134 MUSCULAR SYSTEM. 



Relations. — Externally, with the panniculus and skin ; inter- 

 nally, with the bone : anteriorly and superiorly, with the levator 

 humeri and pectoralis parvus ; posteriorly and inferiorly, with 

 the next muscle : below, with the shoulder joint. 



Directioti. — Oblique; from above downward, and from be- 

 hind forward. 



. Structure. — Surface aponeurotic, with a tendinous intersection 

 through its middle. 



Attachment. — Tendinous and fleshy : inferiorly, the fleshy part 

 ])resents two terminations, united by an intervening expansion of 

 tendon, which fills up the interspace between them. At the point 

 of the shoulder is sent off" a tendinous expansion, between which 

 and the tendon of the biceps is interposed a bursa mucosa. 



Action. — To extend the humerus upon the scapula; at least, 

 to approach that bone to the straight line. 



posTEA-spiNATUS. — Sub-dcromio-trochiterius. 



Situation. — Occupying the fossa postea spinata. 



Figure. — Triangular; flattened: broader, but not so thick in 

 substance as the preceding muscle. 



Attachment.— Superiorly, to the surface of the fossa postea 

 spinata, and to the spine of the bone ; inferiorly, to the outer side 

 of the greater tubercle of the humerus, to a bony ridge extending 

 down from it, and to the capsular ligament of the shoulder 

 joint. 



Relations. — On the outer side, with the panniculus and skin, 

 and also (superiorly) with the trapezius ; anteriorly, with the 

 foregoing muscle ; posteriorly, with the teres minor and triceps ; 

 inferiorly, with the shoulder joint. 



Structure. — Superior attachments, aponeurotic as well as 

 fleshy. Its middle presents several broad tendinous intersections, 

 from the principal of which originates a flattened tendon, fixing 

 the muscle to the tubercle. Below the tendon, is the tendinous 

 and fleshy portion fixed to the ridge ; and still lower is a distinct 

 and separate fasciculus, proceeding to a small tubercle upon the 

 same ridge, which both Bourgelat and Girard regard as another 

 muscle. 



Action. — To assist in the flexion of the humerus; and, at the 

 same time, to roll it outwards. 



2.— INTERNAL SCAPULAR REGION 

 Contains but one muscle. 



suB-scAPUi.ARis. — Sub-scapulo-trocltineus. 

 Situation. — Occupying the venter scapuhc. 

 Form. — Triangular; broad, flattened, thin in substance. 



