J THE MUSCLES OF THE BUTTOCK. 349 
muscle, its fibres converging to the great trochanter, to be inserted by a strong 
short tendon into a diagonal line on its outer surface. 
The muscle is covered along its anterior border by the tensor fascize femoris. Its 
surface is covered over by the fascia lata and the gluteus maximus. Its inferior 
border is separated 
from the pyriformis 
muscle by the super- 
ficial branch of the 
gluteal artery. Its 
deep surface is in 
contact with the 
gluteus minimus, 
the gluteal vessels, 
the superior gluteal 
nerve, and the in- 
sertion of the pyri- 
formis. A bursa is 
placed heneath the Mss! pte nene™ 
tendon at its inser- internus 
tion. 
The gluteus 
minimus arises from 
the dorsum ili be- Ae! 
tween the middle Appvctor macwus—l gran 4N\\ ME = GLUTEUS MAXIMUS 
and inferior curved Wi | 
lines. This muscle BE el tee 
is fan-shaped, and 
its fibres converge to 
the antero-superior 
angle of the great 
trochanter, to be 
inserted into the Fic. 257.—THE MuscLes aND NERVES OF THE BUTTOCK. 
of the niveag ate 
outer eae b f The gluteus maximus is reflected ; and the gluteus medius is cut in part to show 
anterlor surlace o the gluteus minimus. 
the trochanter, and 
sometimes also into the front part of the upper border. It is also inserted into 
the capsule of the hip-joint. The muscle is concealed by the tensor fascize femoris 
and gluteus medius. The pyriformis is in contact with its inferior border, and 
beneath it are the capsule of the hip-joint and the reflected tendon of the rectus 
femoris muscle. A bursa is placed beneath the tendon in front of the great trochanter. 
The pyriformis is one of the few muscles connecting the lower limb to the 
axial skeleton. It arises (1) within the pelvis from the pedicles of the second, 
third, and fourth sacral vertebrae ; passing outwards through the great sacro-sciatic 
foramen, it receives an additional origin (2) from the upper margin of the great 
sciatic notch of the ilium. In the buttock it forms a rounded tendon, which is 
inserted into a facet on the upper border of the great trochanter of the femur. 
The pyriformis, besides appearing in the buttock, lines the posterior wall of the 
pelvis. In the pelvis it les behind the rectum, covered by a thin layer of the 
parietal pelvic fascia. In the buttock it is covered by the gluteus maximus, and 
at its insertion by the gluteus medius, and it lies upon the ium and the capsule 
of the hip-joint. At its upper border are the gluteus medius and gluteus minimus, 
separated by the superior gluteal nerve and the gluteal artery; its lower border 
is separated from the gemelli and obturator internus by an interval in which the 
sciatic and pudic vessels and the nerves of the sacral plexus appear. The anterior 
fibres of the muscle may be separate (scansorius). 
The obturator internus arises on the pelvic aspect of the hip bone, from (1) the 
whole of the margin of the thyroid foramen (except the obturator notch); (2) the 
surface of the obturator membrane; (3) from the smooth surface of the hip bone 
behind the thyroid foramen ; and (4) slightly from the parietal pelvic fascia covering 
. 
Superior gluteal nerve 
Nw— GLUTEUS MEDIUS (cut) 
Inferior gluteal nerve 
\ Pyrirormis 
OBTURATOR INTERNUS 
AND GEMELLI 
OBTURATOR EXTERNUS 
QUADRATUS FEMORIS 
_ Great sciatic nerve 
(and subdivisions) 
Small sciatic nerve 
GRACILIS 
ADDUCTOR MAGNUS 
