In Brown-Sequard syndrome at the level of injury, which tract is primarily responsible for ipsilateral motor loss?

In Brown-Sequard syndrome at the level of injury, which tract is primarily responsible for ipsilateral motor loss?

• A. Lateral corticospinal tract.
• B. Dorsal column.
• C. Spinothalamic tract.
• D. Anterior corticospinal tract.

Answer: (A)

The main idea is that voluntary movement of the limbs is carried primarily by the lateral corticospinal tract. After the motor commands descend from the cortex and cross in the medulla, the fibers travel down the spinal cord in the lateral corticospinal tract to synapse on ventral horn neurons that control the limbs on the same side. If the cord is hemisectioned on one side, this tract on that side is damaged, producing ipsilateral weakness or paralysis below the level of injury. The dorsal column is a sensory pathway for fine touch and proprioception on the same side, the spinothalamic tract carries pain and temperature contralaterally, and the anterior corticospinal tract is smaller and mainly influences trunk muscles, contributing less to limb weakness. So the lateral corticospinal tract is the tract responsible for the ipsilateral motor loss.

The main idea is that voluntary movement of the limbs is carried primarily by the lateral corticospinal tract. After the motor commands descend from the cortex and cross in the medulla, the fibers travel down the spinal cord in the lateral corticospinal tract to synapse on ventral horn neurons that control the limbs on the same side. If the cord is hemisectioned on one side, this tract on that side is damaged, producing ipsilateral weakness or paralysis below the level of injury. The dorsal column is a sensory pathway for fine touch and proprioception on the same side, the spinothalamic tract carries pain and temperature contralaterally, and the anterior corticospinal tract is smaller and mainly influences trunk muscles, contributing less to limb weakness. So the lateral corticospinal tract is the tract responsible for the ipsilateral motor loss.