Question

at the pyramidal decussation, upper motor neurons in the medulla cross from one side of the brainstem to the other side. which of the following tracts immediately follows this decussation and controls appendicular muscles? a.) corticospinal tract b.) lateral corticospinal tract c.) corticobulbar tract d.) anterior corticospinal tract

Explanation:

The lateral corticospinal tract is the main descending motor pathway. After the pyramidal decussation (where upper motor neurons cross), the lateral corticospinal tract continues and is responsible for controlling the appendicular (limb) muscles. The corticospinal tract is a more general term (includes both lateral and anterior corticospinal tracts). The corticobulbar tract is involved in controlling cranial - nerve motor nuclei (head and neck muscles). The anterior corticospinal tract does not immediately follow the decussation in the way described for appendicular muscle control as its fibers may decussate at spinal cord levels and is more involved in proximal muscle control (especially trunk muscles) compared to the lateral corticospinal tract which is key for distal appendicular muscle control.

Answer:

B. Lateral Corticospinal Tract