SECTION IV. 

 LAMENESS IN THE HIND LEG. 



Anatomo-Physiological Consideration of the Pelvic Limbs. 



The pelvic bones as a whole constitute the analogue of the 

 scapulae with respect to their function as a part of the mechan- 

 ism of locomotive and supportive apparatus of the horse. The 

 manner of attachment or connection between the ilia and the 

 trunk is materially different from that of the scapulae, how- 

 ever, and the angles as formed by the long axes of the ilia in 

 relation to the spinal column are maintained by two functionally 

 antagonistic structures — the sacrosciatic ligaments, and the a1j- 

 dominal muscles by means of the prepubian tendon. The sacro- 

 iliac articulations are such that a very limited amount of move- 

 ment is possible; free movement, however, is unnecessary be- 

 cause of the enarthrodial (ball and socket) femeropelvic joint. 



The various muscles which exert their effect upon the pelvis 

 in changing their relationship between the long axes of the ilia 

 and spinal column, are concerned but little more in propulsion 

 and weight bearing than are the pectoral muscles. A general 

 treatise on the subject of lameness does not properly include 

 such structures any more than it does the various affections of 

 the dorsal, lumbar and sacral vertebrae or inflammation of the 

 abdominal parietes. Involvement of such parts cause manifesta- 

 tions of lameness but the matter of establishing a diagnosis is 

 difficult in many instances and in some cases impossible. 



The femeropelvic articulation is formed by the hemispherical 

 head of the femur and the acetabulum ; the latter constituting a 

 cotyloid cavity which is deepened by the cotyloid ligament. 



The round ligament (ligamentum teres) is the principal bind- 

 ing structure of the hip joint and it arises in a notch in the 

 head of the femur and is attached in the subpubic groove close 

 to the acetabular notch. Another ligament, peculiar to Equidae 

 — the accessory (pubiofemoral) — is attached to the head of the 

 femur near the round ligament and passes through the cotyloid 



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