316 The Nerves and Muscles of the Leg 
the obturator foramen a position approximately shown in the following 
diagram. The position occupied by the chief bulk of the fibres of each 
of the main nerves of distribution is shown in outline while the approxi- 
mate area of the 23d spinal (3d lumbar) nerve is indicated by stippling, 
in this diagram. 
3. Variation in the Branches of Distribution Arising from the 
Obturator Nerve. 
In the great majority of instances the obturator nerve divides at the 
proximal border of the adductor brevis muscle in such a way that the 
nerves of supply to the gracilis muscle and to the adductor longus and 
brevis muscles pass in the anterior division of the nerve external to the 
R. cutaneous 
-R. gracilis 
R.add_ brevis 
R. obt. externus : 
R.add. maenus 
Fic. 5. Diagram to illustrate the position occupied in the obturator nerve 
. by the nerve fibers going to the muscular and cutaneous branches. 
adductor brevis muscles, while the nerves to the adductor magnus muscle 
and to the obturator externus muscles arise from the posterior division 
of the nerve. Very often the nerve to the obturator externus muscle is 
given off before the obturator nerve passes through the obturator fora- 
men or above the place of division of the obturator nerve into anterior 
and posterior divisions. The nerves of distribution, the fibres of which 
occupy contiguous areas in the cross section of the main trunk shown 
above, may be associated for some distance in a common trunk before 
ultimately becoming independent. 
In the following table are indicated the relations of the chief muscular 
and cutaneous branches of the obturator nerve in 88 instances. In all 
instances the branch to the obturator externus is included with the in- 
ternal division of the obturator nerve, although in the majority of in- 
stances this branch was given off from the main trunk of the nerve before 
it split into anterior and posterior divisions. The articular and arterial 
