PHARYNX 285 



lower part of the superior constrictor. The three muscles are 

 inserted, in the median plane, into the median raphe which 

 descends from the basilar portion of the occipital bone along 

 the posterior aspect of the pharynx. 



Musculus Constrictor Pharyngis Inferior (Fig. 107, /). 

 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 backwards and 

 medially, in 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 base of the skull. The 

 lower margin of the inferior constrictor overlaps the com- 

 mencement of the oesophagus, and the inferior laryngeal 

 nerve and the laryngeal branch of the inferior thyreoid artery 

 pass upwards, ^nder cover of it, to reach the larynx. It is 

 supplied by twigs from the. pharyngeal plexus and the recur- 

 rent nerve. 



Musculus Constrictor Pharyngis Medius. The middle con- 

 strictor is a fan-shaped muscle (Fig. 107, e). It arises from 

 the greater and lesser cornua of the hyoid bone and from 

 the lower part of the stylo-hyoid ligament. From those origins 

 its fibres pass round the pharyngeal wall, to be inserted with 

 the corresponding fibres of the opposite side into the median 

 raphe. As they curve backwards and medially, the lowest 

 fibres descend, the highest ascend, and the intermediate fibres 

 run horizontally. The lower portion of the muscle is over- 

 lapped 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. It is supplied by twigs from the pharyngeal 

 plexus. 



Dissection. To bring the extensive origin of the superior 

 constrictor fully into view the internal pterygoid muscle must 

 be cut through about its middle, if that has not been done already 



