DISSECTION OF THE HEAD AND NECK. 171 



Action. — To flex the temporo-hyoideal joint, and carry backwards the 

 hyoid bone and the parts attached to it. 



The Stylo-Hyoid (Plate 31). Only the origin of this muscle, from the 

 heel-like part of the great cornu, will at present be seen. It should be 

 identified, and preserved for examination at a later stage. 



The submaxillary gland is to be preserved without disturbance until 

 it can be exposed in its entirety. The guttural pouch will be described 

 to more advantage at a later stage. 



The External Carotid Artery (Plate 28). Only the termination of 

 that vessel is here seen. It is one of the terminal branches of the 

 common carotid, which divides above the cricoid cartilage, under cover 

 of the submaxillary gland. The first part of the artery — at present con- 

 cealed — rests on the guttural pouch, and is covered by the stylo-max- 

 illaris, digastricus, and stylo-hyoid muscles. As now seen it appears 

 between the last of these muscles and the hinder edge of the great 

 cornu ; and, crossing obliquely upwards and forwards on the surface of 

 that bone, it terminates by dividing into the superficial temporal and 

 internal maxillary arteries. The vessel detaches three collateral 

 branches, viz., the submaxillary, maxillo-muscular, and posterior auricu- 

 lar arteries, of which the first is concealed by the digastricus and stylo- 

 hyoid muscles. 



The Maxillo-Muscular Artery. This branch is given off at the 

 upper edge of the stylo-maxillaris muscle, immediately after the parent 

 trunk emerges between the stylo-hyoid muscle and the great cornu. It 

 forms with the continuation of the main trunk a very obtuse angle. 

 Passing forwards and downwards, it divides into an outer and an inner 

 branch, which embrace between them the edge of the vertical ramus. 

 The outer branch appears on the face at the anterior edge of the parotid 

 gland, and enters the masseter muscle. The inner branch passes to the 

 internal pterygoid muscle. 



The Posterior Auricular Artery. This vessel has its origin a little 

 beyond the preceding, but from the opposite side of the carotid. Its 

 distribution to the ear is given at page 167. 



The Superficial Temporal Artery (Plate 28). Originating by 

 the division of the external carotid on the great cornu, this artery, 

 after a very short course below and behind the condyle of the 

 lower jaw, divides into the transverse facial and anterior auricular 

 arteries. 



The Transverse Facial Artery turns round the ramus below the 

 condyle, and will be followed in the dissection of the face. 



The Anterior Auricular Artery ascends to the front of the ear, on 

 the capsular ligament of the temporo-maxillary joint. Its distribution 

 is given at page 166. 



The Internal Maxillary Artery. This, much the larger terminal 



