Sciatic nerve

Question 1

Sciatic- Site of impingement

Answer 1

Sciatic nerve is composed of- common fibular (perineal) nerve, and tibial nerve

site of impingment:
– can be compromised anywhere along the corse of the nerve:
—- from the greater sciatic notch to popliteal fossa

– can be compromised by the piriformis muscle (piriformis syndrome)

Question 2

Sciatic- Common causes of impingement

Answer 2

Nerve root irritation (L4-S4):
– Disc herniation
– osteoarthritis
– lumbar facet dysfunction

L5 is the most common level for sciatic nerve nerve root irritation

Question 3

Sciatic- Less common causes of impingement

Answer 3

Misplaced intramuscular injections

Pelvic tumours

Back labour

Vertebral/pelvic fractures

Piriformis syndrome

Hip dislocations

Question 4

Sciatic- Signs and symptoms

Answer 4

Most common for the more superficial common fibular/peroneal part of sciatic nerve to be affected

– pain or loss of sensation along course of nerve from buttocks, posterior thigh, leg and foot (except the medial leg supplied by the saphenous nerve)

– weakness of hip extension and knee flexion

– foot drop with subsequent stoppage gait

Question 5

Tibial nerve (from popliteal fossa to leg and foot) site of impingement

Answer 5

Less often affect due to nerve being very well protected

If it is affected:
– often due to direct trauma but possible compromise from nerve root irritation

Question 6

Tibial nerve entrapment signs and symptoms

Answer 6

Pain or loss of sensation to the sole of the foot, weakness in plantar flexion

Question 7

Common fibular (peroneal) nerve site of impingement and causes

Answer 7

Most often affected at the head or neck of the fibula

Common causes:
– anterior compartment syndrome (when anterior muscle on shin swells up, ‘shin splints)
—- extensor digitorum longus

– fractures

– fibula head dislocation

May also be affected by:
– tight cast, splint or brace of the knee/leg

Question 8

Common fibular nerve signs and symptoms

Answer 8

Mild pain or loss of sensation to anterolateral leg and dorsum foot

Foot drop with subsequent stoppage gait

Anterior compartment syndrome may compromise the deep branch of the common peroneal nerve resulting in isolated sensation loss to web space between 1st and 2nd toe