MUSCLES IN FRONT OF THE THIGH. 273 



The connection of the psoas with the bodies of the bones is effected by means of 

 five distinct parts, each of which is attached to the upper and lower margins of two 

 vertebrae and the interposed fibro-cartilage ; the highest to the neighbouring margins 

 of the last dorsal vertebra and the first lumbar, and the lowest to the edges of the 

 fourth and fifth lumbar vertebrae with the intervertebral substance. These attach- 

 ments are connected by thin tendinous arches, extending over the middle of each 

 vertebra, covering the lumbar vessels and communicating branches of the sympathetic 

 nerve, and giving origin to other muscular fibres. The psoas muscle, at its superior 

 extremity, passes behind the diaphragm, below the arch of the ligamentum arcuatum 

 internum. Resting on its inner border, along the margin of the pelvis, is the external 

 iliac artery, and deeply in the substance of the muscle is the lumbar plexus of nerves. 

 The ilio-inguinal and external cutaneous nerves cross the iliacus muscle, and the 

 anterior crural nerve descends on the tendon of the psoas. The iliac fascia extends 

 over the surface of the whole ilio-psoas muscle in the abdomen. The muscle emerges 

 from the abdomen beneath Poupart's ligament, and turning over the brim of the 

 pelvis rests on the capsule of the hip-joint, on which it glides by means of a large 

 synovial bursa, which occasionally communicates with the interior of the joint ; its 

 outer margin is in contact with the rectus muscle, and its inner margin is separated 

 from the pectineus by the internal circumflex artery. 



The psoas parvus, an occasional muscle, placed on the surface of the 

 ppoas magnus, arises from the bodies of the last dorsal and first lumbar 

 vertebrae, and from the fibro-cartilage between them, and soon ends in a 

 flat tendon, which passes along the front and the inner side of the psoas 

 magnus, to be inserted into the ilio-pectineal line and eminence. 



This muscle, although it is well developed and constant in animals, is most fre- 

 quently absent in the human subject. It was found in only one of twenty bodies 

 examined by Theile with special reference to its existence. When present, it is 

 liable to many changes in the place of origin ; thus, it may be connected only with 

 the first lumbar vertebra, or with the second and the intervertebral substance above 

 it, and it has been observed to commence by two parts or heads separated by an 

 interval. 



ANTERIOR FEMORAL REGION. 



The tensor vagina femoris, or ilio-aponeurotic muscle of the thigh, arises 

 by muscular and tendinous fibres from the external surface of the iliac crest 

 close to its fore-part, and from part of the notch between the two anterior 

 iliac spines, external to the attachment of the sartorius ; and passing down- 

 wards and a little outwards it is inserted between two laminse of the fascia 

 lata, about three inches below the great trochanter of the femur. The 

 outer of these laniinsB is continued upwards on the muscle in its whole 

 extent, being part of the general investment of the limb, the deeper is 

 connected above with the origin of the rectus muscle, and with the fibres 

 attaching the gluteus minimus to the hip-joint. The part of the fascia, 

 made tense by the action of the muscle, forms a strong tendinous band, 

 which descends to the outer and back part of the knee-joint. 



The sartorius is very long, narrow, and ribbon -shaped, and presents the 

 longest fibres of all the muscles in the body : it arises by a short tendon 

 from the anterior superior spiuous process of the ilium, and from a small 

 part of the anterior margin of that bone immediately below, and, passing 

 downwards and inwards across the front of the thigh, is inserted by an 

 expanded aponeurosis into the upper and inner side of the tibia, near to the 

 tubercle, and for about an iuch below it. 



In this long course the muscle is directed over the anterior part of the thigh, 

 obliquely inwards in the upper third, and vertically at the inner aspect of the limb 



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