Talk:Book - Contributions to Embryology Carnegie Institution No.22

INTEGUMENT.

The dome of the head is narrowed and flattened, and is covered with lightbrown hair, 1 cm. in length. Just above and behind the ears the hair is 2 cm. long and is ({uite thick. Across the middle of the forehead at the hair margin is a narrow raised ridge of puckered skin, 2 cm. long. A section through this area shows the structures of the skin to be well develoi)ed and similar to the adjoining noi-mal skin, except that where the surface is raised the jiapilla' are somewhat flattened underneath. The ridge is probably the result of rough handling before fixation.

From the back of the head protrude three encephaloccles in a horizontal line, extending from a point 6 cm. behind the tip of the left ear to a point 2 cm. behind the tip of the right ear. These are best dis])laved in figures 1 and 3. They nu'iisure 13 cm. horizontally along their superior margin, and the vertical diameter is 4.3 cm. The midline of the specimen comes between the left and middle encephaloccles. In the midline their vertictU diameter extends from a point 3.6 cm. below the vertex to within 6 cm. (»f the amis. The middle swelling is the largest of the

ENCEPHALOCELES AND OTHER ABNORMALITIES. 93

three and is cone-shaped, whereas the other two are smaller and hemispherical. All are of soft consistency. The large coneUke swelling measures 6 cm. from the superior margin to its tip and 2.5 cm. from tip to inferior margin, its base being circular and measuring 4.3 cm. in diameter. This cone lies pendant over the back; the proximal half of its superior surface is covered with scalp and fine brown hair 2.5 cm. long. A strip of coarser hair of the same length follows the median margin of the sweUing to its lowest point. The covering of the distal half of the superior surface and the entire inferior surface resembles smooth, fine-grained leather. No hairs are present, but it is dotted with minute pores which on microscopical examination are seen to be the mouths of sweat-ducts. The wall of the sac is 3 mm. thick, a section through which shows an extremely thin layer of epidermis h'ing immediately over a vascular connective tissue, containing the sweat-glands mentioned above; but no hair follicles. There are two oval naevi near the tip of the sac, which in the gross resemble scars. These lie in the same long axis directed laterall}' through the tip of the sac. The smaller of the two is 5 mm. to the left of the tip and measures 7 by 3 mm. The larger lies 10 mm. to the right of the tip and measures 25 by 17 mm. The color of these areas is lighter than the surrounding tissue and the surfaces are stiff, smooth, and slightly raised. In their neighborhood the thickness of the sac wall is increased to 9 mm. Histologically the epitheUum is lacking here and a very vascular connective tissue forms the raised surface. The lining of the upper part of the sac is smooth fibrous tissue continuous with the dura of the main cerebro-spinal cavit5^ Near the tip, however, it is made up of shaggy strands of blood-vessels whose compUcated, interweaving pattern is like the early capillary plexus of the dura, as described by Streeter (1915). This suggests that the irregular vascularization in this region may be due to arrested development of the vascular system. There is marked engorgement of these vessels and congestion in all the tissues. Part of this extreme engorgement was probably caused by birth trauma.

The left encephalocele measures 5 by 4 cm. and protrudes 1 cm. from the surface. Its upper half is covered with fine hairs and the lower half with normalappearing skin. The wall is 1 to 2 cm. thick, composed chiefly of a layer of subcutaneous fat. On its left lower border there is a rounded bleb of porous, wrinkled skin 1 cm. in diameter, over which are scattered a few hairs 2 cm. long, and which contains around its depressed circumference a much thicker growth of similar hairs. A section through the wrinkled skin shows that it lies over a funnel-shaped canal, the wider mouth of which extends down through 1.5 cm. of subcutaneous fat to the subdural space, where the canal becomes narrow. This canal is filled with fluid and contains a few blood-vessels supported by loose connective-tissue septa. Its walls are formed of rather dense connective tissue.

The right encephalocele is 4 cm. in diameter at its base, and the surface, which is covered with, hairy scalp, is but slightly raised above the adjoining structures. Its wall, consisting of epidermis, connective tissue, and fat, is but 3 mm. thick.

A summing up of the integument findings shows that both normal skin and scalp are found over the areas adjoining the encephaloceles and over parts of the

94 STUDY OF A HUMAN SPINA BIFIDA MONSTER WITH

enccphaloccles as well. In addition to this, in the adjoining areas there are hypertrichosis and thickened subcutaneous fat, varying from 5 to 25 mm. in thickness. The wall of the large encephalocele varies from 3 to 9 mm. in thickne.ss and is formed by angiomatous tissue covered with a thin layer of epidermis penetrated by sweatglands. In two places near the tip of the sac naevi are formed by the vascular tissue extending to the surface. The walls of the small sacs vary from 3 to 20 mm. and are formed chiefly by subcutaneous fat covered with scalp. On the left a pore and canal pierce through to the subdural space.

Spietscka in 1894 collected the various forms of skin changes associated with spina bifida. Besides the varieties here found, he described pigment blotches and such a marked increase of fatty tissue as to amount to lipomata. In an article on skin anomalies by Bettmann, in Schwalbe's Morphologic der Missbildungen, naevi are noted as among the most frequent anomalies.

METHODS.

A sagittal section was made of the specimen under discussion (see fig. 9). The spinal column shoAvs extreme lordosis, undeveloped arches throughout, and .shortening and fusion of the upper vertebrae. The central nervous system is very much disturbed, a large part of it having slipped down below the cranium, through a much enlarged foramen magnum. This portion lies on the thoracic and lumbar vertebrae and protrudes into the sacs already described. The brain and cord were removed, and a clay impression was made of the entire space occupied by the central nervous system. This was then cast in wax and photographed, as shown in figures 4, 5, 6, and 7. By the help of this model the general shape taken ])y the central nervous system was demonstrated and the study of its internal arrangement and relation to other structures was facilitated. The consideration of these will be taken up later in this paper.

In the sagittal section, thick subcutaneous pads of fat are seen in the imdifferentiated region of the neck between chin and thorax, above the sj'mphysis, and over the sacral region. Dissection shows this sul)cutaneous fat to be likewise particularly abundant over the back and shoulders. There is also found an extreme grade of undeveloped or | split soft palate, associated with which is a bilateral anlage of the uvula, that on the left side being shown in figure 9a. Consideration of the normal development of the .soft palate will help to indicate how this defect originated. It is generally agreed that at a very early date the tongue occupies the area which is later occupied by the septum and palate. The normal rearrangement of these parts to their final po.sitions is acconi])li,'<hed by medial growth of the palate and downward growth of the sejjtum, associated with independent shifting of the tongue. If for any reason the tongue can not withdraw, the palate remains sjilit to a greater or less degree. That such a cause was operative in this specimen seems lik(!ly; the distorted position of the cervical spine might easily have caused a crowding in the adjoining pharyngeal region and so prevented the tongue from receding.

ENCEPHALOCELES AND OTHER ABNORMALITIES. 95

SKELETON.

A dissection of the skeleton was made, the vertebrae and ribs being left connected bj' their ligaments, so that the specimen could be easily mounted. To facilitate handling, two transverse cuts in the skeleton were made at the level of the first thoracic and first lumbar vertebra?. A study of the skeleton shows marked maldevelopment and distortion, as may be seen in figures 10, 11, and 12. The axial skeleton is most affected, the arches of all the vertebrae being defective; these are open posteriorly in the midline and are flattened outward, forming wide anterior support for the central nervous system. In the cervical and thoracic regions the bodies of the vertebrae are fused, shortened, and dorsally flexed, so that the spine is bent almost double. The occiput actually rests on the gaping vertebral arches and fuses with them.

Viewing the occiput in figures 13 and 14, the inferior and medial two-thirds of the squama occipitahs is seen to be defective. A bilateral bony excrescence on its dorsal surface, near the defective medial margin of the squama and close to its junction with the partes laterales joins it to the everted arches of the second lumbar vertebra on the left side and to the first lumbar vertebra on the right. The defect of the squama in the midline, together with a widening of the angles formed by the junction of the pars basahs with the partes laterales, has greatly increased the size of the foramen magnum. This is oval in shape and measures 4.5 bj' 3.7 cm. The long diameter is antero-posterior, and posteriorly it slants slightly to the left. For purposes of comparison the size of a normal foramen is indicated in figure 13 by means of dotted lines. The large foramen resembles that of the chondrocraniumat a very early stage of development. The participation of both the squama occipitalis and the vertebral arches in the midline defect, as it exists here, has been regarded as teratological evidence of the homology of these parts, and probably has been a factor in advancing the opinion, which has slowlj' gained ground, that some cranial defects, even when existing alone, belong in the same category with certain vertebral abnormalities.

The two partes laterales are well formed and but slightly asymmetrical. The left jugular process is more marked than the right. On the left inferior surface directly under the jugular process there is a cartilaginous prominence which meets the tip of the transverse process of the underlying atlas. The hypoglossal foramen on the left side is a single canal, and while the right hypoglossal foramen has a single perforation on the medial surface of the pars lateralis, it has a double exit on the outer surface of the bone. A small rod of bone divides it into a smaller anterior and a larger posterior foramen, as is demonstrated in figure 11. A division similar to this has been observ-ed frequently in embryological studies and appears on the left side in a skull of a human fetus modeled by MackUn. The condition is of rather frequent occurrence. Lillie gives a ratio of 14 per cent complete division and 36 per cent indicated division, out of 305 left and right canals examined by him. The explanation generally offered is that it is persisting tissue from primitive cranial divisions which usually disappear at a very early stage.

96 STUDY OF A HUMAN SPINA BIFIDA MONSTER WITH

In our specimen the pars basalis of the occiput is oval and asymmetrical along its mferior margin, as shown in figure 11, and measures 18 by 14 mm. Its sphenoidal margin is 6 mm. thick, and the thickness of the bone elsewhere is 3 mm. Its I)()sterior surface is slightly concave, there being a rather deeper depression immediately under the sphenoidal articulation than elsewhere. The anterior surface of the pars basalis is nearly flat. The inferior margin has a notch near the midline and on either side of this the bone projects downward, 2 mm. on the right and 4 mm. on the left. A slit-like foramen 2.7 mm. wide directed forward and upward pierces the pars basalis near its center. On each temporal bone the eminentia arcuata is very prominent and the fossa subarcuata deeply depressed below. The ear ossicles are well developed and the other relations of the bone are normal. With the exception of the small size of the cranial vault the rest of the skull is well formed.

The bodies of all the cervical and thoracic vertebrae and the dorsal surface of the first lumbar vertebra are fused together in a bent and irregular central plate of cartilage containing irregular ossification centers. The roots of the arches and the ribs project from this plate. The relations of the various parts are shown in figures 10, 11, and 15. At the superior end of this plate the foveal surfaces of the atlas and its transverse processes are distinguishable, but, as may be seen in figure 10, both posterior and anterior arches are lost. The fovese are shifted to the right in relation to their transverse processes, as may be seen in figure 11. This shifting causes the right atlantal transverse process to lie immediately under the fovea. The left is uncovered by the fovea on that side, but is fused at its tip with the left pars lateralis.

Viewed from the side in figure 12, the cervical and lower thoracic jjortions of the central vertebral plate form the two arms of a wide-mouthed U, while the bent base of the U occurs in the plate from the level of the first to the sixth ribs. Besides this marked lordosis, there is a very slight lateral bend which shows in the dorsal view of the skeleton (fig. 10), giving the vertebral plate a slightly curved S-shaf)e. (This condition of scolisosis and lordosis in varying degrees is very frcHjuently noted in the extreme forms of si^ina bifida.) The concavity at the right margin of the vertebral plate is opjjosite the first rib and at the left opposite the sixth rib. From the central plate of this specimen throughout its extent the radices project outward on both sides and formed between them are two uneven rows of intervertebral foramina. The processes are tiny spicules of bone in the cervical and U[)per thoracic region, becoming larger in the lower ])art of the colunm. In the cervical region 7 radices are distitict and 12 in the thoracic region. The former could not all be shown in the drawings.

The arches of both cervical and thoracic regions are everted and fused. This formation, together with the antero-posterior bend of the plate, makes a rather deep pocket of bone which contains parts of the much disturbed central nervous system. The lumbar and sacral vertebral colunm is much less afTected than the upper part. The dorsal part of the first lumbar vertebral body is fused with the thoracic vertebra?, its ventral surface, however, being distinct. The four lower

ENCEPHALOCELES AND OTHER ABNORMALITIES.

97

lumbar and the five sacral vertebral bodies are well formed, as are the transverse processes of all the lumbar vertebra? and the partes laterales of the sacrum (figs. 10 and 12). The first four lumbar arches are everted, as are the thoracic arches, though individually they are distinct and not fused. The fifth lumbar and the five sacral arches are incomplete, but project medially toward one another and arc not everted. The lumbar column is 4.3 cm. long and the sacrum 3 cm. in length. The coccyx is composed of four segments, which measure 1.6 cm. and are bent to the left. In studying the proportions of the vertebral column, Aeby 's tables of relations in normal vertebral columns in the new-born were used, with the results shown in table 1.

Tabi,e 1. — Comparison in miUimelcrs of the vertebral lengllis of specimen with those given by Aeby for normal neio-bom.

Total.

Cervical.

Thoracic.

Lumbar.

Aeby (normal) .... No. 862a

176.5 105.0

45.1 15.0

83.9 45.0

47.5 43.0

A comparison of these vertebral lengths shows the lumbar portion of this specimen to be within the limits of normal, though near the minimal margin. The cervical portion is less than half, and the thoracic portion a trifle more than half the length of the normal. Aebj' gives 26.4 mm. for the transverse diameter of the atlas, 12.2 mm. for the width of the body of the sixth thoracic vertebra, and 17.5 mm. for that of the fifth lumbar. In this specimen the lateral limits of the foveae are 31.0 mm. and the width of the transverse processes of the atlas 38.0 mm. The width of the vertebral plate in the midthoracic region is 23 mm. and the width of the fifth lumbar vertebra is 21 mm. These differences show an irregular widening process to have taken place in the vertebral bodies themselves, the change being most marked in the thoracic and cervical regions. The absence of lateral pressure from ununited arches must have been an important factor in this broadening process.

There are twelve ribs on each side which ha^•e undergone considerable disturbance. On the right, the first sL\ are fused near their bases (figs. 10, 11, and 15). The second rib terminates at the end of its proximal third in a plate of bone by which it is joined to the first and third ribs. On the left, the fifth to nmth ribs are crowded together in their proximal half (figs. 10, 12, and 15). The fifth and sixth have but one costal cartilage between them. The sLxth and seventh ribs are fused for a few milUmeters just proximal to their termination. Further fusion occurs in pairs at the bases of the follo\\ing ribs: on the right, between seventh and eighth, ninth and tenth; on the left, between the first and second, third and fourth. This shows on the ventral surface in figure 15.

The sternum, as seen in figure 16, has four ossification centers near the median line at the level of the first costal cartilage and of the first, second, and third left intercostal spaces. There are six costal cartilage connections on each side. The last on each side, however, belongs to the seventh rib. The discrepancy occurs on the right side through the aborted second rib and on the left side through the

98

STUDY OF A HUMAN SPINA BIGIDA MONSTEK WITH

fifth and sixth, having but one cartilage between them. The first and seventh costal cartilages of the two sides are opposite each other. The arrangement of the other cartilages is such that the third to the fifth on the left side are from 0.5 to 1 cm. lower than the corresponding cartilages on the right, yet not quite opposite the succeeding one. A small cartilaginous knob (2 by 5 by 3 mm.) above the manubrium is a persistent episternum. The measurements of the sternum are given in table 2.

Table 2. — Dimensions in centimeters.

Body lengths: cm.

Vertex-anus 14 .0

umbilicus 32 .0

Lower hair border-anus (length of back) 10.0

Head:

Circumference of head 32 .5

Biparietal diameter 8.5

Anterior fontanel 2.7 cm. transverse by 2 .5

Posterior fontanel 1.6 cm. " by 1 .7

Face, vertical length (border of hair to chin). . 9 .5

Clear breadth (from free edges of tragi) 9.2

Eyes apart 1-8

Nose across 2.3

Mouth across 2.0

Trunk:

Circumference at umbilicus, passing around the

back at base of middle sac 33 .0

Distance across shoulders 12.0

Nipples apart 6.4

Trunk — Continued. cm.

Diameter of right nipple .9

left nipple 7

Sternum, episternum, and zyphoid:

Length of sternum with episternum and 6.9

zyphoid sternum alone 6.0

Width of sternvmi 1.0

Thickness of sternum 3

Length of episternum 3

Length of zyphoid 9.6

E.xtremities:

Upper arm (circumference of both left and

right) 9.0

Lower arm (circumference of both left and

right) 7.0

Hand with middle finger 6.0

Right trochanter— heel 20 .9

Right foot 7.5

The two scapulae which are shown in figures 18 and 20 are distorted, as will be seen by comparison with figures 17 and 19, representing normal left and right scapulae. In both the pathological^ bones the supraspinous portions are poorly formed and the inferior vertebral margins are concave. Graves designates a concavity of the vetebral margin of the scapula as scapula scaphoidea. He notes that it is of fairly frequent occurrence and claims that it is associated with syphilis in the i)arents. He gives as his figures, however, no definite rate of occurrence. Here it m:iy l)e mentioned that the Levaditi stain done on the tissues of this specimen showed no spirocha^tes. On the right scapula the vertebral margin i^asses as a straight line from the medial termination of the spinous process to the incisura next the glenoid process. The vertical diameter of the right scapula measures 36 mm. from the tip of the cartilaginous process at the inferior angle to the superior margin near the incisura. Its transverse diameter along the base of the spinous process, near the termination of the latter, to the center of the glenoid fossa is 26 mm. The subscapular angle is 128°, the infraspinous angle is 122°, and the supraspinous angle is 110°. On the left scapula, the vertebral margin above the spinous process projects at a fairly sharp angle near its middle. The vertical diameter taken from the tip of the inferior angle to the end of the projecting point of the supraspinata is 29 mm. The horizontal diameter of the left scai)ula, measured similarly as the right, is 36.5 mm. The vertebral margin of the left scapula at the termination of the sjiinous i)roccss is elongated by a bony and cartilaginous knob, which is attached to a curved rod of bone 10 mm.

ENCEPHALOCELES AND OTHER ABNORMALITIES.

99

long and 2 mm. in diameter. This rod is joined at its other end to the everted arches of the vertebrae underlying it. On the left scapula the subscapular angle is 117°, the supraspinous angle is 109.5° and the infraspinous angle is 133.5°. The left scapula shows a rather interesting condition, presenting three out of four features often associated with Sprengel's deformity (congenital elevation of the shoulders). These are, according to Horwitz: (1) changed relations of the diameters to each other; (2) bending forward of the supraspinous process; (3) prolongation or rounding of superior median angle; (4) presence of exostoses and articulations with the vertebral column.

In this case the exception to the above conditions is the superior median angle, which can hardly be called prolonged. Scajnilar measurements of the new-born could not be foimd in the literature, but two supposedly normal sets were obtained from mounted skeletons belonging to the Obstetrical Department of the Johns Hopkins Hospital, and the measurements of several other scapulse were available through the courtesy of Dr. A. H. Schultz.

Table 3. — Comparison in miUiiiwtcrs of the scapular measurements of specimen with those of several normal new-born.

Specimen.

Schultz, No. 3 . Schultz, No. 4 .

Obstetrical Department skeleton.

Do

No. 862 a

Vertebral length.

165 151

169

172

Transverse diameter.

R. 24 / L. 24 \ R. 29 ( L. 30 \ R. 27 / L. 27 I R. 26

L. 31

Vertical diameter.

R. 33 L. 31 R. 38 L. 38 R. 36 L. 35 R. 36 L. 29

Morphological index.

72.7 77.4 76.3 78.7 75.0 77.1 72.2 106.8

Table 3 shows that the ratio of the diameters of the right scapula of 862 o is near those of the supposedly normal bones. The left scapula, on the other hand, has the relations of its diameters reversed. The transverse diameter exceeds the vertical. Thus its morphological index is 106.8, while none of the norrnal indices exceeds 80. The subscapular angle on the left side is somewhat smaller than on the right. The bony articulation joining the left scapula to the vertebral column is attached in the upper third of the vertebral scapular margin as in most of the Sprengel deformity cases. Some interest is attached to this abnormal bony spicule and various suggestions have been made concerning it. The opinion seems to be generally accepted that it arises from its scapular end. Cases are recorded in which other anomalous bones are joined only to the scapula, and their occurrence substantiates this view. Case xvi in von Recklinhausen's paper is a monster very like No. 862a. In it there is "ein 1 cm. langer knocherner, rippenartiger, am oberen Winkel des knorpeligen Schulterblatts articulierender Korper." Gruber gives a case found in an adult male cadaver of a "fortsatzartigen, cylindrischen Hocker an der Vorderflache des Angulus superior der Scapula." No satisfactory hypothesis has been advanced to further explain the origin of these bones. The length of the right clavicle is 39 mm. while the left clavicle measures 34 mm. and is shghtly

100 STUDY OF A HUMAN SPINA BIFIDA MONSTER WITH

more bent at its distal end than the right. This shortening of the clavicle on the side of the abnormal scapula is frccjuent in Sprengel's deformity. The hunched position of the shoulders, so ]irominent externally in this case, may be seen to be due to the defective cervical and upper thoracic vertebrae, which lie crumpled to half their normal length under the scajjulae, their normal relations to these bones being quite changed.

MUSCLES.

The region of abnormal musculature corresponds, as would be supposed, to the skeleton derangements. This is limited to the neighborhood of the axial skeleton, where the affected muscles are both under and intermingled with an unusually large amount of fascia. On superficial dissection, the topmost layer of muscles is well formed, except for the trapezius, which is represented similarlj' on the two sides by thin strap-like bands of muscle, 3 by 1 cm. The fibers run parallel with the long diameter, from the origin of the muscle, situated in fascia lying over the everted and crumpled cervical and thoracic vertebral arches, to their insertion on the acromial extremity of the clavicle, the acromion, and spine of the scapula. Those fibers which insert on the scapular spine have become folded under the others, owing to the contracted and lowered origin of all the fibers. A condition of the trapezius similar to this has been noted in a case of total rachischisis given by Kermauner, in which case, also, lordosis and marked shortening of the spine were the underlying skeletal conditions. As Kermauner says, the association of this variety of muscle and bone defect is only natural, "for, with the marked shortening of the trunk, there necessarily exists a reduction in the cranio-caudal diameter of the muscles of this region."

Upon further dissection, the condition of the underlying muscles was determined. The rhomboidei are represented bilaterally by very thin and short muscles, onlj'^ 3 mm. in length. They arise from the connective tissue over the fused and everted arches of the thoracic vertebra, and are inserted in fascia along the inferior vertebral borders of the scapula?. (In Le Double's work a reduction in the thickness of these muscles is recorded.) The two levator scapulae are present. They arise from the fused transverse processes of the upper cervical vertebrae and are inserted in fascia along the superior vertebral margins of the scapulae. There is no reduction in the size of either muscle. They are directed horizontally out instead of slanting downwards as usual. This is due to the scapuhe lying directly over the cervical vertebr:e. A cross-section of the left muscle at its origin is shown in figure 21. Figure 18 shows the left scapula and the rhomboideus and levator scapulae muscles inserted in fascia which forms a sheet between the irregular projections of the vertebral margins of the bone. The abnormal spicule of bone is attached to the scapula at the mcflian angle between the insertions of the levator scapulae and the rhomboidcnis.

On each side most of the dorsal inusck's consist of ;ui irregular longitudinal bundle which extends along the sides of the vertebrae from sacrum to occiput and which sends scattered projections on to the ribs. Under this bundle in the lumbar region the quadratus lumborum and psoas muscles lie undisturbed. On the left

ENCEPHALOCELES AND OTHER ABNORMALITIES. 101

side this bundle is shown somewhat diagrammatically in figure 21 and labeled sacrospinalis. In the lumbar region it is cjdindrical and measures 1.5 cm. in diameter. It grows flatter and broader as it nears the upper part of the spine, this formation being due to a state of arrested development of the sacrospinalis and short back-muscles. The early condition of dorsal musculature which it simulates is strikingly illustrated in Bardeen and Lewis's model of an 11 mm. embryo (1901), where a bundle distinct from the ventral-lateral muscles lies bilaterally in the trough formed at the sides of the vertebrae. In another model given in the same paper of a 20 mm. embryo, the bundle may still be seen lying under the connective tissue of the region, and this divided condition of the back-muscles persists normally until about the 60 mm. stage.

The serati posterior inferior are shown by projections from the dorsal bundle which on both sides cover the proximal half of the three lowest ribs. In the upper thoracic region, lying on the surface of the bundle on each side, is a thin strip of muscle near the base of the ribs. These strips extend cranio-caudally and measure 20 by 3 mm. On the left the strip lies over the third to eighth rib ; on the right side it extends over the first to the sixth rib. The serati posterior superior are not identifiable.

The direction of the muscles of the anterior cervical region, as well as of those attached to the skull, is distorted vvith the underlying skeleton, but the muscles are well developed and not defective. Both sterno-cleido-mastoid muscles have normal origins and insertions. The two splenii arise bilaterally from fascia under the scapulae and are inserted normally on the mastoid process under the sterno-cleido-mastoid, and posterior to this on the occipital bone. The longissimi can be traced arising from the fascia over the cervical vertebral region and inserted on the mastoid proces.ses. The semi-spinalis capitis muscles, arising from the upper ribs near their origin, are inserted on the occipital bone and are next to the deepest layer of musculature. The latter on each side consists of short fibers, rudiments of the short neck-muscles, the recti, and obliqui. More anteriorly most of the neck muscles are recognizable. The digaster, stylohyoid, omohyoid, and sternohyoid muscles are well developed. The longiis capitis and colli are represented by a few strands along the anterior surfaces of the vertebral plate. The scaleni medii and posteriores are present as flattened bands of muscle arising in this region and inserted in the first and second ribs near their bases. The scaleni anteriores are symmetrical. They arise from the lateral processes of the superior cervical vertebrae and insert on the first rib near its center. The nerve trunks of the cervical and brachial plexus pass under these muscles and are tightly bound down bj^ them.

Of the more anterior thoracic muscles, the pectorales are not disturbed. Both serati anterior muscles are defective and difTer in their defects. On the right side there is more complete development. Here slips of the muscle arising from the distal portions of the first four ribs and from the eighth to the tenth ribs converge and are inserted around the inferior angle of the scapula. A few strands of muscle on the chest wall between the pectoraUs minor and the seratus are present, which might be remnants of th(! latter. They are shaped like half a crescent, with fibers running longitudinally, and extend from the first rib, where they are 3 mm. broad, to the fifth rib, where they are 15 mm.

102 STUDY OF A HUMAN SPINA BIFIDA MONSTER WITH

On the loft side the seratus anterior is very imperfect. It is represented l)y a thin sheet of fascia, which originates from the first three ribs and is inserted in the scapula along the vertebral margin near the medial angle. A few scattered musclefibers, which also probably represent remnants of the serati, arise over the fourth rib near its base and are inserted into the inferior angle of the scapula. The origin of the fascia and these muscle-fibers is shown in figure 21 by dotted lines. Some other muscles on the left chest wall, consisting of irregular projections from the dorsal bundle which covers the proximal part of the first seven ribs, may be serati fibers which remained in their embryonic position close to the axis. Fibers which jjrobably represent intercostal muscles pushed to the outer surface of the ribs are arranged along the lower border of the fourth rib. These extend onto the lower adjoining ribs. At the outer end they are 2 mm. across and near the base of the ribs they measure 20 mm. (See fig. 21.) Three small muscle bundles are situated at the distal end of the above-mentioned fibers.

The lateral and anterior abdominal muscles are well developed. Each rectus is 7.4 cm. by 3.2 cm. The right rectus has two inscriptiones tendinae in its upper one-third opposite the sixth and seventh ribs.

To summarize : Those muscles which have undergone most disturliance are the trapezei, the rhomboidei, the serati posteriores superiores, the serati anteriores, and the sacrosi)inalis and short back muscles. The location of these muscular abnormalities, situated near the chief skeletal abnormalities, demonstrates still further that the ijathological process is a rather sharply circumscribed one, limited to the neighborhood of the axis. The inclusion of the anterior serati in this group does not contradict the statement, as the early anlage of the serati is very near the axis.

The muscle disturbances of "monsters" have been but little investigated or recorded. From the scattered observations at present obtainable, any correlation is impossible.

VISCERA.

On dissection, the viscera are found crowded and somewhat distorted, but, with the excejition of the right lung, are well developed. The thyroid is bilobed and measures 1.5 by 1 cm., the thymus measures 6 by 2.8 by 1.1 cm. The esophagus measures 4 cm. from epiglottis to cardia. The lesser curvature of the stomach is 1 cm. and its greater curvature 8 cm. The intestines are well formed. The api)endix measures 8.5 cm. The cok)n is much bent upon itself. Because of unskillful handling the positions asssunied l)y the rest of the intestinal tract were not ascertained. The pericardium, ])leura, and diapluagm are intact. The heart is well developed. Sagittal section sliows it cut through the right ventricle and left auricle. The valves are well formed. The ductus arteriosus is patent. The left lung is approximately normal; its lateral surface is shown in figure 23; it consists of two lobes and measures 3.9 cm. antero-posteriorly by 3.1 cm. perpendicularly by 1.7 cm. in its thickest niedio-lateral diameter near the hilum. The right lung, side view of which is shown in figure 22, about ('(juals the left in volunu^ and is roughly a flattened cone-shape with apex directed anteriorly. Its corresi)onding measurements are 5.1 by 3.2 by 2.9 cm. it is formed of only one lobe. Along tlie margins four short fissures exist, directed toward tlu' center; one 12 mm. in length

ENCEPHALOCELES AND OTHER ABNORMALITIES. 103

is situated on the posterior margin at the junction of the superior third with the middle third; on the inferior margin near its middle a similar fissure is situated, and halfway between it and the anterior end of the lung a shorter fissure 3.5 mm. long exists; on the superior margin another, 3.5 mm. in length, is present slightly anterior to the middle. These fissures are very superficial and extend for only a few millimeters on the medial surface of the lung. The relations of the bronchial tree were not determined.

The liver is flattened out horizontally and shaped like an L with the angle projecting anteriorly, the gall-bladder, which is 4.1 cm. in length, being situated on the inferior surface of the long arm of the L. The closed end of the gallbladder lies near the tip of the angle and its long axis is directed diagonally toward the upper end of the latter. The spleen is 2.2 by 1.3 by 1 cm. The presence of the pancreas is determined histologically. It lies embedded in ti.ssue near the vertebral column. Both kidneys and adrenals are somewhat compressed and distorted, the left much more than the right. The right kidney is somewhat flattened from side to side and at its upper end, and measures 4.5 by 1.2 by 3.5 cm. The right adrenal lies above it and measures 3 by 2 bj^ 0.5 cm. The left kidney is bent upon itself and folded in with its closely adherent adrenal, so that together they form a rounded mass measuring 4.7 by 3.4 by 2.4 cm. The greater distortion of the left kidney and adrenal is very probably due to crowding, a result of the left-sided concave bending of the vertebral column in this region and fusion of the lower ribs on that side. The ureters and bladder are well formed. The uterus, tubes, and ovaries are well developed. Blocks of tissue of heart, kidney, liver, and adrenal were run through by the Levaditi method for spirochaetes by Dr. Bullard, with negative findings. It is to be noted that the tissues had been kept in carbolic, which is not the fixation recommended for this method.

The developmental anomalies of the soft palate and the right lung are the most marked changes which have taken place in the soft tissues anterior to the vertebral column. They are both examples of arrested development and are secondary to, and probably the mechanical result of, 'the deformit.y of the vertebrae.

CRANIAL CAVITY AND CENTRAL NERVOUS SYSTEM. The shape assumed by the cerebro-spinal cavity or subdural space is shown by figures 4, 5, 6, and 7 of the wax model. In figures 12 and 21 the model is given in its relation to the skeleton. The space consists of a shallow dome which contained the frontal and part of the parietal cerebral lobes. Below this dome a relatively slight constriction in the model denotes the enlarged foramen magnum (figs. 4, 5, 7, and 12). Under the foramen three rounded encephaloceles project posteriorly, and below these the pointed termination of the spinal canal may be seen. Situated ventral to the encephaloceles and continuous with them and with the base of the dome and the spinal canal is a blunt, wedge-shaped mass marked iv in figures 4, 5, and 6. This portion fits into the pocket of bone formed by the thoracic and vertebral plate. With the exception of the inside of the large encephalocele, the space occupied by the central nervous system is lined with a continuous sheet of smooth dura. At the foramen magnum and in between the eminentiae arcuatae of the tem

104 STUDY OP A HUMAN SPINA BIFIDA MONSTER WITH

ponil bones and the sella turcica it is drawn into numerous folds. On the inside of tlio large encephalocele the smooth dural surface changes to a tissue composed of many blood-vessels, fibrin, and extravasated blood, as described in the beginning of the paper. The fabc cerebri lies well over on the left side in its anterior and middle portions; posteriori}' it ends in a single fold about the center of the superior margin of the occipital bone. The tentorium cerebelli is absent. The ventral surface of the subdural space is pierced by two rows of cranial and spinal nerves. These number 43 in all, 12 cranial and 31 spinal, the latter distributed as follows: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal. Both the anterior roots and the posterior roots with their ganglia are identified. In the cervical and thoracic regions they are extremely crowded.

The arrangement of the central nervous system is very complicated. The cerel)rum lies part above and part below the foramen magnum. The cerebellum lies entirely below it. The medulla and cord lie bent and crumpled ventral to the other structures below the foramen. The surface of that part of the cerebrum which lies above the foramen shows definite fissure and sulcus formation. Below the foramen a large part of the contents of the encephaloceles consists of a hemorrhagic mass and much of the surface of this is covered with caked blood, so that only in a few [)laces can typical cerebral surface markings be identified, flections of these regions, however, show definite though rather undifferentiated cortical lamination.

From a brief studj' of sections of other parts of the left cerebrum, made by Dr. Charles Bagley, the following points are determined : The cortical structure for the most part is composed of a very wide granular zone, which is characteristic of the early and undifferentiated stage of lamination. There is, however, a prominent vertical fissure lying at tlie junction of the middle and posterior two-thirds of the cranial dome, which can be identified as the central fissure of Rolando; the ventral termination of this fissure rests on the eminentia arcuata of the temporal bone. The cortical tissue anterior to this fissure shows a definite lamination. There is a welldefuied first layer; a broad and poorl}' differentiated second layer; the third laj^er is of medium width and is filled with small pyramidal cells; the fourth layer is inconsi)icuous, suggesting the agranular naotor tyi)e; while the fifth layer is represented l\y large pyramidal cells, ])r()l)ably Betz cells. These cells are at least three times as large as an}' other cells which could l)e found in the cortex and it is owing to their presence and to the very narrow gramilar layer that this area is identified as motor cortex. Immediately posterior to this fissure there is a sharp change in lamination types. Thc^ large cells are lost and the fifth layer is represented by definitely sha])ed pyramidal cells of not more than one-third the size of those cells de.signated as Jietz cells. Above this layer there is present a very heavy granular layer which is (|uite a contrast to the narrow granular layer of the area just described. It may be said, therefore, with a fair degre(> of certainty, that the tissue posterior to the fissure represents sensory cortex.

From the rather limited amount of material studied the only other localization that could be determined is that the cortical tissue i)ushetl down on the side of the wedge-shaped mass (11' in the model) represents subiculum. Here, passing from a cortex of (|iiilc deep cxlcnl, it becomes suddenly shallow and consists of atypical

ENCEPHALOCELES AND OTHER ABNORMALITIES. 105

first-zone layer containing few cells and a well-marked second layer with only a narrow zone of undifferentiated cortex beneath it. No calcarine type of cortex was identified, but the occipital lobe was probably included in the hemorrhagic mass in the encephaloceles, which was in such a bad state of preservation that no sections could be made.

On the right side of the cerebrum the fissure corresponding to the left central fissure of Rolando is situated slightly more anteriorly than on the left. The frontal lobes thus occupy most of the shallow vault and rest in the anterior and in the medial cranial fossae as well, which latter normally hold the temporal lobes. The sulci of the frontal lobes are changed considerably from their normal positions. The anterior ends of the superior medial and inferior frontal sulci are bent very sharply downward. They are all situated nearer the base of the brain than usual, as if the tissue had been pulled down on the lateral surfaces. Thus the superior sulci lie halfway down the sides, with the medial and inferior sulci correspondingly below them. With the exception of part of the parietal lobes on each side, the rest of the cerebrum lies below the foramen magnum. The left-sided position of the falx cerebri allows more room in the cranial cavity proper for the right cerebral hemisphere than for the left. This results in a larger portion of the parietal lobe on the right side lying above the foramen magnum than on the left side, and correspondingly a larger amount of parietal surface lying below the foramen on the left than on the right side.

The cerebral tissue which lies below the foramen is partly contained in the large bony pocket formed bj' the upper vertebral plate, and partly in the middle and left encephalocele. Sulci are present over its surface, but are so distorted that they can not be identified, nor can the identity of the lobes be determined. In the contents of the middle and left sacs one can easily discern cerebral gyri, and the general histological structure of these is similar to that of the cerebral tissue situated above the foramen. In the middle sac there is a large amount of clot. The cerebral tissue which lies in the cervical and thoracic vertebral pocket is pressed out into a thin shell, and hes next the dura, being limited anteriorly by the emerging cranial nerves. On the sides and back it is continuous with the cerebral tissue lying in the cranial vault and with that pressed out into the encephaloceles.

In the interior of the brain the optic thalami may be identified, h'ing above the foramen. A small space representing the third ventricle, greatly compressed, lies between the thalami. Choroid plexus tissue is present. Its relations, however, to the adjoining structures could not be determined. The cerebral peduncles may be seen as flattened bundles lying central to the shell of the cerebral cortex. The optic nerves are present. The hypophysis lies embedded in the well-formed sella turcica. No other structures in this region or below can be identified until, in the pocket of bone formed by the thoracic vertebrae, the inverted floor of the fourth ventricle is recognized.

The midbrain wiih attached fourth nerves, the colliculi, and the aqueduct of Sylvius were not identified. The fourth nerves, however, were found at their dural exit. Judging from the position of the fourth ventricle floor, a sharp bend

106 STUDY OF A HUMAN SPINA BIFIDA MONSTER WITH

with the angle directed posteriorly must have occurred in the midbrain region. At the beginning of the spinal cord a bend in the opposite direction is present. This bending of the brain stem and cord must have been in lateral outline shaped like a crudely drawn letter Z, as shown in figure 24, which is a diagram of various structures in the central nervous system near the midline. The surface of the inverted fourth ventricle floor is shaped like an isosceles triangle with its tip, which is its normal anterior end, directed backward toward the encephaloceles. The median sulcus is well defined. The tissue next to the median sulcus on both sides is slightly raised. The rest of the surface is flat. For estimating roughly the amount of distortion this fourth ventricle floor had undergone, a comparison of it with the fourth ventricle floor of three normal full-term fetuses was made. Each of the three showed a similar longitudinal ridge to be the extent of their surface markings. The main difference which this specimen showed seemed to be in a blunting of the posterior end which forms the base of the triangle already referred to.

From both lateral margins of the fourth ventricle floor cortical tissue resembling the flocculus is drawn backward, downward, and to the right, joining the cerebellar cortex contained in the right sac. It must be noted that while the flocculus is directed toward the posterior end of the specimen as a whole, it is drawn toward the end of the ventricle floor normally anterior. There is a much disturbed choroid plexus folded in with the cerebellar tissue. A fairly large amount of cerebellar tissue is present; part of this is drawn out into a sheet which is continuous with the flocculus and which passes posteriorly and to the right into the right encephalocele, where it lies next to a rounded mass of cerebellar cortex. Bands of tissue connecting the cerebellum and cerebrum i^robably represent the brachium conjunctivum. There are smaller flat bands of tissue passing backward near the flocculus to the rounded cerebellar cortex .which may have been remnants of the inferior cerebellar peduncles. There is no pontine enlargement.

From the tissue superior to and continuous with the floor of the fourth ventricle, the third and the fifth to the twelfth paired cranial nerves pass forward to . their normal exits from the subdural space. They are elongated to between 20 and 30 mm. Their origin from the brain-stem lies ()i)i)osite the first thoracic vertebra. In this region the beginning of the flattened cord can be made out, which is bent double upon itself. Some interest is attached to this Z bend of the brain-stem and cord. It seems to have been brought about in this case through traction on these parts by the major portions of the central nervous system slipping through the enlarged foramen magnum. \'arying degrees of such kinking have been described. The condition in its milder forms has received the name of Chiari deformity, from a case described by Chiari in which the medulla is l)ent l)ack over the cord for only a short extent. In Nageli's case of cyclopia there is a marked degree of such bending associated with splitting of the cord.

Caudal to the bend as a flat band the .spinal cord extends to the level of the lumbar vertebra, where it terminates in a cauda etiuina. From its ventral surface the spinal nerves extend into the dura. At the level of the twelfth thoracic verte])ra the spur in the vertebral plate has left an indentation on the flat cord and on the right anterior third of the inverted floor of the fourth ventricle.

ENCEPHALOCELES AND OTHER ABNORMALITIES. 107

The central canal, as such, is absent. Throughout the extent of the cord it is changed to a flat space following the contour of the vertebral column, whose floor is the cord and whose roof is partly the same cord inverted, partly the inverted floor of the fourth ventricle, and partly cerebellar tissue.

This fragmentary description of the central nervous system leaves much to be desired. It would have been especially desirable had we been able to present a clear picture of the relationships of the meninges. The main conclusion which can be drawn from its study is that the chief disturbance here evidenced is primarily one of distortion, rather than of absence or real lack of development of nerve-tissue.

CONCLUSION

The exterior alone of such a specimen as this certainly presents striking evidence that an organism can undergo most serious disturbances and yet maintain a definite though limited growth balance ; but in order to ascertain in detail exactly what constitutes the limitations of this equilibrium more intensive study is necessary. A rather intereisting series of anomalies is the result of such a study in this ca.se. It may be noted that these anomahes are centered about the axis. The bony parts, the central nervous S3^^tem, certain adjacent muscles, and overlying areas of integument share profoundly in this disturbance. Subsidiary disturbances of development are evidenced in a split soft palate and a one-lobed right lung. These facts, in addition to supplying a clearer knowledge regarding the individual specimen, contribute their small share in providing data for the better understanding of certain general problems of development. Classifications and analyses included in such subjects as osteolog}^, myology, and organology can not be regarded as complete until they contain a comprehensive picture of teratological phenomena. This is almost entirely lacking at present. The teratological material has been so scanty that any satisfactory correlation of it has been impossible.

Up to f airh" recent times teratology was considered an isolated science ; it was thought that the laws applying to most jiatural phenomena were not applicable to its conditions, that it could not learn from or contribute to the normal sciences. Studies of the past half century have entirely reversed this view. Teratology today has for its basis the same fundamental sciences of chemistry, biology, and physics as has those sciences whose subject-matter deals with normal phenomena. It is constantly learning from these latter sciences, and in turn has been able to contribute suggestions on points of analysis or exposition regarding puzzling phases of normal development.

The necessity of furthering our knowledge regarding the etiological factors of specific abnormal conditions has been^considered. Material at such an advanced stage of development as this specimen can contribute but Uttle along this line. We can not determine by means of it the primary defect, nor again, except in a very general way, a chronological picture of the early processes. We must turn to embryological material and to other than morphological methods to obtain such knowledge.

BIBLIOGRAPHY.

Aebt, Chb., 1879. Die Altersverschiedenheiten der menschlichen Wirbelsaule. Arch. f. Anat. u. Physiol., Anat. Abt., pp. 95, 109.

Baldwin, \V. M., 191.5. The action of ultra-violet rays upon the frog's egg. Anat. Record, i.\, SG.^-SSl.

Ballantyne, J. VV., 1904. The embryo. Antenatal pathology and hygiene, Edinburgh, 272, 285.

Bardeen, C. R., and W. H. Lewis, 1901. Development of the limb.s, body-wall, and back in man. Amer. Journ. Anat., l, 1-35.

Bayer, C, 1889, 1890, 1892. Zur Chirurgio der Ruckenmarksbriiche. Prager med. Wochenschr., xiv, 227-230; xv, 48; xvii, 317, 332, 345.

Bettmann, 1912. Die Missbildung der Haut. In E. Schwalbe, Die Morphologie der Missbildungen, III Teil, VII Lieferung, 2. Abt., 7. Kap. Jena.

Binder, 1899. Das Morelsche Ohr. Arch. f. Psychiat., XX, 514-564.

Brodman, K., 1910. Feinere Anatomic des Gros.shims, p. 206. In M. Lewandowsky, Handbuch der Neurologic. Erster Teil, ii. .\natomie. Berlin.

ChiaRI, 1891. Veriinderungen des Kleinhirns in Folge von Hydrocephalic des Grosshirns. Deutsche med. VVochensclir., xvii, 1172-1 175.

Ernbt, Paul, 1909. Missbildungen des Nervensystems. I. Storungen des Verschlusses in der hinteren Mittellinie des Korpers. In E. Schwalbe, Morphologie der Missbildungen, III Teil, I Lieferung,

II Abt., II Kap., I. p. 72.

, 1909. Mis.sbildungen des Nervensystems, X.

Entwickelungsstorungen des Kleinhirns. In E.

Schwalbe, Morphologie der Missbildungen, III

Teil, I Lieferung, II Abt., II 2. Kap., (X) p. 223 GiLLASPiE, C, L. I. Miller, and M. Baskin, 1916.

Anomalies in lobation of lungs. .Vnat. Rec, xi,

65-75. Good, J. Percy, 1912. Spina bifida in the neck region of

a ferret embryo, 8 mm. Journ. Anat. and Physiol.,

XLVi, 391-399. Graves, Wm. W., Scapula scaphoidea, eine hiiufig

vorkonunende .\nomalie des SiOiulterblattes. Ihr.

Zusammcnhang mit Syphilis in der Ascondens.

Med. Klin., 1911, No. S, p. 298. Gruber, Wenzel, 1872. Ueber einen fortsatzartigen

cylindrischen Hocker an der Vorderfliiche des

Angulus superior der Scapula. Virchow's Arch.

f. path. Anat., Lvi, 425. GrUnbero, Karl, 1913. Die Mi.sslMldungen des Kop fes. Die Spalte des weichen (laurneiis. In K.

Schwalbe, Die MorphoIogi(' der Mis.sl)ildungen.

III Teil, IX Lieferung, 1 Abt. 4. Kap. Gudden, II., 1898. Fall von Knickung der Medulla

oblongata und Theilung des Riickenmarks.

Arch. f. Psychiat., XXX, 866-876. Hebtwio, O., 1892. IJrmund und Spina bifida. .\rch.

f. mikr. Anat., xxxix, 353-530. HiLDEBRAND, 1893. Ucber Spina bifi<la. Verhandl.

d. deiitschen Gesellsch. f. Chir., xxil, 41-43.

HoRwiTZ, A. E., 1908. Congenital elevation of the

scapula, Sprengel's Deformity. Amer. Journ.

Orthop. Surg., vi, 260-311. Kermauner, 1909. Missbildungen des Rumpfes. In

E. Schwalbe, Morphologie der Missbildungen, III

Teil, I Lieferung, I .\bt., 3. Kap., p. 86. Koch, Wilhelm, 1881. Mittheilungen iiber Fragen der

wissenschaftUchen Medicin. 1. Heft. Beitrage

zur Lehre von der Spina bifida. Kassel. Lewis, H. F., 1897. Iniencephalus. Amer. Journ.

Obst., xxxv, 11-53. Lewis, W. H. (See Bardeen and Lewis.) LiLLiE, Ralph D., 1917. Variations of canalis hypo glossi. Anat. Record, xiii, 131-144. Macklin, C. C., 1914. The skull of a human fetus of

40 mm. Amer. Journ. Anat., xvi, 317, 387. Mall, F. P., 1908. A study of the causes underlying the

origin of human monsters. Wistar Institute

of Anatomy and Biology. Philadelphia. (Journ.

Morphol., XIX, 1-367.) Marchand, 1899. Spina bifida. Missbildungen. Real

Encyclopadie der gesamraten Heilkunde, von A.

Eulenburg. 3 Aufl., 1899, xxii, 578-601. Martin, Rudolf, 1914. Lehrbuch der Anthropologic.

Jena. Marx, Hermann, 1911. Die Missbildungen des Ohres.

In E. Schwalbe, Morphologie der MLssbildungen,

III Teil, V Lieferung, II Abt., 6. Kap. Jena. Mdscatello, 1894. L^eber die angeborenen Spalten des

Schadels und der Wirbelsaule. Arch. f. klin.

Chir., XLVii, 162, 257. Naeqeli, O., 1897. Ueber eine neue mit Cyclopie ver kniipfte Missbildung des Contralnervensystems.

Arch. f. Entwickelungsmechanik, v, 168-218. VON Recklinghausen, F., 1886. Untersuchung ilber

die Spina bifida. Virchow's Arch. f. path. .4nat.,

cv., 243, 373. Schneider, 1912. Die Missbildungen der .\tmung9or gane. In E. Schwalbe; Die Morphologic iler Missbildungen, III Teil, VIII Lieferung, II Abt., 8.

Kap. Spietschka, T., 1894. Hautveriinderiing bei Spina

bifida. Prager med. Wochenschr., xix, 117, 131. Sprenqel, 1891. Die angeborene Ver.schiebung des

Schulterblattes nach oben. Arch. f. klin. Chir.,

XLii, 54.5-549. Streeter, G. L., 1903. Anatomy of floor of the fourth

ventricle. Amer. Journ. Anat., ii, 299-313. , 1915. Development of the venous sinuses of

the dura mater in the human embryo. Amer.

Journ. Anat., xviii, 145-178. TiLLMANNS, H., 1905. Die Verletzungen und chirur gischen Krankheiten des Beckens. Deutsche

Chirurgic, Lieferung 62a, p. 497. WHed, Lewis H., 1916. The development of the

cerebro-spinal spaces in pig and in man. Contributions to Embryology, v. 5, No. 14. Carnegie

Inst. Wash. Pub. No. 226.

108

EXPLANATION OF PLATES. ABBREVIATIONS.

anth.,

anthelix.

m. obi. ext..

antitr.,

antitragus.

m. pect. maj..

b. occ,

basioccipitales.

m. pect. min.,

c. i.,

first coccygeal segment.

m. quad, lumb..

c. c. 7,

costal cartilage of seventh rib.

m. rect..

c. eq.,

Cauda equina.

m. rhomb.,

cer.,

cerebrum.

m. sacraspin.

cereb.,

cerebellum.

m. ser. ant..

cr. 2,

second cranial nerve.

m. ser. post, inf

cr. 5,

fifth cranial nerve.

naev.,

dep. em.,

depression made by eminenlia arcuata

r. 1 (rib).

of temporal bone.

r. hyp.,

epist.,

episternum.

rt. en..

eust. t.,

eu.stachian-tube orifice.

s. 1,

exos.,

exostosis.

sp. 1,

fak.,

falx cerebri.

sq. occ.

fl. IV,

floor of fourth ventricle.

St.,

for. mag.,

foramen magnum.

tr.,

1. 1,

first lumbar segment.

uv.,

1.2,

second lumbar segment

V'l

1. 1 rib,

left first rib.

V. pi..

1. en.,

left encephalocele.

w..

1. pars lat..

left pars laterahs.

mid. en..

middle encephalocele.

X.,

m. lat. dors..

m. latissimus dorsi (origin).

xyph..

m. lev. scap.,

m. levator scapulae (cross-section, fig.

iii.,

17, insertion fig. 14).

m.obliquuscxternus abdominis (origin), m. pectoralis major (origin), m. pectoralis minor (origin), m. quadratus lumborum. m. rectus abdominis (origin), m. rhomboideus (insertion), m. .sacrospinaUs (insertion), m. seratus anterior (insertion). , m. seratus posterior inferior, naevus.

right first rib. right hypoglossal canal, right encephalocele. first sacral segment, first spinal nerve, squama occipitaUs. sternum, tragus, uvula, vertex.

vertebral plate, central nervous system occupying bony

vertebral pocket, anomalous bone and its insertion, xyphoid. third ventricle, absence of soft palate.