Professional and Linguistic Assessments Board (PLAB) Practice Exam

What is the main sensory function associated with the L5 spinal level?

1. Dorsum of foot

2. Medial leg

3. Lateral foot

4. Plantar surface

The correct answer is: Dorsum of foot

The primary sensory function associated with the L5 spinal level is indeed the dorsum of the foot. This area is innervated by the sensory fibers that arise from the L5 nerve root, which is responsible for transmitting sensory information from the skin and other tissues in that region. The dorsum of the foot refers to the upper surface, which includes the area over the metatarsals and toes. The distribution of sensory fibers at the L5 level is crucial because it assists healthcare professionals in identifying neurological deficits that may occur with compression or injury to this spinal segment. While other areas like the medial leg, lateral foot, and plantar surface are associated with different spinal levels—medial leg correlating primarily with the L4 level, lateral foot being more involved with S1, and the plantar surface mainly linked to S1 and S2—the L5 level is specifically important for sensory input from the dorsum of the foot. Understanding the precise sensory distribution related to spinal levels enhances diagnostic accuracy in clinical practice.