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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 arytænoid cartilages and the combined action of laryngeal muscles (arytænoideus, thyreoarytænoideus, 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 æsophagus. 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 cesophagus, 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 ots 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.

B

Nerve-Supply. - The scalene muscles are supplied by branches which arise directly from the

anterior rami of the lowest four Serratus posterior superior (insertion)

or five cervical nerves.

Actions.—The actions of those Scalenus

muscles are twofold. They are posterior

lateral flexors of the vertebral (insertion)

column, and are also important Scalenus medius (insertion) muscles of respiration, as elevators

of the first and second ribs.
A
Serratus anterior

M. Longus Capitis.(origin)

The longus capitis (O.T.

rectus capitis anticus Scalenus anterior (insertion),

major) arises from the an

terior tubercles of the transSerratus anterior (origin)

verse processes of the third, fourth, fifth, and sixth cervi

cal vertebrae. Subclavius

It forms a flat triangular (origin) muscle, which is directed up

wards, alongside the longus colli muscle and behind the

carotid sheath, to be inserted Pectoralis minor (occasional origin)

into an impression on the

inferior surface of the basilar Fig. 414.- MUSCLE-ATTACHMENTS TO THE SUPERIOR SURFACE OF the part of the occipital bone,

FIRST RIB, AND THE EXTERNAL SURFACE OF THE SECOND RIB anterior and lateral to the (Right Side). A, First rib; B, Second rib.

pharyngeal tubercle (Fig.

417, p. 469). 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.

RECTUS CAPITIS M. Rectus Capitis

RECTUS CAPITIS Anterior.-The rectus

RECTUS CAPITIS capitis anterior (0.T. rectus capitis anticus

LONGUS CAPITIS 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 SCALENUS

LONGUS COLLI preceding muscle and the occipital condyle (Fig. 417,

SCALENUS
ANTERIOR

SCALENUS Nerve-Supply.—The mus

MEDIUS cle is innervated by the loop

SCALENUS between the first two cervical

POSTERIOR 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

Fig. 415.—THE PRÆVERTEBRAL MUSCLES OF THE NECK.

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p. 469).

is divisible into three portions—a vertical, an inferior oblique, and a superior oblique portion.

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

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

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

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The inferior oblique portion arises from the bodies of the first three thoracic vertebra. It is inserted into the anterior tubercles of the fifth and sixth cervical vertebrae.

Serratus anterior

B

Serratus anterior

Nerve-Supply. - The scalene muscles are supplied by branches which arise directly from the

anterior rami of the lowest four Serratus posterior superior (insertion)

or five cervical nerves.

Actions. The actions of those Scalenus

muscles are twofold. They are posterior

lateral flexors of the vertebral (insertion)

column, and are also important Scalenus medius (insertion) muscles of respiration, as elevators

of the first and second ribs.

M. Longus Capitis. (origin)

The longus capitis (O.T.

rectus capitis anticus Scalenus anterior (insertion),

major) arises from the an

terior tubercles of the trans(origin)

verse processes of the third, fourth, fifth, and sixth cervi

cal vertebrå. Subclavius

It forms a flat triangular (origin)

muscle, which is directed upwards, alongside the longus colli muscle and behind the

carotid sheath, to be inserted Pectoralis minor (occasional origin)

into an impression on the

inferior surface of the basilar FIG. 414. — MUSCLE-ATTACHMENTS TO THE SUPERIOR SURFACE OF the part of the occipital bone,

FIRST RIB, AND THE EXTERNAL SURFACE OF THE SECOND RIB anterior and lateral to the (Right SIDE). A, First rib; B, Second rib.

pharyngeal tubercle (Fig.

417, p. 469). 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.

RECTUS CAPITIS M. Rectus Capitis

LATERALIS

RECTUS CAPITIS Anterior.The rectus capitis anterior (O.T. RECTOS CAPITIS rectus capitis anticus

LONGUS CAPITIS 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 SCALENUS

LONGUS COLLI preceding muscle and the occipital condyle (Fig. 417,

SCALENUS p. 469).

ANTERIOR

SCALENUS Nerve-Supply.—The mus

MEDIUS cle is innervated by the loop

SCALENUS between the first two cervical

POSTERIOR 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

Fig. 415.—THE PRÆVERTEBRAL MUSCLES OF THE NECK.

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is divisible into three portions—a vertical, an inferior oblique, and a superior oblique portion.

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

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.

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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 vertebra.

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