CHAPTER, V. 
APUSCLES “OF FTE THORAX—DISSEC- 
ITON OF THE NECK THE SYMPA- 
THETIC SVSLEM THE BRACHIAL 
PELEMES TANG MLHE LAK VN X. 
MUSCLES OF THE THORAZ. 
Make a median tnciston through the skin of the 
thorax along the line of the sternum, and transverse 
zncistons at the shoulders. Daussect off the flaps of skin 
* from the thorax, shoulder, and upper part of the ab- 
domen. In removing the skin notice the thin skin-mus- 
cle extending over the posterior and outer portion of the 
thorax and the abdomen. Remove the fat and fascia 
from the thorax, and the group of pectoralis muscles 
well be exposed. 
1. Pectoralis Major Muscle. This name is applied 
to the large muscle arising from the sternum and ribs, 
and inserted into the humerus. In reality the muscle 
can be divided into five or more separate divisions or 
muscles, whose origin and insertion extend along the 
lines named. The two or three most anterior of these 
divisions arise from the anterior end of the sternum 
as far back as the junction of the 3d rib. They forma 
group of fibres which pass nearly transversely outward 
to be inserted into the middle and lower third of the 
shaft of the humerus. Cut across the fibres of this 
