Numbered below are various descending motor tracts: 1. Lateral corticospinal tract, 2. Anterior corticospinal tract, 3. Rubrospinal tract, 4. Tectospinal tracts. Choose the correct statement:

Correct Answer: A

Rationale: Tracts 1 and 2 originate from the precentral gyrus of the frontal lobe . The lateral corticospinal tract and anterior corticospinal tract are pyramidal tracts arising from the primary motor cortex in the precentral gyrus, controlling voluntary movements. Choice B is incorrect; rubrospinal originatfrom the red nucleus (midbrain), and tectospinal from the superior colliculus (midbrain), not cerebellum. Choice C is wrong; lateral corticospinal tract crossin the medullary pyramids, not midbrain. Choice D is false; anterior corticospinal tract remains ipsilateral until synapsing in the spinal cord, with some fibers crossing locally. Thus, A correctly identifithe origin of corticospinal tracts 1 and 2, making it the right answer.

Correct Answer: C

Rationale: In corticospinal tract hemisection of the right half of the spinal cord in the cervical region result in motor deficit in the left side of the body . This reflects intent but requirclarification: corticospinal fibers decussate in the medulla, so a right cervical hemisection below decussation affects right (ipsilateral) motor function. Above decussation, damage causcontralateral loss (making A wrong). Choice B is false (below is ipsilateral). Choice D is incorrect (ventral horn). Assuming a higher lesion intent, C aligns with contralateral logic if misworded.

Correct Answer: C

Rationale: Damage to corticospinal tract above the level of decussation results in ipsilateral paralysis . This is incorrect: above decussation, damage causcontralateral paralysis. Choice A is wrong (right hemisection is right deficit). Choice B is false (ventral horn). Choice D is incorrect (below is ipsilateral). Assuming intent, C should be contralateral possible error.

Correct Answer: D

Rationale: Under involuntary control only , which is false. The swallowing center is in the medulla oblongata (A is true), coordinating the reflex via the nucleus ambiguus and vagus nerve. Swallowing is initiated voluntarily (B is true) in the oral phase (cortex, tongue), then becominvoluntary in pharyngeal and esophageal phases. It involvcranial nerv5 (trigeminal, mastication), 7 (facial, lips), 9 (glossopharyngeal, sensation), and 10 (vagus, motility) (C is true), orchestrating the process. Choice D is incorrect; while the reflex phase is involuntary, the initial act is voluntary, distinguishing it from fully reflex actions like vomiting. Stroke affecting cortical input or medullary centers shows this dual control, making D the exception and the correct answer.

Correct Answer: D

Rationale: The swallowing center is located in the cerebellum , which is not true. The swallowing center is in the medulla oblongata (A is true), specifically the nucleus ambiguus and dorsal motor nucleus, coordinating the reflex phase via cranial nerv9 and 10. Choice B is true; swallowing begins voluntarily in the oral phase (cortex-driven tongue movement) before becoming reflexive. Choice C is correct; the reflex involvcranial nerve 5 (trigeminal, mastication/sensation), 9 (glossopharyngeal, pharyngeal sensation), and 10 (vagus, pharyngeal/esophageal motility), with 7 also contributing (lips). Choice D is false; the cerebellum coordinatmovement but not swallowing, which relion medullary control. Damage to the medulla (e.g., stroke) causdysphagia, unlike cerebellar lesions affecting gait. Thus, D is the untrue statement, making it the correct answer.