THE POSTERIOR LIMB 275 



{b) The glutaeus medius. Anterior border of the wing of the 

 iHum and the ihac crest and fascia of the first two sacral 

 vertebrae. Insertion: Greater trochanter. Some of the 

 fibres pass around the medial surface of the tip of the 

 greater trochanter and are inserted in the lateral wall of 

 the trochanteric fossa. 



The muscle should be divided. 



(c) The glutaeus minimus. Origin : Entire lateral surface of the 

 body and wing of the ilium. Insertion : Greater trochanter. 



Remove the entire muscle. The piriformis is in contact 

 with its dorsal margin posteriorly. 



(d) The tensor fasciae latae. Origin: Anterior portion of the 

 ventral border of the wing of the ilium. Insertion: Broad 

 fascia of the lateral surface of the thigh. The muscle is 

 fused with the first head of the rectus femoris in front, and 

 with the second portion of the glutaeus maximus behind. 



(e) The piriformis. Origin : Lateral portions of the second and 

 third sacral vertebrae. Insertion : Tip of the great trochan- 

 ter. The muscle passes through the greater sciatic notch. 



The muscle should be divided, care being taken to avoid 

 injury to the nerves and blood-vessels beneath it. 

 (/) The gemellus superior. Origin: Tendinous from the 

 ischial spine and fleshy from the body of the ischium im- 

 mediately in front of it. Insertion: Lateral wall of the 

 trochanteric fossa, by a thick tendon common to this and 

 the next two muscles. 



The muscle extending from the ischial spine to the sacrum is the 

 abductor caudae anterior (p. 343). 



(g) The obturator intemus. Origin: Internal surface of the 

 coxal bone all round the edge of the obturator foramen, 

 extending forward along the medial surface of the ilium to 

 the sacroiliac articulation, where a few fibres are attached 

 to the sacrum. Insertion: Trochanteric fossa. The muscle 

 passes over the ischium in the lesser sciatic notch, only its 

 thick, white tendon of insertion appearing from the lateral 

 surface. To see its origin, reflect the tendon through the 

 lesser sciatic notch and examine the muscle from the internal 

 surface of the pelvis. 



