206 OUTLINES OF EQUINE ANATOMY. 



forms a flat tendon whicli passes nnderneatli tlie inferior 

 portion of tlie internal lateral ligament, where it is lubri- 

 cated with synovia, and becomes inserted into the internal 

 surface of the head of the radius and into the inner 

 sharpened border of the ulna. 



Muscles attached to the capsular ligament of the sca- 

 pulo -humeral joint : 



Antea spinatus, postea spinatus, subscapularis, scapulo- 

 humerales externus and posticus, and caput magnum. 

 Flexor brachii is separated from it by a quantity of fat 

 and its bursa, coraco-humeralis by the subscapularis ten- 

 don and a bursa. 



The axillary artery must now be viewed as a whole. 

 It commences from the anterior part of arteria innominata 

 within the chest, and takes a turn around the anterior 

 margin of the first rib below the inferior head of scalenus 

 at its posterior attachment. It thus gains the external 

 part of the thorax and the internal surface of the limb, 

 so that on raising the limb after division of the pectoral 

 muscles we see this vessel with its corresponding vein, and 

 the axillary plexus of nerves, with the axillary lymphatic 

 glands embedded in loose cellular tissue, in the neighbour- 

 hood of the shoulder- joint. It gives off arteria dorsalis 

 scapulse (or anterior scapular artery), posterior scapular 

 (or subscapular), external thoracic, and humeral arteries, 

 the course of which we have already noticed; also the 

 humeral thoracic which runs to supply pectoralis magnus 

 and antea spinatus at the point of the shoulder. The 

 humeral artery in its course along the internal surface of 

 the humerus gives off a hrcmch anteriorly, which passes 

 hehveen the tivo heads of coraco-humeralis to flexor hrachii, 

 a large branch hackivards to tricejos extensor hrachii,^ and a 

 branch inwards opposite the superior part of the inferior 

 third of the bone, which pierces its substance by imssing 

 through the medullary foramen. The artery then passes to 

 the anterior margin of the bone and breaks up into the 

 ulnar, spiral, and radial arteries. The ulnar runs back- 

 wards, and very soon breaks up to form a number of 

 smaller vessels, which all run to structures near the ole- 

 cranon. The spiral passes over the front of the elbow- 

 joint, and runs down the anterior surface of the radius 

 in company with a vein and nerve. The radial, after 

 passing over the internal surface of the elbow -joint, dips 



