The dorsal part has its insertion into the distal one and one-half to two centimeters of the ridge which is continued from the medial epicondyle of the femur onto the shaft; and into the sesamoid bone of the medial epicondyle.
Relations.—Lateral surface with the semitendinosus ([Fig. 90], j), the biceps femoris ([Fig. 68], t), and distad with a small part of the adductor femoris ([Fig. 92], g), and with the gastrocnemius ([Fig. 92], j). Medial surface with the gracilis ([Fig. 91], b) and distad with the sartorius ([Fig. 91], a). Cranial (or dorsal) border at the origin with the quadratus femoris ([Fig. 90], f); for the remainder of its length with the adductor femoris ([Fig. 90], h). Caudal border with the integument proximad.
Action.—Extensor of the thigh.
[Fig. 91].—Muscles on the Medial Side of the Leg.
![[Fig. 91]](#3418956513767812439_illo197lg.jpg.id-277817741231562105.wrap-0.html.html){kind=link}
a, M. sartorius; b, M. gracilis; c, M. iliopsoas; d, M. rectus femoris; e, M. vastus medialis; f, M. pectineus; g, M. adductor longus; h, M. adductor femoris; i, M. semimembranosus; j, M. semitendinosus; k, medial head of M. gastrocnemius; l, M. plantaris; m, M. flexor longus hallucis (m′, its tendon); n, M. flexor longus digitorum; (n′, its tendon); o, M. tibialis posterior; p, M. tibialis anterior; q, M. interosseus of second digit. 1, patella; 2, calcaneus; 3, medial malleolus; 4, second metatarsal; 5, transverse ligament of the lower leg.
M. sartorius ([Fig. 91], a; [Fig. 68], q).—A large flat muscle along the medial side of the thigh near its cranial (dorsal) border.
Origin from the ventral half of the crest of the ilium and from the medial half of its ventral border craniad of the auricular impression. The caudal third of the origin is by a thin tendon, the rest by fleshy fibres.
Insertion on a long S-shaped line which begins on the dorsal border of the tibial shaft about two centimeters from its proximal end, passes thence to the middle of the proximal end of the medial surface of the tibia, thence across the ligaments of the knee-joint and the medial surface of the medial epicondyle to the patella, crosses the patella obliquely to the middle of its proximal end, and may be continued for some distance proximad along the middle line on the fascia.
Relations.—Medial surface with the integument and proximad with the internal oblique muscle ([Fig. 68], p). Lateral (inner) surface with the tensor fasciæ latæ ([Fig. 68], r), the vastus lateralis ([Fig. 90], d), the superficial fascia, the vastus medialis ([Fig. 92], c), the rectus femoris ([Fig. 92], b), and the distal end of the semimembranosus ([Fig. 92], h′).