564 THE ARTERIES. 



muscles the vertebral artery and vein will be found passing into the foramen in the 

 sixth transverse process ; a small portion of the origin of the Rectus capitis anticus 

 major may also be seen in the floor of the space. 



The Superior Carotid Triangle is bounded, behind, by the Sterno-mastoid ; 

 below, by the anterior belly of the Omo-hyoid ; and above, by the posterior belly 

 of the Digastric muscle. It is covered by the integument, superficial fascia, 

 Platysma, and deep fascia, ramifying between which are branches of the facial 

 and superficialis colli nerves. Its floor is formed by parts of the Thyro-hyoid, 

 Hyo-glossus, and the inferior and middle Constrictor muscles of the pharynx. 

 This space contains the upper part of the common carotid artery, which bifurcates 

 opposite the upper border of the thyroid cartilage into the external and internal 

 carotid. These vessels are occasionally somewhat concealed from view by the 

 anterior margin of the Sterno-mastoid muscle, which overlaps them. The external 

 and internal carotids lie side by side, the external being the more anterior of the 

 two. The following branches of the external carotid are also met with in this 

 space : the superior thyroid, running forward and downward ; the lingual, 

 directly forward ; the facial, forward and upward ; the occipital, backward ; 

 and the ascending pharyngeal directly upward on the inner side of the internal 

 carotid. The veins met with are: the internal jugular, which lies on the outer 

 side of the common and internal carotid arteries, and veins corresponding to the 

 above-mentioned branches of the external carotid viz. the superior thyroid, the 

 lingual, facial, ascending pharyngeal, and sometimes the occipital, all of which 

 accompany their corresponding arteries and terminate in the internal jugular. 

 The nerves in this space are the following : In front of the sheath of the common 

 carotid is the descendens hypoglossi. The hypoglossal nerve crosses both carotids 

 above, curving round the occipital artery at its origin. Within the sheath, between 

 the artery and vein, and behind both, is the pneumogastric nerve ; behind the 

 sheath, the sympathetic. On the outer side of the vessels the spinal accessory 

 nerve runs for a short distance before it pierces the Sterno-mastoid muscle ; and 

 on the inner side of the external carotid, just below the hyoid bone, may be seen 

 the superior laryngeal nerve ; and, still more inferiorly, the external laryngeal 

 nerve. The upper part of the larynx and lower part of the pharynx are also found 

 in the front part of this space. 



The Submaxillary Triangle corresponds to the part of the neck immediately 

 beneath the body of the jaw. It is bounded, above, by the lower border of the 

 body of the jaw and a line drawn from its angle to the mastoid process ; below, 

 by the posterior belly of the Digastric and Stylo-hyoid muscles ; in front, by the 

 anterior belly of the Digastric. It is covered by the integument, superficial fascia, 

 Platysma, and deep fascia, ramifying between which are branches of the facial and 

 ascending filaments of the superficial cervical nerves. Its floor is formed by the 

 anterior belly of the Digastric, the Mylo-hyoid, and the Hyo-glossus muscles. This 

 space contains, in front, the submaxillary gland, imbedded in the substance of 

 which are the facial artery and vein and their glandular branches ; beneath this 

 gland, on the surface of the Mylo-hyoid muscle, are the submental artery and the 

 mylo-hyoid artery and nerve. The back part of this space is separated from the 

 front part by the stylo-maxillary ligament : it contains the external carotid artery, 

 ascending deeply in the substance of the parotid gland : this vessel here lies in 

 front of, and superficial to, the internal carotid, being crossed by the facial nerve, 

 and gives off in its course the posterior auricular, temporal, and internal maxil- 

 lary branches : more deeply are the internal carotid, the internal jugular vein, 

 and the pneumogastric nerve, separated from the external carotid by the Stylo- 

 glossus and Stylo-pharyngeus muscles and the glosso-pharyngeal nerve. 1 



1 The same remark will apply to this triangle as was made about the inferior carotid triangle. 

 The structures enumerated as contained in the back part of the space lie, strictly speaking, beneath 

 the muscles which form the posterior boundary of the triangle ; but as it is very important to bear in 

 mind their close relation to the parotid gland and its boundaries (on account of the frequency of sur- 

 gical operations on this gland), all these parts are spoken of together. 



