_Origin._—From the margin of the shaft of the median metacarpal. _Insertion._—To the anterior part of the base of the distal phalanx of the index digit. _Shape._—Short, delicate, with long tendon. _Relations._—Internally, the metacarpal bone. _Action._—Extends the last bone of the middle finger. =Interosseus Palmaris= (Fig. 13, No. 32). _Location._—On the opposite side of the bone from the interosseous dorsalis. _Origin._—From the shaft of the median metacarpal under the preceding. _Insertion._—To the apex of the last joint of the second, or middle finger. _Shape._—Small, delicate, with long slender tendon. _Relations._—Beneath the preceding and along the metacarpal bone. _Action._—Flexes the terminal phalanx. =Flexor Metacarpi Brevis.= _Location._—To the lateral side of the metacarpal bone. _Origin._—From the outer side of the distal extremity of the ulna. _Insertion._—To the base, in front, and on the ulnar side of the proximal phalanx of the index digit. _Shape._—Delicate, with long slender tendon. _Relations._—On the lateral side of the ulna and the metacarpal bone. _Action._—Flexes the metacarpus. MUSCLES OF THE POSTERIOR LIMB Sartorius Gluteus medius Extensor femoris Biceps flexor cruris Semitendinosus accessorius Femoro-caudal Obturator internus Abductor longus Gluteus primus Gluteus minimus Vastus internus Semitendinosus Semimembranosus Obturator externus Gemellus Adductor magnus =Sartorius= (Fig. 23, No. 7). _Location._—Extreme anterior portion of the thigh. _Origin._—From the outer two-thirds of the superior surface of the raised emarginations of the anterior border of the ilium, and by fascia from the neural spines of the fourth dorsal vertebra. _Insertion._—Obliquely by a semitendinous fascia to the inner edge of the ligamentum patella, and to the inner and adjacent border of the anterior half of the summit of the tibia. _Shape._—Large, fleshy. _Relations._—Posteriorly, with the gluteus primus and the vasti. _Action._—Extends the leg, flexes and adducts the thigh. =Gluteus Primus= (Fig. 23, No. 8 and 9). _Location._—The outer flat massive muscle of the thigh. _Origin._—By a thin fascia from nearly the entire length of the supero-internal margin of the pre-acetabular portion of the ilium, above the antitrochanter, and from the entire length of the post-acetabular ridge. _Insertion._—Near the patella it joins the tendon of the extensor femoris, and by aponeurosis spreads over the knee and is inserted to the crest of the upper border of the tibia, the patella being incorporated in its aponeurotic ligament.