Myotomes & Nerve Roots Lower Limb

Question 1

What are the myotomes of the lower limb motor functions.

Answer 1

L1/L2 Hip Flexion (Iliopsoas - Femoral Nerve)
L3 - Knee Extension (Quadrieceps - Femoral Nerve)
L4 - Ankle Dorsiflexion (Tibialis Anterior - Deep peroneal nerve)
L5 - Hallux Extension (Extensor Hallucius Longus - Deep peroneal nerve
S1 - Hallux Flexion (Flexor Hallcius Longus - Tibial Nerve)
S1 - Ankle Plantar Flexion (Gastronemius/Soleus) - Tibial Nerve
L5 - Knee Flexion (Sciatic Nerve L5/S1)

Question 2

What is the nerve sensory distribution of the lower limb?

Answer 2

L1 - Trochanteric Region and groin
L2 - Superior aspect anterior thigh
L3 - Anterior thigh and knee (medial aspect of the knee)
L4 - Postolateral thigh, anterior knee and medial portion leg
L5 - Lateral aspect of leg, dorsum of foot and great toe
S1 - Dorsum and lateral aspect of the little toe

Question 3

What would L3 Radiculopathy show?

Answer 3

Hip adduction weakness, decreased sensation of anterior thigh and knee

Question 4

Would would L4 Radiculopathy show?

Answer 4

Weakness knee extension, absent knee reflex, decreased sensation over medal leg.

Question 5

What would L5 radiculopathy show?

Answer 5

Weakness dorsiflexion (foot drop), weakness toe extension, decreased sensation great toe & lateral leg. May have hip adductor weakness.

Question 6

What would S1 radiculopathy show?

Answer 6

Posterior lower leg weakness, absent ankle jerk reflex. Decreased sensation over little toe.