380 The Nerves and Muscles of the Leg 
while the anterior portion becomes differentiated into the various perineal 
muscles. The details of this process I have not followed. 
For the comparative anatomy of the perineal muscles, see H. Eggeling, 
96, M. Holl, 96. 
b. Nerve Variation in the Adult. 
There is considerable variation in the origin and distribution of the 
nerves of the perineal region in man. Commonly the hemorrhoidal and 
the perineal nerves and the dorsal nerve to the penis (clitoris) are 
branches of a common trunk, the pudie nerve, which arises from the 
27th and 28th spinal (2d and 3d sacral) or the 28th and 29th spinal 
(3d and 4th sacral) nerves. The origin may, however, be from the 26th 
and 27th; the 27th; the 26th, 27th, and 28th; the 28th; the 27th, 28th, 
and 29th; or from the 28th, 29th, and 30th spinal nerves. In the accom- 
panying table the frequency of these various modes of origin is shown. 
Not infrequently (in 20 out of 235 instances, 8.5%) the hemorrhoidal 
branch has a separate origin from the plexus, usually from the 28th, or 
28th and 29th spinal nerves. 
Less frequently the dorsal nerve of the penis (clitoris) has an inde- 
pendent origin (in 9 out of 235 instances, 3.9%). In such instances 
the nerve arises from the 27th; 27th and 28th; or 28th spinal nerves 
(see Table XXIX). 
The chief nerve to the levator ani muscle arises usually in conjunction 
with viscereal branches from the 29th spinal (4th sacral) nerve. It may 
arise from the 27th and 28th; the 28th; the 28th and 29th; or the 29th 
and 30th spinal nerves (see Table XXX). Other small branches are 
also frequently given to this muscle. 
The nerves to the coccygeus muscle arise from the last spinal nerve 
contributing to the pudic plexus and also usually from the next more 
distal spinal nerve. 
The visceral branches usually arise from the last two spinal nerves 
entering the pudic plexus and also often from the next most distal spinal 
nerve. 
The charts which I have show great variation in the peripheral course 
and distribution of all of these nerves. The difficulties of making thor- 
oughly accurate dissections and charts of the nerves of the perineal region 
make it seem inadvisable to try to use these charts for statistical pur- 
poses. In general the distribution corresponds with that given in the 
anatomies of Poirier and Charpy and Quain, and with those pictured in 
the atlases of Toldt and Spalteholz. 
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