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It descends, between the internal pterygoid muscle and the medial pterygoid lamina, and ends in a tendon which hooks round the pterygoid hamulus. The tendon is inserted, beneath the levator veli palatini, into the posterior border of the hard palate, and into the aponeurosis of the soft palate.

M. Glossopalatinus. The glossopalatinus (O.T. palatoglossus), occupying the inferior surface of the soft palate and the glosso-palatine arch, has already been described with the muscles of the tongue (p. 463).

Nerve-Supply. The muscles of the soft palate (except the tensor veli palatini, which is innervated through the otic ganglion by the trigeminal nerve) are supplied through the pharyngeal plexus by the accessory nerve.

Actions of the Muscles of the Pharynx and Soft Palate.-The muscles of the pharynx and soft palate are chiefly brought into action in the act of swallowing. This act is divided into a voluntary stage, in which the bolus lies anterior to the arches of the fauces, and an involuntary stage, during which the food passes from the mouth through the pharynx. The movements occurring during the passage of food through the mouth are as follows: the cheeks are compressed by the action of the buccinator muscles; the tongue, hyoid bone, and thyreoid cartilage are successively raised upwards by the action of the muscles which close the mouth and elevate the hyoid bone. By these means the food is pushed backwards between the palatine arches.

At the same time, by the contraction of the glosso-palatinus and pharyngo-palatinus, the palatine arches of the fauces are narrowed, while the muscles of the soft palate, contracting, tighten the soft palate, and by bringing it in contact with the posterior wall of the pharynx, shut off the nasal portion of the cavity. The elevation of the tongue, hyoid bone, and larynx simultaneously causes the elevation of the epiglottis and the superior aperture of the larynx, which is closed by the approximation of the arytenoid cartilages and the combined action of laryngeal muscles (arytenoideus, thyreoarytenoideus, and thyreoepiglotticus). The food thus slips over the anterior surface of the epiglottis and the closed superior aperture of the larynx, and between the palatine arches on either side, into the pharynx. It is now clasped by the constrictor muscles, which, by their contractions, force it down into the oesophagus. The contraction of the constrictor muscles results in a flattening of the pharynx and elevation of its anterior attachments.

During the act of swallowing, it is generally thought that the auditory tube is opened by the contraction of the tensor veli palatini muscle, which arises from it. It has been held, on the other hand, that the auditory tube is closed during swallowing by the compression of its wall by the contraction of the levator veli palatini.

Deep Lateral and Prævertebral Muscles of the Neck.

Three series of muscles are comprised in this group: (1) vertebro-costal (scaleni, anterior, medius, and posterior), (2) vertebro-cranial (longus capitis and rectus capitis anterior, and lateralis), and (3) vertebral (longus colli). They clothe the anterior surface of the cervical portion of the vertebral column for the most part, and are in relation anteriorly with the pharynx and oesophagus, and the large vessels and nerves of the neck.

M. Scalenus Anterior. The scalenus anterior (O.T. anticus) arises from the anterior tubercles of the transverse processes of the third, fourth, fifth, and sixth cervical vertebræ.

It descends, posterior to the carotid sheath and subclavian vein, to be inserted into the scalene tubercle and ridge on the first rib (Fig. 414, p. 468).

It is separated posteriorly from the scalenus medius by the roots of the brachial plexus, the subclavian artery, and the pleura, and it is concealed by the sternomastoid muscle.

M. Scalenus Medius.-The scalenus medius arises from the posterior tubercles of the transverse processes of the cervical vertebræ, from the second to the sixth inclusive.

It descends in the posterior triangle, behind the subclavian artery and the roots of the brachial plexus, to be inserted into the rough impression on the first rib behind the subclavian groove (Fig. 414, p. 468). The muscle is pierced by the dorsal scapular and long thoracic nerves.

It is separated from the scalenus anterior by the subclavian artery and the roots of the brachial plexus.

M. Scalenus Posterior.-The scalenus posterior arises, behind the scalenus medius, from the posterior tubercles of the fourth, fifth, and sixth cervical transverse processes. It is inserted into an impression on the outer side of the second rib.

Serratus posterior superior (insertion)

Scalenus posterior(insertion)

B

Serratus anterior (origin)

Pectoralis minor (occasional origin)

Nerve-Supply.-The muscle receives nerves directly from the anterior rami of the first four cervical nerves.

Action. Flexion of the head and cervical vertebræ.

M. Rectus Capitis Anterior. The rectus capitis anterior (O.T. rectus capitis anticus minor) arises, under cover of the preceding muscle, from the lateral mass of the atlas. It is inserted into the basilar part of occipital bone between the preceding muscle and the occipital condyle (Fig. 417, p. 469).

It forms a flat triangular muscle, which is directed upwards, alongside the longus colli muscle and behind the carotid sheath, to be inserted into an impression on the inferior surface of the basilar part of the occipital bone,

FIG. 414.-MUSCLE-ATTACHMENTS TO THE SUPERIOR SURFACE OF THE

FIRST RIB, AND THE EXTERNAL SURFACE OF THE SECOND RIB anterior and lateral to the (RIGHT SIDE).

A, First rib; B, Second rib.

Nerve-Supply.—The muscle is innervated by the loop between the first two cervical nerves (anterior rami).

Action. Flexion of the head on the vertebral column.

M. Longus Colli.-The longus colli is a flattened. muscular band extending from the third thoracic vertebra to the atlas. It

Actions. The actions of those muscles are twofold. They are lateral flexors of the vertebral column, and are also important

Scalenus medius (insertion) muscles of respiration, as elevators of the first and second ribs.

Serratus anterior
(origin)

Scalenus anterior
(insertion),

RECTUS CAPITIS

ANTERIOR

Nerve-Supply.-The scalene muscles are supplied by branches which arise directly from the anterior rami of the lowest four or five cervical nerves.

Subclavius
(origin)

M. Longus Capitis.The longus capitis (O.T. rectus capitis anticus major) arises from the anterior tubercles of the transverse processes of the third, fourth, fifth, and sixth cervical vertebræ.

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pharyngeal tubercle (Fig. 417, p. 469).

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RECTUS CAPITIS
LATERALIS

RECTUS CAPITIS
ANTERIOR

LONGUS CAPITIS

LONGUS COLLI

FIG. 415. THE PREVERTEBRAL MUSCLES OF THE NECK.

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Semispinalis capitis (insertion)
Rectus capitis posterior minor
(insertion)

Rectus capitis posterior major (insertion)

FIG. 416.-SCHEME OF MUSCULAR ATTACHMENTS TO CERVICAL VERTEBRÆ,

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SCALENUS
ANTERIOR

The vertical portion of the muscle arises from the bodies of the first three thoracic and the last three cervical vertebræ.

Passing vertically upwards, it is inserted into the bodies of the second, third, and fourth cervical vertebræ.

LONGUS CAPITIS

LONGUS COLLI

Attached
to anterior
tubercles of
transverse
processes

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Sterno-cleido-mastoid

intusy ca Obliquus capitis superior (insertion)

Rectus capitis lateralis (insertion)

Rectus capitis anterior (insertion)

Longus capitis (insertion)

FIG. 417.-MUSCLE-ATTACHMENTS TO THE OCCIPITAL BONE.

Superior constrictor of pharynx (insertion)

The inferior oblique portion arises from the bodies of the first three thoracic vertebræ.

It is inserted into the anterior tubercles of the fifth and sixth cervical vertebræ.

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Attached to
posterior
tubercles of

transverse
processes

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Attached to
articular

processes

SCALENUS MEDIUS
LEVATOR SCAPULE
SPLENIUS CERVICIS

SCALENUS POSTERIOR

ILIOCOSTALIS CERVICIS
LONGISSIMUS CERVICIS

The vertical portion of the muscle arises from the bodies of the first three

LE thoracic and the last three cervical vertebræ.

Passing vertically upwards, it is inserted into the bodies of the second, third, and fourth cervical vertebræ.

LONGISSIMUS CAPITIS

SEMISPINALIS CAPITIS
SEMISPINALIS CERVICIS

MULTIFIDUS

Semispinalis capitis (insertion)

FIG. 416.-SCHEME OF MUSCULAR ATTACHMENTS TO CERVICAL VERTEBRÆ,

Rectus capitis posterior minor
(insertion)

Rectus capitis posterior major (insertion)

10 Obliquus capitis superior

(insertion)

SCALENUS
ANTERIOR

Rectus capitis lateralis (insertion)

LONGUS CAPITIS

LONGUS COLLI

Attached

to anterior tubercles of transverse processes

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Sterno-cleido-mastoid

Superior constrictor of pharynx (insertion)

Longus capitis (insertion)

FIG. 417.-MUSCLE-ATTACHMENTS TO THE OCCIPITAL BONE.

The inferior oblique portion arises from the bodies of the first three thoracic vertebræ.

It is inserted into the anterior tubercles of the fifth and sixth cervical vertebræ.

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