The Anterior Limb. 



211 



An tenor 



(b) The deltoideus: 



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. 



oc r ! 



Lateral 



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 



■"■•>■ Medial. 



.L.e.ap. 



Posterior 



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.3, long, lateral, and 

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

 vein; v.c, cephalic vein. 



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 removal of the 

 loosely attached fleshy parts of the pectorals from its surface. 



