Nerve Injuries Lower Limb

Question 1

Prolapsed intervertebral disc where, effects Lumbar spine

Answer 1

Lumbar region- spinal nerve roots travel obliquely via cords equina to site they exit vertebra, column in intervertebral foramina

Most common site slipped disc: L4/5 and L5/S1

Nerve root emerges same level as intervertebral disc = exiting NR and the nerve root emerges at level below = traversing NR. E.g. the L5 nerve root = traversing NR at L4-L5 level and is the exiting NR at L5-S1 level.

Paracentral herniation -> compresses traversing nerve root (L3/L4 disc herniation compresses L4) use dermatomes and mytomes to work out effects . Lateral herniation-> exiting NR

Question 2

Sciatic nerve injury where does it inner age

Answer 2

Largest nerve, nerve roots L4-S3 inner ages hamstring muscles (biceps femoris, semitentindinous, semimembranous, hamstring part adductor Magnus) common peroneal -> shirt head reclusive femoris, other hamstrings by tibial N. Skin lateral leg and dorsum superficial and deep peroneal. Lower lateral posterior leg and sole tibial N.

90% sciatic never emerges inferior to piriformis

Question 3

Piriformis syndrome what, symptoms, ✅

Answer 3

Sciatica-like symptoms do not originate compression spinal nerve roots but compression by piriformis e.g. spasm, due overuse or direct trauma.

Dull ache buttock, typical sciatic pain thigh, leg, foot, pain walking up/ prolonged sitting, reduced range motion hip

✅Activity modification, non-steroidal anti-inflammatories (NSAIDS), physiotherapy

Question 4

Injury sciatic nerve buttock how, effects

Answer 4

Stab wounds/ misplaced intramuscular injections/ posterior dislocation hip

Hip normal (gluteus max, flexors, adductors, abduction fine) Paralysis hamstrings: knee flexion, dorsiflexion, plantarflexion, inversion, eversion paralysed, movements toes.)

Anaesthesia: lateral leg and foot

Question 5

Injury superior gluteal nerve muscles and sign

Answer 5

Glut medius and minimus and tensor fascia latae. L4/5, S1.

Injury -> contractural hip drop on leg raised opposite to affected side. = trendelenburg sign, foot catch ground walking or lurk trunk towards affected side- gait.

Question 6

Meralgia paraesthetica what, where, risks, cause, symptoms, treatment

Answer 6

Injury to lateral cutaneous nerve of thigh. Branch of lumbar plexus L2-3.

Compression nerve as it pierced inguinal ligament or fascia lata in thigh.

Obesity, pregnancy, tight clothing, tool belt

Burning/ stinging anterolateral thigh aggregated walking or standing, relived lying down with hip flexed, tenderness palpation of trapped nerve, sometimes positive Tinel’s sign (percussions nerve site entrapment -> tingling/ paraesthesia in distribution) absence motor signs and excluding pelvic causes such as Tumour.

✅Wearing tight avoided, local nerve blacks, surgery release trapped nerve

Question 7

Femoral nerve injury how, where, symptoms

Answer 7

L2/3/4 lumbar plexus- femoral triangle beneath inguinal ligament lateral to femoral artery-> anterior thigh muscles flex hip and extend knee. Sensory: anteromedial thigh by anterior femoral
Cutaneous nerve. And medial leg and foot saphenous nerve.

Lesions uncommon- penetrating wounds to groin/ hip or pelvic fractures, surgery.

Weakness and wasting quadriceps, hip flexion compromised, extension knee lost absent knee jerk reflex. Anaesthesia/ paraesthesia: anteromedial thigh and medial leg onto medial foot.

Question 8

Tibial nerve injury where, effects

Answer 8

Branch sciatic nerve L4-S3, crosses popliteal fossa passes deep soleus. Heel, sole of foot, deep and superficial posterior leg

Damage in popliteal fossa-> paralysis gastrocnemius and soleus (can’t plantarflex, or flex toes, inversion compromised, tibialis posterior) calcaneovalgus posture foot (heel down, foot deviated laterally) loss sensation majority sole.

Question 9

Common peroneal nerve injury where, effects

Answer 9

Branch of sciatic nerve L4-S2. Arises superior popliteal fossa-> around neck fibula pierce peroneus longus-> superficial and deep. Cutaneous branch upper lateral leg.

Prolonged bed rest, tight plaster cast, poorly placed stirrups, fractures neck of fibula.

Foot drop- paralysis tibialis anterior, inversion ankle paralysis peroneus longus and brevis, loss sensation lateral leg and dorsal foot.

Question 10

Superficial peroneal nerve injury where, effects

Answer 10

Branch common peroneal nerve L4-S1. Innervates kateral leg starts neck fibula supplies peroneus longus and brevis then cutaneous anterolateral leg. Dorsum foot bar first web space and lateral border.

Fractures proximal fibula/ penetration lateral leg, ankle arthroscopy-> peroneal muscles unaffected on,y sensorybloss foot

Loss active eversion, loss sensation distal anterolateral leg and dorsum

Question 11

Deep peroneal nerve injury where, effects

Answer 11

L4/5 branches common peroneal. Innervates anterior leg, commences neck fibula-> anterior leg piercing inter muscular septum. Extensor digitorum longus divides medial and lateral branches at ankle.

Tibialis anterior, extensor hallucius longus, EDL, peroneus tertius. First dorsal we space skin.

Mononeuropathy- motor neurone disease, diabetes, ischaemia, vasculitis, TKR

Foot drop, can’t extend toes, numbness first dorsal webspace

Question 12

Injury saphenous nerve where, effects

Answer 12

Largest cutaneous branch femoral nerve L3/4, sensory,

Branches in femoral triangle, anterior to femoral artery pierces fascia lata, skin medial leg and medial foot.

Saphenous vein shut down/ orthopaedic surgery distal tibia/ medial malleolus/ saphenous vein harvest for bypass surgery -> loss cutaneous sensation

Question 13

Injury Sural nerve where, effects

Answer 13

Sensory from tibial nerve and common peroneal unite posterior leg. Posterolateral direction-> lateral foot and ankle

Removal sural nerve minor deficit- harvested nerve grafting and reconstructive surgery