NCS Neuroanatomy and Physiology 3 β Questions and Answers
Question 1: In the spinal cord, the spinothalamic tract carries pain and temperature information and crosses at which level?
- At the brainstem
- Within 1-2 spinal segments of entry via the anterior commissure (Correct answer)
- At the thalamus
- At the postcentral gyrus
Correct answer: Within 1-2 spinal segments of entry via the anterior commissure
Second-order spinothalamic neurons cross the midline through the anterior white commissure within 1-2 segments of their dorsal horn synapse before ascending contralaterally.
Question 2: The preganglionic sympathetic neurons are located in which spinal cord region?
- C1-C8 anterior horn
- T1-L2 intermediolateral cell column (Correct answer)
- S2-S4 sacral parasympathetic nucleus
- Cranial nerve nuclei only
Correct answer: T1-L2 intermediolateral cell column
Sympathetic preganglionic neurons are located in the intermediolateral cell column (lateral horn) of spinal cord segments T1 through L2.
Question 3: Which ascending tract conveys proprioception from the lower limb directly to the ipsilateral cerebellum without relay in the thalamus?
- Dorsal column
- Spinothalamic tract
- Posterior spinocerebellar tract (Correct answer)
- Cuneocerebellar tract
Correct answer: Posterior spinocerebellar tract
The posterior spinocerebellar tract transmits unconscious proprioception from the lower limb ipsilaterally through the inferior cerebellar peduncle directly to the cerebellar cortex.
Question 4: Which spinal cord segment level corresponds to the umbilicus dermatome, a key landmark for sensory level testing?
- T6
- T8
- T10 (Correct answer)
- T12
Correct answer: T10
The umbilicus is innervated by the T10 dermatome, making it a standard clinical landmark for determining the level of a thoracic spinal cord lesion.
Question 5: In the autonomic nervous system, postganglionic parasympathetic fibers release which neurotransmitter to act on target organs?
- Norepinephrine
- Epinephrine
- Acetylcholine acting on muscarinic receptors (Correct answer)
- Acetylcholine acting on nicotinic receptors
Correct answer: Acetylcholine acting on muscarinic receptors
Postganglionic parasympathetic fibers release acetylcholine that acts on muscarinic receptors of target organs, while nicotinic receptors are found at all autonomic ganglia.
Question 6: A lesion of the posterior cord of the brachial plexus would produce weakness in which combination of movements?
- Shoulder abduction and elbow flexion
- Wrist extension, finger extension, and shoulder extension (Correct answer)
- Elbow flexion and forearm supination
- Wrist flexion and finger flexion
Correct answer: Wrist extension, finger extension, and shoulder extension
The posterior cord gives rise to the axillary and radial nerves; a posterior cord lesion causes weakness of shoulder extension, elbow extension, wrist extension, and finger extension.
Question 7: Which lamina of the spinal cord gray matter contains the substantia gelatinosa, a key area for pain modulation?
- Lamina I
- Lamina II (Correct answer)
- Lamina IV
- Lamina VI
Correct answer: Lamina II
Lamina II (substantia gelatinosa) is a major site of endogenous pain modulation, receiving C-fiber and AΞ΄ nociceptive input and containing high concentrations of opioid receptors.
NCS Neuroanatomy and Physiology 3
In the spinal cord, the spinothalamic tract carries pain and temperature information and crosses at which level?