MUSCLES OF THE PELVIC LIMBS. 199 



sus (Fig. 92, h) and the femur. Its proximal part is covered 

 by the semimembranosus, while its distal part lies outside of it. 



Origin by muscle-fibres from the rami of the pubis and the 

 ischium along the whole of the length of the symphysis; from 

 the ramus of the ischium between the symphysis and the 

 tuberosity, and from the tendon of origin common to the two 

 gracilis muscles. 



Insertion into nearly the whole of the ventral surface of the 

 shaft of the femur. The area begins at the base of the great 

 trochanter opposite the proximal end and the insertion area of 

 the gluteus maximus. It extends thence distad along the 

 caudal border of the surface as an area about one millimeter 

 wide. At the junction of the first and second thirds of the 

 shaft the area expands and occupies the whole of the ventral 

 surface of the bone, ending at the intercondyloid fossa. 



Relations. — Lateral surface with the biceps (Fig. 68, /), the 

 great sciatic nerve (Fig. 163, a), the tenuissimus (Fig. 90, g), 

 and the semimembranosus (Fig. 92, //) ; dorsolateral border in 

 contact with the vastus lateralis (Fig. 92, e). Dorsal sinfacc 

 with the quadratus femoris (Fig. 90, f) and obturator externus 

 (Fig. 90, e). Caudal surface with the semimembranosus (Fig. 

 92, //). Medial surface with the gracilis (Fig. 91, /;), adductor 

 longus (Fig. 92, /), pectineus (Fig. 92, e), vastus medialis 

 (Fig. 92, c), and distad with the medial head of the gastroc- 

 nemius (Fig. 92,7). if^ , ^ 



Action. — An extlensor of the thigh. '' '■ > 



M. adductor longus (Fig. 91, ^; Fig. 92, /). — A thin 

 muscle which covers the dorsal half of the medial surface of the 

 adductor femoris (Fig. 92, g). 



Origin by muscle-fibres from the ipedian three-fourths of 

 the cranial border of the pubi^, the line of origin forming a 

 medial continuation of that of the pectineus (Fig. 92, r). 



Insertion by a thin aponeurosis into the external linea 

 aspera of the femur along the second and third fifths of the 

 bone. 



Relations. — With its medial or cranial surface the adductor 

 longus forms part of the boundary of a depression among the 

 muscles at the proximal end of the medial side of the leg. 



