CONSTRICTOR SUPERIOR STYLO-PHARYNGEUS. 193 



the fibrous raphe of the middle of the pharynx, the inferior fibres being 

 almost horizontal, and the superior oblique, and overlapping the middle 

 constrictor. 



Relations. By its external surface with the anterior surface of the ver- 

 tebral column, the longus colli, the sheath of the common carotid artery, 

 the sterno-thyroid muscle, the thyroid gland, and some lymphatic glands. 

 By its internal surface with the middle constrictor, the stylo-pharyngeus, 

 the palato-pharyngeus, and the mucous membrane of the pharynx. By its 

 lower border , near the cricoid cartilage, it is in relation with the recurrent 

 nerve ; and by the upper border with the superior laryngeal nerve. The 

 fibres of origin of this muscle are blended with those of the sterno-hyoid, 

 sterno-thyroid, and crico-thyroid, and it frequently forms a tendinous arch 

 across the latter. 



This muscle must be removed before the next can be examined. 



The CONSTRICTOR MEDIUS arises from the great cornu of the os hyoides, 

 from the lesser cornu, and from the stylo-hyoidean ligament. It radiates 

 from its origin upon the side of the pharynx, the lower fibres descending 

 and being overlapped by the constrictor inferior, and the upper fibres 

 ascending so as to cover in the constrictor superior. It is inserted into the 

 raphe and by a fibrous aponeurosis into the basilar process of the occipital 

 bone. 



Relations. By its external surface with the vertebral column, the longus 

 colli, rectus anticus major, the carotid vessels, inferior constrictor, hyo- 

 glossus muscle, lingual artery, pharyngeal plexus of nerves, and some 

 lymphatic glands. By its internal surface, with the superior constrictor, 

 stylo-pharyngeus, palato-pharyngeus, and mucous membrane of the pha- 

 rynx. 



The upper portion of this muscle must be turned down, to bring the 

 whole of the superior constrictor into view ; in so doing, the stylo-pharyn- 

 geus muscle will be seen passing beneath its upper border. 



The CONSTRICTOR SUPERIOR is a thin and quadrilateral plane of muscu- 

 lar fibres arising from the extremity of the molar ridge of the lower jaw, 

 from the pterygo-maxillary ligament, and from the lower half of the inter- 

 nal pterygoid plate, and inserted into the raphe and basilar process of the 

 occipital bone. Its superior fibres are arched and leave an interval be- 

 tween its upper border and the basilar process, which is deficient in mus- 

 cular fibres, and it is overlapped inferiorly by the middle constrictor. 

 Between the side of the pharynx and the ramus of the lower jaw is a 

 triangular interval, the maxillo-pharyngeal space, which is bounded on the 

 inner side by the superior constrictor muscle ; on the outer side by the 

 internal pterygoid muscle ; and behind by the rectus anticus major and 

 vertebral column. In this space are situated the internal carotid artery, 

 the internal jugular vein, and the glosso-pharyngeal, pneumogastric, spinal 

 accessory, and hypo-glossal nerve. 



Relations. By its external surface with the vertebral column and its 

 muscles, behind ; with the vessels and nerves contained in the maxillo- 

 pharyngeal space laterally, the middle constrictor, stylo-pharyngeus. and 

 tensor palati muscle. By its internal surface with the levator palati, 

 palato-pharyngeus, tonsil, and mucous membrane of the pharynx, the 

 pharyngeal fascia being interposed. 



The STYLO-PHARYNGEUS is a long and slender muscle arising from the 

 inner side of the base of the styloid process ; it descends between the 

 17 N 



