THE MUSCLES OF THE BUTTOCK. 347 
adductor brevis, adductor longus, and sartorius. The deep femoral artery lies on 
it above. It forms the floor of Hunter’s canal below, where the femoral vessels he 
upon it. The hamstring 
aries and great sciatic 
nerve are behind the ad- 
ductor magnus; the ob- 
turator externus and 
quadratus femoris are at Orie or uamsrrinc 
its upper border ; and along aan 
its inner border .are the 
gracilis and sartorius 
muscles. 
The obturator ex- ADDUCTOR MAGNUS ¥ 
ternus is a fan-shaped 
muscle lying horizontally 
in the angle between the GRACILIS 
hip bone and the neck of 
the femur. It arises from 
the inferior half of the 
margin of the thyroid 
foramen and the corre- 
sponding portion of the 
outer surface of the ob- 
turator membrane. Its 
fibres converge towards the 
great trochanter, and end 
in a tendon which, after Popliteal vessels —# 
passing below and behind 
the hip-joint, is inserted 
into the digital fossa of 
the great trochanter. The 
inferior surface of the 
muscle is in contact with 
the pectineus, adductor 
brevis, and adductor mag- yee) | 
nus muscles, separated SEMIMEMBRANOSUS 
from them by the internal Guseztion) 
circumflex artery. The 
superior surface is in con- 
tact with the obturator 
membrane and the neck of SARTORIUS 
the femur. The tendon 
hes below and behind the 
capsule of the hip-joint, 
and near its insertion 1] 
appears in the buttock Fic. 255.—THE PosTERIOR SURFACE OF THE THIGH (superficial 
muscles removed), 
PYRIFORMIS 
—__OBTURATOR INTERNUS 
AND GEMELLI 
OBTURATOR EXTERNUS 
QUADRATUS FEMORIS 
GLUTEUS MAXIMUS 
(insertion) 
Biceps (short head) 
Biceps (long head) 
GASTROCNEMIUS (outer 
head) 
GRACILISS 
(beneath the gluteus 
maximus) between the inferior gemellus and quadratus femoris muscles. 
THE MUSCLES OF THE BUTTOCK. 
This group includes the three glutei muscles, the tensor fasciv femoris 
pyriformis, obturator internus and gemelli, and quadratus femoris. 
The gluteus maximus is a large quadrilateral muscle, with a crescentic origin, 
from (1) the dorsum ilii above the superior curved line; (2) the tendon of the 
erector spine; (3) the posterior surface of the sacrum and coccyx; and (4) the 
posterior surface of the great sacro-sciatic ligament. The fibres of the muscle are 
directed obliquely outwards over the buttock, invested by the fascia lata, and are 
inserted partly into the fascia lata over the great trochanter of the femur (joining 
