84 Neuroanatomy: Draw It to Know It
Cutaneous Nerves — Lower Limb
Here, we will map the cutaneous innervation of the
lower limb. First, let’s draw the anterior and posterior
aspects of the lower limb and label their medial and lat-
eral surfaces. Begin with the thigh. Indicate that the
lateral cutaneous nerve of the thigh (aka lateral femoral
cutaneous nerve) covers the lateral aspect of the com-
plete thigh. Th en, show that the posterior cutaneous
nerve of the thigh (aka posterior femoral cutaneous
nerve) covers the back of thigh. Next, show that the
anterior femoral cutaneous nerve covers the anterior and
medial thigh. And fi nally, show that the obturator nerve
covers a small sensory patch on the medial aspect of the
thigh. Note that the lateral and posterior cutaneous
nerves of the thigh are direct branches from the lum-
bosacral plexus, whereas the anterior femoral cutaneous
nerve is a branch of the femoral nerve. Th e anterior fem-
oral cutaneous nerve is oft en subdivided into the inter-
mediate and medial femoral cutaneous nerves.
Now, move to the leg. Show that the lateral sural
cutaneous nerve, which is derived from the common
peroneal nerve, covers the upper lateral aspect of the leg
and that the superfi cial peroneal nerve covers the lower
lateral aspect of the leg. Th e superfi cial peroneal nerve
also covers the dorsum of the foot except as follows:
the deep peroneal nerve covers the webbing between the
great toe and second digit, and the distal sural branches
cover the extreme lateral foot. Next, indicate that the
medial calcaneal nerve covers the heel.
Show that the sural nerve, which is derived from both
the common peroneal and tibial nerves, covers the pos-
terior leg. Th e medial sural cutaneous branch of the tibial
nerve provides the upper sural coverage and the distal
sural branches (the lateral calcaneal and lateral dorsal
cutaneous nerves) provide the distal coverage.
To complete the leg, show that the femoral-derived
saphenous nerve covers the medial aspect of the leg and
instep of the foot. Include the clinically important infra-
patellar branch of the saphenous nerve, which covers the
anterior knee; this small branch is sometimes injured
during arthroscopic knee surgery.^1 – 4 , 8 – 10