injury to sciatic nerve the most common part affected is common peroneal
component resulting in foot drop and high stepping gait
nerve can be injured in total hip replacement (1% of cases )
syndrome – Due to the hypertrophy of the muscle piriformis, the sciatic nerve
is compressed, resulting in pain along the course of the sciatic nerve in the
It is the shooting pain along the cutaneous distribution of the sciatic nerve –
pain is felt in the gluteal region or even higher, radiates along the back of
thigh and lateral side of leg, to the dorsum of foot.
of sciatic nerve can occur after sitting for a long time called “sleeping foot”.
posterior dislocation of hip joint causes injury to the sciatic nerve. When the
nerve is injured it results in excessive movement of foot and difficulty in
Common peroneal nerve.
The common peroneal part supplies only
the short head of the biceps femoris.
Tibial part supplies all the hamstring
muscles namely the semitendinosus, semimembranosus, long head of biceps femoris
and the ischial part of the adductor magnus.
branches to the hip joint.
Fig. No 2
·It remnant of the axis artery of lower
·It is a branch from internal iliac artery.
·The artery to the sciatic nerve is Arteria nervi sciatica ischiadici.
is crossed by long head of biceps femoris.
It runs vertically downwards up to the
superior angle of the popliteal fossa at the junction of the upper 2/3 and the
lower 1/3 of the thigh where it terminates.
lies on adductor magnus
enters the back of thigh at the lower border of the gluteus maximus.
In the thigh:
posterior cutaneous nerve of thigh and
the inferior gluteal artery are medial to the nerve.
structures in the gluteal region mentioned above form the sciatic bed
externus and the hip joint are separated by the quadratus femoris.
then crosses posterior to tendon of obturator internus, the gamelli.
on the posterior surface of ischium separated by the nerve to quadratus femoris.
part of the nerve is deep to gluteus maximus.
runs downwards passing between the ischial tuberosity and the greater
In the gluteal region:
emerges out of the pelvis via the greater sciatic
foramen below piriformis and passes down between the greater trochanter and
ischial tuberosity. Sometime it passes above or through piriformis
lies in front of the piriformis covered by its fascia.
In the pelvis:
Course and relation (Fig. No 2):
the division may be above, in such a case, the tibial component passes below piriformis
and the fibular component through the piriformis
terminates in the superior angle of popliteal fossa into tibial and common
Fig. No 1
Common peroneal component – Formed by the dorsal divisions of anterior primary rami of L4, L5,
Tibial component – Formed by the ventral divisions of
anterior primary rami of L4, L5, S1, S2,
nerve is made up of 2 components: Tibial and common peroneal components (fig.no
L4, L5, S1, S2, S3
is the largest branch of the sacral plexus formed in the pelvis
Formation (root value):
The sciatic nerve is the thickest nerve
in the body; 2cm wide;
1. Describe the root value, course , relations branches and
distribution and applied anatomy of sciatic nerve