730 THE ANATOMY OF THE RUFFED GROUSE 



M. vastus inedialis extends along the internal aspect of the femur. It is wider at the distal 

 end and there passes over the inner edge of the mesial t-ondyle to insert on the crest of the 

 tibia. The origin is along the femur, beginning about 5 nun. distal of the head. In GalUts, 

 the origin is at the head and is fleshy. , 



M. piriformis is a small triangular muscle originating on the ilium immediately above the 

 acetabulum. The tendon passes over the insertion of the tendon of M. obturator and inserts 

 on the femur just posterior to the insertion of the tendon of M. gluteus profundus. In Callus, 

 this muscle is relatively large. 



M. psoas is a slender muscle originating from the lateral border of the ilium anterior to 

 the prepubis. There is a small knob at this point. The insertion is on the mesial aspect of 

 the femur between the head and the insertion of M. vastus medialis. 



M. ambiens is a small muscle and is visible only from the medial side. The origin is on the 

 ventral face of the prepubis. Its tendon passes over the condyles of the femur and then 

 laterally and obliquely through the fascia of M. vastus lateralis and down to join M. flexor 

 perforatus. The distal portion of M. extensoriliotibialis lateralis internus covers much of the 

 tendon. 



M. extensor iliofibularis is a triangular muscle which originates along the postacetabular 

 ridge of the ihum and is situated below the pars posterior of M. extensor iliotibialis lateralis 

 and anterior to M. flexor cruris lateralis. The fibers converge distally and pass posterior to 

 the knee joint, to form the tendon. A wide and thin division of the tendon extends down 

 onto the fascia of pars externa of M. gastrocnemius. In Gallus, this slip passes mesially, 

 entering the pars externa and also has a slip to M. flexor perforans digiti IV pars media. 

 The main tendon passes through a fibrous loop and then downward to insert on a tubercle 

 of the fibula. The inner part of the loop is attached to the anterior border of the femur just 

 proximal to the external condyle. The outer and shorter end of the loop merges with the 

 tendinous origin of the external head of M. flexor perforans digiti IV and then passes to the 

 lateral crest of the tibia. In Colinus, the origin does not extend as far anteriorly, and does 

 not cover any of the head of the femur. 



M. flexor cruris lateralis is typically developed. It arises from the posterior border of the 

 ilium and the fascia of the caudal muscles. Its fibers pass obliquely to insert distally along 

 the tendinous raphe which forms the posterior margin of M. femorocruralis. From this 

 area a broad tendon extends to the fascia of pars interna of M. gastrocnemius. M. femoro- 

 cruralis has its fibers parallel to the tibia, passing from the tendinous raphe, as a broad 

 muscle, up to the femur, to insert along the distal one-third on the lateral border. One portion 

 passes mesiad to the insertion of M. flexor perforans digiti IV and then inserts in the cavity 

 between the two condyles. In Callus, these fibers merge on the distal border with M. gastroc- 

 nemius. In Colinus, M. femorocruralis is relatively very wide, inserting along one-half of the 

 femur. 



M. flexor ischiofemoralis arises in the concavity of tiie iscliiiiin and passes as a broad, thin 

 muscle forward. It forms a wide tendon whirit inserts on the external aspect of the femur 

 just below the trochanter. 



M. flexor cruris medialis originates from the outer edge of the ischium, al the jmint where 

 the pubis and ischium fuse. The muscle is ribbon-like and passes below M. flexor cruris 

 lateralis to terminate mesial to the tendinous raj)he of the latter, in a fascia which merges with 

 that of the pars interna of M. gastrocnemius. A broad tendinous fascia, common to M. flexor 



