396 NERVOUS SYSTEM. 
branches, forming thus the lumbar plexus. They are also 
connected with the sacral plexus, so that the two are often 
considered together as the lumbosacral plexus (Fig. 162). 
In some other animals the first three lumbar nerves form also 
a part of the plexus; but they are not connected with it in the 
cat. 
The fourth lumbar nerve forms the genitofemoral (c) and 
part of the lateral cutaneous (7) nerves, and is connected by a 
short strand with the fifth. The fifth aids in forming the 
lateral cutaneous (@) and femoral (/) nerves, and is connected 
by a short branch with the sixth. The sixth lumbar is large; 
it forms the major part of the femoral (/) and a large part of 
the obturator nerve (g), and sends a large connecting branch 
caudad to join the seventh and thus pass into the sacral plexus. 
The seventh passes caudad to join the sacral plexus and aid in 
forming the great sciatic nerve (4); by its connection with the 
sixth it aids in forming also the obturator nerve (g). 
4. N. genitofemoralis (or N. lumboinguinalis) (c¢, c’, c’’).— 
This is a direct continuation of the fourth lumbar nerve. Its 
medial branch (c’’) passes along the medial surface of the 
iliopsoas (8) and the psoas minor (9) to the external iliac 
artery, accompanies this, lying on the ventral surface, from its 
origin to the point where it gives off the profunda femoris, then 
accompanies the latter artery and passes onto that branch of it 
that spreads out under the integument of the ventral pelvic 
region. It crosses the spermatic cord and ramifies in the skin 
of the proximal part of the medial side of the thigh. The 
lateral branch of the genitofemoralis (c’) pierces the psoas 
minor (9), appearing on its ventral surface opposite the fifth 
lumbar vertebra. It passes caudad on the ventral surface of 
this muscle, crosses the iliolumbar artery, then turns caudo- 
laterad, passes through the abdominal wall, and is distributed 
to the craniomedial surface of the thigh and to the adjacent 
abdominal wall. 
This nerve is variable in origin and in distribution. “Its 
lateral branch is sometimes lacking. 
5. N. cutaneus femoris lateralis (¢).—The lateral cuta- 
neous nerve arises from the connecting strand between the fourth 
