OP DIDELPIIYS VIRGINIANA. 



123 



Psoas magmis. — (Fig. 31, b, and fig. 32, n.) A stout pyriform muscle, partially pin- 

 natiform, arisino- fleshy from the sides of the bodies and the transverse processes of two or 

 three lumbars next above the top of the ilium, and the two sacral vertebrae. It is inserted 

 by a stout rounded tendon 

 into the trochanter minor, 

 blending more or less with 

 the tendon of the iliacus. 

 Fleshy fibres continue almost 

 to the insertion on the pos- 

 terior aspect of the muscle ; 

 on the anterior, a tendinous 

 expansion reaches half way 

 up. 



Iliacus. — (Fig. 32, m, and 

 fig. 31, a.) A rather nar- 

 row, elongated and slightly 

 curved muscle, arising from 

 the tip and expanded face of 

 the bone, between the psoas 

 and glutoeus mimimus ; the 

 usual insertion, by a flat- 

 tened tendon, with the pre- 

 ceding, into the trochanter 

 minor. Flexion and out- 

 ward rotation of the thigh, 

 as usual. 



Glutceus maximus. — (Fig. 32, k.) Remarkable for its great superficial extent, and at 

 the same time for its extreme thinness. Its ordinary character, as a fleshy " mass," is 

 changed to that of a layer muscle ; its texture is not very appreciably coarser than that 

 of surrounding muscles ; nor is it divided into bundles by inward prolongations of the fascia 

 covering it. It forms a wide-spread, thin plane, arising from the tip of the ilium, and by 

 a broad aponeurosis (the fascia over the caudal extensors) from thence to a point of the 

 vertebral column opposite the tuberosity of the ischium. Its anterior border is, as it were, 

 tucked under, and continuous with the glutseus minimus, by complete blending of muscular 

 fibres. The relation of its posterior border to the femoro-coccygeus is described below. 

 From such broad origins the muscle converges, fan-shaped, to the trochanter major, passes 

 over the latter, and is inserted into the ridge on the back of the femur for an inch (and 

 sometimes much more) below the head of the bone. The line of traction of this muscle 

 makes it only a feeble extensor of the thigh ; it chiefly abducts and everts. 



Glutceus medius. — (The dotted line in fig. 32 shows the extent of the muscle.) This is 

 the most bulky of the three. It arises fleshy from the dorsum of the ilium (all that part 

 not occupied by the succeeding), and by aponeurosis from a corresponding extent of the 

 vertebral column, separating the lateral caudal extensors. It is inserted into the apex of 



Fig. 31. — Inner aspect of left leg — thigh flexed, rotated inward and strongly 

 abducted, so tliat the iliacus and psoas muscles are brought nearly in the same 

 plane; nearly natural size, x, the os marsupiale. 



the great trochanter, between the other two glutaji, by a short, stout, flattened tendon, 

 flexes, abducts, and inverts the thigh. 



It 



