a 
THE LUMBAR PLEXUS. 601 
along with the vas deferens and spermatic vessels, enters the inguinal canal at the 
internal abdominal ring. It terminates by supplying small branches to the skin of 
the scrotum and adjacent part of the thigh. Im the female it accompanies the 
round ligament to the labium majus. This nerve gives off in its course the follow- 
ing small branches: (1) to the external iliac artery ; (2) to the cremaster muscle ; 
(3) to communicate with the spermatic plexus of the sympathetic. The crural 
branch continues the course of the parent nerve into the thigh, lying on the outer 
side of the femoral artery. It becomes cutaneous by passing through the saphenous 
_ opening or the iliac portion of the fascia lata, and supplies an area of skin over 
Searpa’s triangle, external to that supplied by the ilio-inguinal (Fig. 442, p. 605). 
It communicates in the thigh with the middle cutaneous branch of the anterior 
H 
OBTURATOR suet 4 Sacrum 
Pyriformis 
Gluteus maximus 
Pubis 
Si 
Psoas SN \ 
BRANCH TO HIP-JOINT 
Pelvie fascia 
Obturator internus 
i Obturator externus 
Ascending branch of internal 
circumflex artery 
Quadratus femoris 
DEEP BRANCH 
Ischium 
/ 
Ascending branch to obturator 
externus 
. Internal circumflex artery 
Internal circumflex artery - 
Descending muscular branches 
\ WIS: —Adductor magnus 
Adductor brevis ~}\\\ 
CuTANEOUS BRANCH : 
BRANCH TO FEMORAL ARTERY Gracilis 
Adductor longus = 
—~— BRANCH TO KNEE-JOINT 
Fie. 441.—ScHEME OF THE COURSE AND DISTRIBUTION OF THE OBTURATOR NERVE. 
erural nerve. Before piercing the deep fascia it gives a minute branch to the 
femoral artery. 
The external cutaneous nerve (n. cutaneus femoris lateralis) is only distri- 
buted to skin (Fig. 440). It arises trom the back of the lumbar plexus, and usually 
from the second and third lumbar nerves. Emerging from the psoas muscle at its 
outer border, the nerve crosses the iliacus muscle, beneath the fascia iliaca, to reach 
the anterior superior iliac spine. It enters the thigh beneath the outer extremity 
of Poupart’s ligament, and either over, under, or through the origin of the sartorius 
muscle. It extends down the outer side of the front of the thigh for a few inches, 
lying at first beneath the fascia lata, and afterwards in a tubular investment of the 
fascia. It gives off smail branches in this part of its course, and finally, piercing 
the fascia about four inches below the anterior superior iliac spine, it separates into 
anterior and posterior terminal branches. The anterior branch is the larger, and is 
distributed on the outer side of the front of the thigh almost to the knee. The 
‘smaller posterior branch supplies the skin of the outer side of the buttock below 
the great trochanter and of the upper two-thirds of the outer side of the thigh 
| (Fig. 442, p. 603). 
SE” — CT a & 
