Overview
The tibial
nerve (L4-S2) is a branch of the sciatic nerve, and is the nerve of the
posterior thigh, posterior leg, and entire foot. It supplies the extensor
compartment of our thigh, extensor compartment of our leg, and intrinsic foot
muscles. It also supplies sensation to the sole of the foot.
Gross Anatomy
The tibial nerve (L4-S2) is a branch
of the sciatic nerve (L4-S3), and runs directly down the thigh. It supplies the
muscles of the posterior compartment of the thigh (semimembranosus,
semitendinosus and biceps femoris (short head only). The tibial nerve also
gives a small communicating branch that joins with an analogous branch from the
common fibular nerve to form the sural nerve (a cutaneous nerve that supplies
sensation to the lateral leg).
It also supplies the posterior
compartment of the leg (popliteus, gastrocnemius, soleus, flexor hallucis
longus, flexor digitorum longus and tibialis posterior). The nerve divides near
the tarsal tunnel into the medial and lateral plantar nerves. The medial
plantar nerve supplies the first lumbrical, abductor hallucis, flexor digiti
minimi brevis and flexor digitorum brevis (this can be remembered by the LAFF
acronym). It supplies sensation to the plantar surface of the medial three and
a half toes, and the (nailbeds dorsally) and the corresponding sole. The
lateral plantar nerve supplies the quadratus plantae, flexor digiti minimi,
adductor hallucis, interossei and abductor digiti minimi. The nerve also
supplies sensation to the plantar surface of the lateral one a half toes.
Clinical Anatomy
Tibial nerve damage-
Damage to the tibial nerve is rare, but usually occurs following direct trauma.
Symptoms include weakened inversion (tibialis anterior still inverts the foot),
knee flexion, ankle plantar flexion and lack of sensation over the nerves
distribution (sole of the foot, lateral leg via the sural nerve).
Quick Anatomy
Key Facts
Developmental precursor- Alar and basal plate of L4-S2
Origin-
Ventral rami of L4-S2
Branches-
Medial and lateral plantar nerves, sural nerve.
Muscles supplied- posterior compartment of thigh (hamstrings), posterior, compartment of
the leg, intrinsic muscles of the foot.
Dermatome-
Lateral leg (lower part via sural nerve), sole of the foot and nailbeds (medial
three and half) via medial and lateral plantar nerves.
Aide-Memoire
The structures innervated by the
medial plantar nerves can be remembered by the LAFF acronym (first Lumbrical,
Abductor hallucis, Flexor hallucis brevis, flexor digiti minimi brevis).
Summary
The tibial
nerve supplies the posterior compartment of the thigh, leg, and intrinsic foot.
It also supplies sensation over the sole, and lateral leg.