100 THE PHARYNX AND (ESOPHAGUS. 



Stefio,^ traverses the outer face of the masseter muscle in a line 

 drawn from the lobe of the ear to the end of the nose. It is white 

 and hard, about the size of a crow-quill, and perforates the cheek 

 through a pad of fat by a very small orifice opposite the second 

 molar tooth of the upper jaw. The external carotid artery passes 

 through the deeper portion of the gland, and it is also traversed by 

 the portio dura nerve. There is sometimes found in front of the 

 gland an accessory portion called socius or accessm'ius parotidis, 

 whose duct empties into that of Steno. 



The submaxillary gland^ is much smaller than the parotid, is 

 irregularly oblong in figure and lobulated in structure. It is situated 

 in a depression on the internal face of the inferior maxillary bone, 

 being covered externally by the skin, superficial fascia, and platysma 

 muscle. Its duct* is called the duct of WJiarton, which empties at 

 the side of the frsenum under the tongue by a very small orifice on 

 the summit of a papilla ; the coats of this duct are very thin, the 

 gland is traversed by the facial artery as it mounts the lower jaw. 

 Sometimes there is an additional gland and duct, called after Bar- 

 tolin. 



The sublingual gland^ is the smallest of the three ; its shape is 

 also oblong, and its structure lobulated ; it is situated under the 

 tongue, between the mucous membrane of the mouth and the mylo- 

 hyoid muscle. Its duct or ducts (for they are frequently numerous) 

 are called after Rivinus, and empty into or near the duct of 

 Wharton. 



THE PHARYNX AND OESOPHAGUS. 



The pharynx is a muscular and membranous sac, communicating 

 with the mouth, nose, oesophagus, larynx, and Eustachian tube. It 

 is situated in front of the vertebral column, and extends from the 

 basilar process of the occiput to the fourth or fifth cervical vertebra. 

 It is funnel-shaped, being larger above than it is below. Its length 

 is about five inches, although this varies by contraction and disten- 

 sion ; it is never collapsed, but its walls are always kept distended 

 by its muscular origins. It consists of three coats, Tniiscular^ cel- 

 lular^ and mucous. 



The inferior constrictor muscle^ arises from the cricoid and thy- 

 roid muscles. The fibres terminate in those of its fellow, along the 

 posterior median line ; those of the upper part are oblique, those of 

 the lower horizontal. 



The middle constrictor m,uscle^^ arises from the cornu of the os 

 hyoides, and the lateral thyreo-hyoid ligament, and is inserted into 

 its fellow in the posterior median line. Its upper fibres ascend ob- 

 liquely to the basilar process of the occiput, and overlap the supe- 

 rior constrictor, while its lower fibres are horizontal or descending, 

 and are overlapped by the inferior constrictor. 



