The Anterior Limb. 



2X1 



-"■*■ MediaL 



(b) Thedeltoideus: 



Acromial portion. Origin: The Acromion. Insertion: Distal 

 portion of deltoid tuberosity. 



Scapular portion. Origin: Infraspinous fascia. The end of 

 the muscle forms a curved line over the dorsal portion of the 

 infraspinatus, leaving only a 



small triangular portion of '^"'"'"^ 



the latter exposed. Insertion : 

 The distal portion of the mus- 

 cle passes beneath the meta- 

 cromion, which also serves as 

 a point of attachment, and is 

 replaced on the lateral surface 

 of the humerus, beneath the 

 acromial portion, by a long 

 thin tendon, through which 

 it is inserted. 



The scapular portion of the 

 deltoideus should- be separated 

 from the infraspinatus and divid- 

 ed, the distal end being reflected 

 together with the metacromion. 



(d) The infraspinatus. 

 Origin: Posterior por- 

 tion of the lateral sur- 

 face of the scapula, in- 

 cluding the spine. In- 

 sertion: Greater tub- 

 ercle of the humerus. 

 The muscle fills the 

 infraspinous fossa. 



(e) The supraspinatus. Origin: Anterior portion of the lateral 

 surface of the scapula (supraspinous fossa), supraspinous 

 fascia, and, to a certain extent, the subscapular fascia. 

 Insertion: Greater tubercle of the humerus. 



The extent of this muscle is evident only after rem6val of the 

 loosely attached fleshy parts of the pectorals from its surface. 



Poalenor 



Fig. 74. Transverse section through the 

 distal portion of the arm; semidiagrammatic; 

 a.b., brachial artery; a.c.i., radial collateral 

 artery; b:, biceps; br.l. and br.m., lateral and 

 medial heads of the brachialis; d.. deltoideus 

 (insertion); e.a.p.,,' extensor antibrachii 

 parvus; f., bracnial fascia; h,, humerus; 

 n.m, me_ian nerve; n.r., radial nerve; n.u., 

 ulnar nerve; tr. i-tr.s, long, lateral, and 

 medial heads of the triceps; v.b., brachial 

 vein; v.c, cephalic vein. 



