Musculature of Indian Elephant. Part III. Musculature of the trunk, neck and head. Tokuichi Shindo (Emeritus Professor) and Masaru Mori

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1 Musculature of Indian Elephant. Part III. Musculature of the trunk, neck and head. Tokuichi Shindo (Emeritus Professor) and Masaru Mori Department of Anatomy, Prof. (Masaru Mori) Faculty of Medicine, Kyushu University, Fukuoka. A. subcutaneous muscles. M. cutaneus trunci (Fig. 1). This muscle lies beneath the tela subcutanea and is a large, thin quadriangular muscle which extends from the middle of the back to the shoulder and the arm. The caudal part ( continued to the fascia covering the caudal half of the trunk._ The cranial part is divided into two parts. The fiber-bundles of the dorsal part run craniad, cross the angulus inferior scapulae, and pass into the fascia infraspinata and fascia tricipitis. A small part of the fiber-bundles acrosses over the scapula, goes in neck region, and passes into a thin, flat tendon to be inserted into the transverse process of the atlas. The ventral part runs craniad and its fiber-bundles converge passing along the medial margin of the triceps to be inserted on the fascia pectoris. The caudal margin of the triceps lies between the dorsal and ventral parts of the cutaneus trunci, and there is a narrow space behind the insertion of the triceps. Three lymphonodi were found in this space. Length and breadth; Dorsal part; length, 30.0cm. breadth, 23.0cm Ventral part; length, 40.0cm, breath, 20.0cm M. cutaneus abdominis (Fig. 1). This muscle lies beneath the tela subcutanea of the abdomen and makes the so called knee-fold. The muscle is thin, flat, and triangular, Its cranial part covers the arising part of pars abdominalis of the pectoralis major. The cutaneus abdominis arises from the ventral.lamina of the rectus-sheath near the linea alba, and the fiber-bundles run caudolaterally. In the course of running to the insertion the muscle narrows into a tendon, which reaches before the knee-joint, and passes into the crural fascia. The length of this muscle is 50.0cm. The breadth is 10.0cm in the middle. The breadth of the insertiontendon is 6.0cm.

2 Is Tokuichi Shindo and Masaru Mori Fig. 1. Subcutanous muscles of the trunk B. Musculature of the back. M. trapezius (Fig ). It is covered merely by thin subcutaneous muscle and fascia, and lies external to the rhomboideus. The trapezius arises from the caudal portion of the lig. nuchae and the vertebral aponeurosis between the 3d and 14th dorsal vertebrae, and is triangle in shape. The fiber-bundles of the cranial part pass obliquely caudo-ventralwards, and the fiber-bundles of the caudal part pass obliquely cranioventralwards. The fiber-bundles pass into a tendon, to be inserted into the posterior surface of the spine of the scapula and the superior border of the processus unciformis scapulae. We could not find the occipital origin. M. serratus dorsalis cranialis (Fig. 4). This muscle is thin and flat, and coyered with the rhomboideus and scapula. It arises from the caudal portion of the lig. nuchae and the vertebral aponeurosis between the 3rd and 12th vertebrae. The fiber-bundles run caudoventrally and are inserted into the anterior margin of the 9th to 15th ribs and also into a strong fascia which underlies to the serratus lateralis.

3 Anatomy of Indian Elephant, Part III. 19 Fig. 2 Abdominal muscles. A small part of transversus abdominis is seen between the fiber-bundles of internal obliquus muscle. M. serratus dorsalis caudalis. It is not found. M. levator scapulae (Fig. 4). It is small, and lies beneath the neck fascia, arising from the transverse process of the atlas by means of a thin, flat, tendinous slip. The fiber-bundles are directed obliquely across the lower part of the outer side of the neck. The muscl e becomes larger passing to the insertion. The insertion is the anterior border of the angulus superior scapulae. M. occipitoscapularis (Fig. 4). In the nuchal region beneath the nuchal fascia we could find a well-developed muscle, which lies between the occipital bone and scapula. The caudal portion of this muscle is covered with the trapezius arising from the lig. nuchae. This muscle is long rectangular, and the fiber -bundles arise from the occipital bone and pass caudad to be inserted into the anterior border of the angulus superior scapulae.

4 20 Tokuichi Shindo and Masaru Mori Fig. 3. Transversus abdominis and rectus abdominis M. splenius (Fig ). This muscle lies beneath the nuchal fascia and the occipitoscapularis. The muscle arises from the lig. nuchae in the region of the third to seventh servical vertebrae. The fiber-bundle's extend upwards and lateralwards, and are inserted by a short, thick tendon into the whole length of the superior curved line of the occipital bone. M. iliocostalia lumborum. (Fig. 5). This muscle lies on the lateral margin of the longissimus, and upon the ribs, the external

5 Anatomy of Indian Elephant, Part III. 21 Fig. 4. Muscle of the shoulder intercostalis and the levator costarum. The muscle arises chiefly from the back of the sacropinal aponeurosis, and from the iliac crest directly. From the mass of fiber-bundles which compose the muscle, fasciculi are given off which are attached chiefly by tendinous slips of the processus transversus of the first vertebra to the nineteenth vertebra, and to the inferior margin of the all ribs near the angles. We could not find the iliocostalis dorsi. M. longissimus cervodorsi (Fig. 5). This muscle lies medially to the iliocostalis lumborum, and is covered with a thick fascia which is the septum between the longissimus cervodorsi and the iliocostalis lumborum. The longissimus cervodorsi arises from the deep surface of the sacrospinal aponeurosis and from the dorsal surface of the sacrum, and from through accessory slips which arise from the transverse processes of the first to 13th thoracal vertebrae. In the lumbar region it is fused dorsolaterally with the iliocostalis. From the musck mass arise fasciculi which are inserted partly directly, partly by mass of tendon, into the lower border of the back of the transverse processes of the lumbar vertebrae and the caudal

6 22 Tokuichi Shindo and Masaru Mori Fig. 5. The deep muscles of the back

7 Anatomy of Indian Elephant, Part III. 23 Fig. 6. The deep muscles of the back margin of all ribs lateral to the tubercles, and the posterior tubercles of the transverse processes of the lower cervical vertebrae. M. longissimus capitis (trachelomastoid) (Fig. 6). It is a long muscle, and arises by tendinous and fleshy slips from the articular processes of two last cervical vertebrae. The muscle forms a flattened

8 24 Tokuichi Shindo and Masaru Mod, brae. band, which passes direct to the mastoid process, and is inserted by tendinous fibers on its superficial aspect, and more deeply by fleshy fibers. The insertion is overlaid by splenius. There is a layer of yellow fascia between the trachelomastoid and the splenus. M. semispinalis. (Fig 5. 6). There are three kinds of M. semispinalis ; M. semispinalis capitis, semispinalis cervicis and semispinalis dorsi. The semispinalis capitis and cervicis are developed well-remarkably and isolated from the other muscles, but the semispinalis dorsi is intermingled with the spinalis. The semispinalis capitis (complex). It arises by tendinous fasciculi from the tips of the transverse processes of upper seven thoracic vertebrae and of the seventh cervical vertebra, and by short fleshy processes from the articular processes and base of the transverse processes of the second to sixth cervical vertebrae. The slightly converging fiber-bundles from a long, and flat belly are inserted into the inner half of the superior curved line beneath the splenius muscle. There is a thin layer of connective tissue between the complex and the splenius. The semispinalis cervicis. This muscle lies beneath the longissimus dorsi and the semispinalis capitis. The semispinalis cervicis arises from the transverse processes of the upper twelve thoracic vertebrae and the last six cervical vertebrae. The fiber-bundles go craniad and are inserted into the lower border of the tuberculum dorsale of the atlas, and into the spine of the second cervical vertebra. The semispinalis dorsi. It is fused with the spinalis dorsi, and it is difficult to separate it form the spinalis dorsi. The semispinalis dorsi arises from the transverse of the tenth to nineteenth thoracic vertebrae by tendinous slips. The fiber-bundles are inserted by a short tendon into the spines of the upper six thoracic vertebrae. M. spinalis dorsi (Fig. 6). It arises by tendinous bands from the sacrum and the tips of all the lumbar and the last five thoracic spines. The slender tendon passes into a long slender muscle belly which is fused laterally with the semispinalis dorsi. The semispinalis dorsi is inserted by tendinous processes into the upper thoracic verte- M. multifidus. This muscle is found in the lumbar and the lower thoracic region. Mm. levatores costarum (Fig. 6). They are found in thoracic region, and there are two kinds : the levator costarum brevi and

9 Anatomy of Indian Elephant, Part III. 25 Fig. 7. The deep muscles of the hack, the rips are removed. levator costarum longi. The levatores costarum brevi consist of a series of flat, triangular muscles, each of which arises from the tip and inferior margin of the transverse process, and extends laterally with diverging fiber bundles to be inserted into the dorsal surface of the rib below, from

10 26 Tokuichi Shindo and Masaru Mori the tubercle to the angle. The first short levator extends form the transverse process of the last cervical vertebra to the first rib. They are not found in the lower thoracic region. Fifteen levatores costarum brevi are found. The levatores costarum longi are six in number. The first arises from the transverse process of the fourteenth thoracic verfebra and acrosses the rib below to join the lateral margin of the short rib levator below. M. rectus capitis posterior major -upper surface of the spine of epistropheus (Fig. 12). It arises from the by tendinous fiber -bundles. The muscle-fibers diverge to form a triangular band which is inserted into the occiput external to the lig. nuchae and immediate below the insertion of the obliquus capitis superior. M. retus capitis posterior minor. It is small, and covered with the rectus capitis posterior major. It arises from the upper part of side of the posterior tubercle of the atlas. The fiber-bundles diverge as they pass upwards, and is inserted into the occiput beneath the insertion of the rectus capitis posterior major. M. obliquus capitis superior (Fig. 12). It is a fan-shaped muscle, and arises from the back of the upper part of the transverse process of the atlas. The fiber-bundles diverge to form a flat, fan-shaped muscle. The obliquus capitis superior is inserted into the lateral third of the inferior nuchal line of the occipital bone, and above the lateral part of the insertion of the rectus capitis posterior major. The obliquus capitis superior is covered by the splenius capitis. M. obliquus capitis inferior It arises from the upper part of the side of the spine of the axis. The fiber-bundles diverge to form a fusiform belly which is inserted by a short tendon into the lower part of the tip of the transverse process of the atlas. Mm. intertransversales These muscle are present, stretching between the tranverse process as is the case with the general animal. Ligamentum nuchae (Fig. 12). There is a pair of nuchal band. This band stretches between the spine of the first dorsal vertebra and the occipital bone, and is strengthened by the bundle derived from the cervical vertebra. Therefore, the lig. nuchae consists of two very distinct masses ; one superficialis, and the other deeper. The superficial portion is a large cord and its cross-section is round. At the insertion on the occipital bone the superficial portion breaks up into many distinct fasciculi. The deeper portion is membranous attached to the spines of the

11 Anatomy of Indian Mephant, Part III. cervical vertebrae. C. Prevertebral muscles. M. rectus capitis lateralis. It arises from the upper surface of the atlas. The fiber-bundles give rise to a quadrilateral sheet which passes upwards to be inserted on the under surface of the pars lateralis of the occipital bone, lying along the anterior border of the longiss imus capitis. M. rectu capitis anterior (minor) (Fig. 11). It is a small muscle, arising by thin slips from the third, fourth and fifth cervical vertebrae, The fiber-bundles extend in a nearly parallel direction upwards and medially to be inserted into the base of the basilar process of the occipital. _ bone. M. longus capitis (M. rectus capitis anterior major) (Fig. 11). It lies medial to the rectus capitis anterior minor, and its form is cylindrical. This muscle arises from the tips of the anterior tubercules of the transverse processes of the third, fourth and fifth cervical vertebrae. The belly runs cranialwards and -the insertion takes place into. the impression on the inferior surface of the basilar process of the occipital bone. M. longus cervicis (M. longus colli). (Fig. 11). It is a strong muscle, lying symmetrically upon each side of the middle line and internal to the longus capitis. The fiber-bundles arise from the tranverse processes of the third, fourth, and fifth cervical vertebrae and from the front of the bodies of third, fourth, fifth and sixth thoracic vertebrae, and from the heads of the corresponding ribs. The insertion takes place into the anterior tubercle of the atlas. M. scalenus anterior (Fig. 4). This arises from the ventral part of the inferior border of the transverse process of the second, third. and fourth cervical vertebrae by means of long, slender tendi- nous process. The tendons soon fuse to form a muscle-belly, and pass towards the thorax, being inserted into the second, thind and fourth ribs. D. Abdominal musculature M. rectus abdominis (Fig. 3). This muscle is long and flat. Cranialwards it is broad and thin, caudalwards it becomes thicker as it

12 28 Tokuichi Shindo and Masaru Mori converges towards the insertion. It is crossed by six incomplete inscriptiones tendineae, better developed on the ventral surface than on the dorsal surface of the muscle, The muscle arises from the ventral surface of the first to seventh costal cartilages. The fiber-bundles of the muscle have a longitudinal course. The insertion takes place on the front border of the pubis. The medial border of the rectus abdominis does not touch the linea alba, In the cranial part the distance between the medial border and the linea alba is about 3cm, and in caudal it is 13cm. The sheath of the rectus is very thick. The length of the rectus abdominis is 106cm. The breadth is 25cm at the level of the umbilicus. M. obliquus externus. (Fig. 2). It arises by fleshy digitations from the external surface of the fourth to the eighteenth ribs immediately lateral to where they join the cartilages. The fiber-bundles which compose the flat fasciculi of origin diverge slightly as they pass forwards and caudad, and by fusion of their edges give rise to a flat sheath of muscle. The muscle passes into broad and strong aponeurosis. The greater part of aponeurosis extends over the rectus to the linea alba, and the rest is inserted into the outer lip of the crest of the ilium. The aponeurosis over the rectus is fused with the aponeurosis of the internal oblique. M. obliquus abdominis internus. (Fig. 2). This muscle is less extensive than the obliquus abdominis externus. It arises by fleshy from the intermediate lips of the ventral two-thirds of the crest of the ilium and the seventeenth, sixteenth, fifteen ribs. The fiber-bundles which extend towards the rectus terminate in an aponeurosis, which in its upper two-thirds divides into two layers, one of which passes in front of and the other behind the rectus muscle to the linea alba. In the lower third the aponeurosis passes as a single membrane in front of the rectus. M. transversus abdomimis. (Fig. 3). It arises from the inner side of the cartilages of the seventh to nineteenth ribs by dentations which interdigitate with the attachments of the diaphragma, from the lumbodorsal fascia, and from the internal lip of the iliac crest. The fiber-bundles give rise to a broad, thin belly and take a nearly transverse course across the inner side of the abdominal wall. But the fiber-bundles from the ribs run caudad and inwards, and pass into the aponeurosis.

13 Anatomy of Indian Elephant, Part III. 29. The development of the lower portion of the transversus abdominis is very poor, and the caudal border of the muscle lies at the level of the umbilicus. M. quadratus lumborum. It arises from the nineteenth and eighteenth ribs, and passes to the innermost part of the crest of the ilium to be inserted. Mm. intercostalis externus and internus. The intercostal muscles are present and arranged as usual. E. Superficial cervical musculature. M. sternomandibularis. (Fig ). It arises from the first rib, adjacent ta the sternum, and its form is a strap-like band of nearly uniform breadth, and runs craniad, and becomes aponeurosis at its insertion into the rostral half of the basis of the mandible. M. sternomastoideus (Fig. 13). It is a long, narrow band-like muscle, and arises from the cranial edge of the sternum. It passes obliquely forwards and outwards, aud finally expands upon the face to,be inserted into the zygoma. M. digastricus (Fig ). It arises by fleshy from the mediocaudal border of the mandible joint cavity, and from behind the root of the styloid process, and from the short process of the styloid process. The fiber-bundles run diverging rostrad, and is inserted into the middle of the basis of the mandible. There is no tendinous intersection. M. stylohyoideus is wanting. M. mylohyoideus (Fig. 9). It arises from the mylohyoid ridge of the mandible. The fiber-bundles take a transverse course and are inserted into a median raphe extending from the middle of the ventral surface of the hyoid Lone to the posterior aspect of the inner margin of the mandile. The caudal portion of this muscle is. separated by fibrous septum from the rostral -larger portion. The fiber-bundles of this caudal portion take a transverse course and they are not inserted into the raphe. They are inserted into the aponeurosis which is triangular and lies in the front of the hyoid bone. M. sternothyreoideus (Fig ). It-arises from the dorsal surface of the first rib, external to its.sternal articulation. The fiberbundles take a nearly parallel course rostrad. The muscle is inserted

14 30 Tokuichi Shindo and Masaru Mori Fig. 8. The muscles of the neck by fleshy into the oblique line of the thyroid cartilage. M. thyreohyoideus. (Fig.. 9) It is short and broad, and arises from the oblique line of the thyroid cartilage, and is inserted into the basi-hyoid. The sternothyreoideus and the thyreohyoideus are overlaid by the sternomandibularis. The medial edges of the two thyreohyoideus touch each other,

15 Anatomy of Indian Elephant, Part III. 31 Fig. 9. Muscles of the suprahyoid region. but two sternothyreoideus lie so as to expose the larynx between their internal edges. M. genioglossus. The muscle-fibers have fan-like arrangement. It arises from the mandibular symphysis in its whole depth. The superior fiber-bundles radiate toward the tip of the tongue ; the inter mediate ones extend directly toward the dorsum of the tongue ; the inferior ones curve back to be inserted into the median part of the superior border of the hyoid bone. M. hyoglossus (Fig. 9 10). There are two kinds of this muscle. 1. M. hyoglossus lateralis arises from the outer surface of the cornt majus of the hyoid bone. The muscle fibers pass upwards and for wards to the side of the tongue, where they blend with the other lingual muscles. 2. M. hyoglossus anterior arises from the anterior edge of the body of the hyoid bone, and is inserted into the lateral margin of the tongue, blending with the stylohyoideus. M. styloglossus It arises from the apex of the long process of the styloid process and from the stylomandibular -ligament. The muscle

16 32 Tokuhi Shindo and Masaru Mori ng. 1U. Muscles 01 the mouth ground. fibers pass downwards and forwards to be inserted into the lateral margin of the tongue. External to the styloglossus lies a large vein. F. Facial musculature. M. occipitofrontalis. (Fig. 13) It lies on the temporal area and extends from the preauricular region to the supraorbital one. It consists of two muscle-bellies and intermediate tendon. The posterior belly is the' larger of the two and arises from the cranial aponeurosis, and it is irregular quadrangle in shape. The intermediate tendon begins from the anterior angle of the posterior belly and runs rostrad on the fascia of the temporalis, and passes into the anterior belly of the occipitofrontalis.

17 Anatomy of Indian Elephant, Part III. 33 Fig. 12 Deep muscles of the neck. The anterior belly is triangular and inserted into the fascia of the supraorbital region. A part of the fiber-bundles is blending with the orbicularis palpebrarum. M. platysma. (Fig. 13). It is a large, thin, quadrangular muscle which extends obliquely from the chin to the neck. The musclefibers arise from the tela subcutanea along a line extending from the larynx to the root of the fore leg. The fiber-bundles pass over the ramus mandibulae and are inserted as follows: (1) the uppermost' fibers to the facial aponeurosis below the zygomatic arch,' (2) a few of the lower fibers pass to the outer surface of the corpus mandibulae, (3) the intermediate and principal portion of the muscle converges to the angle of the mouth, where its fibers interlace with those of the

18 34 Tokuichi Shindo and Masaru Mori Fig. 11. Muscle of the external base of the skull.,orbicularis oris and the angularis. M. orbicularis oris. Its development is poor. It arises from the middle line of the lower lip, where it joins the corresponding muscle of the opposite muscle and passes to the angle of the mouth. Here it is partly blended with fibers of the platysma and the angularis. The principial fibers passing in the upper lip are united with the muscle in the ventral side of the proboscis. M. angularis (M. zygomaticolabialis) Fig. 13). It is band-like muscle and extends from the rn.clial canthus to the angle of the mouth. The origin of this muscle is thin and broad, and as it des-

19 Anatomy of Indian Elephant, Part III. 35 Fig. 13. Muscles of the face. cends it becomes smaller and more round, and passes over the large branch of the facial nerve to be inserted into the angle of the mouth, where it blends with the fiber-bundles of the orbiculasis oris. We think that the angularis described by us corresponds to the praeorbicularis described by Miss Eales. M. buccinator. (Fig 13). It arises from the alveolar margin of both jaws, as well as from a powerful ligament, which extends from the styloid process down to the inner surface of the mandible. The fiber-bundles of the muscle are divisible into four sets. The most cranial extends directly into the orbicularis oris of the upper lip, the

20 16 Tokuichi Shindo and Masaru Mori Fig. 14. Deep muscles of the neck. next passes through the commisure at the corner of the lips into the orbicularis oris of the lower lip, the third through the commissure into the orbicularis oris of the upper lip, the fourth directly into the orbicularis oris of the lower lip. The parotid duct passes forwards over the buccinator into the mouth. M. orbicularis oculi (Fig. 13). It :arises from the medial palpebral ligament. The fiber-bundles spread out as they pass into the eyelids and again are concentrated towards their insertion into the nuter surface of the lateral palpebral ligament. The fiber-bundles

21 Anatomy of Indian Elephant, Part III. 37 are considerably more developed in the lower eyelid. A part of fiber-bundles on the medial canthus spread upwards and downwards. A small part of the fibers spreat downwards blends with the angularis. The fiber-bundles on the lateral canthus also spread upwards and downwards. G. Musculature of the proboscis. The proboscis of the elephant consists mainly of muscular tissue, the nasal cartilages simple serving as valves to the entrance of the bony nares. The muscles consists of a superficial set, the fibers of which are L'pre or less longitudinal in direction, and of a deep set of the intrinsic muscles, which are radiate and transverse. The longitudinal fibers are further divisible into the anterior, the lateral and the posterior. The anterior longitudinal muscle fibers. It arises from the frontal bone, along a semicircular line arching upwards above the nasal straight and between the orbits. The fiber-bundles run in nearly bones lines, extend entire length of the proboscis along its anterior surface, to the extremity of the proboscis. The fiber-bundles of the two sides blend on the medianline. Miall and Greenwood named this muscle " Levator proboscidis." The posterior longitudinal fibers. The fiber-bundles arise from the anterior surface and the lower margin of the premaxillare and the fascia along the posterior surface of the proboscis. The muscle -fibers are divided into two layers ; superficial and deeper. The fibers of the superficial layer are directed downwards and outwards from the median line, and disappear by curving over the sides a little above the end of the proboscis. The deeper layer takes the reverse direction and make the raphe with the fibers of the opposite side. Miall and Greenwood named this posterior longitudinal fibers " Depressor proboscidis." The lateral longitudinal muscle. This muscle lies on the lateral side of the proboscis and its development is poor. It consists of two sets of the fiber-bundles ; one is derived from the angularis, which arises from the inner canthus, and the other springs from the orbicularis oris. The fiber-bundles of the two sets run downwards intermingling with each other, and are inserted by a series of slips between the anterior and posterior longitudinal muscles along the proximal half of the proboscis.

22 38 Tokuichi Shind and Masaru Mori All these muscle in the proboscis are very intimately connected with the integmentum, especially in,the lower two-third s of their extent. The intrinsic muscle of the proboscis. We can find two kinds of intrinsic muscles, radiating and transverse. The radiating muscle consist of very numerous distinct fasciculi, which stretch directly outwards from the anterior and lateral surface of the nasal canal to the subcutaneous layer. The transverse fiber-bundles are divided into two sets. One is short and lies between the nasal canals. The other is found between behind the nasal canals and its fiber-bundles run transversely in the posterior longitudinal muscle. H. Auricular musculature. M. auricularis anterior (Fig. 13). It is a small, flat, triangular muscle, which arises from the temporal fascia. The fiber-bundles converge from the origin to the tendon of the insertion, The insertion is the front part of the helix, The lower margin of this muscle is fused with the occipitofrontalis. M. auricularis inferior. It is a small muscle arising from the outer and lower surfaces of the root of the zygoma. The fiber-bundles run beneath the external porus of the external auditory canal and is inserted into the posterior and inferior surface of the cartilage of the ear. M. tragicus (Fig. 13). Its development is considerable and lies between the root of the zygoma and the back end of the occipitofrontalis. The tragicus muscle arises from the cartilaginous border of the external acustic meatus. The fiber-bundles run upwards and backwards to be inserted into the cartilaginous process of the auricular cartilage. The muscle-fibers are inserted into the posterior surface of the auricle. We can find four muscle, which are inserted into the posterior surface of the auricle (Fig. 15): Each muscle is long and narrow. We call them with name of number instead of functional name. The first muscle. It arises from the temporal fascia by a thin and flat tendon. The fiber-bundles run downwards and backwards, and pass into the posterior surface of the pinna. The second muscle. It arises from the nuchal fascia by a thin

23 Anatomy of Indian Elephant, Part III. 39 Fig. 15. Muscles of shoulder and auricle. tendon. The fiber-bundles run downwards to be inserted into the subcutaneous tissue of the back of the pinna. The third muscle. It arises from the fascia between the trapezius and the splenius by two thin tendons. The fiber-bunbles from the two tendons are fused to one belly. The belly runs downwards to be inserted into the subcutaneous layer of the back of the pinna. The endpart is divided into two portions.

24 40 Tokuichi Shindo and Masaru Mori The fourth muscle. It arises from the fascia between the trapezius and the splenius by thin tendon behind the origin of the third muscle. The fiber-bundles pass downwards to reach the lower margin of the pinna, and go into the pinna to be inserted into its back. I. Masticatory musculature. M. temporalis (Fig. 13). It arises from the whole of the temporal fossa and from the fascia covering the temporalis. The muscle is thin near its superior margin, and it becomes thicker as its insertion is approached, The muscle is very thick where it passes beneath the zygoma. Insertion is into the tip of the posterior and anterior border, and into the whole internal surface of the coronoid process of the mandible, and into the anterior portion of the medial surface of the ramus mandibulae. M. masseter (Fig. 13). This muscle is composed of two layers. The superficial layer is the principal portion of this muscle and arises from the lower border of the zygomatic arch. The fibers pass downwards and backwards to be inserted into the lower two-thirds of the external surface of the ascending ramus of the mandible as far as the angle. The deeper layer arises.from the posterior one-third of the internal surface of the zygomatic arch, and are inserted into the mandible immediately below the sigmoid notch. M. pterygoideus externus. It arises from the temporal crest, from the under surface of the great wing of the sphenoid, from the lateral surface of the lateral lamina of the pterygoid process, from the under surface of the palate bone, and from the adjacent portion of the maxillary. The muscle is very thick and powerful. The fiberbundles converge towards the insertion, which takes place into the neck of the mandible and into the.capsular ligament in front of the articular disk. M. pterygoideus internus. It arises from the pterygoid fossa, from the under surface of the palate bone. The fiber-bundles take a nearly parallel course downwards, backwards and outwards, and are inserted in part in a multipenniform manner into the internal surface of the mandibular body and the lower half of the ramus mandibulae. The part of insertion is very thick and seen as a large swelling on the inner surface of the mandible angle.