Professional and Linguistic Assessments Board (PLAB) Practice Exam

What sensory function is associated with the sural nerve?

1. Sensation in medial leg

2. Loss of sensation in lateral leg

3. Knee sensation

4. Sensation in the foot

The correct answer is: Loss of sensation in lateral leg

The sural nerve is primarily responsible for providing sensory innervation to specific areas of the lower leg and foot. It sensory fibers are derived from the tibial nerve and the common fibular nerve, making it vital for sensation in the posterior and lateral aspects of the lower leg. The correct association for the sural nerve involves its role in sensation. It provides sensory input to the skin on the lower part of the lateral leg and along the lateral side of the foot. Therefore, while the answer suggests a loss of sensation in the lateral leg, the key point is that damage or injury to the sural nerve can lead to a reduced or absent sensation in this area. This leads to a clinical presentation where patients may report numbness or tingling along the lateral aspect of their leg and foot, thus highlighting the nerve's sensory function. In regard to sensation in the medial leg, the knee, and the foot, those areas are typically innervated by different nerves: the medial leg is served by the saphenous nerve, knee sensation is through multiple nerves including the femoral and obturator nerves, and general foot sensation involves a combination of the tibial and superficial fibular nerves. Thus, these choices do not directly reflect the primary sensory role