Paper - The supracondyloid variation in the human embryo
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Adams JL. The supracondyloid variation in the human embryo. (1934) Anat. Rec. : 314-329.
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The Supracondyloid Variation in the Human Embryo
Julia Lindsay Adams
Department Of Anatomy, Washington University, St. Louis, Missouri
One Plate (Four. Figures)
Knowledge of the supracondyloid variation in man extendsback over more than a century. Contributions to the subjectby anatomists up to the present time are summarized by Bartaand Petrovits (’27) and by Hrdliéka who has compiled anexcellent bibliography of the subject. Four names stand outprominently as the chief contributors to the subject. Tiedemann (1822) is regarded as the discoverer of the process.Otto (1839) established its homology with the bony bar thatcompletes the supracondyloid foramen in mammals. Gruber(1865) described exhaustively a large number of cases of theVariation and especially advanced knowledge concerninganomalies of the soft parts about the supracondyloid processand the lower end of the humerus. Struthers (1873) ﬁrstdrew attention to the hereditary nature of the variation, anddescribed stages of the development of the supracondylarbar in the cat as typical of an animal normally possessingthe supracondyloid foramen.
Ruge (1889) regarded the process as an atavistic struc-ture, inherent in the mammalian line, and extended greatlythe knowledge of the morphology of vessels and muscles ofthe arm, in reference to the variation. The important contribution made by Testut (1889) aroused a new interest inthe variation of the incidence reported for different Europeangroups. Notwithstanding the ever increasing knowledge ofthe subject, however, the development of the process in theindividual is still obscure.
The development of the variation in man is practically unknown. There are but four brief notes in the literature regarding its appearance in early life. Hyrtl in 1889 noted acase from his own museum of a newborn child having theprocess bilaterally. A short, unsigned editorial note in theJournal of Anatomy and Physiology for 1898 mentions aspecimen in the Cambridge Museum of a 27-month—old child’shumerus, bearing a supracondyloid process 3 mm. long, andwell ossiﬁed. The next year (1899) in the same journal, Cunningham noted the process in a male child of 3 years and ina full term stillborn male fetus. Terry has found the variation in a newly born child in the Huntington Collection,College of Physicians and Surgeons, New York (referred toby Cady, ’22).
The present work is the record of the supracondyloid variation presented in two human embryos. We are indebted toProf. H. D. Senior for directing our attention to the variationwhich he had discovered in the collection of the CarnegieInstitution of Washington, Department of Embryology.Through the kindness of Prof. George L. Streeter, director,we were enabled to examine the two complete series of sections, conﬁrming Professor Senior’s discovery of the presenceof the supracondyloid variation bilaterally in both specimens,and affording the opportunity of constructing models of thehumeri and related soft parts.
Material and Methods
Series no. 75, Carnegie Institute Collection, is derived froma male embryo, white, 30 mm. in length, of approximately 8weeks, or 2 lunar months’ gestation. Nothing is known of thefamily history, excepting that the parents were from NewHampshire and Nova Scotia. The second series, no. 229,Carnegie Institute Collection, is a female, probably white,19 mm. in length, approximately 7 weeks’ gestation. Parentage unknown. The sections of both series were cut 15 u inthickness and were double stained, resulting in good differentiation of the tissues. In order to make clearer the relationships of the process tothe soft parts, Wax models were accurately made to scale according to Born’s method of reconstruction. The fourmodels include the entire humerus, the proximal two-thirdsof the radius and ulna, the complete course of ulnar and median nerves in the arm and forearm, and the brachialartery with its branches. The cut ends of the other nerve branches of the brachial plexus are modeled only at the headof the humerus, since their consideration in their arm relations was considered not essential. Branches of the brachialartery were traced in the sections as far as possible, and havebeen represented in the models as far as compatible withaccuracy.
Embryo, 19 mm. The right humerus of the 19—mm. embryois cartilaginous throughout and as yet shows no evidence ofossiﬁcation. The model (ﬁg. 1) of the future bone is approximately 5 cm. in length. It is not a small replica of the adultform, but differs from it in several respects. It is thickerand shorter and presents a straight rather than a twistedform. The extremities of the bone are relatively large andprominent, especially the distal end.
The upper extremity consisting of the head and tuberositiesforms a conical mass with the tip of the cone directed proximally and medially, forming the head of the humerus. Thegreater tuberosity is especially prominent dorsally andlaterally, but the lesser is barely visible. The axis of theproximal extremity makes an angle of about 150° with theaxis of the shaft (ﬁg. 1). The shaft is subcylindrical, somewhat prismatic proximally, ﬂattened in a dorsoventral direc~tion distally. The surfaces are all smooth and gently convex.The anterior and lateral borders converge in the distal thirdof the shaft to form the single lateral margin, which continues distally into the lateral epicondyle. The medial borderis, in general, straight, and is continuous with the medialside of the head proximally. The coraco-brachialis muscle isinserted into this border approximately halfway along the318 JULIA LINDSAY ADAMSshaft. Distal to this insertion the border is sharper. - Proximal to the medial epicondyle and projecting slightly from themedial and ventral aspects of the shaft, is a supracondyloidprocess. It is a small conical projection, pointing in a medialand slightly ventral direction. Directly medialward and abit ventral lies the brachial artery, and medial to that, but alittle dorsal is the median nerve (ﬁg. 1). Distal to the supracondyloid process, the medial border of the humerus is thickerand merges into the proximal border of the medial epicondyle.The latter is recurved and closely approaches the supracondyloid process, leaving between them a deep supracondyloid notch occupied by the median nerve; the brachial arterylies at the entrance of the notch.
The distal extremity of the humerus is much expanded andﬂattened and presents the two epicondyles. The lateral epicondyle is the larger and more prominent, and is directed distally as Well as laterally, terminating in a blunt rounded end.The medial epicondyle is smaller, more slender and pointed,and is directed medially, proximally and somewhat dorsally.The level of the medial epicondyle is proximal to that of thelateral epicondyle, so that a line connecting the two wouldmake an acute angle with the axis of the shaft of the humerus,open medially and proximally. This is opposite to the direction of inclination of the same axis in the adult humerus.Dorsally the ulnar nerve loops around the base of the medialepicondyle, leaving the tipifree. The pronator teres muscletakes its origin from nearly the whole volar surface of thisepicondyle. The articular surfaces for radius and ulna arenot well deﬁned, the inferior edge of the articular part beingnearly straight. The trochlear surface extends further distallythan the capitulum which projects ventrally. A small depression in the middle of the posterior surface forms theolecranon fossa. The radius and ulna are in ﬂexion and theformer in extreme pronation (ﬁg. 1). Such is the obliquity ofthe humeral articular surface that the forearm is stronglyinclined medially. In extension, the forearm would be adducted, i.e., the carrying angle just reversed. Since this is a feature of both arms in the present and older stages, it isregarded not as an artifact, but as a natural condition.
The radius is ﬂattened dorsoventrally, and slightly expanded at its proximal end. The pronator teres muscle hasits insertion over a considerable length of the lateral borderand volar surface. The proximal end of the ulna expandsdorsally to form the rounded olecranon, and ventrally in theprojecting coronoid process.
The soft parts modeled in the arm lie medial to the humerus,but in close contact with it. Opposite the head of the humerus,the branches of the brachial plexus surround the axillaryartery. The radial and axillary nerves are most dorsal; themusculo—cutaneous nerve pierces the medial surface of thecoraco-brachialis muscle. The ulnar nerve runs distallyparallel to the medial border of the shaft to the dorsal aspectof the medial epicondyle where it curves dorsally to enter theforearm and to follow the shaft of the ulna. In the proximalpart of its course it lies dorsal to the brachial artery, indirect contact with it. The superior ulnar collateral arterylies laterally. Distally, the nerve is dorsal and medial tothe median nerve, but separated from it. In the forearm theulnar nerve is in contact with and dorsal to the ulnar artery.
The median nerve lies parallel and medial to the ulnarnerve as far as the level of the supracondyloid process. Atthis level the ulnar nerve passes distally to reach the dorsalsurface of the medial epicondyle, Whereas the median nerveruns ventral to the distal end of the humerus to enter the forearm. Here it passes subjacent to the belly of the pronatorteres muscle at about its mid—portion. In the upper half ofits course, the nerve lies ventral to the brachial artery andmedial to the coraco-brachialis muscle, in contact with both.At the level of the insertion of the coraco-brachialis the nervecrosses ventrally the brachial artery, so that it comes to bemedial and slightly dorsal to the artery, and is thus separatedfrom the supracondyloid process by the artery. Distally, themedian nerve passes through the supracondyloid notch, dorsalto the humeral head of the pronator teres, and enters theforearm where it is accompanied by the median artery.320 JULIA LINDSAY ADAMSThe brachial artery lies medial to the median aspect ofthe humerus throughout its course in the arm. It emergesfrom the brachial plexus between the median and ulnar nerves,the former ventral, the latter dorsal. It passes thus distallyto the level of the insertion of coraco-brachialis muscle whereit winds dorsally and laterally around the median nerve tolie lateral to it. It continues past the supracondyloid processdirectly medial to whose tip it lies, to the dorsal surface ofthe belly of the pronator teres muscle, where it divides intoits terminal branches, radial and ulnar arteries (18 and 19).
Only two of the branches of the brachial artery, aside fromthe terminal branches, were modeled. The ﬁrst branch, thea. profunda brachii, arises before the artery emerges fromthe brachial plexus. It passes distally and dorsally betweenaxillary and radial nerves. The second branch, the superiorulnar collateral, is given off from the brachial just after itpasses between the median and ulnar nerves. Its course, sofar as could be traced, did not extend to the supracondyloidprocess, which lies ventral and distal to the artery. A branch,identiﬁed as the inferior superﬁcial brachial artery, arosefrom the brachial between the origins of the profunda brachiiand superior ulnar collateral and passed to the biceps muscleand the medial side of the arm. The radial artery (18), oneof the terminal branches arises just beyond the proximalborder of the pronator teres muscle on its volar surface. Itpasses medially and slightly distally over the dorsal surfaceof the muscle to its distal edge, parallel to the radius. Theulnar artery (19) passes directly distally, crosses the mediannerve ventrally, and dorsal to the pronator teres muscle, givesoff two branches. One (22) follows the median nerve and isundoubtedly the median artery. The other (20) passes to theinterval between radius and ulna, but close to the former. Itis identiﬁed as the common interosseous artery. The ulnarartery itself then passes distally to meet the ulnar nerve,which it accompanies through the forearm.
The corac0—brachialis muscle is modeled only in its lowertwo—thirds. It has a slightly ﬂattened cylindrical belly, and is inserted on the medial border of the humerus about themiddle of the shaft. It is pierced in its distal portion by themusculo—cutaneous nerve; ventrally it is free, medially it isin contact with the median nerve, and dorsally with the headand upper portion of the shaft of the humerus.
The In. pronator teres originates on the ventral surface ofthe medial epicondyle of the humerus. A coronoid head oforigin was not recognized. The muscle, close to its origin,covers superﬁcially the median nerve and brachial arteriesas these lie in the supracondyloid notch. It is inserted on thelateral volar edge of the radius, at about the middle of theforearm. The muscle presents dorsal and volar surfaces,proximal and distal borders. Figure 1 indicates the relationsof other parts to the muscle.
The left humerus of the 19-mm. embryo is not exactlyidentical with the right (ﬁg. 2). Slight differences in the contour of the skeletal parts may be noted by comparing withﬁgures 1 and 2. The supracondyloid process occupies a posi~tion at about the same level, and is of a similar form and size.The main axis of the distal end of the humerus forms an acuteangle with the shaft just as does that of the right’ side. Thesupracondyloid notch between the extremity of the medialepicondyle and the supracondyloid process is occupied by themedian nerve.
The course of the left brachial artery is not identical withthat on the right side. The artery lies in about the sameposition opposite the proximal part of the shaft of thehumerus, is crossed superﬁcially by the median nerve andcomes to lie lateral to both the median and ulnar nervesinstead of lying between them as on the right. The leftbrachial artery passes along the tip of the supracondyloidprocess, twists about the median nerve medially and dorsallyto divide into its terminal branches on the volar surface ofthe pronator teres muscle.
Branches of the left brachial are the same as on the right,but arise at slightly different levels. The profunda brachiiarises opposite the head of the humerus, between the axillary322 JULIA LINDSAY ADAMSand radial nerves. An inferior superﬁcial brachial arisesfurther distally. The superior ulnar collateral artery is givenoff just proximal to the insertion of the coracobrachial muscle.The division into terminal branches occurs at about the samelevel as on the right, and the radial artery (18) follows thesame course as on the right. The ulnar artery (19), however,immediately gives off a volar branch (ii), not identiﬁed, whichwas not observed on the right side. This vessel passes distallyand laterally toward the head of the radius and the lateralepicondyle. The ulnar artery passes to the medial edge of thepronator teres where it gives off three branches close together(not shown in ﬁg. 2). These are identiﬁed as the medianartery, the volar and dorsal interosseous arteries. The ulnarartery then continues in contact with the ulnar nerve whichit accompanies into the forearm.
The two muscles, shown in the model, are very much likethose on the right, except that the pronator teres originatesfrom the tip of the medial epicondyle, as well as from theventral surface, which alone is concerned in the origin of theright pronator teres. The area of insertion is smaller onthe left and situated more proximally on the radius.
Embryo, 30 mm. Both humeri of the 30—mm. embryo resemble those of the 19—mm. specimen in being entirely cartilaginous. The essential differences from the younger stagewill be indicated in the following description.
Right humerus (ﬁg. 3): The head and greater tuberosityare relatively more prominent, the shaft more slender, and theline through the epicondyles less oblique to the axis of theshaft than in the earlier stage. The medial border of theshaft of the humerus distally becomes thin, sharp and quiteprominent. It presents a Ventral elevation, forming a supracondyloid ridge which extends almost to the tip of the medialepicondyle, ending abruptly. Between this end and the medialepicondyle is a small but conspicuous supracondyloid notch.The ulnar nerve lies dorsal to the supracondyloid ridge, themedian nerve medial, and still more medially, the brachialartery, none of them in contact with the humerus. The medial epicondyle curves medially and proximally as in the 19-mm.embryo. The approximation of its extremity to the supracondyloid ridge and the notch between them are retained asjust stated. The medial epicondyle gives origin on its Ventraland medial aspects to the pronator teres muscle. The ulnarnerve hooks around the epicondyle dorsally, forming a sharperangle than is the case in the younger embryo. The articularsurfaces show the same characteristics in general. The depression dorsally, forming the olecranon fossa, is less sunkenin the older humerus.
The forearm is ﬂexed and pronated. The adducted positionnoted in the earlier stage is present, but, following the slighterobliquity of the distal articular surface of the humerus, isless marked.
The branches of the brachial plexus are in the same relative position in the older as in the younger embryo (ﬁg. 3).The ulnar nerve takes the same course, lying medial, thendorsal to the brachial artery. The median nerve likewise follows a course similar to that in the 19-mm. embryo, crossesthe brachial artery ventrally, but is at all times furtherseparated from the humerus than it is in the younger embryo.At the level of the supracondyloid ridge, the nerve passesdistally subjacent to the pronator teres muscle, and then intothe forearm, but has no accompanying artery as in the 19-mm.embryo. It does not occupy the supracondyloid notch, butpasses opposite its entrance.
The brachial artery diﬁers from that of the younger specimen in respect to the origin of its collateral branches, in beingseparated from the humerus, and in the level of origin ofits terminal branches. It crosses the median nerve dorsallyto lie on its medial side and at the level of the supracondyloidnotch is far removed from the humerus. Three collateralbranches arise close together at about the level of the middleof the arm; the two divisions of the profunda brachii andthe superior ulnar collateral artery. A superior superﬁcialbrachial artery takes origin from the axillary artery andenters the arm parallel to the brachial artery from which it324 JULIA LINDSAY ADAMSis separated by the median nerve. Its course ends in the arm(compare ﬁgs. 1 and 3). Of the terminal branches, the radialseems the more direct continuation and passes medially alongthe ventral surface of the belly of the pronator teres towardthe lateral border near the insertion of the muscle. It hastwo branches, the ﬁrst, the radial recurrent artery (21), passing directly laterally; the second, a small unidentiﬁed branchwhich courses near the radius. The ulnar artery passesdirectly distally dorsal to the pronator teres to accompanythe ulnar nerve.The model of the left humerus, radius and ulna, and softparts of the 30—mm. embryo (ﬁg. 4) is very nearly identicalwith the right save for a slight difference in the branching ofthe radial and ulnar arteries, and a slightly less prominentsupracondyloid ridge. It is to be noted that in the presentcase as in the others described, the main axis of the distalextremity of the humerus is sharply inclined so as to givethe medial epicondyle a direction proximally as well asmedially. A small supracondyloid notch separates the latterfrom the supracondyloid ridge. The soft parts bear the samerelation to the ridge as on the right, separated from andmedial to it. The pronator teres muscle arises from the verytip rather than from the volar surface of the medial epicondyle.
The superior superﬁcial brachial artery (14) on the leftarises from the axillary and, emerging between median andulnar nerves, passes ventrally across the median nerve to itsmedial aspect; it terminates in the arm. The brachial artery,together with the median nerve, passes opposite the supracondyloid notch, but is removed from it by a considerableinterval. The brachial artery terminates at a lower level, i.e.,on the volar surface of the pronator teres muscle at its lateralborder, by dividing into the radial and ulnar arteries. Thetwo divisions of the profunda brachii arise separately fromthe brachial artery; the superior ulnar collateral somewhatfurther distally.
The notes occurring in the literature on the early appearance of the supracondyloid process have been mentioned atthe beginning of this paper. The youngest individuals werefull—term, newly born infants, in all of which the process waswell developed and fully ossiﬁed. Apparently the earlierdevelopment of the process in man has so far remainedunknown.
The humerus, in the stages modeled, is cartilaginousthroughout and differs in form from that of the adult bone.It is relatively shorter and thicker, the shaft shows dorsoventral ﬂattening, the distal extremity is relatively more expanded than is the case in the adult. Whereas the proximalhalf of the shaft approaches a cylindrical form, the distalhalf is markedly ﬂattened dorsoventrally. Torsion, a characteristic feature of the mature bone, has not appeared inthese early stages. These several characters are of interestsince they recall similar features in the primitive form of thehumerus in Amphibia and Reptilia.
The extreme obliquity of the axis of ﬂexion and extension atthe elbow is of special interest. The fact that the inclinationis from the lateral to the medial side and proximally, insteadof distally as it is in the adult, raises the question of its beinga defect in development or a distortion produced artiﬁcially.Against these possibilities is the fact that the peculiarityoccurs bilaterally in both embryos and that the proximal inclination is considerably less in the older stage, that is, the axisis approaching its adult position. We have found no referencein the literature to this inclination of the axis at the elbowbut Bardeen (Keibel and Mall) has pointed out in connectionwith the development of the elbow joint, that the distal endof the humerus undergoes marked changes in form duringdevelopment.
Under the conditions of the obliquity of the axis of ﬂexionand extension, the medial epicondyle being directed proximally as well as medially, extends into the vicinity of thesupracondyloid process or ridge. This relation is such as to326 JULIA LINDSAY ADAMSleave between the epicondyle and the supracondyloid process,a supracondyloid notch, within which lie the trunks of thebrachial artery and median nerve. Although the supracondyloid notch is present in the 30-mm. embryo, it is small becauseof the low projection of the supracondyloid ridge, and theartery and nerve do not occupy it, but stand opposite itsentrance. The approximation of condyle and process recallsa somewhat similar relation in the cat embryo described byStruthers (1863) who found the internal condyle participating with the supracondyloid process of the humeral shaft,in the boundary of the supracondyloid foramen. Struthers’observation has been conﬁrmed by Seib (’26). In the maturehumerus a supracondyloid process is distant several centimeters from the medial epicondyle and no longer presents anotch separating these processes. In developing, the notchas such has given place to a broad shallow concavity, but stillholding the original relations in boundaries and contents.New evidence presented by Schaeffer (’32) indicates that inthe cat the supracondyloid foramen ﬁrst appears in theoriginally continuous cartilage of the medial supracondyloidridge.
The question has been raised as to whether the supracondyloid process develops in continuity with the shaft of thehumerus or arises independently and secondarily joins theshaft. Evidence in support of the former mode of originis given by the present investigation. The humerus is in thechondral stage earlier than our 19—mm. embryo, and whereasit is possible that a separate chondral center has appearedfor the supracondyloid process and had united with the shaft,it is improbable that such was the case, in the absence of anyevidence of the union in the present stage. The cartilage ofthe process is quite continuous with that of the diaphysis.
The forms taken by the supracondyloid variation in thetwo embryos under consideration are quite different, being aridge-like elevation in the older and a conical projection inthe younger specimen. Since both of these forms have beenrecognized in the adult humerus, it is hardly a question that the differences represent stages in the ontogeny of the process.It will be recalled that in the adult humerus presenting thevariations, a spine—like process is very commonly compressedand arises from a ridge on the shaft. The ridge is found tooccur in the adult in the absence of a spine-shaped process,but the latter commonly springs from a ridge. In distribution, the ridge form either by itself or in connection withthe spine form is the prevailing type of supracondyloid variation. The relations of soft parts to these two forms arediscussed below.
In the adult, the bony spur projecting from the anteromedial surface above the medial epicondyle is connected withthe latter by a ﬁbrous tissue bridge which converts the broadand shallow groove of the shaft, condyle and spur (derivedfrom the supracondyloid notch) into an elongate foramen ortunnel, occupied often by the median nerve, the brachialartery or a subdivision of this vessel. Tandler (1895) hasreported ﬁnding an ossicle in this connective tissue bridge;Dwight (’04) discovered an ossiﬁed bar extending from asupracondyloid process to the medial epicondyle, givingthereby a bony walled supracondyloid foramen in man.
Although no well—deﬁned connective tissue bridge was foundin either embryo, a feature of another sort showing a relationbetween the medial epicondyle and the supracondyloid process was presented. This is the proximal inclination of theepicondyle toward the process, referred to above, resulting inthe formation of the supracondyloid notch between them. Thetwo processes are so close in the embryo as to suggest thatonly a slight precocity in growth of either one would resultin the conversion of the notch into a supracondyloid foramen.It is possible that this may be the explanation of Dwight’scase referred to above.
According to Adachi ( ’28), there are two types of relationbetween soft parts and the supracondyloid variation. In onetype the brachial artery and median nerve, or the deep(normal) brachial artery and median nerve (if the superﬁcial brachial artery is well developed) pass through a canalTHE ANATOMICAL RECORD, VOL. 59, NO. 3328 JULIA LINDSAY ADAMSformed by the supracondyloid process, and a supernumeraryhead of pronator teres muscle. In the second type, the supracondyloid process bears no relation to the soft parts, whichare not anomalous. The brachialis muscle commonly coversthe process, which is smaller than in the ﬁrst class. Thissmall process may give origin to a few ﬁbers of the muscle.The second of the two divisions noted above undoubtedly isexempliﬁed in the 30-mm. embryo, where there is no closerelation between soft parts and supracondyloid variation.It must be noted that since the artery and nerve do not passthrough a canal that would retain them, they would be broughtnearer the humerus in the extended forearm than they are inthe ﬂexed condition of the embryo.
Since the humerus, in the stages studied, is cartilaginousthroughout and the ossiﬁc center for the shaft has not appeared even in the older embryo, no evidence is given as tothe mode of ossiﬁcation of the supracondyloid process.Whether this is brought about from a center separate fromthat of the shaft or by extension from the latter are questionsthat will be answered from the evidence of the ossifying armbone which carries the supracondyloid variation. In the cat,according to Schaeffer (’32), it seems that the bony bar onthe medial side of the supracondyloid foramen is ossiﬁed incontinuity with the diaphysis.
Regarding the muscles coraco-brachialis and pronator teres,the former was apparently not associated with the supracondyloid Variation, reaching its insertion at the middle ofthe humerus. The pronator teres, although very near thesupracondyloid process and ridge, was not attached to either.
Because of the not infrequent occurrence of anomalies ofthe brachial artery in association with the supracondyloidvariation, the course, relations and branching of this vesselwere given careful attention. In all four specimens but asingle trunk artery in the arm was found and this pursuedthe usual course and bore the usual relations to the mainstructures of the arm. It was crossed ventrally by the mediannerve and was accompanied by this nerve at the elbow. superﬁcial brachial artery was identiﬁed, in all four specimens, its course and distribution limited to the arm. Itsorigin in the younger embryo was from the brachial; in theolder from the axillary artery. In none of the arms did itunite with the brachial artery or approach the supracondyloidprocess. The radial collateral and middle collateral rami ofthe profunda brachii arose separately from the brachialartery in the older embryo. The superior ulnar collateralartery, where traced, passed to the back of the medial epicondylar region, some distance removed from the supracondyloid process. The brachial, in both pairs of arms, dividedat the elbow into radial and ulnar arteries.
The brachial artery accompanied by the median nervepassed through the supracondyloid notch in both humeri ofthe younger specimen; its course, in the older embryo, wasopposite the notch but ventral to it some distance. In noneof the cases was a ligamentous or muscular bridge foundspanning the notch.
Concerning the median nerve, it remains to be emphasizedthat in its course in the arm, it crossed the brachial arterysuperﬁcially and remained in association with that vessel tothe level of the elbow. In the younger embryo the nervepassed through the depth of the supracondyloid notch.
- The supracondyloid variation was found bilaterally intwo human embryos, 19 mm. and 30 mm. in C. R. length.
- The humeri and adjacent soft parts of the embryos werestudied in serial sections and by means of wax models, reconstructed to scale.
- The humeri are entirely cartilaginous and no centers ofossiﬁcation are present.
- The supracondyloid variation occurs in the 19 mm.embryo in the form of a prominent conical process, in the30-mm. embryo as a sharp ridge.
- These processes and ridges are cartilaginous projectionscontinuous with the cartilage of the shaft of the humerus. The axis of the condylar articular surface of the humeriin both pairs of limbs was very oblique in relation to the axisof the shaft so as to result in the recurving of the medialepicondyle and its near approach to the supracondyloid process or ridge. There was thus formed a deep supracondyloidnotch between the two, in relation to which passed the mediannerve and brachial artery.
- There is no high division of the brachial artery in eitherembryo, although a superior superﬁcial brachial artery arising from the axillary was present bilaterally in the olderembryo; the principal arm artery is the normal brachialartery, which divides at the elbow into the radial and ulnararteries.
- There is no supracondylar head of the pronator teresmuscle, nor supracondylar attachment of the corac0-brachialis.
In conclusion, I wish to acknowdedge the assistance givenme by Dr. R. J. Terry in the preparation of this paper andto extend my thanks to Dr. H. D. Senior for his criticism of my results.
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GRUBER, W. 1865 Ein Nachtrag zur Kenntnis des Processus supracondyloideusinternus humeri des Menschen. A1-ehiv fiir Anat. und Physiol., S. 367HRDLICKA, A. 1923 Incidence of the supraeondyloid process in whites and otherraces. Am. J. Phys. Anthrop., vol. 6, pp. 405-412.
HYRTL, J. 1889 Lehrbuch der Anatomic, Bd. 20, S. 384. Braumiiller, Wien.
KEIBEL AND MALL 1912 Manual of human embryology, vol. 1, pp. 380-383.Ibid., vol. 2, pp. 659-667. J. B. Lippincott Co., Philadelphia.
OTTO 1839 De rarioribus quibusdam sceleti humani cum animalium sceletoanalogiis, vol. 27. Vratislaviae.
QUAIN, R. 1908 Elements of anatomy, 11th ed., vol. 1, p. 224. Longman’s,Green & 00., London.
RUGE, G. 1884 Beitrage zur Gefasslehre des Menschen. Morphologisches Jahrbuch von Gegenbaur, Bd. 9, S. 329-388.
SCHAEFFER, HERMANN 1932 Die Ossiﬁcationsvorgiinge im Gliedmassenskelettder Hauskatze. Morph. Jahrb., Bd. 70, S. 548-600.
SEIB, G. 1926 Preparations and drawings to show the development of thesupracondyloid foramen and bar in the cat. Anat. Rec., vol. 32, p. 241.
SENIOR, H. D. 1933 The arteries in Morris’ human anatomy. Blakiston, Philadelphia. _STRUTHERS, J. 1854 Points in the abnormal anatomy of the arm. British andForeign Med.-Surg. Review, vol. 13, p. 405-415, and vol. 14, pp. 170179, 1863.
TANDLER, J. 1895 Beitrag zur Anatomie des Processus supracondyloideus.Anat. Anz., Bd. 2, S. 468-469.
TESTUT, L. 1889 L’Apophyse susepitrochleene chez l’homme. InternationaleMonatsehrift fﬁr Anatomie, Bd. 6, Heft 9, S. 391-400. Ibid., Heft 10,S. 401~438.
TIEDEMANN, F. 1822 Tabulae Arteriarum corporis humani. Carlsruhe.3"
Plate 1 Models of embryonic arm
Right arm and forearm of the 19-mm. embryo. Lateral aspect.
Left arm and forearm of the 19-mm. embryo.Right arm and forearm of the 30-mm. embryo.Left arm and forearm of the 30-mm. embryo.
head of humerus greater tuberosity lateral epicondyle medial epicondyleradiusulnapronator teres musclecoraco—brachia.lis musclecut ends of brachial plexusmusculo-cutaneous nervemedian nerveulnar nervebrachial arteryLateral aspect.Lateral aspect.Lateral aspect.
KEY TO FIGURES
14, superior superﬁcial brachial artery
15, radial collateral and middle collateral rami of the profunda brachii
16, superior ulnar collateral artery
17, inferior ulnar collateral artery
18, radial artery19 ulnar artery
20, common interosseous artery
21 radial recurrent artery
22, median artery
23 supracondyloid process24, supracondyloid ridgex.
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Adams JL. The supracondyloid variation in the human embryo. (1934) Anat. Rec. : 314-329.
Cite this page: Hill, M.A. (2023, November 28) Embryology Paper - The supracondyloid variation in the human embryo. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Paper_-_The_supracondyloid_variation_in_the_human_embryo
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