THE MUSCLES. 141 



muscles of the hyoitl bone and larynx, between, upon, behind 

 and external to the Sterno-dei do-mast oidei. We distinguish: 



a. Superficial layer, fixed to the lig. inter davicul., manubrl 

 sterni. 



b. Deep Iny^r. passing away behind the sterno-deido-mast.; 

 it forms a sheath for jugular, interna and carolis commun., 

 enveloping and attaching the omo-hyoid to the superior border of 

 the first rib; and uniting itself with the fibro-cellular tissue upon 

 the scaleni and levator scapulse, which is : 



211. c. Fascism prsevertebralis, which surrounds the longus 

 colli and reef, capitis. antic, major , contains below much fat 

 and fills up the fossa supradavicularis. It attaches itself to the 

 superior part of the clavicle as far forward as the acromion, and 

 forms a boundary between the fossa mperdavicul. and the cavity 

 of the axilla; behind, it embraces the cucullares [Trapezius m.]. 

 Anteriorly it is covered by Trachea, pharynx, and oesophagus. 



III. Muscles of the Chest, Regio thoracica. 

 9.1 9. 1. Pectoralis major, great pectoral muscle. 



Pos.: beneath the skin and mammae, on the anterior surface of 

 the thorax and before the axilla; covering the subdavius and 

 pect. minor. Or.: 1. Clavicula (one-third to one-half of the 

 anterior border). 2. Sternum. 3. Carlilagines Costar., 2 to 7. 

 Ins. : Humerus (spina tubercul. major) ; between biceps (cap. 

 breve) and triceps, with a tendon two inches broad, under that of 

 the Deltoideus. Use: to draw the arms inwards, so that they 

 may be crossed over the chest; fixing the humeri, to draw the 

 ribs outwards and expand the thoracic cavity (as in inspiration). 



213. 2. Pectoralis minor (s. serralus anticus minor). 



Pos. : behind the last muscle, and the Nervi and Vasa thorac.; 

 its superior border separated from the Clavicula by a triangular 

 space, behind which, Art. axillaris, separated from Pectoral, 

 major and serralus by fat. Or.: Cos/a HI. to V. (superior 

 border and external surface). Ins. : Proc. coracoideus (internal 

 border and apex). Use: to draw the shoulder forwards, inwards 

 and downwards; if this is fixed, to elevate the third to the fifth 

 ribs (in. inspirator). 



Nerves: (1 2) thoracici, irierco.td., supraclavicular. 



214. 3. Subdavius (cosla-davicularis). 



Pos.: along the inferior surface and behind the Clavicula, 

 above the Vasa axillaria, Plex. brachial. and first rib. Or. : 



