_Relations_.--Outer surface with the caudofemoralis (Fig. 68, _s_) and the biceps femoris (Fig. 68, _t_); distad with the integument. Inner surface with the obturator internus (Fig. 90, _e_), quadratus femoris (_f_), semitendinosus (_j_), adductor femoris (_h_), semimembranosus (_i_), and distad with the muscles of the lower leg.
=M. caudofemoralis= (=parameralis=, Strauss-Durckheim) (Fig. 68, _s_, page 117).
_Origin_ by a flat tendon from the transverse processes of the second and third caudal vertebræ. The muscle forms a flat band which passes distad along the middle of the lateral side of the thigh over the pelvis and caudad of the great trochanter. At the middle of the thigh it ends in a very thin tendon. The tendon passes distad along the medial surface of the biceps femoris (Fig. 68, _t_), pierces the fascia lata near the knee, and passes to its
_Insertion_ into the middle of the lateral border of the patella.
_Relations._--Outer surface with the superficial fascia and a few fibres of the cutaneus maximus; distad with the biceps femoris (Fig. 68, _t_). Cranial border with the gluteus maximus; caudal border with the biceps femoris. Inner surface with the tenuissimus (Fig. 90, _g_), the gluteus maximus, the abductor caudæ internus, and with the obturator internus (Fig. 90, _e_); distad with the vastus lateralis.
_Action._--Abducts the thigh and helps to extend the shank.
=M. semitendinosus= (Fig. 90, _j_).--A long slender muscle on the ventral (caudal) border of the thigh, between the semimembranosus (_i_) and the biceps femoris (Fig. 68, _t_).
_Origin_ from the apex of the tuberosity of the ischium beneath the origin of the biceps femoris. The muscle passes to the medial side of the shank and ends in a thin but strong tendon (Fig. 92, _i′_) about five millimeters broad. The tendon curves proximad and passes beneath the gracilis tendon (Fig. 91, _b_) to its
_Insertion_ into the crest (dorsal border) of the tibia one or two centimeters from its proximal end.
_Relations._--Lateral surface with the biceps femoris (Fig. 68, _t_), the integument, a mass of fat, and distad with the gastrocnemius (Fig. 92, _j_) and popliteus (Fig. 92, _k_). Caudal surface with the integument. Medial surface with the semimembranosus (Fig. 90, _i_) and distad with the integument of the lower leg.