MUSCLES OF THE PHARYNX. 



2S7 



the thyroid body, the carotid artery, and the Btemo-thyi'oid muscle ; and 

 from this last, -R-here the two muscles meet on the thjToid cai-tilage, some fibres 

 are continued into the constrictor. By its inner sm-face it is related to the 

 middle constrictor, the stylo-phaiyngeus. the palato-pharjTigeus, and the mucous 

 membrane of the pharynx. The two larj-ngeal nerves pass inwards to thelaiynx, 

 close respectively to the upper and lower margins of this constrictor — the upper 

 being interposed between it and the middle constrictor, the lower between it and 

 the oesophagus. 



Fig. 212.— View op Fig. 212. 



TUE IVIUSCLES OP 



THE Pharynx, &c., 

 FUOM BEHIND (after 

 Bourgery). J 



The back part of 

 the skull, tbe ver- 

 tebral columa and 

 back parts of the 

 ribs are removed, a, 

 cut surface of the 

 basilar process ; b, 

 the clavicle ; c, the 

 first rib ; d, the 

 ramus of the lower 

 jaw ; e, posterior ex- 

 tremity of the great 

 cornu of the hyoid 

 bone ; /, posterior 

 surface of the manu- 

 brium of the ster- 

 num ; 1, superior 

 constrictor muscle of 

 the pharynx ; above 

 it the fibrous mem- 

 brane which closes 

 the pharynx ; 2, mid- 

 dle constrictor ; 2', 

 a dotted line, indi- 

 cating the direction 

 of the lower part of 

 the muscle ; 3, the 

 inferior constrictor ; 

 4, cesophagus ; 5, in- 

 ternal pterygoid ; 6, 

 stylo-glossus ; 7, pos- 

 terior belly of the 



digastric ; 8, a jiortion of the stylo-hyoid surrounding the tendon of the digastric ; 9, 

 sterno-mastoid ; 10, upper belly of the omo-hyoid ; ll,stemo-thyroid muscle (represented 

 somewhat too broad). 



The middle constrictor muscle arises from the upper surface of the 

 cornua of the os hyoides, and from the stylo-hyoid ligament : its fibres, 

 diverging greatly, pass back to the middle line of the pharynx behind, 

 the lowest fibres inclining downwards, beneath the inferior constrictor, 

 the highest ascending and overlapping the superior constrictor, and 

 the intermediate fibres running transversely. 



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

 pharyngeus muscle and the glosso-jiharyngeal nerve, while between its origin 

 and that of the inferior constrictor the superior larj-ngeal nerve pierces the thyro- 

 hyoid membrane. 



Varu'tien. — Fibres of the middle constrictor have been observed to arise from 

 the body of the os hyoides and the thyro-hyoid ligament, {syndesmo-2}haryngeus 



