278 The Nerves and Muscles of the Leg 
with Plate VII, Fig. 1. The fascia lata which covers the lateral, anterior 
and medial cutaneous nerves for a considerable part of their course is 
just beginning to be differentiated in Embryo XXII. 
b. Variation. 
1. N. Cutaneus Femoris Lateralis. 
The lateral cutaneous nerve in the adult usually springs by one or more 
roots from the lumbar plexus and takes a direct course through the psoas 
muscle and beneath the iliac fascia to a region near the anterior superior 
spine of the illum whence it passes for some distance beneath the fascia 
lata and is finally distributed to the skin of the lateral region of the 
thigh. 
The nerve varies considerably in origin. Out of 287 instances I found 
it arising in 39% from the 20th, 21st and 22d; in 48% from the 21st, 
22d and 23d; and from the main trunk of the femoral in 18%. (Bardeen, 
02). 
The region where the nerve passes out into the thigh varies somewhat. 
It may be over the crest of the ium just above the anterior superior 
spine or some distance below the latter. In two instances out of 146 it 
was found to emerge near the femoral nerve and then curve sharply out- 
wards toward the lateral surface of the thigh. Rarely it is absent, its 
place being supplied by branches which spring directly from the femoral 
nerve below the inguinal ligament. 
It varies considerably in extent of distribution. The distribution of 
the chief branches was found to be lateral to a line drawn from the an- 
terior inferior iliac spine to the outer edge of the patella in 92 out of 
146 instances (63%), Plate VII, Fig. 1. The area of distribution cor- 
responds here essentially with that given as the normal one in most text- 
books. In 45 instances (30.8%) the branches of the lateral cutaneous 
extended medially over the anterior portion of the thigh taking the place. 
to a greater or less extent of the anterior cutaneous branches of the 
femoral nerve. An instance of this sort is figured on the right side of 
the Léveillé figure mentioned above (p. 276). In 9 instances out of 
148 (6.2%) a “lumbo-inguinal” branch, given off by the lateral cuta- 
neous nerve, was distributed to the skin of the upper antero-medial 
region of the thigh. In two instances out of 148 the lateral cutaneous 
nerve was missing, its place being supplied by a large nerve which in 
origin, course through the psoas muscle and entrance into the fascie of 
the thigh resembled a lumbo-inguinal nerve. In two of the instances in 
which the “anterior or middle” distribution was extensive the lateral 
