278 BUREAU OF AmMAL INDUSTEY. 



hj their coaptation, the ball and socket joint. The articulation of the 

 arm and shoulder is an example of the first kind, Avhile that of the hip 

 with the thigh bone is a perfect exhibition of the latter. 



The structure whose office is to retain the articulating surfaces in 

 place is the ligament. This is usually a white, llbrous, inelastic tissue; 

 sometimes, however, it is elastic in character and 3-elloM'ish. In some 

 instances it is funicular shaped or corded, serving to bind more firmlj'^ 

 together the bones to which its extremities are attached; in others it 

 consists of a broad membrane, wholly or partially surrounding the 

 broad articulations, and calculated rather for the protection of the 

 cavity from intrusion by the air than for other security. This latter 

 form, known as capsular^ is usually found in connection with joints 

 which possess a free and extended movement. The capsular and 

 funicular ligaments are sometimes associated, the capsular appearing 

 as a membranous sac whollj^ or partipJly inclosing the joint; the funic- 

 ular, here known as an interariicidarWgd^nianU occup34ng the interior, 

 and thus securing the union of the several bones more tirmly and 

 effectively than would be possible for the capsular ligament unassisted. 



The universal need which pertains to all mechanical contrivances 

 of motion has not been forgotten while providing for the perfect work- 

 ing of the interesting piece of living machinery which performs the 

 function of locomotion, as we are contemplating it, and nature has con- 

 sequently^ provided for obviating the evils of attrition and friction, 

 and insuring the eas.y play and smooth movement of its parts, by the 

 establishment of the secretion of the synovia^ the vital lubricant of 

 which we have before spoken, as a yellow, oily, or rather glairy secre- 

 tion, which performs the indispensable ofHce of facilitating the play 

 of the tendons over the joints and certain given points of the bones. 

 This fluid, which is deposited in a containing sac, the lining (serous) 

 membrane of which forms the secreting organ, is of an excessively 

 sensitive nature, and while it lines the inner face of the ligaments, 

 both capsular and fascicular, is attached only upon the edges of the 

 bones without extending upon their length, or between the laj'ers of 

 cartilage which lie between the bones and their articular surfaces. 



Our object in thus partially and conciseh'^ reviewing the structure 

 and condition of the essential organs of locomotion has been rather 

 to outline a sketch which may serve as a reference chart of the gen- 

 eral features of the subject than to offer a minute description of the 

 parts referred to. Other points of interest will receive due attentior 

 as we proceed with the illustration of our subject and examine the 

 matters which it most concerns us to bring under consideration. The 

 foundation of facts which we have thus far prepared will be found 

 sufficiently broad, we trust, to include whatever may be necessar\' to 

 insure a read\' comprehension of the essential matters which are to 

 follow as our review is carried forward to completion. What we 



