DISEASES OF THE LEG. 971 



be taken not to incise a dropsical stifle-joint in mistake for enlarge- 

 ment of the prepatellar bursa. The hydrops swelling lies deeper 

 and cannot be so easily displaced under the skin as that now in 

 question. 



G. DISEASES OF THE LOWER THIGH OR LEG. 



The thigh, especially'in the horse, is surrounded by a tense, stretched 

 skin, which on the external face is strong, but on the internal somewhat 

 thin. Towards the front or the internal surface of the thigh, the skin and 

 fascia of the leg lie directly in contact with the tibia, which, therefore, at 

 this point is particularly exposed to injury. About three-quarters of the 

 bone, i.e., the entire external and the posterior portion of the internal 

 surfaces, are covered with muscles which are singly clothed with aponeurosis 

 and protected by the fascia lata. The latter arises from the muscles of 

 the quarter and upper parts of the thigh, and is partly inserted into the 

 crest of the tibia, partly extends below the hock, to become continuous 

 with the aponeurosis of the metatarsus and pastern. 



I._WOUNDS AND INJURIES. 



Injuries of the tibia are commonest in horses, and are caused 

 by kicks, and by the leg being passed over bales or over the carriage- 

 pole. Sometimes the skin alone is inflamed or lacerated, but not 

 infrequently the periosteum and even the bone are bruised. The 

 bone is sometimes fissured by kicks, a condition which will later 

 receive attention ; or diffuse periostitis is caused, though it also 

 follows bruising of the fascia, without the bone itself being injured. 



Tibial periostitis produces well-marked swinging-leg lameness 

 and shortening of the forward stride, while the thigh is moved slowly 

 and stiffly. It usually lasts three to four weeks, and is succeeded 

 by thickening over the tibia. The local pain shown on palpation 

 prevents any mistake in diagnosis. Injuries of the tibia itself can 

 usually be detected by probing. 



The presence of strong fascia covering the muscles of this region 

 causes wounds, which would otherwise heal without trouble, to be 

 followed by very dangerous consequences. Injury to the fascia is 

 troublesome, because the muscular tissue protrudes through the rent 

 (muscular hernia), and being irritated by its edges, commences to 

 proliferate actively ; — or suppuration may extend beneath and 

 lead to necrosis of fascia, and before the necrotic portions can be 

 shed, excessive fungous granulations, the growth of which is favoured 

 by the continuous movement of the muscle, arise and greatly impede 

 healing. This condition is commonest on the lower portions of the 

 biceps femoris muscle, but may occur in any region of the tibia. 



