2l6 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. 



Fig. 298. — The deep layer of muscles of the anterior surface of the thigh. 

 The iliopsoas, sartorius, rectus femoris, pectineus, adductor longus, and gracilis have been removed. 



Fig. 299. — The insertion of the iliopsoas and the origin of the obturator externus. 

 The adductors have been divided and reflected; the femur has been sawed through below the trochanters, and is 

 slightly flexed and rotated outward. 



Fig. 300. — The origins of the piriformis and the obturator internus. 

 The pelvis has been divided in the median line. 



THE INTERNAL OR ADDUCTOR GROUP. 



The muscles of this group arise from the pubis and ischium in such a way that they form a 

 series of rings about the obturator foramen. The outermost ring is formed by the obturator 

 externus, the middle by the adductor brevis and minimus, and the inner by the pectineus, the adduc- 

 tor longus, the gracilis, and the adductor magnus. 



The pectineus (Figs. 296 and 297) is a flat, strong, quadrangular muscle situated between 

 the iliopsoas and the adductor longus in the subinguinal and anterior femoral regions, and form- 

 ing, together with the iliopsoas, the iliopectineal fossa. It arises from the crest of the pubis as far 

 forward as the pubic tubercle, passes obliquely from above downward and from within outward, 

 and is inserted by a short tendon into the pectineal line of the femur. The insertion is partly 

 concealed by the iliopsoas, covers the obturator externus and the upper part of the adductor brevis, 

 and passes over the inner surface of the articular capsule of the hip-joint. 



The pectineus adducts the thigh and also assists flexion. It is supplied by the obturator and femoral nerves. 



The adductor longus (Figs. 296 and 297) is a thick, flat, almost triangular muscle, situated 

 between the pectineus and the gracilis. It arises by a rather narrow but short and strong tendon 

 from the superior pubic ramus, between the origins of the pectineus and gracilis, becomes decidedly 

 broader as it passes downward, and is inserted by a short tendon into the middle third of the inner 

 lip of the linea aspera. The fibers of the muscle pursue a direction similar to those of the pecti- 

 neus, although they run more directly downward. If the muscle is well developed its upper mar- 

 gin is immediately continuous with the lower margin of the pectineus, and while it is situated 

 between the pectineus and the gracilis above, its lower portion lies upon the adductor magnus, 

 which is exposed between the adductor iongus and the gracilis. The upper portion of the adduc- 

 tor longus covers the adductor brevis, the lower the adductor magnus, its tendon of insertion is 

 concealed by the sartorius and is adherent to the origins of the vastus medialis (see page 215), 

 and, together with the sartorius and the inguinal ligament, the muscle forms a triangle, the femoral 

 triangle (triangle of Scarpa). 



The adductor longus is supplied by the obturator nerve; it adducts the thigh. 



The gracilis (Fig. 297) is a long, thin, slender muscle, situated upon the inner aspect of the 

 thigh. It arises by a flat tendon from the superior and inferior rami of the pubis near the sym- 

 physis, becomes somewhat broader at first, but soon narrows and, just above the knee-joint, 

 passes into a long, round, slender tendon which runs to the inner border of the tubercle of the 

 tibia and radiates into the pes anserinus as the second tendon of that structure. 



