INFLAMMATION OP BURSA OF BICEPS MUSCLE. 769 



IV.— INFLAMMATION OF THE BURSA OF THE BICEPS, FLEXOR 

 BRACHII OR CORACO RADIALIS MUSCLE (BURSITIS 

 INTERTUBERCULARIS). 



During flexion and extension of the shoulder-joint the tendon of the 

 flexor brachii glides over the bicipital groove of the humerus, which is 

 covered with fibro-cartilage, and forms one of the boundaries of an extensive 

 bursa (bursa intertubercularis). The bursa extends from the periphery 

 of the cartilage-covered tuberosities, over the tendon, clothes a portion of 

 its surface, then its sides, and finally its under face. The sides of the bursa 

 are covered by the lower points of insertion of the supraspinatus muscle, 

 and its cavity is divided from the capsule of the shoulder-joint by a mass 

 of fat. In swine and carnivora, the bursa is continuous with the shoulder- 

 joint. Its position is nearer the central line of the body than in the horse. 



In horses, the extensive intertubercular bursa is sometimes the 

 seat of acute or chronic inflammation, in which the biceps tendon 

 shares, and which almost always results from severe bruises, such as 

 are caused by collisions when the shoulder is struck and the biceps 

 receives the full shock. Wounding of the bursa may be followed 

 by acute septic inflammation. Runaway horses frequently suffer. 



A chronic bursitis (which may be bilateral) is produced in tramway 

 and omnibus horses by half -falls, or slipping in rapid driving. 



As in acute inflammation of other synovial bursse, serous and 

 fibrinous exudates occur ; in infected wounds and metastatic diseases 

 purulent inflammation of the bursa of the tendon may set in. 

 Dieterichs saw symptoms of acute inflammation, hyperemia, and 

 exudation in horses which had shortly before fallen ill. Necrosis of 

 the bursa in the horse was seen by Moller. The tendon was partially 

 necrotic, the gliding surface on the humerus deprived of fibro-cartilage 

 and eroded. 



Chronic bursitis produces abrasion of cartilage, formation of 

 exostoses on the humerus, and ossification of the biceps. Williams 

 and Dieterichs found the muscle almost entirely ossified, though in 

 Dieterichs's case the biceps had become adherent to the humerus. 

 The gliding surface of the biceps is frequently roughened from friction 

 against the altered bicipital groove. Villate has also seen ossification 

 of the muscle, with abrasion of its gliding surface. 



Symptoms. Acute bursitis intertubercularis is shown by excessive 

 lameness when the leg is advanced (swinging leg lameness). On 

 attempting to move the animal, the foot is not carried forward, but 

 remains at a point behind that of the other side, giving the impression 

 that the foot cannot be lifted from the ground. When forced to 

 move, the horse places absolutely no weight on the lame leg (Fig. 459). 

 It moves back without much difficulty, and may then be able to 



