27 



CLASS I. 



LAMENESSES ARISING FROM DISEASES OF JOINTS AND 



BURS^ MUCOSA. 



General Observations on the Diseases of Joints. 



In a pathological sense, we might define lameness to be, disease 

 or derangement of some part or other of the apparatus of loco- 

 motion. The organs of locomotion are the bones and muscles : 

 the one constituting that framework of figure and support to which 

 the other are attached for the purposes of motion. Very many 

 bones, of different shapes and sizes, enter into the composition of 

 this framework ; but, divided and subdivided as it is, such is the 

 harmony of arrangement, and complete adaptation and secure fast- 

 ening of one bone to another, through the media of joints, that, with 

 all the strength of an entire structure, the framework possesses 

 every necessary capability and variety of motion. 



A joint may be said to be an union, by means of ligaments, of 

 two — in some instances of three — bones, whose opponent ends or 

 surfaces are shaped so as to fit into each other, are covered by 

 cartilage, and inclosed within a capsular ligament, forming a shut 

 cavity, which is lined throughout by a sort of internal capsule, to 

 which, from its secreting the synovia or joint-oil, the name of 

 synovial membrane is given. Of this, which constitutes the most 

 perfect description of joint, the best examples are to be found in 

 the limbs, the main bones whereof are articulated together in a 

 manner that fits them for every required variety of movement : 

 two of them, the shoulder and hip-joints, have ball-and-socket 

 articulations, conferring upon them circumductive and rotatory 

 moving faculties; the others, for the most part, are of the gin- 

 glymoid or hinge-kind, possessing great extent of motion, though 

 that motion is limited to flexion and extension. 



There is, however, a description of joint which has neither 

 cavity nor joint-oil, and yet, within certain limits, admits of mo- 

 tion : this is the Jibro-cartilaginous joint. The splent bones, as 



