Functions of afferent nerve tracts MCQs With Answer

Functions of afferent nerve tracts MCQs With Answer

This concise introduction explains afferent nerve tracts for B. Pharm students, focusing on sensory pathways, physiological roles, and clinical relevance. Afferent tracts—dorsal column–medial lemniscus, spinothalamic, spinocerebellar and trigeminothalamic pathways—convey fine touch, vibration, proprioception, pain and temperature to higher centers. Understanding first-, second- and third-order neurons, decussation points, receptor types (e.g., mechanoreceptors, nociceptors) and neurotransmitters (glutamate, substance P) is essential for neuropharmacology and pain management. This topic links anatomy to drug actions (local anesthetics, opioids, gabapentinoids) and clinical signs (Brown-Séquard, sensory ataxia). Now let’s test your knowledge with 50 MCQs on this topic.

Q1. Which afferent tract primarily conveys fine touch and vibration from the lower limb to the brain?

• Dorsal column–medial lemniscus
• Lateral spinothalamic tract
• Dorsal spinocerebellar tract
• Spinoreticular tract

Correct Answer: Dorsal column–medial lemniscus

Q2. Which sensory modality is chiefly transmitted by the lateral spinothalamic tract?

• Temperature and pain
• Proprioception
• Fine touch and vibration
• Unconscious proprioception to cerebellum

Correct Answer: Temperature and pain

Q3. Where are the cell bodies of first-order neurons for the dorsal column located?

• Dorsal root ganglion
• Dorsal horn of spinal cord
• Gracile nucleus
• Thalamic ventral posterolateral nucleus

Correct Answer: Dorsal root ganglion

Q4. Which tract conveys unconscious proprioceptive information to the cerebellum?

• Dorsal spinocerebellar tract
• Anterior spinothalamic tract
• Dorsal column–medial lemniscus
• Lateral corticospinal tract

Correct Answer: Dorsal spinocerebellar tract

Q5. At what level does the dorsal column decussate (cross) to form the medial lemniscus?

• Medulla oblongata
• Spinal cord at the same segment
• Pons
• Midbrain

Correct Answer: Medulla oblongata

Q6. Which receptor type is primarily responsible for detecting noxious heat?

• TRPV1 receptor
• Merkel disc
• Pacinian corpuscle
• Muscle spindle

Correct Answer: TRPV1 receptor

Q7. Which fiber type is fastest and transmits proprioceptive and motor-related afferent signals?

• Aα fibers
• Aδ fibers
• C fibers
• Aβ fibers

Correct Answer: Aα fibers

Q8. Substance P is primarily associated with which function in afferent pathways?

• Enhancing nociceptive transmission in dorsal horn
• Conveying fine touch to the thalamus
• Accelerating proprioceptive conduction to cerebellum
• Inhibiting nociceptive input presynaptically

Correct Answer: Enhancing nociceptive transmission in dorsal horn

Q9. A lesion of the right dorsal column at T6 produces which deficit?

• Loss of ipsilateral vibration and proprioception below T6
• Contralateral loss of pain and temperature below T6
• Ipsilateral motor weakness below T6 only
• Loss of stereognosis on the contralateral side above T6

Correct Answer: Loss of ipsilateral vibration and proprioception below T6

Q10. Which nucleus receives trigeminal sensory input for discriminative touch from the face?

• Main (principal) sensory nucleus of trigeminal nerve
• Spinal trigeminal nucleus
• Mesencephalic nucleus
• Solitary nucleus

Correct Answer: Main (principal) sensory nucleus of trigeminal nerve

Q11. The spinothalamic tract ascends in which part of the spinal cord white matter?

• Lateral funiculus
• Dorsal funiculus
• Ventral horn
• Anterior funiculus only

Correct Answer: Lateral funiculus

Q12. Which neuron order decussates in the spinothalamic pathway?

• Second-order neuron
• First-order neuron
• Third-order neuron
• There is no decussation

Correct Answer: Second-order neuron

Q13. Which pharmacological agent blocks voltage-gated sodium channels and can inhibit afferent transmission when applied locally?

• Local anesthetics (e.g., lidocaine)
• Opioids (e.g., morphine)
• NSAIDs (e.g., ibuprofen)
• SSRIs (e.g., fluoxetine)

Correct Answer: Local anesthetics (e.g., lidocaine)

Q14. Which tract conveys crude touch (light pressure) to the brainstem and thalamus?

• Anterior spinothalamic tract
• Dorsal column–medial lemniscus
• Dorsal spinocerebellar tract
• Lateral corticospinal tract

Correct Answer: Anterior spinothalamic tract

Q15. Which thalamic nucleus relays somatosensory input from the body to the sensory cortex?

• Ventral posterolateral nucleus (VPL)
• Ventral posteromedial nucleus (VPM)
• Mediodorsal nucleus
• Lateral geniculate nucleus (LGN)

Correct Answer: Ventral posterolateral nucleus (VPL)

Q16. Which fibers mediate slow, burning pain sensations?

• C fibers
• Aδ fibers
• Aβ fibers
• Aα fibers

Correct Answer: C fibers

Q17. Which ascending tract travels ipsilaterally and conveys lower limb proprioception to the cerebellum?

• Dorsal spinocerebellar tract
• Ventral spinocerebellar tract
• Lateral spinothalamic tract
• Medial lemniscus

Correct Answer: Dorsal spinocerebellar tract

Q18. Which clinical test assesses dorsal column function related to proprioception?

• Romberg test
• Babinski sign
• Hoffmann reflex
• Froment’s sign

Correct Answer: Romberg test

Q19. Which neurotransmitter is the primary excitatory mediator at first synapses in dorsal horn pain pathways?

• Glutamate
• GABA
• Glycine
• Acetylcholine

Correct Answer: Glutamate

Q20. Brown-Séquard syndrome (hemisection) causes which characteristic sensory pattern?

• Ipsilateral loss of proprioception and contralateral loss of pain and temperature
• Contralateral loss of all modalities only
• Bilateral loss of vibration only
• No sensory deficits, only motor

Correct Answer: Ipsilateral loss of proprioception and contralateral loss of pain and temperature

Q21. Where do second-order neurons of the dorsal column pathway synapse before thalamic relay?

• Gracile and cuneate nuclei in the medulla
• Dorsal horn lamina II
• Cerebellar cortex
• Red nucleus

Correct Answer: Gracile and cuneate nuclei in the medulla

Q22. Which receptor type detects vibration and deep pressure?

• Pacinian corpuscle
• Merkel disc
• Ruffini ending
• Nociceptor free nerve ending

Correct Answer: Pacinian corpuscle

Q23. Opioids act on which receptors in the dorsal horn to reduce afferent nociceptive transmission?

• Mu opioid receptors
• NMDA receptors
• Alpha-1 adrenergic receptors
• GABA-B receptors

Correct Answer: Mu opioid receptors

Q24. Which pathway carries visceral pain to the brain and contributes to referred pain?

• Spinoreticular and spinothalamic pathways
• Dorsal column–medial lemniscus
• Dorsal spinocerebellar tract
• Medial lemniscus exclusively

Correct Answer: Spinoreticular and spinothalamic pathways

Q25. Which spinal lamina contains nociceptive second-order neurons (substantia gelatinosa)?

• Lamina II
• Lamina IX
• Lamina V only
• Lamina I exclusively

Correct Answer: Lamina II

Q26. Which ion channel modulation underlies gabapentinoid (gabapentin/pregabalin) analgesic effects on afferent neurons?

• Inhibition of presynaptic voltage-gated calcium channels (α2δ subunit)
• Block of voltage-gated sodium channels
• Activation of NMDA receptors
• Enhancement of acetylcholine release

Correct Answer: Inhibition of presynaptic voltage-gated calcium channels (α2δ subunit)

Q27. Which tract transmits pain and temperature from the face to the thalamus?

• Spinal trigeminal tract to VPM
• Dorsal column from the face
• Spinocerebellar tract from the face
• Medial lemniscus directly from the face

Correct Answer: Spinal trigeminal tract to VPM

Q28. Activation of which descending modulatory neurotransmitter system reduces dorsal horn nociceptive transmission?

• Serotonergic and noradrenergic pathways from brainstem
• Cholinergic pathways from cortex
• Glutamatergic projections from hippocampus
• Histaminergic tuberomammillary nucleus output

Correct Answer: Serotonergic and noradrenergic pathways from brainstem

Q29. Which clinical sign suggests dorsal column dysfunction specific to vibration sense loss?

• Reduced vibration perception with tuning fork
• Hyperreflexia of stretch reflexes only
• Loss of pain sensation with pinprick only
• Muscle fasciculations

Correct Answer: Reduced vibration perception with tuning fork

Q30. Which tract conveys sensory information that influences autonomic and arousal responses to pain?

• Spinoreticular tract
• Dorsal column–medial lemniscus
• Dorsal spinocerebellar tract
• Medial longitudinal fasciculus

Correct Answer: Spinoreticular tract

Q31. In the medial lemniscus pathway, where do third-order neurons reside before projecting to the sensory cortex?

• Thalamus (VPL)
• Medulla (gracile nucleus)
• Cerebellar cortex
• Basal ganglia

Correct Answer: Thalamus (VPL)

Q32. Which fibers are mainly responsible for sharp, fast pain transmission?

• Aδ fibers
• C fibers
• Aβ fibers
• Aα fibers

Correct Answer: Aδ fibers

Q33. Which lesion produces contralateral loss of pain and temperature beginning a few levels below the lesion?

• Hemisection affecting lateral spinothalamic tract
• Midline dorsal column lesion
• Lesion of ipsilateral dorsal root ganglion
• Lesion of cerebellar peduncle

Correct Answer: Hemisection affecting lateral spinothalamic tract

Q34. Which mechanoreceptor is specialized for light touch and texture discrimination?

• Merkel disc
• Pacinian corpuscle
• Muscle spindle
• Nociceptor free nerve ending

Correct Answer: Merkel disc

Q35. Which pathway provides ascending input to the reticular formation influencing arousal to sensory stimuli?

• Spinoreticular tract
• Dorsal column–medial lemniscus
• Dorsal spinocerebellar tract
• Corticospinal tract

Correct Answer: Spinoreticular tract

Q36. NMDA receptor antagonists can reduce central sensitization by blocking which process in dorsal horn neurons?

• Long-term potentiation and wind-up
• Peripheral nerve conduction velocity
• Presynaptic neurotransmitter release only
• Activation of G-protein-coupled receptors

Correct Answer: Long-term potentiation and wind-up

Q37. Where are the cell bodies of the second-order neurons of the spinothalamic tract located?

• Dorsal horn of the spinal cord
• Dorsal root ganglion
• VPL nucleus of thalamus
• Gracile nucleus

Correct Answer: Dorsal horn of the spinal cord

Q38. Which pathological process preferentially damages large myelinated dorsal column fibers, causing loss of vibration and proprioception?

• Vitamin B12 deficiency (subacute combined degeneration)
• Peripheral small fiber neuropathy from diabetes
• Pure autonomic failure
• Motor neuron disease only

Correct Answer: Vitamin B12 deficiency (subacute combined degeneration)

Q39. Which modality would be preserved if a small-diameter fiber neuropathy affects only C and Aδ fibers?

• Vibration and fine touch transmitted by Aβ fibers
• Temperature and pain
• Autonomic sweating only
• Nociceptive slow pain exclusively

Correct Answer: Vibration and fine touch transmitted by Aβ fibers

Q40. Which ascending tract crosses at the spinal level and ascends in the contralateral lateral funiculus near its origin?

• Spinothalamic tract
• Dorsal column tract
• Dorsal spinocerebellar tract
• Corticospinal tract

Correct Answer: Spinothalamic tract

Q41. Which therapeutic class reduces prostaglandin-mediated sensitization of peripheral nociceptors?

• Nonsteroidal anti-inflammatory drugs (NSAIDs)
• Opioids
• Local anesthetics
• Antidepressants

Correct Answer: Nonsteroidal anti-inflammatory drugs (NSAIDs)

Q42. The mesencephalic nucleus of V contains primary sensory neuron cell bodies for which modality?

• Proprioception from jaw muscles
• Fine touch from the face
• Temperature from the face
• Auditory reflexes

Correct Answer: Proprioception from jaw muscles

Q43. Which drug class enhances descending noradrenergic inhibition of dorsal horn nociceptive neurons and is used in neuropathic pain?

• SNRIs (e.g., duloxetine)
• Beta-blockers
• Calcium channel blockers (dihydropyridines)
• Proton pump inhibitors

Correct Answer: SNRIs (e.g., duloxetine)

Q44. Which spinal tract transmits information from muscle spindles for reflexes and posture control to the cerebellum?

• Dorsal spinocerebellar tract
• Lateral spinothalamic tract
• Dorsal column–medial lemniscus
• Spinoreticular tract

Correct Answer: Dorsal spinocerebellar tract

Q45. Where do first-order neurons for facial pain and temperature have their cell bodies?

• Trigeminal (Gasserian) ganglion
• Dorsal root ganglion at C2 only
• Facial nucleus
• Superior cervical ganglion

Correct Answer: Trigeminal (Gasserian) ganglion

Q46. Which mechanism explains referred pain from visceral afferents?

• Convergence of visceral and somatic afferents on the same dorsal horn neurons
• Direct crossover of visceral fibers into dorsal columns
• Exclusive thalamic segregation of visceral inputs
• Visceral fibers bypass the spinal cord entirely

Correct Answer: Convergence of visceral and somatic afferents on the same dorsal horn neurons

Q47. Which electrophysiological property correlates with myelination and large fiber diameter in afferents?

• High conduction velocity
• Low threshold for C fiber activation
• Irregular refractory periods
• Slow conduction and temporal summation

Correct Answer: High conduction velocity

Q48. Which drug target in the dorsal horn would most directly reduce glutamate-mediated excitatory transmission?

• NMDA receptor antagonists
• μ-opioid receptor agonists only in periphery
• Beta-2 adrenergic agonists
• Cholinesterase inhibitors

Correct Answer: NMDA receptor antagonists

Q49. Anterior cord syndrome primarily affects which functions due to ventral horn and tract involvement?

• Motor function and pain-temperature sensation with preserved dorsal column modalities
• Vibration and proprioception only
• Cranial nerve nuclei exclusively
• Autonomic function only without motor loss

Correct Answer: Motor function and pain-temperature sensation with preserved dorsal column modalities

Q50. Which spinal afferent termination region is crucial for integrating nociceptive input and initiating local spinal reflexes?

• Dorsal horn, especially laminae I–V
• Ventral horn motor neurons only
• Gracile nucleus in the medulla
• Ventral posterolateral thalamus

Correct Answer: Dorsal horn, especially laminae I–V

G S Sachin

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.

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