MUSCLES OF THE ANTERIOR LIMBS. 



311 



spinatus across, and to throw back the sections : an operation requiring some care, because of 

 the intimate adherence of the short abductor to the infra-spinatus. 



1. External Scapular Aponeurosis. 



This aponeurosis, to which the pectoralis 

 parvus and long adductor of the arm act as tensors, 

 gives origin, by its internal face, to several septa 

 which penetrate between the scapular muscles, 

 and form around them more or less complete 

 contentive sheaths. Its external face is separated 

 from the skin by the panniculus carnosus, trape- 

 zius, mastoido-humeralis, and the aponeurotic 

 fascia which unites the last two muscles. It is 

 continuous, in front, with the thin fibrous ex- 

 pansion extended over the internal scapular 

 muscles ; behind and downwards, it is prolonged 

 over the muscles of the arm and insensibly de- 

 generates into connective tissues ; above, it is 

 attached to the fibro-cartilaginous prolongation 

 of the scapula. 



2. Long Abductor of the Arm (Teres Ex- 

 TERNus), OR Scapular Portion of the 

 Deltoid (Fig. 179, 1, 1). 



Synonyms. — Scapiilo-humeralis magnus — Girard. 

 (Teres major — Percivall. Great scapulotrochiterius — Leyh.) 



Situation — Composition — Form — Direction . — 

 This muscle is situated beneath the scapular 

 aponeurosis, behind the infra-spinatus, and is 

 composed of two portions placed one above the 

 other, separated by a superficial interspace. The 

 posterior portion, the most considerable, is elon- 

 gated from above to below, bulging in its middle, 

 narrow at its extremities, plane on its external 

 and convex on its internal surface. It accompanies 

 the posterior border of the infra-spinatus, and is 

 lodged in a depression in the large extensor muscle 

 of the forearm. 



The anterior portion, much shorter than the 

 preceding, extends over the infra-spinatus and 

 short abductor, by sUghtly crossing the direction 



Fig. 179. 



EXTERNAL MUSCLES OF THE 

 RIGHT ANTERIOR LIMB. 



1, 1, Long abductor of the arm; 1', 

 its humeral insertion; 2, supra- 

 spinatus ; 3. infra-spinatus ; 3', its tendon of insertion ; 4, short abductor of the arm ; 5, biceps ; 

 6, anterior brachialis ; 7, large extensor of the forearm ; 8, short extensor of the forearm ; 9, 

 anconeus; 11, anterior extensor of the metacarpus; 11', its tendon; 12, aponeurosis separating 

 that muscle from the anterior brachialis; 13, oblique extensor of the metacarpus; 14, anterior 

 extensor of the phalanges ; 14', its principal tendon; 15, the small tendinous branch it furnishes 

 to the lateral extensor ; 16, lateral extensor of the phalanges ; 16', its tendon ; 17, the fibrous 

 band it receives from the carpus; 18, external flexor of the metacarpus; 19, .its metacarpal 

 tendon; 20, its supra-carpal tendon; ulnar portion of the perforans ; 22, tendon of the perforans, 

 23, its carpal ligament ; 24, its reinforcing phalangeal sheath ; 25, tendon of the perforatus. 



