136 ANTHROPOLOGY. 
last posterior nerves are very small, and are distributed to the integuments 
of the glutzeal region. | 
The anterior branches of the lumbar nerves are much larger than the 
posterior, and increase in size as they descend. In the psoas magnus 
muscle they unite with each other into a plexus. 
6. THE LuMBAR PLEXUS is long and somewhat triangular, situated alongs 
the sides of the lumbar vertebrz, in front of their transverse processes, and 
near the posterior surface of the psoas magnus muscle; in addition to its 
three principal and terminal branches, the anterior = the obturator, 
and the lumbo-sacral, it gives off some lees superficial iirenielees 
The superficial Latieiiies of the lumbar plexus supply the inferior portion 
of the abdominal muscles and integuments, the integuments of the groin, 
of the upper and outer part of the thigh, and also those of the inguinal and 
pubic regions.. The principal of these are the superior musculo-cutaneous 
(external ilio-inguinal, ilio-hypogastric, ilio-scrotal), the meddle musculo- or 
wmnguino-cutaneous, the inferior musculo-cutaneous or external cutaneous, and the 
genito-crural. 
The anterior crural nerve arises in the lumbar plexus from the four 
superior nerves, principally from the third and fourth; it is destined to 
supply the integuments on the anterior and inner sides of the lower extre- 
mities, also extensors of the leg, and the principal flexors of the thigh or 
hip-joint. It subdivides into a superficial and a deep fasciculus. The prin- 
cipal branches of the superficial division are, the middle cutaneous, the 
wmternal cutaneous, the vaginal branches to the sheaths of the vessels, and the 
long saphena. ‘The branches of the deep division are wholly muscular. 
The obturator nerve arises chiefly from the third and fourth lumbar, per- 
forates the psoas-‘muscle, and descends obliquely inwards to the inside of the 
thigh, where it descends into two branches, an anterior and a posterior. 
The anterior or superficial branches are lost in the graciles, adductor brevis, 
pectinzeus, and vastus externus. The posterior or deep branches supply the 
obturator externus and adductor magnus; one long branch extends to the 
back part of the knee joint. 
The lumbo-sacral nerve is the largest branch of the 1itiital plexus; it is 
formed by a large portion of the anterior division of the fourth, and the 
whole of that of the fifth lumbar nerves; enters the pelvis, and behind the 
iliac vessels divides into two branches. Of these, the communicating is 
inferior or anterior, and joins the first anterior sacral nerve, forming part 
of the sacral plexus; the other, posterior and superior, is the great or supe- 
rior gluteal nerve. ‘This has various muscular branches for the muscles of 
the thigh. 
‘7. THE SACRAL NERVES are six - pairs. They form their ganglions, and 
divide within the spinal cord into anterior and posterior branches. The 
posterior sacral nerves are very small, pass through the posterior sacral 
foramen, and supply the muscles and integuments of the sacral and glutzeal 
regions. 
The anterior sacral nerves are very large, especially the three superior ; 
the three last are much smaller, and the sixth is very minute, and sometimes 
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