802 DISEASES OF THE KNEE. 



difficulty in movement had first appeared twelve to fifteen days 

 after the fall. Permanent recovery followed division of the flexor 

 metacarpi externus. 



C. DISEASES OF THE KNEE. 



The knee, a composite joint, consists of three principal and several 

 subsidiary articulations. The principal joints are : — (1) the radio- 

 carpal articulation ; (2) the inter-carpal articulation ; (3) the carpo- 

 metacarpal art icul at ion . 



The first two are incomplete ginglymoid joints, because, in addition 

 to flexion and extension, they allow of slight lateral movement, and, in the 

 flexed position, of some amount of rotation, most marked in carnivora. 

 The lower row of hones forms with the metacarpus an arthrodial joint, the 

 movement of which, in all animals except carnivora, is exceedingly limited. 

 Each of these three joints is surrounded by its own synovial membrane, 

 though the lower is connected with the middle by a narrow slit. 



The anterior capsular ligament arises from the radius, is applied to 

 both rows, and ends on the metacarpus. Two strong lateral ligaments 

 attach the radius to the metacarpus, while the bones of the carpus itself 

 are united to one another and to the radius and metacarpus by interosseous 

 ligaments which limit the movement of the knee-joint. A strong fibrous 

 expansion protects the joints behind. 



The fascia covering the carpus and metacarpus, which is an extension 

 of the deep portion of the fascia of the fore- arm, forms, on the anterior 

 surface of the knee-joint, sheaths for the extensor tendons, and is in close 

 connection with the capsule of the joint. On the outer surface of the 

 carpus the fascia becomes continuous with the ligaments of the joint, 

 with the periosteum of the external surface of the pisiform bone, with 

 the tendon of the flexor metacarpi externus, and with the extensor pedis. 

 On the inner side of the carjDus the fascia becomes attached to the ligaments 

 of the joint, to the lower extremity of the radius, and to the inner small 

 metacarpal, and posteriorly it covers the carpal arch and the flexor pedis 

 tendons. 



The skin lies immediately over the fascia, and on the dorsal side especially, 

 is thick, tense, and provided with a moderately well developed subcutis. 

 In addition to the synovial sheaths of the extensor tendons, subcutaneous 

 bursa? are sometimes found on the os magnum, as well as on the lower 

 anterior surface of the radius towards the inner side of the sheath of the 

 extensor pedis. The discharge of synovia after injury to the front of the 

 knee is therefore no proof that the knee-joint has been opened, although 

 it always calls for special precautions in treatment. 



I.— FRACTURES OF THE BONES OF THE KNEE. 



Fracture of these bones is in general prevented by their small 

 size and sheltered position. In large animals like horses, fractures 

 are commonest from falls on hard ground. They usually occur in 



