304 



Muscles of the Arm. 



M. 



supraspinatus 



Spina _ 

 scapulae 



Clavicula 



Bursa sulscutanea 

 acromialis 



M. infra- 

 spinatus 



M. teres 

 minor 



M. teres major 

 ]\r. triceps brachii (caput longura) 



M. 



cleltoideus 



M. triceps 

 ^__. ^m^^^j^m- ' l'i"'iclili (caput 



349. Muscles of the ^.^v m^Mmit lateraie, 



right upper arm, 



viewed from behind. 



Bursa subcutanea 

 mialis see ]>. 2lt 



M. supraspinatus (see 



Figs. 350:111(1351). Form 

 triangular, thick. Position: in the 

 fossa siipraspinata scapulae, covered 

 medianwani by the m. trapezius, 

 lateralward hy the acromion , lig. 

 coracoacroinialc and m. deltoideus. 

 Orif^in: fossa supraspinata and 

 fascia supraspinata. Insertion: 

 the iihers ctinverye lateralward and, 

 becoming tendinous, extend to the 

 tuberculum majus humeri: there 

 thoy become fused with the capsuli- 

 of the joint. Action: it lilts the 

 upper arm lateralward. Inner- 

 vation: n. siqirascapularis. 



M. infraspinatus (see also 

 Fig. 350). Form: flat, oblong- 

 triangular , thick. Position: in 

 the fossa infraspinata scapulae, par- 

 tially covered iiiedianward by the 



m. trapezius, lateralward by the m. di'ltmcleus. Origin: fossa infraspinata and fascia infra- 

 spinata. Insertion: the fibers converge as they pass lateralward to become inserted by a 

 strong tendon at the tuberculum majus humeri (bursa m. inft-aspiuati see Fig. 351); they 

 are there fused with the capsule of the joint. Action: it rolls the upper arm outward. 

 Innervation: n . suprascapularis. 



M. bracbioradiali.s 



M. extensor carpi 

 radialis longUM 



Ei)icondylus 



lateralis 



anconaeus 



M. extensor 

 digitorum 

 coraniuiiis 

 JNI. extensor 

 carpi uli;aris 



