior of the adult to the  
 
n. tibialis is discussed on page 84.  
 
  
 +
Rete dorsale. The dorsal rete of the embryonic arises from the r. perforans tarsi. It forms all the arteries which are distributed upon the dorsum of the adult foot.
  
  
Rete dorsale. The dorsal rete of the embryonic arises from  
+
Rete plantare. This embryonic plexus arises from the terminal branches of the a. interossea. It furnishes the arcus plantaris and all the other arteries of the adult sole excepting the aa plantares.  
the r. perforans tarsi. It forms all the arteries which are
 
distributed upon the dorsum of the adult foot.  
 
  
  
  
Rete plantare. This embryonic plexus arises from the terminal
+
<references/>
branches of the a. interossea. It furnishes the arcus plantaris
 
and all the other arteries of the adult sole excepting the aa.
 
plantares.
 
  
 
==Bibliography==
 
==Bibliography==
Line 4,330: Line 1,671:
 
Leboucq 1893 Verhandl. d. Anatom. Gesellsch., auf. d. siebenten Versamml. Anat. Anz., Erganzungsh. zum. B. 8.  
 
Leboucq 1893 Verhandl. d. Anatom. Gesellsch., auf. d. siebenten Versamml. Anat. Anz., Erganzungsh. zum. B. 8.  
  
Levy, G. 1902 Morphologia delle arteriae iliache. Parte 2. Archiv. Ital. di  
+
Levy, G. 1902 Morphologia delle arteriae iliache. Parte 2. Archiv. Ital. di Anat. edi Embriol., V. 295.  
 
 
Anat. edi Embriol., V. 295.  
 
  
 
McMuRRiCH, J.P.I 904 The development of the human body, 2nd ed., Philadelphia.  
 
McMuRRiCH, J.P.I 904 The development of the human body, 2nd ed., Philadelphia.  
Line 4,340: Line 1,679:
 
1894 Das Arteriensystem der unteren Extremitaten bei den Primaten. Anat. Anz., B. 10, S. 55 u. 99.  
 
1894 Das Arteriensystem der unteren Extremitaten bei den Primaten. Anat. Anz., B. 10, S. 55 u. 99.  
  
Qtjain, R. 1 844 The anatomy of the arteries of the human body. London.  
+
Quain, R. 1 844 The anatomy of the arteries of the human body. London.  
  
 
RxJG, C. 1 863 Anomalie der Arteria cruralis. Wtirzb. mediz. Zeits., B. 4, S. 344.  
 
RxJG, C. 1 863 Anomalie der Arteria cruralis. Wtirzb. mediz. Zeits., B. 4, S. 344.  
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[[Category:1910's]][[Category:Draft]][[Category:Limb]][[Category:Cardiovascular]]

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Senior HD. The development of the arteries of the human lower extremity. (1919) Amer. J Anat. 22:1-11.

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This historic 1919 paper by Senior described development of the arteries in the lower limbs. Note the later correction published in 1920 paper. Senior HD. The development of the human femoral artery, a correction. (1920) Amer. J Anat..


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1853 Bone | 1885 Sphenoid | 1902 - Pubo-femoral Region | Spinal Column and Back | Body Segmentation | Cranium | Body Wall, Ribs, and Sternum | Limbs | 1901 - Limbs | 1902 - Arm Development | 1906 Human Embryo Ossification | 1906 Lower limb Nerves and Muscle | 1907 - Muscular System | Skeleton and Limbs | 1908 Vertebra | 1908 Cervical Vertebra | 1909 Mandible | 1910 - Skeleton and Connective Tissues | Muscular System | Coelom and Diaphragm | 1913 Clavicle | 1920 Clavicle | 1921 - External body form | Connective tissues and skeletal | Muscular | Diaphragm | 1929 Rat Somite | 1932 Pelvis | 1940 Synovial Joints | 1943 Human Embryonic, Fetal and Circumnatal Skeleton | 1947 Joints | 1949 Cartilage and Bone | 1957 Chondrification Hands and Feet | 1968 Knee

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The Development of the Arteries of the Human Lower Extremity

H. D. Senior

Department of Anatomy, New York University

Eleven Figures

I. Introduction

a. General Considerations

It is well known that considerable differences exist between the various types of arterial distribution which are nor encountered in the pelvic limb of the different representatives of the mammalian series. In all mammals in which the developmental history of the arteries of the limb has been investigated, however, it has been found that the adult arterial system of the part results from the elaboration of two embryonic vessels. Both of the embryonic arteries in question take origin from the dorsal (secondaiy) root of the a, umbilicalis. One of them, the primitive artery of the limb, traverses the axis of the thigh and leg and divides into a number of branches for the supply of the foot. This vessel is present before the limb forms a distinct prominence upon the surface of the body and is known as the axial or ischiadic artery.


The other is an artery of later development which traverse the pelvis and the ventral region of the thigh. It joins the axial artery a short distance above the knee and gives rise to the a. iliaca externa, the a. femoralis, and the a. epigastrica inferior and to the branches which arise from these vessels. All other arteries of the limb arise from the axial artery itself or from the branches to which it gives origin.


Whether the relations of the embryonic axial artery to the other constituents of the limb are identical in the embryos of all mammalian forms is a question to Avhich direct observation of the vessel has not yet furnished an answer. Much indirect evidence bearing upon this subject is furnished by Zuckerkandl's comparative study of the arteries of the leg which appeared in 1895.


The study in question, although it is mainly concerned with the relations of the adult arteries, is influenced throughout by embryological considerations. It includes, in fact, a study of the arteries in a series of vertebrate embryos in which the mammalia are represented by the rabbit and cat. Zuckerkandl's work is obviously based upon the conception of the identity of the course of the axial artery throughout the mammalian series. It may be said that the general results of the investigation are greatly in favor of the correctness of the author's conception.


The principal relations of the axial artery of the embryo have been established by the present study. An adequate account of the relations of this and other arteries of the developing limb of one of the quadruped mammals would be of great value for purposes of comparison.

only consecutive account which has been given of the development of the arteries of the pelvic limb in any mammalian form is that of DeVriese, which appeared in 1902. It deals with the human embryo. The other papers contained in the literature of the subject are concerned with isolated stages in the development of one or more forms rather than with a complete history of the arteries of any particular mammal.


Hochstetter showed for the first time, in 1890, that the primitive artery of the mammalian thigh, which he termed the a. ischiadica, follows the course of the n. ischiadicus in the embryos of both the cat and the rabbit. He also described the development of the a. femoralis, which, appearing at a later stage, supersedes the proximal part of the a. ischiadica as the artery of the thigh. The secondary assumption of the original function of the a. ischiadica by the a. femoralis was shown to occur in man by DeVriese in 1902.


Hochstetter did not succeed in following the continuation of the a, ischiadiea through the leg. Leboucq, however, described it in 1893, as pursuing, in the human embryo, an axial course between the tibia and fibula and finally perforating the tarsus to reach the dorsum of the foot.

In 1894, Zuckerkandl described the continuation of the a. ischiadiea of the rabbit as traversing the flexor region of the leg and dividhig into a number of branches for the supply of the sole. He also described two branches of the artery which supply the extensor aspects of the leg and foot, respectively. In 1895 the same author described the perforating artery of the tarsus in rabbit embryos and made considerable progress in the nomenclature to the primitive artery of the limb.


In Zuckerkandrs second paper a distinction was made between the terms axial and ischiadic which formerlv had been used more or less interchangeably to denote the primitive artery of the

For the entire artery Zuckerkandl employed the name He restricted the use of the term ischiadic to the part of it which traverses the thiah and used the term a. interossea for the remainder of the vessel. The same paper contained the first accurate description which had been given of the distal part of the axial artery of any mammal. The a. interossea was described in the rabbit as lying between the interosseous membrane and m. tibialis posterior.


Grosser, in 1901, and DcYriese, in 1902, described the a. interossea (the a. nervi interossei cruris of the latter in bat and human embryos, respectively, as pursuing the course it had been described b}^ Zuckerkandl as following in the rabbit.


Both of these observers also recorded the presence, in subjects of their respective studies, of the r. perforans tarsi.

During the course of the present investigation it has become apparent that the existing literature contains no definite statement regarding the course taken by the part of the axial artery which traverses the popliteal fossa. It is questionable whether the popliteal section of the axial artery has been tacitly included as a part of the a. ischiadiea or not, since the distal limit of the latter artery does not appear to have been definitely fixed. In the following description the term a. ischiadica has been restricted to the part of the axial artery proximal to the site at which it is subsequently joined by the a, femoralis. restriction has necessitated the use of a new term for the part of the axial artery which extends from the hiatus tendineus (the approximate site of the femoro-ischiadic junction) to the point (in the neighborhood of the distal border of the m. popliteus) at which the a. mterossea begins.


An examination of the popliteal portion of the human axial artery shows that its distal part does not lie upon the posterior surface of the m. popliteus as does the distal part of the adult a, popliteal but upon the anterior surface of that muscle. It seems clear, therefore, that the distal part of the a. poplitea of the majority of adult mammals, which lies upon the anterior surface of the m. popliteus represents a persisting portion of the embryonic axial artery. On this account the name a. poplitea has been used in the following pages to designate entire popliteal section of the human axial artery.


The solution of Zuckerkandl's difficulty regarding the difference of the mutual relations between the a. poplitea and the m. popliteus in man on the one hand and in the majority of other mammals upon the other has thus been furnished by determining the course of the popliteal portion of the axial artery of the human embryo.[1]


The part of the adult human a. poplitea which extends from the hiatus tendineus to the origin of the a. genu inferior medialis is a direct survival of the embryonic a. poplitea profunda. The part of that artery which lies upon the posterior surface of the m. popliteus is derived from an embryonic vessel of later formation referred to in the following pages as the a. poplitea superficialis.


The literature dealine; with the arteries of the mammalian pelvic limb shows a tendency towards the perpetuation of a conception regarding the relation of the adult human a. peronaea to the embryonic a. interossea which Zuckerkandl has already shown to be erroneous. Stieda stated, in 1893, that the study of the variations of the arteries of the human leg had led him to the conclusion that the a. peronaea represents a persisting portion of the embryonic axial artery. A similar opinion regarding the between these two arteries was expressed by Zuckerkandl in 1894. In 1895 the recognition of the course of the a. interossea led Zuckerkandl to a modification of the views he had previously expressed upon the subject. He drew attention to the fact that it would be impossible for the part of the a. peronaea which is separated from the interosseous membrane by the m. tibialis posterior to be a derivative of the part of the a. interossea which lies between the membrane and the muscle. In 1902 DeVriese revived the conception of the identity of the aa. interossea and peronaea, notwithstanding the obvious justice of ZuckerkandUs contention.


A careful examination of the embryos which form the basis of the present study and of a large number of others belonging to the collection of the Carnegie Institution has been made in the search for a r. saphenus of the a. femoralis comparable in extent to that of the a. saphena which occurs very rarely in adult man and invariably in most of the other mammals. The result has been entirely negative.


That the a. saphena occurs occasionally in the huinan embryo is indicated by the fact that its presence has been noted at least five times in the adult. In the embryos examined in connection with the present study, however, the r. saphenus has not been found to extend in a single instance beyond the middle of the leg.

I take this opportunity of expressing my gratitude to Professor Thyng for the trouble he has taken in the revision of manuscript.

b. Material

In the present investigation the lower extremities of embryos have been studied in seven stages of develop)iient, one extremity or both having been reconstructed in wax. The selection of stages depended upon the accessibihty of well-preserved material rather than upon a preconceived plan regarding the most instructive stages to use.[1]

The following embryos have been studied, the right having been reconstructed in all cases. The embryos of which both lower limbs have been reconstructed are marked with an "+"


Embryo CRL Collection Catalogue No.
6.0 mm+ Carnegie Institution, Embryological Collection (C.T.E.C.) No. 1075
8.5 mm+ Cornell University, Embryological Collection (C.E.C.) No. 9.
12.0 mm+ Cornell University, Embryological Collection (C.E.C.) No. 3.
12.0 mm+ Minnesota, Embryological Collection (M.E.C.) No. H. 16.
14.0 mm Cornell University, Embryological Collection (C.E.C.) No. 5.
17. 5 (?) Harvard University, Embryological Collection (H.E.C.) No. 839.
18.0 mm Carnegie Institution, Embryological Collection (C.I.E.C.) No. 409
22.0 mm Cornell University, Embryological Collection (C.E.C.) No. 1.
Note: The following embryos have been studied, the right having been reconstructed in all cases. The embryos of which both lower limbs have been reconstructed are marked with an "+"
Carnegie Embryos - Senior (1919) - Lower Limb Blood Vessels 
Embryo CRL Collection Catalogue No.
6.0 mm+ Carnegie Institution, Embryological Collection (C.T.E.C.) 1075
8.5 mm+ Cornell University, Embryological Collection (C.E.C.) 9
12.0 mm+ Cornell University, Embryological Collection (C.E.C.) No. 3.
12.0 mm+ Minnesota, Embryological Collection (M.E.C.) H. 16
14.0 mm Cornell University, Embryological Collection (C.E.C.) 5
17. 5 (?) Harvard University, Embryological Collection (H.E.C.) 839
18.0 mm Carnegie Institution, Embryological Collection (C.I.E.C.) 409
22.0 mm Cornell University, Embryological Collection (C.E.C.) 1
Note: The following embryos have been studied, the right having been reconstructed in all cases. The embryos of which both lower limbs have been reconstructed are marked with an "+"
Reference: Senior HD. The development of the arteries of the human lower extremity. (1919) Amer. J Anat. 22:1-11.

For their generosity in placing their material at my disposal, I wish to express my great obligation to Profs. C. M. Jackson, F. T. Lewis, F. P. Mall, C, R. Stockard, and G. L, Streeter.


Toward the end of the investigation, there were a number of difficulties, for the solution of which the examination of rather close intermediate stages was required. Such stages were found in the collection of the Carnegie Institution at Baltimore.


In the formation of this valuable collection, so ably cared for and sympathetically administered. Professor Mall has available to his fellow workers a wealth of material adequate for the solution of any ordinary problem in human embryology.


The reconstruction of vascular plexuses in wax, using every second or fourth section as the case may be, is somewhat difficult. The practice followed has been to unite the parts of the adjacent plates which fit after careful adjustment and to remove those which do not join. In this way the plexus represented in the reconstruction is probably less dense than that occurring in the embryo. The reconstruction in fact, reproduces the spirit rather than the letter of the original.


In reconstructing the stage of 6 mm. consecutive sections were used, and these were comparatively thick (20 um). In this case the parts usually fitted so accurately that the plexuses, as reproduced, must represent, as nearly as possible, the actual conditions in the original.

c. Nomenclature

As already noted, the term a. poplitea profunda is used in the following account to denote the popliteal section of the embryonic axial artery. The term a, ischiadica and a. interossea have been retained for the proximal distal parts of that artery, respectively.

To the artery which normally perforates the tarsus of adult ungulates, and which has been recognized in all embryos hitherto observed, numerous terms have been applied.[2]

The name ramus perforans tarsi is used here.

For two of the embryonic arteries the names used by Hyrtl in 1864 have been retained. They are the r. coronarius (of the medial malleolus) and the a. peronaea posterior superficialis.

The description of a number of embryonic vessels, the existence of which has not been noted heretofore, has necessitated the use of several new terms. These conform, as nearly as may be, with current usage.


In referring to the relative positions of the structures of the limb, the adult terms of orientation have been used throughout. This course has been adopted in order to avoid the confusion which might arise from the alternative use of two sets of terms in making comparisons between the relative positions of structures in the adult and embryonic limb, respectively.


The limb preserves its primitive position which, with the exception of progressively increasing flexion of the knee, remains unchanged throughout the period of development under consideration. The flexor aspect of the embryonic thigh and leg and the plantar aspect of the sole are directed medially; the great toe is preaxial or cephalic. The term posterior for the adult has, therefore, the same significance as the term medial for the embryo; so have, respectively, the terms anterior and lateral, medial and pre-axial, lateral, and post-axial. For the parts above the hip-joint there can be no possibility of confusion, since like terms of orientation serve equally well for the postnatal and embryonic periods.

II. The Arterial System Of The Lower Limb In Progressive Stages Of Development

a. Stage of 6 mm

C. I. E. C, no. 1075, figs, 1 and 9 A

In the lumbar region the nerve roots are not recognizable. The ganglia of the lumbar and sacral regions appear as segmentally disposed swellings upon the continuous neural crest. Distal to the second lumbar segment the postcardinal vein becomes plexiform. The medial part of the plexus receives the segmental veins, the lateral part represents the still indefinite marginal vein.


The dorsal segmental arteries, with the exception of the fifth lumbar and second sacral, pass directly to the spinal cord with arteries, the ventral roots of which are still very large, arise opposite the intervals between the third and fourth lumbar segmentals.


The secondary, or dorsal, roots of the umbiUcal arteries are present, but are smaller than the original or ventral roots of that vessel. Each dorsal root, in the embryo under consideration, arises from the union of two arteries.


The chief share in the formation of the dorsal root of the a. umbilicalis is taken by a vessel which arises from lumbar segmental artery a short distance beyond its root, vessel in question is joined almost perpendicularly near its origin by a smaller one which springs from the aorta in interval between the fourth and fifth lumbar segmental arterie

The dorsal root of the a. umbihcalis; which may be said -to begin at the junction of the two vessels mentioned above, continues the transverse direction of the larger of the two, until it reaches the dorsal aspect of the Wolffian duct of its own side. In this situation it turns vent rally, passing upon the lateral side of the duct, w is now enclosed between the two roots of the umbilical artery, to join the ventral root. As the dorsal root of the a. curves around the lateral side of the Wolffian duct it gives origin to the axial artery of the lower extremity and to the a. pudenda interna.

The axial artery, takes an almost transverse, slightly recurrent, course towards the surface. It ends by dividing into two branches, each of which breaks up into a plexus which passes over into the postcardinal venous plexus. The a. pudenda interna follows the dorsolateral surface of the Wolffian duct towards the urogenital sinus and enters the pelvic arterial plexus.


Senior1919 fig01.jpg

Fig. 1. Reconstruction showing the distal end of the aorta; also the arteries of the right lower extremity and neighboring parts in a human embryo of 6 mm. C.I. E.G., 1075). Medial aspect. X 40 diams.


In addition to the arteries already described, there are two extensive arterial plexuses, which may be called the abdominal pelvic plexuses, respectively. Of these the abdominal arises by seven or eight stems from the concavity of the umbilical artery somewhat distal to the junction of its two roots. It invades the flexor region of the thigh, although it is uncertain to what extent, for the lower limb bud is not distinctly circumscribed at this period.


The abdominal plexus has no connection whatever with the segmental arterial series. It is drained partly by postcardinal plexus, but mainly by the umbiucal vein. The plexus arises by two roots from the convexity of the umbilical artery opposite the roots of the abdominal plexusi It covers the cloaca and receives the pudendal artery and a large branch from the second sacral segmental. It is drained, by the postcardinal plexus. The abdominal and pelvic plexuses appear to be connected by a few vessels passing to the umbilical artery: It is probable that all the visceral branches of the adult a. hypogastrica (excepting the superior vesical) arise out of the primitive pelvic plexus of the original umbilical artery. The branches (as far as they are present before the stage of 22 mm.) arise from, or very near to, the axial artery. They are therefore connected with the dorsal root.[3]

This stage agrees in most essentials with the 5-mm. embryo (II) described by Tandler (^03). The inferior mesenteric artery arises opposite the first lumbar segmental.


b. Stuge of 8.5 mm

C. U. C., no. 9, figs. 2 and 9 B

The femoral, obturator, genitofemoral, and peroneal nerves are readily recognized as short relatively unbranched trunks. The extremity of the tibial is divided into what appear to be the medial and lateral plantar nerves.


The aa. umbilicales have lost their original (ventral) roots now spring from the aorta in the intervals between the fourth and fifth dorsal pairs of lumbar segmental arteries.[4] The fifth lumbar segmental arteries have thus regained their independence, and, like the other segmental arteries in this region, pass to the spinal cord without branching.


The axial artery passes distally into the lower Umb, crossing the n. tibialis posteriorly from the medial to the lateral side. It then follows the posterior aspect of the skeletal mesenchyme throughout the leg into the sole. In the latter situation it breaks up into a flattened plexus which extends somewhat beyond the extremities of the plantar nerves. Just as it is breaking up axial which pierce

Senior1919 fig02.jpg

Fig. 2. Reconstruction showing the arteries of the right lower extremity in a human embryo of 8.5 mm. (C.E.C.; 9). Medial aspect. X 20 diams.

Senior1919 fig03.jpg

Fig. 3. Reconstruction showing the arteries of the right side of the pelvis, right thigh, leg, and dorsum of the foot in a human embryo of 12 mm. (M.E. C.,H. 14). Medial aspect. X 20 diams,

mesenchymal foot reach

Up


perforating branches prod

another flattened plexus- The two plexuses (or retia) of the foot are separated from one another by the mesenchymal skeleton of the foot, the plantar rete lying between the latter and the plantar nerves.


In passing from the medial to the lateral side of the sacro- axial artery runs between the main plexus

The branch referred to has

pudendal plexus, the and a branch from i been removed from the reconstructions illustrated in figures 1 to 6, since it partially covers the artery when viewed from the medial side.


aspect of the concavity of the umbilical artery, some distance proximal to the origin of the axial artery, there now arises a new vessel, the a. iliaca externa. This vessel takes a cephalic direction, nearly parallel to the aorta, coursing medially to the origin of the obturator nerve. At this stage the wall of the external iliac artery is .thin and its course slightly tortuous. The artery is not connected with the dorsal segmental arterial series or with any other artery. The further history of the external iliac is rather remarkable. It soon becomes quite straight and acquires a wall of great thickness, but remains unbranched until a stage of (approximately) 12 mm. externa appears as a thick-walled straight artery in the well- known pig embryo of 12 mm.


The place of origin of the a. iliaca externa marks the permanent subdivision of the dorsal root of the umbilical artery into two parts. The part becomes the adult a. iliaca communis while the distal part represents the a. hyjDogastrica and a short proximal section of its

al branch. At marginal vein is fully formed; its caudal

root, represented by the v. ischiadica, runs in close contact with the proximal of the corresponding artery


c. of 12 mm

M. E. C, no. H. 16, figs. 3 and 9 C

Condensation of the mesenchymal skeleton is now well advanced. It is not sufficiently definite in the tarsal region, however, for the determination of the course taken by the connection between the axial artery and the dorsal rete of the foot, surfaces of the growing nerves are considerably roughened by the beginning outgrowth of numerous branches^ many of which can be identified.


The course of the axial artery is somewhat less straight than in the preceding stage. This is due chiefly to a sharp convexity directed toward the growing extremity of the a. femoralis. The convexity is surmounted by a short sprout indicating the point


at w


the femoral is later to unite with

Although the axial artery is straighter in the

than at the stage of 12 mm., an irregularity is

preceding stage

at the

stage of 8.5 mm. in a similar situation. It seems to represent


an earlier indication of the convexity the present stage of dev Distal to the knee the between the tibia and

is so pronounced at

artery lies in the narrow interval The interosseous membrane and

muscles are still unrecognizable, but, although the ges toward the extensor region, its course


artery

clearly indicates that it does not leave the flexor aspect of the

Ipcr


proximal

econd bend

This bend is so pronounced as to practically amount to the bud of the vessel which is shortly to grow into the extensor aspect of the leg from this point.

The dorsal and plantar retia of the foot are richer than in the preceding stage. The connection between the axial artery and

the dorsal rete is r. perforans tarsi.


The a.

externa has


into the a. epigas

inferior and the a. femoralis.® The latter is contrasted sharply from the a. iliac externa by the thinness of its walls, which con- sist of endothelium only. Its structure resembles very closely that of the femoral vein which accompanies it. The

runs parallel with and upon the medial side of the n.

nus. Its extremity, now about half way along the femur, is bifurcated into a lateral and a medial branch. The former is

and will later join the axial artery; it may be called the


  • That the a. epigastrica inferior is an indejiendent branch of the a. iliaca externa, which considerably antedates it and the a. femoralis in has already been pointed out by the writer (Senior, '17).


ment,

ramus commumcans superius

The latter is

er

and

IS

recognizable as the ramus saphenus of the a. genu suprema.

The difficulty in finding developmental stages in which the a. femoralis is present, but not yet united with the axial artery, coupled with the thinness of the wall of the femoral artery at this stage, indicates that the artery is one of extremely rapid growth. In a 12-mm. embryo slightly younger than the specimen described (C. E. C, No. 3), reconstruction was begun under the impression that the femoral was absent. After more thorough study the artery was identified, bifurcated as in IVI. E. C, No. H 16, but much shorter. At this stage the a. femoralis has no branches, other than the terminal bifurcation already referred to.

m

d. Stage of I4 mm

C E. C, no. 5, figs. 4 o.nd 9 D

the a. femoralis in the blood

of the leg and by the

the two

appearance of three branches of the axial artery.

The r, communicans superius of the a, femoralis has joined axial artery at the more proximal noticed in the preceding stage.

can be traced to the level of t the more distal bend of tl

bend


The r. sa

remam

branch

proximal end

space and takes a recurrent course toward


The

proxim

formation

a. tibialis anterior.

may be referred to as the ramus cruris. The recurrent vessel continuing from the r. perforans cruris is the arteria recurrens tibialis anterior of the


The


k.


upon the axial artery by means of the r. and by the origin of the r. perforans

cruris, respectively, may be used tor tlie convenient subdivision of the vessel into three parts. The part upon the proximal side


of the r. communicans superius w

be

to as

a.

ischiadica and that upon the distal side of the r. perforans cruris

Senior1919 fig04.jpg

Fig. 4. Reconstruction showing the arteries of the right side of the pelvis and right thigh and leg in a human embyro, of 14 mm. (C.E.C., 5). X 20 diams.

Senior1919 fig05.jpg

Fig. 5. Reconstruction showing the arteries of the right side of the pelvis and right lower extremity in a human embryo of 17.6 mm. (H.E.C., 839). aspect. X 20 diams.

Senior1919 fig06.jpg

Fig. 6. Reconstruction showing the arteries of the right side of the pelvis and right lower extremity in a human embryo of 18 mm. (C.E.LC, 409) X 20 diams.


as the a. interossea- The intervening jDart will be called the a. poplitea profunda.

At this stage the a. poplitea profunda has two branches which course longitudinally through the posterior crural region. One of these resembles, in a general way, the a. tibialis posterior of the adult, it may be called the a. tibialis posterior superficialis.

The slightly more


in its place of


origin is the a, peronaea posterior superficialis (of HyrtVjJ The relations borne by these arteries to the n. tibialis remain constant throughout a prolonged period of development.

The a* tibialis posterior superficialis passes at first backward

side of the n. tibialis to reach its posterior aspect. Running upon the posterior aspect of the n. tibialis in the leg, it passes into the sole upon the inferior aspect of the n.


plantaris


t of the artery which enters the sole becomes the a. plantaris medialis of the adult.

The a. peronaea posterior superficialis passes from the to the lateral aspect of the n. tibialis by skirting around


proximal and


s of a large muscular ramus of the


nerve. It follows the anterior and lateral aspect of the n. tibialis as far as the place of origin of the nn. plantares. In this situation the artery bifurcates into a lateral and a medial The branches are both short and end blindly.


Two branches now spring from the lateral side of the a.

One of these is situated upon the proximal side of the r. saphenus and represents the r. musculo-articularis of the .adult a. genu suprema. The other is the a. circumflexa femoris lateralis of the adult a. profunda femoris.

The branches arising from the medial side of the a. femoralis which will be discussed under stages E and F.

The a. glutaea superior is present and takes origin from the

root of the a. ischiadica.


^ According to the system of nomenclature in use at the present time, the iective 'posterior' as used by Hyrtl is redundant. In view of the essentially


fugitive nature of anatomical terminology it has seemed unnecessary to modify Hyrtl's original term, which adequately meets the requirements of the case.

i musculares for the mm. popliteus,


s This is resolved later into the tibialis posterior, flexor digitorum longus, and flexor longus hallucis.


e. Stage of 17.8 mm

H. E. C.^ no. 839,^ figs. 5 and 9 E

During the iDreceding stages of develoi3ment the arterial retia of the foot have received their blood supplj^ exclusively through the a. interossea; the reta plantare directly, and the rete dorsale by means of the r. perforans tarsi. The mesenchymal skeleton of the foot is now definitely circumscribed, and it is plain that the latter vessel reaches the dorsum by way of the tarsal sinus. The arterial retia of the foot lie in close contact with the tarsus and metatarsus and represent the following vessels of the adult circulation — the arcus plantaris and its articular branches, the aa. tarseae mediales and laterales, the a. arcuata, the aa. metatarseae and digitales (both dorsal and plantar), and the rami perforantes (including the ramus plantaris profundus).


The present stage is characterized by the presence of four arteries which traverse the leg for the supply of the sole. The a. interossea is still present, the aa. tibialis posterior superficialis and peronaea posterior superficialis have formed their definitive connections, and a new vessel, the a. tibialis anterior, pars distalis, has arisen.


The a. tibialis posterior superficialis and the a. peronaea posterior superficialis preserve in the leg the same relations to the n. tibialis as obtained in the preceding stage. At the ankle the medial terminal branch of the a. peronaea posterior super- ficialis has traversed the fork formed by the diverging plantar nerves to join the a. tibialis posterior superficialis. The lateral terminal branch of the same artery has reached the lateral side of the sole to join the plantar arterial rete. The connection thus formed between the a. rete plantare becomes the a. plantaris lateralis of the adult foot. At the present stage of development it receives blood from two


  • The greatest total length of this embryo, measured in formalin, was 17.8 mm. In 80 per cent alcohol it measured 13.6 mm. It has been described by Thyng as a 17.8 mm. embryo (Am. Jour. Anat., vol, 17, p. 31), and referred to by Thyng (Am. Jour. Anat., vol. 7, p. 489) and hy Thyng and Lewis (Am. Jour. Anat., vol. 7, p. 505) as an embrj^o of 13.6 mm. The distribution of the arteries of the lower extremity resembles that of other embryos of about 15 or 16 mm.


The part of the a. tibiaus posterior superncialis distal to the origin of the a. plant aris lateraUs now the a. plantaris mediahs. The portion of the remainder of that, vessel which is not concerned in the formation of the a. poplitea. becomes the a. tibialis posterior.


The branches of the medial plantar artery anastomose, upon the lateral side of the foot, with the plantar rete, thus consti- tuting a (transitory) superficial plantar arch.


The a. tibialis anterior, pars distalis, extends from the part of r. perforans cruris which lies in the extensor region of the leg to the rete dorsale. The portion of the r. perforans which now lies beyond the proximal end of the pars distalis corresponds to the adult a. recurrens tibialis anterior. The portion which extends, from the a. poplitea profunda to the pars distalis enters into the composition of the adult a. tibialis anterior. The a. recurrens. tibialis anterior is connected by means of a plexiform anastomosis, with the r. saphenus of the a. femoralis.


Upon the medial side of the a. femoralis there are at this, stage three branches exclusive of the r. saphenus. Of these the most distal, which has a longer individual course than the others, takes a recurrent direction. The three branches break up to form an extensive plexus (not indicated in the figures) which ramifies throughout the thigh and is particularly rich around, the perichondrium. It is probable that this plexus is eventually taken over by the adult a. profunda femoris and its branches. Two branches arise from the lateral side of the a. femoralis as. in the preceding stage.

The a. glutaea superior now takes du-ect origin from the a. hypogastrica upon the proximal side of the origin of the a. ischiadica.


Stage of 18 mm

C. I. E. C, no. 409, figs. 6 and 9 F

From the time of the junction between the r, communicans

superius and the axial artery the caHber of the a. femoralis has

exceeded that of the a. ischiadica^ which has now become exceedingly slender. After having traversed the lower of the sacropudendal plexuS; the a. ischiadica passes.

to the region of the hiatus tendineus upon the lateral side of the n. tibiaUs. The n. peronaeus lies immediately upon its lateral


In a general way the aa. poplitea profunda and interossea and their branches have the same arrangement as in the preceding stage. The exact course taken by these vessels can now


ed, since it is possible to identifv the individual


muscles of the limb.

The a. poplitea profunda runs between the m. popliteus and

. At the proximal border of the muscle the artery gives off the a. genu media and a short trunk which is being formed by the progressive union of the proximal ends of the aa. tibialis posterior superficialis and the a. peronaea posterior super- ficialis. This short trunk, which lies upon the posterior surface of the m. popliteus, may now be called the a. poplitea super- ficialis. It forms the distal part of the a. poplitea of the adult. A short distance below the origin of the a, poplitea superficialis there arises the a. genu inferior medialis.

The a. interossea passes down the leg between the m. tibialis posterior and the interosseous membrane. Just above medial malleolus it gives off a branch which passes around the posterior to the medial side of the tibia, the ramus coronarius of the medial malleolus (Hyrtl).^^ At the malleolus the a.

  • In this vessel lies, according to Hyrtl, the key to the deep supramalleolar

anastomosis (i.e., the r. communicans) between the a. perong^ea and the a. tibialis posterior. The r. coronarius is regarded by Hyrtl as primarily passing from the a* peronaea around the medial side of the tibia to unite with the a. tibialis anterior. By means of a secondary connection occurring between the r. coronarius and the a. tibialis posterior, the former vessel eventually becomes converted into an anastomosing chain in which the aa. malleolaris anterior medialis, malleolaris posterior medialis and r. communicans are the named components. At the stage of 18 mm. of this series the r. coronarius arises from the part of the a. interossea which persists to take part in the formation of the adult a. peronaea. It runs, at this stage, as at the stage of 22 mm,, toward the a. tibialis anterior as described by Hyrtl, and would, no doubt, eventually join it. Since in both these stages the a. tibialis posterior is situated upon a plane superficial to that occupied by the r. coronarius, no junction of the vessels in question has occurred. There can be little doubt, however, that Hyrtl has interpreted the nature of the r. coronarius correctly. His views upon this subject, which were derived from an extensive study of the normal and abnormal conditions found in adult legs, have been of the greatest assistance in the interpretation of the conditions obtaining during development.


interossea lies upon the lateral side of the tendon of the m. tibialis posterior (i.e., between tendon and malleolus) and then passes across the plantar end of the sinus tarsi to join the plantar

rete.

The a. peronaea posi^erior superficialis is placed anteriorly and laterally to the n. tibialis and lies upon the posterior surface of the m. flexor hallucis longus. At the distal border of the muscle the artery lies near the a. interossea and interosseous membrane. In this situation it gives off a very large r. calcaneus lateralis which runs upon the lateral side of the tuber calcanei. This branch eventually forms the termination of the a. peronaea.


The a. tibialis posterior superficialis follows the posterior surface of the n. tibialis until the latter bifurcates in the neighborhood of the medial malleolus. Here the artery is placed between the n. tibialis and the tendon of the flexor hallucis longus. The a. tibialis anterior, pars distalis, has relations identical with those of the adult.


The relations existing between the various structures of the leg were ascertained by making a reconstruction which, from the fact that it yields but little information when entirely built


up, IS uns



The data gained from an examination of its separate parts are embodied in two diagrams (fig 7, A and B) which may serve as a rough guide to the inter- pretation of anomalies. These diagrams show, approximately, the course taken by the embryonic aa. poplitea profunda,


interossea, and peronaea posterior superficialis.

The order in which the various structures passing from the leg to foot are arranged in the hollow between the medial mal- leolus and tuber calcanei is as follows: m. tibialis anterior and a. interosseus together: m. flexor digitorum longus; a. peronaea


posterior superficialis; n. tibialis, a. tibialis posterior super- ficialis, and m. flexor hallucis longus.

Embryos of about this age are instructive mainly by reason of the fortunate circumstance that the individual muscles are


differentiated before the continuity of the axial artery has been broken. Only one important change has occurred at this stage of development; this consists in the appearance of a communicating branch which foreshadows the development of the

^e a. peronaea.

. The communicating branch in question leaves the a, peronaea posterior superficialis at the proximal border of the m. flexor

gus. It passes distally between the mm. flexor hallucis longus and tibialis posterior to join the a. interossea, as that artery lies upon the interosseous membrane. It may be called the r. communicans inferius.


Senior1919 fig07.jpg

Fig, 7. Indicates the course of three arteries of the embryonic lower extremity, represented diagrammatically as they would appear if persisting in the adult. The vessels which normally persist are indicated by shading. A, A. poplitea profunda and a. interossea. B. A. peronaea posterior superficialis. d. L m. flexor digitorum longus; h, L, m. flexor hallucis longus; L p., m. tibialis posterior.



The entire r. communicans inferius persists in the adult as the portion of the a, peronaea which lies between the mm. flexor hallucis longus and tibialis posterior. The portions of the aa. peronaea posterior superficialis and interossea with which the


and distal ends of the r. communicans inferior are


connected


a* peronaea.


Of the branches of the a* femorahs^ those arising from the

lateral side are identical with the branches of the preceding stage. There are three branches upon the medial side, recurrent branch {R in figures) seems to be identical with the



similar branch of the preceding stage. It is doubtful whether the two other medial branches correspond to those observed in the preceding stage or not.


g. Stage of 22 mm

C /. C no. 1, figs. 8 and 9 G


At this stage of development the continuity of the a. ischiadica has been interrupted and the a. femoralis alone conveys blood to the region beyond the knee.

The femoral artery pursues a more direct course than before and gives origin to most of its important branches. In addition to the a. circumflexa lateralis which appeared at the stage of 14 mm., it gives origin to the a. pudenda externa and the a. profunda. The r. musculo-articularis has migrated to the em-




nic r. saphenus. The root of the latter branch, now appears as the a. genu suprema and gives origin to the r. saphenus and the rr. muscularis and articulares of the adult.

The a. profunda arises from the a. femoralis quite close to the origin of the a. circumflexa lateralis. It seems probable that

onic a. profunda sometimes arises from the root of the latter artery and sometimes directly from the femoral. In the former case the adult a. circumflexa lateralis would appear to arise from the a. profunda and in the latter from the femoral. The great variation in the site of the origin of the vessel is well known.

The a. profunda femoris gives origin to one perforating artery y since it pierces the adductores brevis and magus, repre- sents the first or second of the adult series. The single a. per- forans is connected, by means of an extensive plexus, with the more distal section of the now interrupted a. ischiadica.


The a. ischiadica passes through the sacropudendal j^lexus as before and reaches the lateral side of the a. tibialis, which is now contained in the same sheath as the n. peronaeus. After its exit from the pelvis the artery gives origin to a few gluteral branches and leaves the n. tibialis with the n. cutaneus femoris posterior. In company with the latter nerve and the v. ischiadica, it passes to the posterior surface of the thigh and ends dividing into several cutaneous branches. This part of the a. ischiadica persists as the a. glutaea inferior.

The more distal portion of the a. ischiadica is traceable as a definite path through a plexus upon the posterior surface of the m. adductor magnus, but has lost its continuity wdth the a.



pophtea. The other vessel participating in the


of


the plexus is the perforating branch of the a. profunda femoris. This plexus evidently represents the terminal anastomosis between the perforating arteries of the adult. It probably takes a large share in the formation of the perforating arteries themselves.

The distal part of the anterior tibial artery has received blood since the time of its first appearance by way of the a. poplitea profunda and r. perforans cruris. An alternative path has now

by the appearance of a vessel which, passing

of the m. popliteus, connects the

around

distal

developing a. peronaea with a more distal part of the a. poplitea profunda. It is the r. communicans medius which will later become the definitive proximal end of the a. tibialis anterior. The significance of this vessel in relation to the formation of the adult aa. profunda and tibialis anterior will be dealt with in the succeeding section.

The principal changes which have occurred in the embryonic arteries of the posterior crural region since the preceding stage

participate in the

of development involve the vessels

formation of the adult a, peronaea- These changes cons' st in the disappearance of considerable parts of the aa, interossea and peronaea posterior superficialis.

The portion of the a. interossea which formerly extended from the r. perforans cruris. to the distal end of the r. communicans

Senior1919 fig07.jpg

Fig. 8. Reconstruction showing the arteries of the right side of the pelvis and right lower extremity in a human embryo of 22 mm. (C.E.I.C, 1.). Medial aspect. X 20 diams.

inferius has practically disappeared. The portion immediately beyond the distal end of the latter vessel lies upon the posterior surface of the interosseus membrane and gives origin to two branches. The remainder of the vessel is involved in the meshes of the rete calcaneum.

The portion of the a. peronaea posterior superficialis which extends from the present termination of the a. popUtea super- ficialis to the proximal end of the r.


commumcan

sists the re


of the

become a part of the adult a. peronaea. ainder of the artery has been lost, but th essel can still be recognized as forming a

aspect of the rete calcaneum. Thi

A large part of artery can be traced through the meshes of the rete as far as

the a.

The rete calcaneum is very

ive at this stage of develop

ment and occuT^ies the concavity upon the medial side of the

surrounds the

m


the


malleolar region of the leg.

The component parts of the a. peronaea are now recognizable. The proximal part is derived from the a. peronaea posterior super-

hallucis longiis and

The

between tibialis posterior represents the entire r. communicans inferius. The immediately succeeding part, which rests upon the mem- brana interossea, is derived from the a. interossea. The terminal part of the artery consists i the a. peronaea posterior su of the r. calcaneus lateraUs of . The connection between

the a. interossea and the part of the latter artery which gives origin to the calcanean branch is effected through the agency of


the plexus calcaneum.

The part of the a. interossea which takes part in the formation of the a. peronaea has been noted as giving rise to a branch, the r. coronarius, at the stage of 18 mm. At the present stage another branch arises from it, namely, the r. perforans. Both


of them become branches of the adult artery. At the stage of 22 mm. the r. coronarius can be traced around the posterior and medial aspects of the tibia almost as far as the a^ tibialis anterior. The views expressed by Hyrtl upon the conversion


Fig. 9 Reconstructions showing the arteries of the right lower extremity in the seven human embryos shown in the preceding figures. Tlie cephalic (embryonic pre-axial, adult medial) aspect is shown in all cases. A, X 40, the others X 20 diams. The skeleton is shown, in part, in E, F and G. Parts of the tibia


a femon a. eplgast. inf.


r. SQphtn.


n SGphen,


I: com. sup. n. obtur.

r. perf, tarsj retc


a pudend int

n, tiblol


C /2 n7An.


and tarsus are omitted in E, the tibia in F and the tibia and medial femoral condyle in G. The fibula is omitted in all. The medial plantar artery has been almost entirely removed from E and F. In C, a. femor. should read a. iliaca ext.


of the r. coronarius into the communicating branch and medial malleolar arteries of the adult have been noted above (footnote 10, p. 73). A small


of

a. peronaea posterior super



I

appears at the present stage as a branch of the a. peronaea. It runs upon the posterior surface of the m. flexor hallucis longus. The disintegrating a. interossea has left a similar vestige of its


'osseous


proximal end upon the posterior surface of its membrane. This vestigial branch occasionally persists as a branch of the adult a. tibialis anterior.^^ The terminal part of the main trunk of the a. peronaea posterior superficialis is now involved in the rete calcaneum. It usually leaves its mark in the adult as a recurrent element among the leash of known as the r. calcaneus medialis of the a. plantaris


The aa. iliolumbalis

sacralis lateralis now arise from



a. elutaea



The root of the latter artery has conse-


quently become the



division of the



a. hypo-


gastrica. All the visceral arteries of the pelvis, with the

their



of the a. vesicalis superior, have



relations


h. Changes occurring in the principal arteries subsequent to stage of 22 mm .


A. Formation of the adult a. poplitea and a. tibialis anterior.


Fig. 10, A, C. I. E. C, 22; B, C E. C, 1; C, C. I. E. C, 840.

The r. communicans medius, the presence of which was noted at the stage of 22 mm., seems to arise at about that stage of

In C. E. C, no 1, it is larger upon the right side than upon the left and in C. E. C , no. 6, which also measures 22 mm., it is absent altogether.



  • ^ Mr. Kimbrig has kindly dissected six adult legs for evidence of persistence

of this vessel. In two instances he found a branch accompanying the n. interos- seus cruris for a short distance. In both cases the branch arose from the root of the ramus fibularis.

It is very questionable whether the B. N. A. is correct in classifying the r. fibularis as belonging to the a. tibialis posterior. It has usually been regarded, in English-speaking countries at all events, as a branch of the a. tibialis anterior.


At the stage of 20 mm. (fig. 10, A) blood traverses the popliteal region to reach the r. perforans cruris through the original channel, namely the a. poplitea profunda. The a. poplitea is longer than at the stage of 18 mm., having increased in length at the expense of the aa. tibialis posterior and peronaea posterior superficialis. At the stage of 22 mm. (fig. 10, B), a junction between the developing a. peronaea and the distal part of the a. poplitea


Senior1919 fig10.jpg

Fig. 10. Three reconstructions, each showing a sagittal segment (0.25 mm. thick) from the left leg of an embryo of the length indicated. Lateral aspect. X 19. A, 20 mm. ; B, 22 mm. ; C, 24.8 mm. The tibia appears in all cases. P. indicates the position of the m. popliteus. c. m., a. communicans media; g, i. m., a. genu inferior medialis; g, m., a. genu media; i., a. interossea; {. m., interosseous membrane; p., a. poplitea; p. c, a. perforans cruris; p- d.^ a. tibialis anterior, pars distalis; p. p., a. poplitea profunda; p. s., a. poplitea superficialis; per., a. peronaea; r. a,, a. recurrens tibialis anterior; r. p., a. recurrens tibialis posterior; t, a., a. tibialis anterior; t, p. s., a. tibialis posterior superficialis.


profunda has been effected by the development of the r. com municans medius. Blood may now pass from the proximal par of the a. poplitea profunda to the a. tibialis anterior, pars distalis by super



routes: 1) anterior to the m. popliteus, by way of the a. poplitea profunda and r. perforans cru or to the m. popliteus, by way of the a. poph developing a. peronaea, r. communicans medius


poplitea profunda, and r. perforans cruris.


At the stage of 24.5 mm. (fig. 10, C) upon the anterior surface of the m.


ect

s

route

to

exist. The part of the a, pophtea profunda not incorporated in

the definitive a, poplitea or


anterior is represented :

1) by the root and a small branch of the a. genu inferior medialis of the former and 2) by the a. recurrens tibialis posterior of the latter. The main arterial channel through the popliteal region has thus been transferred from the anterior to the posterior surface of the popliteus muscle. Both the a. poplitea and the a. tibialis anterior have assumed their adult arrangement.

The formation of the adult a. poplitea results from the combination of two embryonic elements. The part of the vessel which extends from the hiatus tendineus to the origin of the a. genu inferior medialis is derived from the embryonic a. poplitea profunda. The remainder of the artery corresponds to the embryonic a poplitea superficialis.

The embryonic components of the a. tibialis anterior consist of the r. communicans medius, a short section of the distal end of the a. poplitea profunda, the proximal part of the r. perforans cruris, and the entire tibialis anterior, pars distalis.

The a. poplitea superficialis reaches' completion at the stage of 24.5 mm. by extending as far as the r. communicans medius becomes one of branches.


means the a. peronaea rehnquishes its temporary in the formation of the a. tibialis anterior.


this


ion

B. The conversion of the

yonic a.

s posterior super

ficiahs into the adult a. tibialis posterior.


a. tibialis posterior superficialis is originally a branch of the a. poplitea profunda and extends into the sole. The distal portion of the artery, marked off from the remainder of the vessel upon the development of the a. plantaris lateralis, becomes the a. plantaris medialis. The proximal portion of the a. tibialis posterior superficialis has blended with the corresponding section of the a. peronaea posterior superficialis at the stage of 24.5 mm. as far as the termination of the popliteal artery. The further blending between these two arteries which is to occur during the later stages of development will cause the migration of the


origin of the a. peroiiaea from the termination of the a. poplitea

tibiali;


com


pleted by the occurrence of these changes the vessel still retains its orig

to


n. The relations between


the


The



a, poplitea lies upon the


side of the n. side of the tibialis. The a. tibialis posterior crosses the

nerve to gain its posterior aspect upon which it runs until it

ends behind the

malleolus. The relations of the aa.

itea and tibialis posterior to the n. tibialis have been

tudied UD to the stage of 22 mm

eem

remain unaltered m the olde been examined in this regard, measures 33.5 nmi.

embryo which has C no. 1134, Tvhich


It is not difficult to see how an agency capable of moving the termination of the a. poplitea across the anterior aspect of the n. tibialis from the medial to the lateral side would produce a condition differing little from that normally encountered in the adult. Since the knee is flexed throughout intrauterine life it would seem that the modification of the relative positions of the arteries and nerve might depend upon the straightening of the n. tibiahs which occurs at birth. In order to put the matter to the test, a foetus of 7.9 cm. was dissected. ^^ The relations, however, were found to be identical with those of the adult.

Apart from the study of a few special points, this investigation has not extended beyond the stage of 22 mm. At that period all the vessels of the adult limb are present with the exception of two of the three aa. perforantes, which usually arise from the adult a. profunda femoris, the a. circumflexa femoris medialis, and the a. obturatoria. At the stage of 22 mm. two obturator veins are present in C. E. C, no. 1, one of these is tributary

V. hypogastrica, the other to the v. femoralis.

The leading features in the process of the arterial development of the limb are indicated in figure 11.

^2 For this dissection and for many others made upon various mammals, I wish to express my indebtedness to Mr. B. Spector.

III. Brief Developmental History Of The Individual Arteries

A. Axis. This artery is a branch of the dorsal root of the a. umbilicalis, its presence has been noted by Tandler as early as the stage of 5 mm. '03). At the stage of 6 mm. it terminates by giving origin to the r. perforans tarsi and to the rete plantare.


The axial artery has three rami communicantes, and gives origin to three rami perforantes as follows:

The r. communicans superius, from the a. femoralis, joins it near the hiatus tendineus shortly before the stage of 14 mm.

The r. communicans medius^ from its own branch the a. peronaea posterior superficiaHs, has joined it near the distal border of the m. popliteus at the stage of 22 mm.

The r. communicans inferius^ from the a. peronaea posterior superficialis, joins it, near the distal border of the m. posterior, between the stages of 17 and 18 mm.

The r. perforans cruris arises between the stages of 13 and 14 mm.

The r. perforans arteriae peronaea arises between the stages of 18 and 22 mm.

The r. perforans tarsio is present at the earliest stages of development at which the axial artery has been observed.

Two points have been marked upon the axial artery at the stage of 14 mm. which may be used for the convenient sub- division of the axial artery into three parts. These points correspond to the termination of the r. communicans superius and to the origin of the r. perforans cruris, respectively.

The respective parts of the artery are defined and named as follows: The part upon the proximal side of the termination of the r. communicans superius is the a. ischiadica, while that upon the distal side, of the origin of the r. perforans cruris is the a. interossea. That part intervening between the other two is the a. poplitea profunda. Further information regarding the axial artery may be found under the headings devoted to the description of its respective parts.

A. dor salts pedis. This artery is a channel through the embryonic rete dorsale. Its importance dates from the appearance


Fig. 11 Diagram to illustrate the general development of the arteries of the human lower extremity. Adult arteries are stippled and their names underlined. The chief embryonic channels are outlined in black. The black line is continuous only in the case of the axial artery, otherwise it is broken. The letter P indicates the position of the m, popliteus; T, that of the m. tibialis posterior, and H that of the m. flexor hallucis longus.


of the distal part of the a. tibiahs anterior Which is developed between the stages of 15 and 16 mm.

Branches. One of the adult rr. tarseae laterales represents

5al end of the r. from the rete dor,

other branches are


A. femoralis. This artery arises from the a.

externa

between the stages of 11 and 12 mm. From the time of the first appearance of the femoral artery its growing end is bifurcated into the r. communicans superius and the r. saphenus. The r, communicans superius traverses the hiatus tendineus and joins the a. axis between the stages of 12 and 14 mm., while the r. saphenus terminates below the region of the knee-joint.

Branches. The A. profunda femoris seems to be derived from an arterial plexus which envelops the femur as early as the stage of 14 mm. The proximal end of the artery is distinguishable at the stage of 22 mm. The a. circumflexa lateralis arises from the femoral trunk shortly before the stage of 14 mm. artery is commonly regarded as a branch of the a. profunda, its original connection with the a. femoralis is frequently retained in the adult. The a. circumflexa medialis is not present at the stage of 22 mm. One of the a. perforantes, the first or second, is present at the stage of 22 mm., and is involved at that period

Although this

of development in an extensive arterial plexus connected with the remainder of the distal part of the a. ischiadica. The other perforating arteries are not present, at the stage of 22 mm.

The

a. pudenda externa is the only superficial inguinal branch present at the stage of 22 mm. The a. genu suprema corresponds to

a

the part of the r. saphenus upon the proximal side of the origin of the rr. musculares and articulares. These branches arise



from the a. femoralis, but have migrated to the embryonic r. saphenus by the stage of 22 mm. The distal portion

of the

xL m


vessel corresponds to the r. saphenus of the adult. strica. The main stem of this artery represents the

part of the dorsal root of the a. umbilicalis which lies beyond the place of origin of the a. iliaca externa.

Branches. The


ior division of the a. hypogastrica is derived from the proximal part of the a. axis, which becomes the

denda


a. glutaea inferior, from the root of from the part of the a. umbilicalis dorsal root. The portion of the contributes to the formation of the a. hypogastrica is the source, in all probabiHty, of all the visceral branches of the artery. The a. obtoratoria is not present at the stage of 22 mm. In consequence of the transference of the origins of the aa. iliolumbalis and sacralis lateralis to the a. glutaea superior, part of that artery becomes the posterior division hypogastrica.

4. iliaca communis. This artery is derived from the portion

of the dorsal root of the a.

lies upon. proximal side of the origin of the a. iliaca externa.

A. iliaca externa. This artery already springs from the con- vexity of the a. ihaca communis at the stage of 8.5 mm. Its termination is unbranched until a period shortly before the stage of 12 mm., when it divides into the a. epigastrica inferior and


the a. femoralis


The a.


arise


from the a. iUaca externa between the stages of 18 and 22 mm.


A. interossea. The course of this part of the axial artery is described on page 73,

The a. interossea is joined before the stage of 18 mm. by the distal end of the r. communicans inferius. The junction occurs at a point immediately beyond the inferior margin of the m.

m

s posterior. This artery has given origin to the r. coronarius at the stage of 18 mm. and to the r. perforans and to branch of communication with the a. peronaea posterior superficialis at the stage of 22 mm.

The part of the a. interossea extending from the termination of the a. popUtea profunda to the distal end of the r. communicans disappears between the


ges of 18 and 22 mm. A


vestige of the proximal end of this part of the artery sometimes persists in the form of a small branch of the a. tibialis anterior or of the r. fibularis.

The small portion of the a. interossea which extends from the distal end of the r. communicans inferius to that of the membrana interossea persists as the third part of the a. peronaea (p. 79).


which arise from this portion of the a. interossea are transferred

They are the r. coronarius

r. communicans,


and the r. perforans. The remainder of the a, interossea has lost its identity at the stage of 22 mm. The r. perforans tarsi disappears at about the same period.


A. ischiadica. The course taken by this part of the artery is described on page 73.

The continuity of the a. ischiadica has been broken in the region of the glutaeal fold^ at the stage of 22 mm. The proximal part of the vessel, which has now become the a. glutaea inferior,

to the


follows the V. ischiadica and the n. surface of the limb where it ends by dividing into cutaneous branches. The more distal portion of the artery is involved, with the single perforating artery present at the stage of 22 mm., in the formation of an extensive plexus upon the posterior surface of the m. adductor niagnus.

A. peronaea. This artery is clearly recognizable at the stage of 22 mm. (p. 79). It may be divided into four parts:

The first part of the a. peronaea, which extends from the origin of the artery to the proximal margin of the m. flexor hallucis longus, is a persisting portion of the a. peronaea posterior superficialis (p. 74).

The second part, which lies between the m. tibialis posterior and the m. flexor hallucis longus, represents the entire embryonic r. communicans inferius (p. 76).

The third part, which is short and rests upon the interosseus membrane near the distal border of the m. tibialis posterior, is R persisting portion of the a. interossea (p. 73).

The fourth part, which ramifies upon the fibula and calcaneum in the neighborhood of the lateral malleolus, represents a survival of the short portion of the a. peronaea posterior super-

and of the entire r. calcaneus lateralis of that vessel

(p. 74).


r, perforans and r. communicans, belong

originally to the a. interossea. The rr. calcanei laterales are branches of the r. calcaneus lateralis of the a. peronaea posterior superficialis.


A. peronaea posterior



The course of this embryonic artery is described on pages 70 and 74.

of the vessel is present at the stage of 14 mm.^ its terminal branches form their definitive connections at a stage of 15 or 16 mm.

The proximal part of the a. unites with the a. tibiahs posterior s

pophtea


and the part of


erior superficialis is to form the a.

posterior

above the root of the a. peronaea. A more distal portion persists as the first part of the a. peronaea^ and a still more distal portion enters slightly into the formation of the fourth part of that

vessel.


The terminal of the a. peronaea posterior superficialis form the adult a. plantaris lateralis. The r. calcaneus medialis of the latter artery represents the end of the stem of the parent vessel. The r. calcaneus lateralis, which arises from the a. peronaea posterior superficialis shortly before the stage of 18 mm., persists to form the major portion of the fourth part of the a. peronaea (p. 79). A. plantaris


The part of this artery represents the medial terminal branch of the a. peronaea pos-

71), which unites with the a. posterior superficialis. The distal part represents the lateral terminal part of the same vessel.

Branches. The r. calcaneus mediahs represents the terminal portion of the main trunk of the embrj^onic a. peronaea posterior superficiaHs. The arcus plantaris and all its branches are de- rived from the embryonic rete plantare.

A. plantaris medialis. This artery is the distal portion of the


'^omc a.

posterior

It is

off from the remainder of that vessel by the medial terminal branch of the embryonic a. peronaea posterior superficialis.

A. poplitea. The part of this artery above the origin of the a.

genu


a surviving portion of the

embryonic a. poplitea profunda (p. 73). The part Ij^ing upon the posterior surface of that muscle represents the embryonic a.

popHtea


The proxi


of

a. genu

inferior mediahs is derived from the a. poplitea profunda.

Branches. The a. genu media is present at the stage of 18 mm. The other branches appear at a later stage of the development.

. poplitea projimda. The course of this vessel is described on page 73. The part of the a. pojDhtea i3rofunda which from the hiatus tendineus to the origin of the a. genu


me


the part of the adult a. poplitea.

The remainder of the artery is represented in part by the root of the a. genu inferior medialis. It is represented also by the a. recurrens tibialis posterior and by the second part of the a. tibialis anterior (p. 84).

A. poplitea superficialis . The formation of this artery results from the gradual union which takes place between the proximal part of the embryonic a. tibialis posterior superficialis and that of the a. peronaea posterior superficialis. The vessel lies upon the posterior surface of the m. popliteus and has nearly reached completion at the stage of 22 mm. The a. poplitea superficialis persists as the distal portion of the adult a., poplitea (p. 84).


anterior. This vessel may be divided into


parts which correspond the adult artery.


the four embryonic components of

The first part extends from the origin of the vessel to the root

of the a. recurrens

posterior. It corresponds to the

whole of the r. communicans medius (p. 84).

The second part occupies the immediate neighborhood of the origin of the a. recurrens tibialis posterior. It represents, like that artery, a persisting portion of the embryonic a. poplitea profunda (p. 84).

The third part extends from the a. redurrens tibialis posterior

to a

beyond the root of the a. recurrens anterior. It is derived from the proximal portion of embryonic r. perforans cruris (p. 68). *

fourth part of the artery extends from the termination of the third part to the proximal end of the a. dorsalis pedis. It


represents embryo (p. 72).

entire a.

anterior, pars distalis, of the


Branches. The a. recurrens tibialis anterior represents the terminal portion of the a. perforans cruris (p. 68).

The a. malleolaris anterior medialis is derived from the r, coronarius of the a, interossea \Yhich arises shortly before the stage of 18 mm.


A. tibialis anterior, pars distalis. This embryonic artery arises at about the stage of 15 or 16 mm. Its course is identical with that of the fourth part of the a, tibialis anterior of the

A. tibialis posterior. The part of this artery proximal to the origin of the a. peronaea is the product of the union between the


a, tibialis posterior superficiahs and the a. peronaea posterior

The remainder of the vessel is a survival of the part of the stem of the a. tibialis posterior superficialis pr to the point at which it is joined by the medial terminal branch of the a. peronaea posterior superficiahs.

Branches. The a. peronaea is described on page 90- The

r. communicans are

a. malleolaris posterior derived from the embryonic r. coronarius malleolaris medialis of the a. interossea (p. 73).

A. tibialis posterior super ficialis . The course of this artery, which arises shortly before the stage of 14 mm., is described on page 70.

The whole of the a. tibialis posterior superficiahs persists in the adult hfe. In combination with the a. peronaea posterior superficiahs, the more proximal part of the artery forms the part of the a. poplitea in contact with the m. popliteus and the part of the a. tibialis posterior proximal to the origin of the a. peronaea.* The more* distal part of the artery persists as the portion of the a. tibialis posterior beyond the origin of the a. peronaea and as the a. plant aria medialis.

The relation of the part of the a. tibialis posterior superficiahs which forms the a. tibialis posterior of the adult to the n. tibialis is discussed on page 84.

Rete dorsale. The dorsal rete of the embryonic arises from the r. perforans tarsi. It forms all the arteries which are distributed upon the dorsum of the adult foot.


Rete plantare. This embryonic plexus arises from the terminal branches of the a. interossea. It furnishes the arcus plantaris and all the other arteries of the adult sole excepting the aa plantares.


  1. In the case of the embryos from the Carnegie Institution and Minnesota University the measurement is crown-rump. The Harvard and Cornell measurements represent the greatest total length.
  2. Ramus and sinum tarsi, Hyrtl ('64); Arteria tarsea perforans, Stissdorf ('89); perforans tarsi, DeVriese C92) Arteria anastomotica tarsi, Salvi ('99).
  3. The distinction between the respective origins of the visceral and parietal branches of the a. hypogastrica has already been pointed out by McMurrich ('04).
  4. It is questionable whether the common iliac artery should be regarded as belonging to the fifth lumbar dorsal segmental or not. At the stage of 8.5 mm. of this series the fifth lumbar segmental has regained its independence, and springs from the aorta (on both sides) between the fourth and fifth. The work of Levy ('02) shows, however, that absence of the a. lumbalis ima is the rule rather than the exception. Whether this vessel is frequently retained by the root of the a. iliaca commimis or merely overshadowed (as it were) by it is doubtful.

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