THE NECK. 69 



4. A considerable number of supraclavicular nerves run downward in the region of the 

 supraclavicular fossa, some of them passing downward anteriorly and posteriorly over the sternum 

 and the acromion; they supply the skin of the superior thoracic region and of the shoulder. 



The spinal accessory nerve, after perforating and supplying the sternocleidomastoid, leaves 

 the posterior margin of this muscle and runs obliquely downward and outward in the space be- 

 tween the splenius and the levator anguli scapulae to the trapezius muscle. [The spinal accessory 

 nerve enters the deep surface of the sternocleidomastoid about one and a half inches or less 

 below the tip of the mastoid process; perforating the muscle, it emerges at or a little below the 

 middle of the posterior border. A line from midway between the angle of the jaw and the tip of 

 the mastoid through the middle of the posterior border of the sternocleidomastoid continued across 

 the posterior triangle to the anterior edge of the trapezius at the level of the seventh cervical spine 

 sufficiently indicates its course. ED.] This muscle is also directly supplied by branches of the 

 cervical plexus which may be found lower down in the posterior triangle. In the neighborhood 

 of the supraclavicular fossa the posterior belly of the omohyoid muscle appears beneath the pos- 

 terior margin of the sternocleidomastoid and runs downward and outward to disappear beneath 

 the clavicle. Together with the clavicle and the posterior margin of the sternocleidomastoid, it 

 bounds the small subclavian triangle (trigonum omoclaviculare). In lean individuals the omo- 

 hyoid muscle may often be seen when the hyoid bone and larynx are elevated during the act of 

 deglutition. 



In the depths of the lateral cervical region (see Fig. 27) above the clavicle, and forming, so 

 to speak, the floor of this triangle, may be seen the scalene muscles. The anterior scalene muscle 

 passes from the transverse processes of the third, fourth, fifth, and sixth cervical vertebras to the 

 scalene tubercle of the first rib; the middle scalene muscle runs from the transverse processes of 

 all of the cervical vertebras to the outer surface of the first rib. These two muscles form the 

 typical scalene slit or scalene triangle, the apex of which is directed upward and the base down- 

 ward. Behind these muscles is the posterior scalene muscle, which extends from the transverse 

 processes of the fifth, sixth, and seventh cervical vertebras to the outer surface of the second rib. 

 Above the scalene muscles is the levator anguli scapula, arising from the transverse processes of 

 the four upper cervical vertebras and inserting into the superior angle of the scapula, and the 

 splenius capitis et cervicis, which arises from the ligamentum nuchae and the spinous processes 

 of the first to the sixth dorsal vertebras and is inserted into the mastoid process and the transverse 

 processes of the first two or three upper cervical vertebras. 



The supraclavicular lymphatic glands are grouped above the clavicle; they receive the lymph 

 from the back of the neck as high up as the ear and are frequently diseased, particularly in tuber- 

 culosis. 



If the sternocleidomastoid muscle is removed, the previously concealed continuatk 

 vascular and nervous trunk is exposed as it passes downward toward the clavicle 

 view is obtained if the clavicle, or at least its sternal half, is also removed. By this procedu 

 expose the first rib, and consequently the dividing-line between the neck and the thorax, si 

 dome of the pleura with the contained apex of the lung extends upward beyond 

 Passing downward upon the right side, we come to the innominate artery, which d 

 right common carotid and the right subclavian behind the upper margin of the sternum. 



