Hoffmann's reflex suggests involvement of which neural pathway?

• A. Corticospinal tract
• B. Dorsal columns
• C. Anterior horn cells
• D. Spinothalamic tract

Answer: (A)

Hoffmann's sign tests upper motor neuron control of spinal reflexes, specifically the corticospinal tract. When you briskly flick the distal phalanx of the middle finger, a positive sign is the reflexive, brief flexion of the thumb and index finger. This happens because a corticospinal tract lesion removes the normal cortical inhibition over spinal stretch reflex circuits, making them hyperexcitable. The result is a seemingly simple stimulus producing a pronounced motor response, which points to a problem in the corticospinal tract.

The other pathways are more tied to distinct sensory or motor functions: the dorsal columns carry fine touch and proprioception, the anterior horn cells are the lower motor neurons for peripheral muscles, and the spinothalamic tract transmits pain and temperature. A positive Hoffmann sign is not a direct indicator of dysfunction in those pathways, but rather of upper motor neuron involvement via the corticospinal tract.