Final answer:
A quick pinch between the big toe and second toe during a neurological exam tests the integrity of the nerves in that area, such as the deep peroneal nerve or plantar digital nerves, which are part of the peripheral nerves responsible for sensory perception in the foot.
Step-by-step explanation:
The nerve being checked when pinching the skin between the big toe and the second toe is related to sensory testing in a neurological exam. In the lower extremity, the sensory nerves (specifically dermatomes) convey sensation from distinct areas of the skin to the spinal cord and brain. Pinching the skin between the toes tests the integrity of the nerves that innervate this specific area, which could include branches of the deep peroneal nerve or the proper plantar digital nerves coming off the tibial nerve, relating to the sensory perception of the foot. Such exams are crucial for assessing the proper function of the peripheral nerves, which include sensory evaluation, and are important for diagnosing neurological conditions.