Lumbosacral Plexus

Label the nerve distribution in the image

Purple = obturator nerve, Green = femoral nerve, red= common fibular/peroneal nerve

What nerve distribution is this

Sciatic nerve

Nerves originating from Lumbar plexus L2-4

Femoral and obturator nerve

Nerves originating from Lumbar plexus L4-S3

Sciatic nerve only

Nerves originating from the sciatic nerve

Tibial and common peroneal/fibular nerves

Nerves originating from the common fibular nerve

Superficial fibular, deep fibular

What is the sensory distribution of the femoral nerve

Anterior thigh, medial leg and medial ankle

What is the sensory distribution of the obturator nerve

Medial side of thigh

What is the sensory distribution of the sciatic nerve

Lateral side of ankle and foot

What is the sensory distribution of the common fibular nerve

Lateral side of leg and dorsum of foot

What is the sensory distribution of the deep fibular nerve

Between the big toe and second toe

what is the key sensory point for T12

Inguinal ligament

What is the key sensory point for L3

Medial condyle of femur

What is the sensory point of L2

Middle between T12 and L3

What is the sensory point for L1

Between T12 and L2

What is the key sensory point for S2

Popliteal fossa midpoint

What is the key sensory point for S1

Lateral calcaneus

Myotome action of L2

Flexion of hip

Myotome action of L3

Extension of knee

Myotome action of L4

Dorsiflexion

Myotome action of S1

Plantarflexion

A fracture at the neck of the fibula is likely to affect what nerve

Common peroneal nerve

What can cause injury to the femoral nerve and what is the presentation

Trauma at femoral triangle and pelvic fracture; loss of knee jerk reflex and sensory loss to anterior thigh

What can cause injury to the obturator nerve and what is the presentation

Anterior hip dislocation, radial retropubic prostatectomy, total anterior hysterectomy; sensory loss in medial thigh + inability to adduct leg

What can cause injury to the superior gluteal nerve and what is the presentation

Surgery, posterior hip dislocation, poliomyelitis; Waddling gait and positive Trendelenburg

Patient walks like this what is the suspected nerve and muscle affected

Superior gluteal nerve injury → Gluteus minimus and medius

What can cause injury to the inferior gluteal nerve and what is the presentation

Surgery, posterior hip dislocation; patient leans body trunk backward at the heel

Patient leans like this what is the suspected nerve and muscles affected

Inferior gluteal nerve → Gluteus maximus

What can cause injury to the common fibular nerve and what is the presentation

Blow to lateral leg, neck of fibula fracture; patient will have foot drop and inverted, cannot stand on heels and foot slaps while walking

Patient presents with foot drop what is the suspected nerve and muscles affected

Common fibular nerve → Lateral and anterior compartments of the leg

What can cause injury to the tibial nerve and what is the presentation

Trauma at popliteal fossa; patient will have dorsiflexed, everted foot, cannot stand on toes

A patient can stand on their heels but cannot stand on their toes, what nerve is likely to be affected

Tibial nerve injury

Patient can stand on toes but cannot stand on heels what is most likely affected

Common fibular nerve injury

How to separate a patient with deep vs superficial peroneal nerve injury

Deep → Patient cannot dorsiflex foot; superficial → Patient cannot evert the foot

What is the main function of the superficial posterior leg muscles

Plantar flexion and knee flexion; (soleus cannot flex knee)

What is the main function of the lateral leg muscles

Eversion of foot

What is the main function of the anterior leg muscles

Dorsiflexion; extensor digitorum and hallucis longus also extend the foot