THE ANTERIOR FEMORAL MUSCLES 



467 



the femoral vessels is also attached to the pectineal line beyond the limits of the 

 attachment of the inguinal aponeurotic falx; at this part it is continuous with 

 the pectineal fascia. The external iliac vessels lie in front of the iliac fascia, but 

 all the branches of the lumbar plexus are behind it; it is separated from the peri- 

 toneum by a quantity of loose areolar tissue. 



The Psoas major (Psoas magnus] (Fig. 430) is a long fusiform muscle placed on 

 the side of the lumbar region of the vertebral column and brim of the lesser pelvis. 

 It arises (1) from the anterior surf aces of the bases and lower borders of the transverse 

 processes of all the lumbar vertebrae; (2) from the sides of the bodies and the corre- 

 sponding intervertebral fibrocartilages of the last thoracic and all the lumbar verte- 

 brae by five slips, each of which is attached to the adjacent upper and lower margins 

 of two vertebras, and to the intervertebral fibrocartilage; (3) from a series of 

 tendinous arches which extend across the constricted parts of the bodies of the 

 lumbar vertebra? between the previous slips; the lumbar arteries and veins, and 

 filaments from the sympathetic trunk pass beneath these tendinous arches. The 

 muscle proceeds downward across the brim of the lesser pelvis, and diminishing 

 gradually in size, passes beneath the inguinal ligament and in front of the capsule 

 of the hip-joint and ends in a tendon; the tendon receives nearly the whole of 

 the fibers of the Iliacus and is inserted into the lesser trochanter of the femur. 

 A large bursa w r hich may communicate with the cavity of the hip-joint, separates 

 the tendon from the pubis and the capsule of the joint. 



The Psoas minor (Psoas parvus) is a long slender muscle, placed in front of the 

 Psoas major. It arises from the sides of the bodies of the twelfth thoracic and first 

 lumbar vertebrae and from the fibrocartilage between them. It ends in a long 

 flat tendon which is inserted into the pectineal line and iliopectineal eminence, 

 and, by its lateral border, into the iliac fascia. This muscle is often absent. 



The Iliacus is a flat, triangular muscle, which fills the iliac fossa. It arises from 

 the upper two-thirds of this fossa, and from the inner lip of the iliac crest; behind, 

 from the anterior sacroiliac and the iliolumbar ligaments, and base of the sacrum; 

 in front, it reaches as far as the anterior superior and anterior inferior iliac spines, 

 and the notch between them. The fibers converge to be inserted into the lateral 

 side of the tendon of the Psoas major, some of them being prolonged on to the body 

 of the femur for about 2.5 cm. below and in front of the lesser trochanter. 1 



Variations. The Iliacus minor or Iliocapsularis, a small detached part of the Iliacus is frequently 

 present. It arises from the anterior inferior spine of the ilium and is inserted into the lower part 

 of the intertrochanteric line of the femur or into the iliofemoral ligament. 



Nerves. The Psoas major is supplied by branches of the second and third lumbar nerve; 

 the Psoas minor by a branch of the first lumbar nerve; and the Iliacus by branches of the second 

 and third lumbar nerves through the femoral nerve. 



Actions. The Psoas major, acting from above, flexes the thigh upon the pelvis, being assisted 

 by the Iliacus; acting from below, with the femur fixed, it bends the lumbar portion of the verte- 

 bral column forward and to its own side, and then, in conjunction with the Iliacus, tilts the pelvis 

 forward. When the muscles of both sides are acting from below, they serve to maintain the 

 erect posture by supporting the vertebral column and pelvis upon the femora, or in continued 

 action bend the trunk and pelvis forward, as in raising the trunk from the recumbent posture. 



The Psoas minor is a tensor of the iliac fascia. 



1 



o 



THE MUSCLES AND FASCIA OF THE THIGH. 



The Anterior Femoral Muscles (Fig. 430). 



f Rectus femoris. 

 Quadriceps I Vastus lateralis. 

 femoris. 



Articularis genu. 



Vastus medialis. 

 [ Vastus intermedius. 



1 The Psoas major and iliacus are sometimes regarded as a single muscle named the Iliopoa. 



