152 COMPARATIVE ARTHROLOGY. 



ribs articulate with their cartilages by means of true diarthroses, and are 

 supplied with synovial membranes. The sternum is furnished with an inferior 

 common ligament, and the presternum or manubrium articulates with the meso- 

 sternum by a diarthrosis of limited motion. The transverse lumbo-sacral and 

 interlumbar articulations, being peculiar to the horse, are entirely wanting here. 



PECTORAL LIMB. 



In the elboru joint the internal lateral ligament is shorter than the external. 

 The carpus, being articulated on the same general plan as that of the horse, calls 

 for no special description. The metacarpo-phalangeal joint is double, each digit 

 articulating in a manner very like the single one of a horse, and each having 

 two lateral ligaments. The sxispensory ligament divides into several parts 

 inferiorly, four of which go to the sesamoid bones, one to each, either of the 

 two external ones giving off a band which winds round to the front, and joins 

 the tendon of the extensor proprius of the digit, while two other bands pass 

 directly from the ligament through the interarticular notch of the metacarpus, 

 separate and likewise join the above-named extensor tendons from the inside ; 

 two slips pass down, unite, and become attached to the small rudimentary 

 digits or claws, afterwards separating to become united postero-superiorly to 

 the distal phalanges ; finally, two deep branches go to the tendon of the flexor 

 perforatus and form two rings through which passes the divided tendon of the 

 flexor perforans. The inferior sesamoid ligaments are small, and consist of two 

 lateral bands, which attach the sesamoid bones to the head of the proximal 

 phalanx, and between them a very small X ligament. The inter sesamoidean 

 ligaments are three in number ; there is one between each pair of bones, and 

 one joining the two internal ones. A common annular ligament is found 

 about the region of the fetlocks, and two smaller special annular ligaments 

 lower down. (Fig. 81,fgg'.) The superior interdigital ligament is crucial, 

 and situated between the two proximal phalanges; in small ruminants it is very 

 rudimentarj'. There are only two fibrous bands wdiich attach the glenoid 

 cartilage to the first phalanx. The inferior interdigital ligament joins the 

 distal phalanges and navicular bones together, and in the ox is connected with 

 the tendon of the flexor perforans. The superior navicidar ligament, coming 

 from the median phalanx, is formed of elastic tissue. 



Pelvic Limb. 



The pubio-fernoral ligament is wanting in all the domesticated animals other 

 than the horse ; the absence of this ligament enables the larger ruminants to 

 deliver those sweeping circular blows with the foot, which are known by the 

 familiar name of " cow-kicks." There is only one straight ligament of the 

 patella in the smaller ruminants. With respect to the tarsus, we may remark 

 that there is more motion in that joint in the ruminant, due to the greater 

 mobility of the astragalus, which possesses gliding motion upon the calcaneum, 

 the cubo-cuneiform bone, the tibia, and the malleolar bone, all of which assist 

 in forming the mobile portion of the joint. 



In the elephant there is no round ligament ; and the femur instead of being, 

 when at rest, inclined downwards and forwards, maintains an almost perpen- 

 dicular position ; this accounts for the peculiar contour of the haunch in that 

 animal. 



