Muscles of the Arm. 



305 



Acromion 



M. supraspinatus 

 Spina scapulae 



M. infraspinatus 



M. tei'cs minor 



M. teres major ,, 



triceps brachii 

 (caput longuni 



M. 

 triceps brachii 

 (caput laterale) 



350. Muscles of the right 



upper arm, viewed from behind, 

 the m. deltoideus haying been removed. 



M. teres miuor (see also Fig. 349). Foriu : 

 flat, oblong-quadrangular. Position: just below 

 the ui. infraspinatus, often fused with it; covered 

 behind and lateralward by the m. deltoideus. 

 Origin: facies dorsalis scapulae, close to the 

 margo axillaris, and fascia infraspinata. Inser- 

 tion: the fibers run , parallel to one another, 

 lateralward and become attached to the tuber- 

 culum majus humeri by a short tendon, which is 

 fused with the capsule of the joint. Action: it 

 rolls the upper arm outward. Innervation: 

 n. axillaris. 



Fascia siipraspiuata (not shuwnin draw- 

 ing) is a fascia, distinctly striated medianward, 



which covers the m. supraspinatus ; it is fused medianward with the margo superior, the margo 

 vertebralis and the spina scapulae and. lateralward, becomes lost. 



The fascia iufraspiuata (see Figs. 329 and 330) is attached to the margo vertebralis 

 and to the spina scapulae, is stronger medianward, covers the mm. infraspinatus and teres 

 minor and becomes lost lateralward below the m. deltoideus. 



M. triceps brachii (see also Figs. 342, 343, 349 and 351). Form: flatly roimded, 

 oblong -quadrangular. Position: it occupies the whole posterior surface of the upper arm. 

 Origin: by three heads. Caput longurn: by a flat tendon from the tuberositas infraglenoidalis 

 scapulae; it runs downward between the mm. teres minor and teres major, the fibers being- 

 parallel, is partly covered above by the ra. deltoideus and overlaps the caput metUale, in part, 

 i'rom behind and medianward; below it is attached to the medial border of the tendon of the 

 caput mediale. Caput mediale: from the facies posterior humeri, medial to and below the 

 sulcus n. radialis, as well as from the septa intermuscularia mediale et laterale; the fibers 

 I'each, below close to the m. anconaeus and run, converging somewhat, to a large quadrangular 

 flat tendon, which begins in the middle of the u])per arm (continued (.m p. 30(>). 



