THE TRUNK. 443 



clavicle. These are to be reflected upwards and downwards. The platysma 

 myoides is to be dissected, the course of the external jugular vein examined, 

 and the muscle divided transversely and reflected. The parts above described 

 occupying the various regions, the boundaries of which should be accurately 

 defined, may be now exposed and dissected in succession. TRANS.] 



694. Chest, Thorax. 



1. Reg. sternalis. a. Skin thick, in the male hairy, in the cen- 

 tral line firmly attached, b. fibre-cellular tissue, with the tendons 

 of sterno-mastoid., pectorales, red. abdom. c. sternum : above, lig. 

 interclaviculare. d. M. triangular, sterni. e. Mediastina an- 

 tica; at the inferior part of the pericardium; above the thymus, 

 ven. anonyma. 



2. Reg. mammittaris, beneath the claviculce, on the sides of the 

 sternum. Parts : 1. Very delicate skin, especially on the nipple. 

 2. Fibro-cellular tissue with much fat, in which, above, nn. clavi- 

 culares, mammary arteries and nerves. 3. Mammary gland, with 

 branches of vasa mammar. interna and thoracica. 4. Loose 

 fibro-cellular tissue. 5. M. pectoral, major, minor , serratus mag- 

 nus. 6. Ribs, intercostal muscles. 



3. Reg. costalis, costal region, a. Before the ribs, on the supe- 

 rior half of the thorax ; behind the shoulder : 1. Skin and thick 

 fibro-cellular tissue. 2. M. trapezius, latiss. dorsi. 3. Rhomboi- 

 deus. 4. Above, m. serratus postic. sup. 5. Ribs. 



On the inferior half: skin, fibro-cellular tissue, branches of nn. 

 and vasa intercost. Then : 1. M. red. abdmn. (in its sheath), 

 obliq. extern., serratus magn., and costal portion oflatissim. dorsi. 

 2. Ribs. 



b. Between the ribs (spatium int.ercostale) : 1. Mm. intercostales 

 externi. 2. Nervi et vasa intercost. (on the inferior border, of 

 angulus costce, also at the superior border of each rib). 3 k Mm. 

 intercost. intern. 



c. Behind the ribs : 1. Fibro-cellular tissue (and mm. infracos- 

 tales). 2. Vasa mammar. interna, above, two lines from the bor- 

 der of the sternum, below, before m. triangular, sterni. 3. Pleura. 

 (The chest should not be opened upon the right side below the 

 fourth, upon the left below the third intercostal space (reckoning 

 from below), if it is wished to avoid injury to the diaphragm). 



4. Regio dorsalis, dorsal region. 



695. Cavity of the Thorax. 



1. Regio mediastini, is bounded m front by the sternum, behind 

 by the vertebrae, above by the neck, below by the diaphragm, right 



