ANTERIOR MEMBER. 221 



Certain horses have the habit of lying down like a cow, — that is to say, of main- 

 taining the anterior members flexed under the chest. It results from this that 

 the heels of the shoe come into direct contact with the point of the elbow, irri- 

 tate and bruise the skin, and cause the formation of a more or less voluminous 

 tumor called shoe-boil, so named from the agent which acts as the exciting cause. 

 A tumor of this kind is sometimes sensitive to the touch, and necessitates suspen- 

 sion from Avork. At other times shoe-boils are not harmful, except as being ugly 

 blemishes. We have had under our observation for several years a horse which 

 performed very active service and carried on each elbow a shoe-boil of the volume 

 of a man's head. 



As soon as any excoriation of the skin of this region is perceived, it is neces- 

 sary to observe the position of the animal in the decubitus, and, if required, to 

 shorten the heels of the shoe, or simply the one on the internal side, which alone 

 is most usually the cause of the " boil ;" or, again, we may protect the foot with 

 a leather boot. 



We may here mention /rarfwres of the olecranon ; these are followed by a 

 permanent deformity of the elbow, the extremity of the bone being displaced 

 upward by the contraction of the extensor muscles of the forearm. Even after 

 the fracture is repaired, this injury causes a lameness the nature of which can 

 always be detected by careful observation. 



D. — The Forearm. 



Situation ; Limits ; Anatomical Base. — The forearm, situ- 

 ated between the arm and the knee, is related, above and behind, to the 

 elbow. 



Two bones constitute its base : the radius and the greater portion of the 

 cubitus. These bones are surrounded by two sets of muscles, which all act upon 

 the metacarpus o'r the phalanges ; the one, the anterior, compressing the extensors 

 of these regions, and the other, the posterior, forming the flexors of the same. 

 Indirectly, through the ligaments, they can also move the forearm, and carry it 

 into extension or flexion, according to the muscles which act. They operate for 

 the most part upon levers of the third class, and hence play their principal role 

 in the production of velocity ; rarely do they concur in an active manner in the 

 support of the body, a function provided for by the special mechanical conforma- 

 tion of the parts. 



Form. — The forearm, as a whole, has the form of a cone, depressed from 

 side to side towards its base or superior extremity, whose volume is in relation 

 with that of the muscles just named. 



Its external face is separated from the arm and the elbow by a furrow, with 

 an inferior convexity, due to the prominence of the extensors of the forearm 

 upon the superior extremity of the antibrachial muscles, extensors of the meta- 

 carpus, and phalanges. A gutter, extending along the external border of the 

 radius, and in its lower part, separates the anterior from the posterior muscles. 



The internal face is devoid of muscles over the greater portion of its extent, 

 and the skin is applied almost directly against the radius. The internal subcu- 

 taneous vein of the forearm, on which phlebotomy is sometimes practised, crosses 

 this face a little obliquely from below to above. Finally, in the lower third of 



