levatores palati, palato-glossi and anterior fasciculus of the palato-pharyngei; posteriorly they have the thin posterior fasciculus of the palato-pharyngei and the mucous membrane.

The two next muscles are brought into view by raising the mucous membrane from off the pillars of the soft palate at each side.

The PALATO-GLOSSUS (constrictor isthmi faucium) [described also with the fourth group] is a small fasciculus of fibres, which arises in the soft palate as a radiated expansion continuous with its fellow of the opposite side; and descends to be inserted into the side of the tongue. It is the prominence of this small muscle, covered by mucous membrane, that constitutes the anterior pillar of the soft palate. It has been named constrictor isthmi faucium, from a function it performs in common with the palato-pharyngeus, viz., constricting the opening of the fauces.

The PALATO-PHARYNGEUS (constrictor isthmi faucium posterior) forms the posterior pillar of the fauces; it arises by two fasciculi from the raphe of the soft palate, where its fibres are continuous with those of the muscle of the opposite side; and is inserted into the inner surface of the pharynx and posterior border of the thyroid cartilage. This muscle is broad above where it forms the whole thickness of the lower half of the soft palate, narrow in the posterior pillar, and again broad and thin in the pharynx, where it spreads out previously to its insertion. The levator palati passes to its insertion between the two fasciculi of origin of this muscle.

Relations. In the soft palate it is in relation with the mucous membrane both by its anterior and posterior surface; above, with the levator palati, and below with the mucous glands situated along the margin of the arch of the palate. In the posterior pillar, it is surrounded for two-thirds of its extent by mucous membrane. In the pharynx, it is in relation by its outer surface with the superior and middle constrictor muscle, by its inner surface with the mucous membrane.

Actions. - The uvulæ shortens the uvula. azygos The levator palati raises the soft palate, while the tensor spreads it out laterally so as to form a septum between the pharynx and posterior nares. Taking its fixed point from below, the tensor palati will dilate the Eustachian tube. The palato-glossus and palatopharyngeus constrict the opening of the fauces, and drawing down the soft palate, serve to press the mass of food from the dorsum of the tongue into the pharynx.

Seventh Group. ·Prævertebral Muscles.

Rectus anticus major,

Rectus anticus minor,

Scalenus anticus,

Scalenus medius,
Scalenus posticus,
Longus colli.

Dissection. These muscles have already been exposed by the removal of the pharynx from the anterior aspect of the vertebral column; all that is further needed is the removal of the fascia by which they are invested.

The RECTUS ANTICUS MAJOR (trachelo-suboccipitalis), broad and thick above, narrow and pointed below, arises from the anterior tubercles of the transverse processes of the third, fourth, fifth, and sixth cervical vertebræ; and is inserted into the basilar process of the occipital bone.

Relations. By its anterior surface with the pharynx, internal carotid artery, internal jugular vein, superior cervical ganglion and trunk of the sympathetic nerve, pneumogastric, and spinal accessory nerve. By its posterior surface with the rectus anticus minor, and superior cervical vertebræ; internally with the longus colli, and externally with the scaleni.

The RECTUS ANTICUS MINOR arises from the anterior border of the lateral mass of the atlas, and is inserted into the basilar process; its fibres being directed obliquely upwards and inwards.

Relations. By its anterior surface with the rectus anticus major, and superior cervical ganglion of the sympathetic. By its posterior surface with the articulation of the condyle of the occipital bone with the atlas, and anterior occipito-atloid ligament.

FIG. 165.

The SCALENUS ANTICUS (costo-trachelius) is a triangular muscle, as its name implies, situated at the root of the neck, and appearing like a continuation of the rectus anticus major; it arises, by a flat and narrow tendon, from the upper and inner border of the first rib; and is inserted into the anterior tubercles of the transverse processes of the third, fourth, fifth, and sixth cervical vertebræ.

Relations. By its anterior surface with the sterno-mastoid and omo-hyoid muscles, suprascapular and transversa colli artery, phrenic nerve, and subclavian vein, by which latter it is separated from the subclavius muscle and clavicle. By its posterior surface with the pleura, the nerves which form the brachial plexus, and below, the subclavian artery. By its inner side with the longus colli, being separated by the vertebral artery; by its outer side with the scalenus medius. Its relations with the subclavian artery and vein are important, the vein being before, the artery behind the muscle.'

The SOALENUS MEDIUS, the largest of the three, arises from the first rib between the groove for the subclavian artery and the tuberosity [i. e. tubercle], and is inserted by separate tendons into the posterior tubercles of all the cervical vertebræ excepting the first.

Relations. By its anterior surface with the brachial plexus and subclavian artery; posteriorly with the scalenus posticus, levator anguli scapulæ, and cervicalis ascendens; internally with the pleura, intertransverse muscles, and cervical vertebræ; externally with the sterno-mastoid, omo-hyoid, suprascapular and transversa colli artery.

PREVERTEBRAL GROUP OF MUSCLES OF THE NECK. 1. Rectus anticus major. 2. Scalenus anticus. 3. Lower part of the longus colli of the right side; it is concealed superiorly by the rectus anticus major. 4. Rectus anticus minor. 5. Upper portion of the longus colli. 6. Its lower portion; the figure rests on the seventh cervical vertebra. 7. Scalenus medius. 8. Scalenus posticus. 9. One of the intertransversales. 10. Rectus lateralis, left side.

The SCALENUS POSTICUS, of small size, arises by a thin tendon from the second rib between its tubercle and angle, and divides superiorly into two or three tendons which are inserted into the posterior tubercles of the two or three lower cervical vertebræ. The scalenus posticus was formerly described with the scalenus medius as one muscle; while Albinus and Soëmmering make five scaleni.

Relations. In front with the scalenus medius; behind with the two upper levatores costarum, and cervicalis ascendens.

The LONGUS COLLI (prædorso-atloideus) is a long and flat muscle, consisting of two portions. The upper, arises from the anterior tubercle of the atlas, and is inserted into the transverse processes of the third, fourth, and fifth cervical vertebræ. The lower portion arises from the bodies of the second, third, and fourth, and transverse processes of the fifth and sixth, and passes down the

In a subject dissected in the school of the Middlesex Hospital during the winter of 1841, by Mr. Joseph Rogers, the subclavian artery of the left side was placed with the vein in front of the scalenus anticus muscle.

neck, to be inserted into the bodies of the three lower cervical and three upper dorsal vertebræ. We may thus arrange these attachments in a tabular

form:

Origin.

Upper portion.

Atlas

Lower portion.

Insertion.

{3d, 4th, and 5th transverse processes.

2d, 3d, and 4th bodies (3 lower cervical vertebræ, bodies.
5th and 6th transverse

3 upper dorsal, bodies.

In general terms, the muscle is attached to the bodies and transverse processes of the six superior cervical vertebræ above, and to the bodies of the last three cervical and first three dorsal below.

Relations. By its anterior surface with the pharynx, oesophagus; sheath of the common carotid, internal jugular vein and pneumogastric nerve; sympathetic nerve, inferior laryngeal nerve, and inferior thyroid artery. By its posterior surface it rests on the cervical and upper dorsal vertebræ.

Transversalis colli anterior.'—Under this name Retzius has described a small muscle (rudimentary in man but large and important in mammiferous animals) situated on the anterior tubercles of the transverse processes of the cervical vertebræ between the rectus anticus major and scalenus anticus. It arises by small tendinous slips from the anterior tubercles of the fourth, fifth, and sixth cervical vertebræ; and is inserted into the corresponding tubercles of the second and third vertebræ, and sometimes into the transverse process of the atlas.

Actions. The rectus anticus major and minor preserve the equilibrium of the bead upon the atlas; and, acting with the longus colli, flex and rotate the head and the cervical portion of the vertebral column. The scaleni muscles are flexors of the vertebral column: and, acting from above, fix the first and second ribs for the inspiratory muscles.

Eighth Group.- Muscles of the Larynx.

These muscles are described with the anatomy of the larynx, in Chapter XI.

MUSCLES OF THE TRUNK.

The muscles of the trunk may be subdivided into four natural groups: viz.,

1. Muscles of the back.
2. Muscles of the thorax.
3. Muscles of the abdomen.

4. Muscles of the perineum.

MUSCLES OF THE BACK.

The region of the back, in consequence of its extent, is common to the neck, upper extremities, and abdomen; and its muscles, which are numerous, may be arranged into six layers.

'Oken's Isis, 1845. Transactions of the Scandinavian Naturalists, 1842.

Dissection.. The muscles of this layer are to be dissected by making an incision along the middle line of the back, from the tubercle on the occipital bone to the coccyx. From the upper point of this incision carry a second transversely outwards to the back of the ear: inferiorly an incision must be made from the extremity of the sacrum, along the crest of the ilium, to about its middle. For convenience of dissection, a fourth may be carried from the middle of the spine to the acromion process. The integument and superficial fascia, together, are to be dissected off the muscles in the course of their fibres, over the whole of this region. The TRAPEZIUS muscle (trapezium, a quadrangle with unequal sides) arises from the inner third of the superior curved line of the occipital bone, from the ligamentum nuchæ, and from the supraspinous ligament and spinous processes of the last cervical and all the dorsal vertebræ. The fibres converge from these various points, and are inserted into the scapular third of the clavicle, acromion process, and upper border of the spine of the scapula, as far back as its tubercle. The inferior fibres become tendinous, near the scapula, and glide over the triangular surface at the origin of the spine, upon some loose cellular tissue. When the trapezius is dissected on both sides, the two muscles resemble a trapezium, or diamond-shaped quadrangle, on the posterior part of the shoulders; hence the muscle was formerly named cucullaris (cucullus, a monk's cowl). The occipital portion of the muscle is extremely thin; and the origin of the cervical and upper part of the dorsal portion tendinous, forming, with the muscle of the opposite side, a tendinous trapezium.

Relations. By its superficial surface with the integument and superficial fascia, to which it is closely adherent by its cervical portion, loosely by its dorsal portion. By its deep surface, from above downwards, with the complexus, splenius, levator anguli scapulæ, supra-spinatus, a small portion of the serratus posticus superior, rhomboideus minor, rhomboideus major, vertebral aponeurosis which separates it from the erector spinæ, and with the latissimus dorsi. The anterior border of the cervical portion forms the posterior boundary of the posterior triangle of the neck. Its clavicular insertion sometimes advances to the middle of the clavicle, or as far as the outer border of the sterno-mastoid, and occasionally it has been seen to overlap the latter. This is a point to be borne in mind in the operation for ligature of the subclavian artery. The spinal accessory nerve passes beneath the anterior border, near the clavicle, previously to its distribution to the under surface of the muscle.

The ligamentum nucha is a thin fibrous band extended from the tubercle and spine of the occipital bone, to the spinous process of the seventh cervical ver

FIRST, SECOND, AND PART OF THE THIRD LAYER OF MUSCLES OF THE BACK; the first layer occupies the right, the second, the left side. 1. Trapezius. 2. Tendinous portion, forming, with a corresponding part of the opposite muscle, the tendinous ellipse on the back of the neck. 3. Acromion process and spine of the scapula. 4. Latissimus dorsi. 5. Deltoid. 6. Muscles of the dorsum of the scapula: infra-spinatus, teres minor, and teres major. 7. Obliquus externus abdominis. 8. Gluteus medius. 9. Glutei maximi. 10. Levator anguli scapulæ. 11. Rhomboideus minor. 12. Rhomboideus major. 13. Splenius capitis; the muscle immediately above, and overlaid by the splenius, is the complexus. 14. Splenius colli, partially seen; the common origin of the splenius is seen attached to the spinous processes below the origin of the rhomboideus major. 15. Vertebral aponeurosis. 16. Serratus posticus inferior. 17. Supra-spinatus. 18. Infra-spinatus. 19. Teres minor. 20. Teres major. 21. Long head of triceps, passing between teres minor and major to the arm. 22. Serratus magnus proceeding forwards from its origin at the base of the scapula. 23. Obliquus internus abdominis.

tebra, where it is continuous with the supraspinous ligament. It is connected with the spinous processes of all the cervical vertebræ, excepting the atlas, by means of a series of small fibrous slips; and is the analogue of an important elastic ligament in animals.

The LATISSIMUS DORSI muscle covers the whole of the lower part of the back and loins. It arises from the spinous processes of the four or six inferior dorsal, and all the lumbar vertebræ, from the supraspinous ligament, spinous tubercles of the sacrum, posterior third of the crest of the ilium, and four lower ribs; the