Regarding the Lateral corticospinal tract, choose the WRONG statement:

Correct Answer: D

Rationale: Their function is subconscious regulation of balance and muscle tone . The lateral corticospinal tract, a pyramidal tract , controls voluntary fine movements, not subconscious balance/tone (extrapyramidal role). Choice B and C are correct (passthrough midbrain pedunculi and pons basilar part). Thus, D misattributfunction, making it the wrong statement and the correct answer.

Correct Answer: B

Rationale: Rubrospinal tract mainly supply the distal extensors musclwith little effect on the proximal muscl. The rubrospinal tract facilitatflexors, not extensors, especially distally. Choice A, C, D are correct (vestibulospinal for antigravity, tectospinal for reflexes, medullary in lateral column). Thus, B misattributflexor/extensor roles, making it the wrong statement and the correct answer.

Correct Answer: D

Rationale: The anterior commissure connect the two halvof the mesencephalon , which is false. The anterior commissure connects the temporal lob(telencephalon), not the mesencephalon (midbrain). Choice A, B, C are true (pyramidal from precentral, sensory to thalamus, association fibers). Thus, D is the false statement, making it correct.

Correct Answer: D

Rationale: fibers terminate on the motor neurons in the ventral horn . The corticospinal tract originatfrom the motor cortex (precentral gyrus, not just premotor, making C incorrect), descends through the brainstem, and decussatin the lower medulla (not pons, making A wrong). Most fibers, especially lateral corticospinal, supply distal muscl(e.g., hands) for fine movement, not proximal (making B incorrect). These fibers synapse on alpha motor neurons in the ventral horn of the spinal cord, directly or via interneurons, to control voluntary movement, making D accurate. For example, corticospinal damage disrupts skilled tasks like writing, reflecting ventral horn innervation. Thus, D is the true statement about the corticospinal tract.

Correct Answer: D

Rationale: control voluntary movement . The corticospinal tract originatfrom the motor cortex (not cerebellum, making B wrong), decussatin the medullary pyramids (not pons, making A incorrect), and terminatin the ventral horn (not posterior, making C false). It controls voluntary movements, such as precise hand actions, via upper motor neurons to spinal motor neurons. This role is evident in clinical deficits like weakness post-stroke. Thus, D is the true statement.