THE MUSCLES OF THE PHARYNX. 



305 



THE MUSCLES OF THE PHAEYNX. 



The pharynx, the dilated upper part of the alimentary tube extending from the 

 base of the skull to the oasophagus, presents at the sides and back a continuous wall, 

 in great part formed and supported by distinct muscles resting posteriorly against 

 the vertebral column, while in front it is open towards the nasal cavity, the mouth, 

 and the larynx. 



The muscles entering into the construction of the wall of the pharynx are dis- 

 posed in two layers, viz., an outer layer in which the fibres have a generally trans- 

 verse direction, and an inner one composed of longitudinal fibres. The outer layer 

 includes three muscles named constrictors, all of which spring in front from bones or 



Fig. 280. DEEP MUSCLES OF THE CHEEK, 

 PHARYNX, &o. (Modified from Cloquet.) 

 (Allen Thomson.) 3 



The pharynx has been distended by stuffing. 

 , external pterygoid plate ; b, styloid process 

 with short portions of the three styloid muscles 

 attached ; c, lower jaw, which has been divided 

 At the place where the pterygo-maxillary liga- 

 ment + is attached ; d, hyoid bone ; e, thyroid 

 cartilage ; /, cricoid cartilage ; g, trachea ; 1, 

 outer part of the orbicularis oris muscle ; 2, 

 buccinator ; 3, superior constrictor of the pharynx; 

 4, middle constrictor ; 5, inferior constrictor ; 

 , oesophagus ; 7, points by three lines to the 

 lower parts of the stylo-glossus, stylo-hyoid, and 

 stylo-pharyngeus muscles respectively ; 8, mylo- 

 hyoid ; 9, hyo-glossus, of which a small part is 

 removed posteriorly to show the attachment of 

 the middle constrictor ; 10, thyro-hyoid. 



cartilages, and terminate behind, where 

 they are much expanded and overlap 

 one another from below upwards, by 

 joining their fellows in the middle line, 

 forming in the upper part a median 

 tendinous raphe. The inner layer com- 

 prises the elevator muscles of the 

 pharynx, two in number, viz., the 



stylo-pharyngeus and the palato-pharyngeus, the latter of which will be described 

 together with the muscles of the soft palate. 



The inferior constrictor muscle, the broadest and thickest of the three, arises 

 .by a series of slips from the side of the cricoid cartilage at its lower and posterior 

 part, and from the inferior cornu, the oblique line and upper tubercle of the thyroid 

 cartilage ; some fibres are also usually continued into it from the sterno-thyroid and 

 crico-thyroid muscles. It curves backwards and inwards, and unites with its fellow 

 in the middle line at the back of the pharynx. The direction of the inferior fibres 

 is horizontal ; the rest ascend with increasing degrees of obliquity, and the highest 

 fibres terminate on the raphe about an inch below the basilar process. From its 

 lower border a few fibres turn downwards into the longitudinal fibres of the osso- 

 phagus. 



Relations. This muscle is in contact posteriorly with the cervical vertebrae and the 

 prevertebral muscles ; laterally with the thyroid body, the carotid arteries and the stemo- 

 thyroid muscle. It covers the middle constrictor, the stylo-pharyngeus, the palato- 

 pharyngeus and the mucous membrane of the pharynx. The superior laryngeal nerve and 

 vessels pass inwards to the larynx above its upper border, and the inferior ascend beneath its 

 lower border. 



