306 



THE MUSCLES AND FASCIA OF THE HEAD AND NECK. 



The middle constrictor muscle arises from the large and small cornua of the 

 hyoid bone, and from the stylo-hyoid ligament : its fibres, diverging greatly, pass 

 back to the middle line of nearly the whole length of the pharynx, the lowest fibres 

 inclining downwards beneath the inferior constrictor, the highest ascending and 

 overlapping the superior constrictor, and the intermediate fibres running trans- 

 versely. 



Relations. This muscle is separated from the superior constrictor by the stylo-pharyngeus 

 muscle, while between its origin and that of the inferior constrictor the superior laryngeal 

 nerve and vessels pierce the thyro-hyoid membrane. 



Varieties. The middle constrictor has been seen to receive fibres from the body of the 



Fig. 281. VIEW OF THE MUSCLES OP 



THE PHARYNX, &C-, FROM BEHIND. 



(After Bourgery. ) 



The back part of the skull, the 

 vertebral column and back parts of 

 the ribs are removed, a, cut surface 

 of basilar process ; b, clavicle ; c, 

 first rib ; d, ramus of lower jaw ; e, 

 posterior extremity of great cornu of 

 hyoid bone ; /, posterior surface of 

 manubrium ; 1, superior constrictor 

 muscle of the pharynx ; above it the 

 fibrous membrane which closes the 

 pharynx ; 2, middle constrictor ; 2', 

 a dotted line, indicating the direction 

 of the lower part of the muscle ; 3, 

 inferior constrictor ; 4, oesophagus ; 

 5, internal pterygoid ; 6, stylo-glossus ; 

 7, posterior belly of digastric ; 8, a 

 portion of the stylo-hyoid surrounding 

 the tendon of the digastric ; 9, sterno- 

 mastoid ; 10, anterior belly of the 

 omo-hyoid ; II, sterno-thyroid mus- 

 cle (represented somewhat too broad). 



hyoid bone, from the tongue, and 

 from the hinder part of the mylo- 

 hyoid ridge of the lower jaw. A 

 slip from the lateral thyro-hyoid 



w iiii'.v s^ ligament (syndesmo - pJiaryngeusT) 



> '/< F 1 ' ,<^E is of frequent occurrence. 



X r* 



The superior constrictor 

 arises by fibres attached in 



series, from below upwards, to the side of the tongue, to the mucous membrane of 

 the mouth, to the extremity of the mylo-hyoid ridge of the jaw, to the pterygo- 

 maxillary ligament, and to the hamular process and lower third or less of the pos- 

 terior border of the internal pterygoid plate. The fibres curve backwards, and are 

 mostly blended with those of the corresponding muscle along the middle line, a 

 few ending posteriorly in the aponeurosis which fixes the pharynx to the base of 

 the skull. The upper margin curves round the levator palati and the Eustachian 

 tube ; and the space intervening between this concave margin of the constrictor and 

 the base of the skull is closed by fibrous membrane. 



Relations. In contact with the outer surface of this muscle are the internal carotid 

 artery, the vagus and sympathetic nerves, the middle constrictor, which overlaps a considerable 

 portion, and the stylo-pharyngeus, which descends to the pharynx between the two constrictors. 

 It conceals the palato-pharyngeus and the tonsil, and is lined by mucous membrane. It is 

 united to the buccinator muscle anteriorly by the pterygo-maxillary ligament. 



The constrictor muscles are invested on their outer surface by a layer of dense 



