LATERAL AND PREVERTEBRAL MUSCLES OF THE NECK. 391 
inserted beneath the levator palati into the posterior border of the hard palate, and 
into the aponeurosis of the soft palate. 
The palato-glossus muscle occupying the under surface of the soft palate and 
the anterior pillar of the fauces, has already been described with the muscles of the 
tongue (p. 382). 
NERVE SUPPLY. 
The chief nerve supply of the muscles of the pharynx and soft palate is the spinal accessory 
nerve, aided by the fifth (otic ganglion) and the ninth (glosso-pharyngeal) nerves and the laryngeal 
branches of the vagus nerve. 
Muscles. | Nerves. Origin. 
Constrictors of ae nx | | 
Palato-glossus | | 
| 
Palato-pharyngeus Pharyngeal plexus . Bailie ea lb 
| Levator palati | 
| Azygos uvulee 
_ Tensor palati . ; : 2 . | Otic ganglion . : : We 
Stylo-pharyngeus . : : Glosso-pharyngeal . oiiy tex 
Cm : External laryngeal eee) 
Inferior constrictor . ‘ : ve Coe ee i : X. 
Inferior laryngeal 
ACTIONS. 
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 in front of the 
pillars 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 thyroid 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 back- 
wards between the pillars of the fauces. 
At the same time, by the contraction of the palato-glossus and palato-pharyngeus, the pillars 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 upper (nasal) 
portion of the cavity. The elevation of the tongue, hyoid bone, and larynx simultaneously raise 
the epiglottis and the opening of the glottis, which is closed by the approximation of the arytenoid 
cartilages and the combined action of laryngeal muscles (arytenoideus, thyro-arytenoideus, and 
thyro-aryteno-epiglottideus). The food thus slips over the posterior surface of the epiglottis and 
the closed opening into the larynx, and between the pillars of the fauces on either side, to the 
een It is now clasped by the constrictor muscles, which, by frequent contractions, force it 
down into the esophagus. The contraction of the constrictor muscles results in a flattening of the 
pharynx and elevation of its anterior attachments. 
During swallowing the tensor palati, besides stretching the soft palate, is generally regarded 
as opening the Eustachian tube. It has been held, on the other hand, that the Eustachian tube is 
closed during swallowing by the compression of its wall by the contraction of the levator palati. 
LATERAL AND PREVERTEBRAL MUSCLES OF THE NECK. 
Three series of muscles are comprised in this group: (1) vertebro-costal 
(scaleni, anticus, medius, and posticus), (2) vertebro-cranial (recti capitis antici, 
major and minor, and lateralis), and (3) vertebral (longus colli). 
The scalenus anticus arises from the anterior tubercles of the transverse 
processes of the third, fourth, fifth, and sixth cervical vertebre, and descends 
behind the carotid sheath, to be inserted into the scalene tubercle and ridge on the 
first rib. In front of the muscle are the subclavian and internal jugular veins, and 
the nerves descending through the neck. Behind, it is separated from the scalenus 
medius by the cords of the brachial plexus, the subclavian artery, and the pleura. 
The scalenus medius arises from the posterior tubercles of the transverse 
processes of the cervical vertebrze, from the second to the sixth. It descends in the 
floor of the posterior triangle, to be inserted into the rough impression on the first 
rib behind the subclavian artery. The muscle is covered anteriorly by the cords of 
the brachial plexus, subclavian artery, and omo-hyoid muscle, and is in contact 
behind with the levator anguli scapulz and the scalenus posticus. It is pierced by 
the posterior scapular and posterior thoracic nerves. 
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