468 



THE MUSCLES AND FASCIA. 



attachment to the sternum and costal cartilages. The muscle should then be reflected outward, 

 and its tendon carefully examined. The Pectoralis minor is now exposed, and immediately 

 above it, in the interval between its upper border and the clavicle, a strong fascia, the costo- 

 coracoid membrane. 



The costo-coracoid membrane is a strong fascia placed between the clavicle 

 and the upper border of the Pectoralis minor muscle, which protects the axillary 



FIG. 302. Muscles of the chest and front of the arm. Superficial view. 



vessels and nerves. Above, it is attached to the anterior margin of the Subclavian 

 groove on the under surface of the clavicle, and is connected with a layer of 

 cervical fascia which overlies the Omo-hyoid muscle, and forms the posterior layer 

 of the sheath of the Subclavius muscle. Internally, it is attached to the first rib 

 internal to the origin of the Subclavius muscle. Externally it is very thick and 

 dense, and is attached to the coracoid process. The portion extending from its 

 attachment to the first rib to the coracoid process is often whiter and denser than 

 the rest ; this is sometimes called the costo-coracoid ligament. Below, it is thin, 

 and at the upper border of the Pectoralis minor it splits into two layers to invest 

 the muscle ; from the lower border of the Pectoralis minor it is continued down- 



