THE MUSCULAR SYSTEM. 157 



PALMAR INTEEOSSEI. Three in number. Origin., the first 

 from the entire length of the metacarpal bone of the index 

 finger on its ulnar side, the second from the ring finger on its 

 radial side, and the third from the little finger on its radial side ; 

 insertion, into the base of the first phalanx and into the ex- 

 pansion of the extensor communis tendon of the same finger 

 from which they arise; action, adduct the fingers toward the 

 median line; nerve, ulnar. 



MUSCLES OF THE LOWER EXTREMITY. 

 ILIAC REGION. 



PSOAS MAGNUS. Origin, from the sides and anterior sur- 

 faces of the transverse processes and bodies of the last dorsal and 

 all the lumbar vertebrae and the intervertebral substances between 

 them ; insertion, into the lesser trochanter of the femur, uniting 

 with the tendon of the iliacus ; this muscle is in relation behind 

 with the capsular ligament of the hip, being separated from it by 

 a synovial bursa; action, flexes and rotates the femur inward, 

 and also flexes the trunk and pelvis on the thigh; nerves, an- 

 terior branches of the lumbar nerves. 



PSOAS PARVUS. Origin, from the lateral surfaces of the 

 bodies of the last dorsal and first lumbar vertebra? and from the 

 intervertebral substances between them; insertion, into the ilio- 

 pectineal eminence, joining the iliac fascia; action, assists the 

 psoas magnus and renders tense the iliac fascia ; nerves, anterior 

 branches of the lumbar. 



ILIACUS. Origin, from the base of the sacrum and the ilio- 

 lumbar ligament behind, from the iliac fossa and inner margin 

 of the crest of the ilium and the anterior superior and anterior 

 inferior spinous processes of the ilium; insertion, into the 

 oblique or intertrochanteric line of the femur to the outer side of 

 the insertion of the psoas; action, flexes and rotates the femur 

 inward and flexes the trunk and pelvis on the thigh; nerves, 

 anterior crural and the anterior branches of the lumbar. 



FEMORAL AND GLUTEAL REGION. 



TKNSOK VAGINA FEMORIS. Origin, from the anterior supe- 

 rior spinous process between the sartorius and the glutens medius, 

 and from the fore part of the outer lip. of the crest of the ilium; 

 insertion, into the fascia lata, about the upper fourth of the 

 outer side of the thigh; action, renders tense the fascia lata; 

 nerve, superior gluteal. 



