Question

The Dorsal (Posterior) White Column Fiber Tract transmits:

A. voluntary commands

B. subconscious commands

C. temperature & pain information

D. touch & proprioception information

E. auditory & vestibular information

Answer 1

The dorsal (posterior) white column fiber tract transmits:

Answer: D) touch and proprioception information.

Explanation: Dorsal (posterior) white column tract is somatosensory pathway which transmits fine touch, proprioception, pressure, vibration, two point discrimination. Its first order neuron begins in the sensory nerve endings in the periphery, cell body lies in the dorsal root ganglion. Its first synapse lies in nucleus gracilis and cuneatus in medulla. In the medulla, decussation (crossing over) of fibers occur. Second order neuron decussates in medulla and ascends contralaterally in medial lemniscus. Second synapse lies in the ventral posterolateral nucleus of thalamus and the third order neuron ultimately reaches the sensory cortex. Temperature and pain information are transmitted by lateral spinothalamic tract. Voluntary commands are transmitted by pyramidal tracts (corticospinal tract).