THE INFRAHYOID REGION 



and exterial carotid arteries, the occipital, subclavian, transversal 

 arteries and veins; the phrenic, vagus, hypoglossal, descendens am 

 nerves; the spinal accessory nerve, which pierces i's upper third; 

 of the thyroid and parotid glands, and deep lymph nodes. 



Nerves. The Sternomastoid is supplied by the spinal accessory n 

 of the cervical plexus. 



Actions. When only one Sternomastoid muscle acts, it draws th< h 

 of the same side, assisted by the Splenius and the Obliquus capitis huerio. 

 At the same time it rotates the head so as to carry the face toward ih 

 the two muscles act together they flex the head upon the neck. If 

 muscles assist in elevating the thorax in forced inspiration. 



Applied Anatomy. The applied anatomy of the Sternomastoi 

 chiefly in connection with the deformity known as wry-neck (torticoli 

 either acquired, congenital, or spasmodic. The acquired may be < 

 enlargement, cellulitis of the neck, myositis of the Sternomastoid, or 

 genital variety is dpe to injury of the Sternomastoid during birth 

 subsequent chronic fibrous myositis (Mikulicz). This is best remedied 

 horizontal incision over the origin of the muscle and exposing it. 

 underneath and the muscle clearly divided, making sure that any tens^ 

 oughlv divided. Spasmodic torticollis is a condition of adult life. \ ( 

 tonic spasm, first of the Sternomastoid, then of many of the other ne 

 to be a disease of the central nerve system. 



2. The Infrahyoid Region (Figs. 300, 301). 

 DEPRESSORS OF THE HYOID BONE AND LARYI 



Sternohyoid. Thy 



Sternothyroid. Omoh 



Dissection. The muscles in this region may be exposed by remo\ i: 

 front of the neck. In order to see the entire extent of the Omohyoi 

 the Sternomastoid at its centre, and turn its ends aside, and to detai 

 clavicle and scapula. This, however, should not be done until the Tr; 



The Sternohyoid (m. sternohyoideus} is a thin, narro\ 

 which arises from the inner extremity of the clavicle, the po*t<- 

 ligament, and the upper and posterior part of the first piec< 

 passing upward and inward, it is inserted, by sht>rt, tendinoi 

 border of the body of the hyoid bone. /This muscle is si 

 its fellow by a considerable interval ; but tne two muscles ( 

 each other in the middle of their course, and from this upw; 

 It sometimes presents, immeo'iately above its origin, F 

 intersection, like those in the Rectus abdominis. As a ru 

 sternohyoidii) lie between the cricothyroid membrane an 

 muscle. 



Relations. By its superficial surface, below, with the sternum, the si 



and the Sternomastoid; and above, with the Platysnia and deep cervic 



i i . .. i.. 



The StemotJrr 



