SHOULDER LAMENESS. 235 



ble. Nothing has reflected brighter light upon the seat and nature 

 of lameness in general than the discovery of navicular thritis. 

 Before the navicular joint was known to be so common a site of 

 disease as it has since been proved to be, ignorance or indecision 

 in regard to the seat and nature of lameness found a ready and 

 secure retreat in a part so concealed from view and touch as the 

 shoulder-joint. The shoulder of the quadruped includes pretty 

 well a fourth part of his body ; it occupies a large space, compre- 

 hends many and various parts, and is complicated altogether in its 

 structure. The bulk of it is made up of muscles. There are but 

 two bones entering into its composition — the scapula and os humeri ; 

 but the joint they form between them, of the ball-and-socket cha- 

 racter, possesses greater variety of motion than any other joint in 

 the limbs ; and, moreover, has connected with it a pulley-like 

 bursal cavity, containing synovia the same as the main joint, which, 

 there exist strong reasons for believing is, if not the ordinary, at 

 least a very frequent seat of shoulder lameness. The tendon of 

 the flexor brachii — a muscle principally concerned in the flexion 

 of the arm of the quadruped — passes down from its attachment to 

 the scapula within a groove formed between the tubercles upon the 

 head of the os humeri, and plays up and down within this groove 

 after the manner of a rope over a pulley ; the surfaces both of ten- 

 don and groove being coated with articular cartilage and enclosed 

 within a synovial sac. Now, from the circumstances of this muscle 

 being mainly employed in bending or raising the arm, of the known 

 liability of bursal joints, such as this, to get out of order, and of 

 the presumed and pretty well ascertained seat of ailment being the 

 point of the shoulder — a part directly opposite to this bursa — there 

 seem good reasons for believing that this said bursa is the especial 

 or usual seat of derangement or disease in shoulder lameness. It 

 may appear strange, or even inexcusable, that in this, the sixtieth 

 year, or thereabouts, of the introduction of veterinary science 

 among us, we should be found making use of language so dubious 

 as this in regard to the site and pathology of the lameness in 

 question. It must be borne in mind, however, that for one case 

 that is in verity shoulder lameness there occur thirty that are not ; 

 and that, being a lameness that is commonly curable or one of 



