UPPER MAXILLARY NERVE. 103 



which supply the muscular structure, and communicate with the gustatory 

 nerve. 



The glosso-pharyngeal cranial nerve (fig. '23,*), issuing between the 

 two carotid arteries, courses over the stylo-pharyngeus and the middle 

 constrictor of the pharynx, and ends under the hyo-glossus in branches for 

 the tongue. See DISSECTION OF THE TONGUE. 



The duct of the submaxillary gland (fig. 23, 3 ), Wharton's duct, issues 

 from the deep part of the glandular mass turning round the border of the 

 mylo-hyoid muscle. It is about two inches in length, and is directed up- 

 wards on the hyo-glossus muscle, and beneath the gustatory nerve, to 

 open on the side of the frsenum lingure in the centre of an eminence : its 

 opening in the mouth will be seen if a bristle be passed along it. The duct 

 has a thin wall, and consists externally of a fibrous layer with much elastic 

 tissue and a few pale muscular fibres, and internally of a mucous lining 

 with flattened epithelium. 



The deep part of the submaxillary gland extends along the side of the 

 duct, reaching in some instances the sublingual gland. 



The sublingual gland (fig. 23, N ) is somewhat of the shape of an almond, 

 and the longest measurement, which is about one inch and a half, is directed 

 backwards. It is situate beneath the anterior part of the tongue, in con- 

 tact with the inner surface of the lower jaw, and close to the symphysis. 

 Separated from the cavity of the mouth by the mucous membrane, the 

 gland is prolonged across the upper border of the genio-hyo-glossus muscle, 

 so as to touch the one of the opposite side. 



The sublingual is an aggregation of small glandular masses, each being 

 provided with a separate duct (Henle). The ducts (ductus Riviniani) are 

 from ten to eighteen in number. Some of them open beneath the tongue 

 along a crescent-shaped fold of the mucous membrane, and others join the 

 Whartonian duct ; one or more form a larger tube, which either joins that 

 duct or opens near it. 



SECTION VIII. 



SUPERIOR MAXILLARY NERVE AND VESSELS. 



Directions. The student may examine next the right orbit, and the 

 remaining trunk, superior maxillary of the fifth nerve. 



Supposing the right orbit to be untouched, the student may vary his 

 former examination of the left cavity (p. 50) by dissecting it from the outer 

 side. 



Dissection. For this purpose divide the margin of the orbit with a saw 

 through the supra-orbital notch, and the roof with a chisel back to the 

 sphenoidal fissure. Cut also with a chisel (from the inside) along the 

 middle fossa of the base of the skull from the sphenoidal fissure in front 

 to the foramen spinosum behind, and outside the line of the foramen ro- 

 tundum and foramen ovale. The side of the skull is next to be sawn ver- 

 tically in front of the petrous part of the temporal bone, so that the incision 

 shall end at the posterior extremity of the cut made in the base. After- 

 wards the outer wall of the orbit is to be sawn horizontally into the spheno- 

 maxillary fissure. The piece of bone forming part of the cranium and 



