Lumbar radiculopathy: lower limb myotomes

Myotomes of lower limb

Most muscles receive innervation from more than one nerve root but there are movements that are strongly associated with certain nerve roots and these can be useful in pinpointing spinal nerve root lesions by clinical presentation. The list below details which movement is most strongly associated with each of the lower limb myotomes:

L2 - Hip flexion
L3 - Knee extension
L4 - Ankle dorsiflexion
L5 - Hallux extension
S1 - Ankle plantarflexion

Lower limb reflexes

Knee jerk - L3/4
Ankle jerk - S1/S2
Plantar - L5/S1