MUSCLES OF THE PELVIC LIMBS. 199 
sus (Fig. 92, “) 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, 7), 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, c). Dorsal surface 
with the quadratus femoris (Fig. 90, /) and obturator externus 
(Fig. 90, ¢). Caudal surface with the semimembranosus (Fig. 
92, #). Medial surface with the gracilis (Fig. 91, 4), adductor 
longus (Fig. 92, /), pectineus (Fig. 92, ¢), vastus medialis 
(Fig. 92, c), and distad with the medial head of the gastroc- 
nemius (Fig. 92, 7). 
Action.—An extensor of the thigh. 
M. adductor longus (Fig. 91, ¢; Fig. 92, 7).—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 median three-fourths of 
the cranial border of the pubis, the line of origin forming a 
medial continuation of that of the pectineus (Fig. 92, ¢). 
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. 
