OF THE THORACIC REGION. 



377 



I. Muscles and Fasciae of the Thoracic Region. 



1. Anterior Thoracic Region. 



Pectoralis major. Pectoralis minor. 



Subclavius. 



The superficial fascia of the thoracic region is a loose cellulo-fibrous layer 

 enclosing masses of fat in its spaces. It is continuous with the superficial fascia of 

 the neck and upper extremity above, and of the abdomen below. Opposite the 

 mamma it divides into two layers, one of which passes in front, the other behind, 

 that gland ; and from both of these layers numerous septa pass into its substance, 

 supporting its various lobes : from the anterior layer fibrous processes pass forward 

 to the integument and nipple. These processes were called by Sir A. Cooper the 

 lii/a>neiita suspensoria, from the support they afford to the gland in this situation. 



The deep fascia of the thoracic region is a thin aponeurotic lamina, covering 

 the surface of the great Pectoral muscle, and sending numerous prolongations 



3. Dissection of 

 Shoulder and Arm. 



1. Dissection of 

 Pectoral Region 

 and A.cilla. 



2 1 2. Bend of Elbow. 



4- Forearm. 



5. Palm of Hand. 



FIG. 228. Dissection of upper extremity. 



between its fasciculi : it is attached, in the middle line, to the front of the ster- 

 num, and above to the clavicle ; externally and below it becomes continuous with 

 the fascia over the shoulder, axilla, and thorax. It is very thin over the upper 

 part of the muscle, thicker in the interval between the Pectoralis major and Latis- 

 simus dorsi, where it closes in the axillary space, and divides at the outer margin 

 of the latter muscle into two layers, one of which passes in front and the other be- 

 hind it; these proceed as far as the spinous processes of the dorsal vertebrae, to 

 which they are attached. As the fascia leaves the lower edge of the Pectoralis 

 major to pass across the floor of the axilla it sends a layer upward under cover of 

 the muscle : this lamina splits to envelop the Pectoralis minor, at the upper edge of 

 which it becomes continuous with the costo-coracoid membrane. The hollow of the 

 armpit, seen when the arm is abducted, is mainly produced by the traction of this 



