372 HEAD AND NECK 



The inferior constrictor muscle is relatively short anteriorly 

 at its origin, and relatively long posteriorly, where it blends with 

 the fellow of the opposite side in the median raphe of the 

 posterior wall of the pharynx. It arises from the posterior 

 part of the side of the cricoid cartilage, and from the 

 inferior cornu, the oblique line, and the upper border of 

 the thyreoid cartilage. The muscle curves posteriorly and 

 medially around the pharyngeal wall to meet its fellow of 

 the opposite side in the median raphe. The lower fibres take 

 a horizontal direction, but the remainder ascend, with increas- 

 ing degrees of obliquity, until the highest fibres reach the raphe 

 at a point a short distance below the basis cranii. The lower 

 margin of the inferior constrictor overlaps the commencement 

 of the oesophagus, and the inferior laryngeal nerve and the 

 laryngeal branch of the inferior thyreoid artery pass upwards, 

 under cover of it, to reach the larynx. 



Musculus Constrictor Pharyngis Medius. This is a fan- 

 shaped muscle (Fig. 148, e). It arises from the great and 

 small cornua of the hyoid bone and from the lower part of 

 the stylo-hyoid ligament. From this origin its fibres pass 

 round the pharyngeal wall, to be inserted with the corre- 

 sponding fibres of the opposite side into the median raphe. 

 As they pass postero- medially, the lowest fibres descend, 

 the highest ascend, and the intermediate fibres run horizontally. 

 The lower portion of this muscle is overlapped by the 

 inferior constrictor, and in the interval which separates the 

 margins of the muscles anteriorly, opposite the thyreo-hyoid 

 interval, the internal laryngeal nerve and the laryngeal branch 

 of the superior thyreoid artery will be seen piercing the 

 thyreo-hyoid membrane to gain the interior of the pharynx. 



Dissection. The superior constrictor possesses a somewhat complicated 

 origin, and to bring this fully into view it will be necessary to cut through 

 the internal pterygoid muscle about its middle, if this has not already been 

 done (p. 293), and turn the upper and lower portions aside. 



Musculus Constrictor Pharyngis Superior (Fig. 148, d}. 

 The superior constrictor has a weak but continuous line 

 of origin from the following parts : (a) the lower third of 

 the posterior border of the medial pterygoid lamina and its 

 hamulus ; (b) the pterygo-mandibular raphe, which is common 

 to it and the buccinator muscle; (c) the posterior end of the 

 mylo-hyoid ridge on the inner aspect of the mandible ; (d) the 

 mucous membrane of the mouth and side of the tongue. 



