204 OUTLINES OF EQUINE ANATOMY. 



part of the humeral ridge to be attached by a wide inser- 

 tion to the tendon of the caput magnum and to the outer 

 surface of the olecranon. Caput parvum arises from the 

 upper part of the internal ridge which bounds the ole- 

 cranian fossa of the humerus and passes to the point of the 

 ulna and to the internal surface of its olecranian process. 

 The internal surface of this head is in contact with the 

 humeral vessels and nerves derived from the axillary 

 plexus; also above with the humeral attachments of 



Teres interims, which arises from the superior part of 

 the posterior costa of the scapula, is externally in contact 

 with caput magnum as above described, and inferiorly 

 terminates by a tendon common also to latissimus dorsi, at 

 a roughened spot on the internal surface of the middle 

 third of the humerus ; over this tendon the humeral artery 

 and vein and several important branches of the axillary 

 plexus of nerves pass. It will be seen that this muscle 

 exactly corresponds in its course to the teres externus on 

 the outside of the limb. To the latissimus dorsi over its in- 

 ferior extremity runs the external thoracic branch of artery. 



On looking at the external surface of the shoulder, we 

 see that the venter surface of the scapula is covered over 

 its inferior two thirds by 



Subseapularis, which is covered by faschia, from which 

 subscapulo-hyoideus arises. Superiorly it presents a margin 

 of attachment divided into three projections, whereby it 

 leaves two triangular spaces for insertion of serratus 

 magnus. Inferiorly it becomes more narrow, and finally 

 for the most part tendinous, and inserted into the tubercle 

 situated on the inner surface of the head of the humerus. 

 The anterior margin of this muscle is in contact with 

 antea spinatus, which here presents a rounded surface apt 

 to be mistaken for another muscle until the limb is turned 

 over ; between these two muscles, above the coracoid pro- 

 cess, the anterior scapular artery (a branch of the axillary) 

 passes with its accompanying vein and nerve. 



Attached to the process on the internal surface of the 

 coracoid process is the tendon of 



Coraco-humeralis, which, emerging from between the two 

 muscles, passes over the insertion of subscapularis, over 

 which it plays through the medium of a bursa, then breaks 

 up into two muscular portions which go to be attached, the 

 superior one to the internal surface of the superior third of 



