Sciatic nerve

AnatomySupplies:Hamstrings (posterior of thigh)Above knee divided into :(1)Common peroneal:

Superficial peroneal: The two peronei Skin of lateral of leg and dorsum of foot except 1st cleft

Deep peroneal: Muscles of anterior compartment of the leg Skin of 1st cleft

(2)Tibial nerve: muscles of the calf Skin of the sole

Causes of injury of the main trunkGunshot Operative accidentsTrauma following hip dislocation or fractures of the acetabulum

Symptoms and signs

Paralysis of (1) Hamstrings (2) All muscles below the kneeFoot dropAbsent sensation in most of the legTrophic ulcers ±

Treatment

Urgent reduction of hip dislocation

Proper treatment of fractures

Open wounds: Repair

While recovery is awaited a drop-foot splint is fitted

Prognosis

•Poor

•At best it will be delayed and incomplete

•If there is no recovery whatever, amputation may be preferable to a

flail, deformed, insensitive limb

Common peroneal nerve injury

Causes

Varus force in the knee

Pressure from a splint or plaster cast

Lying with the leg externally rotated

Anterior compartment syndrome (pressure on deep peroneal nerve)

Symptoms and signs

Wasting of dorsiflexor and peronei muscles

Drop foot

Loss of sensation of dorsum of foot

Nerve entrapment syndromes

Whenever peripheral nerves traverse fibro-osseous tunnels,

they are at risk of entrapment or compression

Causes

↑ in soft tissue bulk( pregnancy, myxoedema, RA)

Local obstruction (ganglion, osteophyte,old #)

Idiopathic

Sites

Carpal tunnel at the wrist (Median nerve)

Cubital tunnel at the elbow( ulnar nerve)

Tarsal tunnel below the ankle( Posterior tibial nerve)

Lateral part of inguinal ligament (lateral cutaneous of the thigh)

Thoracic outlet( C8+ T1)

Clinical features

Intermittent tingling OR pain OR numbnessThese symptoms are related to specific postures which compromise the nerve. e.g. CTS : flexion or hyperextension of the wrist Ulnar neuropathy : flexion of the elbow for a long time(driving, using telephone)

Areas of altered sensation

Motor weakness

Muscle wasting

Treatment

Avoiding compromising postures

Light splints

Local steroid injection

If all above failed : Surgical decompression

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