Examination of a patient demonstrates foot drop with weakness of the anterior tibial, posterior tibial, and peroneal muscles. Sensory loss is demonstrated over the anterior shin and dorsal foot. These findings suggest a radiculopathy at which of the following cord levels?
The findings are typical for involvement at the L5 level. Most ruptured disks involve either the lumbar area (L5 and S1 most common) or the cervical area (C-6 and C-7 most commonly). Compression by a disk of the cervical cord can produce a spastic paresis of the lower limbs; compression of the cauda equina can cause urine retention or incontinence.C-7 supplies the back of the shoulders, down the back of the arm, past the elbow, to the back of the second and third fingers.S-3 supplies a small area on the buttocks.T-9 supplies a band on the abdomen and back that passes above the umbilicus.T-12 supplies a similar band that passes below the umbilicus.Also Know: The dermatomes for C5, C6, C7, C8, and T1 are confined to the arm, and the C4 and T2 dermatomes are contiguous over the anterior trunk.The thumb, middle finger, and fifth digit are within the C6, C7, and C8 dermatomes, respectively.The nipple is at the level of T4.The umbilicus is at the level of T10.
C-7
L-5
S-3
T-9