SUBMAXILLARY REGION 197 



and the veins which accompany it ; (2) the dorsales linguae 

 arteries and veins ; (3) the posterior part of the genio-glossus ; 



(4) the origin of the middle constrictor of the pharynx ; and 



(5) the attachment of the stylo-hyoid ligament. 



Musculus Genioglossus. The genio-glossus is a flat tri- 

 angular muscle, the medial surface of which is in contact with 

 its fellow of the opposite side, in the median plane. It arises 

 by a short pointed tendon from the upper mental spine on 

 the posterior aspect of the symphysis of the mandible, and, 

 from that point, its fleshy fasciculi spread out in a fan-like 

 manner. By far the greater part of the muscle is inserted 

 into the tongue, by an insertion which extends throughout 

 the whole length of the organ, from the tip to the base ; 

 below the tongue, a few fibres reach the side of the pharynx. 

 The genio-glossus is supplied by twigs from the hypoglossal 

 nerve. It can project the tip of the tongue forwards and 

 depress the whole organ in the floor of the mouth. 



Arteria Lingualis. As the lingual artery is now fully 

 exposed, it can be conveniently studied at this stage. 

 It springs from the anterior aspect of the external carotid, 

 and is separable into two parts viz., (i) a part extending 

 from its origin to the posterior border of the hyoglossus 

 muscle; (2) a part lying in relation to the upper border of 

 the hyoid bone, and extending to the anterior border of the 

 hyoglossus, where it divides into two terminal branches, the 

 sublingual and the deep artery of the tongue (Figs. 68, 70). 



The first part has been fully examined in a previous 

 dissection. It lies in the carotid triangle of the neck, and 

 is therefore comparatively superficial. It is crossed, super- 

 ficially, by the hypoglossal nerve, and lies, medially, against 

 the middle constrictor.- The second part passes forwards along 

 the upper border of the greater cornu of the hyoid bone, 

 and is covered by the hyoglossus muscle, which intervenes 

 between it and the hypoglossal nerve. The nerve, how- 

 ever, is placed at a slightly higher level. The deep or 

 medial relations of the artery, in the second stage of its 

 course, are the middle constrictor of the pharynx and the 

 genio-glossus. 



The branches of the lingual artery are : 



1. Supra-hyoid, from ihz first part (p. 133). 



2. Dorsales linguae, from the second part. 



3. Sublingual. 



4. Profunda. 

 in 13 a 



