NCS Neuroanatomy and Physiology 2 — Questions and Answers
Question 1: Which brainstem structure contains the nucleus for cranial nerve VII and is responsible for facial motor control?
- Midbrain
- Pons (Correct answer)
- Medulla oblongata
- Diencephalon
Correct answer: Pons
The facial nerve (CN VII) motor nucleus is located in the pons, which also houses nuclei for CN V, VI, and VIII.
Question 2: The dorsal column-medial lemniscal pathway decussates at which level of the central nervous system?
- Spinal cord at the level of entry
- Cervical spinal cord
- Caudal medulla (nucleus gracilis/cuneatus) (Correct answer)
- Internal capsule
Correct answer: Caudal medulla (nucleus gracilis/cuneatus)
First-order neurons ascend ipsilaterally to synapse in the nucleus gracilis and cuneatus in the caudal medulla, where second-order axons then cross to form the medial lemniscus.
Question 3: Which cerebellar lobe is most associated with vestibulocerebellar functions, including balance and eye movement control?
- Anterior lobe
- Posterior lobe
- Flocculonodular lobe (Correct answer)
- Vermis only
Correct answer: Flocculonodular lobe
The flocculonodular lobe (archicerebellum) receives direct vestibular input and controls balance, gaze stabilization, and postural reflexes.
Question 4: A patient presents with ipsilateral Horner syndrome, ipsilateral facial sensory loss, and contralateral limb pain/temperature loss. Which structure is most likely affected?
- Ventral pons
- Dorsolateral medulla (Correct answer)
- Midbrain tegmentum
- Internal capsule
Correct answer: Dorsolateral medulla
Lateral medullary (Wallenberg) syndrome results from occlusion of the posterior inferior cerebellar artery affecting the dorsolateral medulla, producing this classic crossed sensory pattern.
Question 5: The corticospinal tract synapses most directly onto alpha motor neurons via interneurons in which spinal cord lamina?
- Lamina I (marginal zone)
- Laminae IV-VI (intermediate zone)
- Lamina VII (intermediate gray)
- Lamina IX (ventral horn motor columns) (Correct answer)
Correct answer: Lamina IX (ventral horn motor columns)
Corticospinal tract fibers primarily synapse directly or via interneurons onto alpha motor neurons in lamina IX of the anterior horn, though some also terminate in laminae IV–VIII.
Question 6: What is the primary neurotransmitter released at the neuromuscular junction?
- Norepinephrine
- Dopamine
- Acetylcholine (Correct answer)
- Glutamate
Correct answer: Acetylcholine
Somatic motor neurons release acetylcholine at the neuromuscular junction, which binds nicotinic receptors on the motor end plate to trigger muscle contraction.
Question 7: Which descending tract is primarily responsible for postural adjustments and gross limb movements, originating in the vestibular nuclei?
- Rubrospinal tract
- Tectospinal tract
- Vestibulospinal tract (Correct answer)
- Reticulospinal tract
Correct answer: Vestibulospinal tract
The vestibulospinal tract originates in the lateral vestibular nucleus (Deiters' nucleus) and facilitates extensor motor neurons to maintain upright posture and balance.
NCS Neuroanatomy and Physiology 2
Which brainstem structure contains the nucleus for cranial nerve VII and is responsible for facial motor control?