Sciatic Nerver

Question 1

Describe the pathway and innervation of the sciatic nerve (until division)

Answer 1

Leaves pelvis
Moves through gluteal region
Enters posterior compartment of the thigh, where it supplies:
Biceps femoris - long head (tibial division), and short head (fibular divison)
Semimembranosus/tendinosus (tibial division)
At apex of popliteal fossa, it divides into two branches
1. Common peroneal (fibular) nerve
2. Common tibial nerve

Question 2

Descibe the pathway and innervation of common peroneal (fibular) nerve

Answer 2

Enters lateral compartment of the leg
Splits into two terminal branches
1. Superficial peroneal (fibular) - supplies lateral compartment of the leg, then pierces crural fascia to supply skin on the dorsum of the foot.
2. Deep peroneal (fibular) - moves anteriomedially, pierces the intermuscular septum to enter anterior leg compartment. Supplies muscles of ant leg and dorsum of the foot. Also supplies skin of web space between toes 1 and 2.

Question 3

Describe the pathway and innervation of the tibial nerve

Answer 3

Leaves popliteal fossa deep to gastrocnemius in the posterior compartment of the leg.
Supplies posterior compartment of the leg (as tibial nerve)
Enters the foot via the tarsal tunnel
splits into medial/lateral plantar nerve, which supplies the muscles in the plantar aspect of foot
2 important branches off tibial nerve
1. sural nerve - cutaneous nerve arising in popliteal fossa, supplies skin of lateral leg and foot
2. medial calconeous, cutaneous nerve arising before tarsal tunnel to supply the skin of the heel

Question 4

What joints does sciatic nerve innervate

Answer 4

Hip joint
Knee, tibfib, ankle and foot joints (via branches of the nerve)
Skin of leg and foot (via branches)