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MYOLOGY 



The Pectoralis minor (Fig. 411) is a thin, triangular muscle, situated at the 

 upper part of the thorax, beneath the Pectoralis major. It arises from the upper 

 margins and outer surfaces of the third, fourth, and fifth ribs, near their cartilage 

 and from the aponeuroses covering the Intercostalis; the fibers pass upward and 

 lateralward and converge to form a flat tendon, which is inserted into the medial 

 border and upper surface of the coracoid process of the scapula. 



Variations. Origin from second, third and fourth or fifth ribs. The tendon of insertion may 

 extend over the coracoid process to the greater tubercle. May be split into several parts. Absence 

 rare. 



Pectoralis minimus, first rib-cartilage to coracoid process. Rare. 





Radius 



b 



Fro. 411. Deep muscles of the chest and front of the arm, with the boundaries of the axilla. 



The Subclavius (Fig. 411) is a small triangular muscle, placed between the 

 clavicle and the first rib. It arises by a short, thick tendon from the first rib and 

 its cartilage at their junction, in front of the costoclavicular ligament; the fleshy 

 fibers proceed obliquely upward and lateralward, to be inserted into the groove 

 on the under surface of the clavicle between the costoclavicular and conoid 

 ligaments. 



Variations. Insertion into coracoid process instead of clavicle or into both clavicle and coracoid 

 process. Sternoscapular fasciculus to the upper border of scapula. Sternoclavicularis from manu- 

 brium to clavicle between Pectoralis major and coracoclavicular fascia. 



The Serratus anterior (Serratus magnus) (Fig. 411) is a thin muscular sheet, 

 situated between the ribs and the scapula at the upper and lateral part of 



