78 THE SURGICAL ANATOMY OF THE HORSE 



There is no such osseous protection to the posterior half of the joint, 

 which is, however, not so exposed to risk of injury. To extend into the 

 joint in this situation it is necessary that punctured or other wounds should 

 be very deep, since they must passthrough the whole thickness of thedeltoid 

 and teres minor, and occasionally also part of the large head of the triceps 

 extensor cubiti muscle. Wounds in this situation are serious, even when 

 they do not extend into the joint on account of the proximity of the 

 circumflex nerve and vessels. 



Treatment of traumatic arthritis of the shoulder is the same as that 

 adopted in the case of any other joint, namely, to disinfect and close the 

 wound immediately if there should be a synovial discharge. If the dis- 

 charge is purulent there is very little hope in the case of this joint, since 

 a horse with a stiff shoulder is of very little use excepting for breeding 

 purposes. 



Shoulder Abscess or Shoulder lumour. — Although not actually con- 

 nected with the shoulder joint, this condition may appropriately be briefly 

 referred to here. 



This is a large swelling which appears in front of the shoulder near 

 the inferior extremity of the jugular furrow. It most frequently occurs 

 in heavy draught horses. 



It will be remembered that the mastoido-humeralis muscle here 

 leaves the neck and passes over the front of the shoulder to descend to its 

 insertion into the outer lip of the musculo-spiral groove, and it is either 

 in or underneath this muscle that the growth develops. 



A full description of the affection will be found in Part IV. together 

 with the operations for its removal. 



THE ELBOW JOINT 



Three bones enter into the formation of this joint, namely, the 

 humerus, radius, and ulna. The two last-named bones are firmly united 



