A 25-year-old man with a severe head injury from a road accident is in the neurosurgery ICU with rising intracranial pressure. To a painful stimulus, his arms and legs stiffen in extension with the arms pronated and the neck arched. What lesion and mechanism produce this posture?

Brainstem lesion below the red nucleus, releasing vestibulospinal drive

Lesion above the red nucleus, leaving rubrospinal flexor drive intact

Isolated lesion of the anterior cerebellar vermis

Lesion of the lower medulla below the vestibular nuclei

A 24-year-old man is stabbed in the back in a brawl and brought to casualty. He has weakness of the right leg with an extensor right plantar, loss of joint position and vibration sense in the right leg, and loss of pain and temperature sense in the left leg and left lower abdomen. Where is the lesion?

Right hemisection of the thoracic cord

Central lesion of the thoracic cord

Left hemisection of the thoracic cord

Anterior lesion of the thoracic cord

A 30-year-old woman with irreversible pulpitis of a molar has had throbbing toothache for two days, worse at night, although she stopped noticing her new ring within minutes of putting it on. Which property of nociceptors explains why her pain persists?

They adapt very little and can become sensitised

They are inhibited by bradykinin and prostaglandins

They send their signals in thick A-beta fibres

They are rapidly adapting encapsulated endings

Sensory and motor systems, reflexes

18 NEET-PG practice questions on Sensory and motor systems, reflexes, part of Physiology. The first 18 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

Question 1 · Easy
A 62-year-old man has right-sided weakness after a stroke. Stroking the outer sole of his right foot makes the big toe extend and the other toes fan out. Damage to which tract does this sign indicate?
1. ARubrospinal tract
2. BVestibulospinal tract
3. CCorticospinal tract
4. DDorsal column
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Answer: C · Corticospinal tract
An extensor plantar response (Babinski sign) indicates damage to the corticospinal (pyramidal) tract anywhere from the motor cortex to the spinal cord. With the tract intact, the plantar reflex is flexor; when it is damaged a primitive spinal withdrawal pattern reappears. It is normal in infants until the corticospinal tracts mature, usually within the first year or two.
- A: Rubrospinal lesions alone do not produce a Babinski sign.
- B: Vestibulospinal tracts control posture and extensor tone, not the plantar response.
- D: Dorsal column damage causes loss of position and vibration sense, not an extensor plantar.
Question 2 · Hard
A 25-year-old man with a severe head injury from a road accident is in the neurosurgery ICU with rising intracranial pressure. To a painful stimulus, his arms and legs stiffen in extension with the arms pronated and the neck arched. What lesion and mechanism produce this posture?
1. ALesion above the red nucleus, leaving rubrospinal flexor drive intact
2. BBrainstem lesion below the red nucleus, releasing vestibulospinal drive
3. CIsolated lesion of the anterior cerebellar vermis
4. DLesion of the lower medulla below the vestibular nuclei
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Answer: B · Brainstem lesion below the red nucleus, releasing vestibulospinal drive
Extensor (decerebrate) posturing follows damage at the level of the midbrain or upper pons, between the red nucleus and the vestibular nuclei. The pontine reticulospinal and lateral vestibulospinal tracts are then left without inhibition from higher centres, and they drive extensor alpha and gamma motor neurons. Because the spindles are driven through gamma motor neurons, this rigidity is abolished by cutting the dorsal roots. It carries a worse outlook than decorticate (flexor) posturing, and scores M2 on the Glasgow Coma Scale.
- A: A lesion above the red nucleus gives decorticate posturing with flexed arms.
- C: A vermis lesion alone causes truncal ataxia, not extensor posturing.
- D: Below the vestibular nuclei the extensor drive is lost too, so the limbs are flaccid.
Question 3 · Medium
A 24-year-old man is stabbed in the back in a brawl and brought to casualty. He has weakness of the right leg with an extensor right plantar, loss of joint position and vibration sense in the right leg, and loss of pain and temperature sense in the left leg and left lower abdomen. Where is the lesion?
1. ACentral lesion of the thoracic cord
2. BLeft hemisection of the thoracic cord
3. CAnterior lesion of the thoracic cord
4. DRight hemisection of the thoracic cord
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Answer: D · Right hemisection of the thoracic cord
This is the Brown-Sequard pattern. Corticospinal fibres and the dorsal columns run on the same side as the limb they serve below the medulla, so motor loss and loss of position and vibration are ipsilateral to the lesion. Pain and temperature fibres cross within one or two segments of entry into the spinothalamic tract, so their loss is contralateral and begins a little below the level of the lesion. A right-sided cut therefore gives right motor and dorsal column loss with left pain and temperature loss.
- A: A central lesion spares the dorsal columns and gives bilateral pain-temperature loss at the level.
- B: A left hemisection would put the weakness and dorsal column loss on the left.
- C: An anterior cord lesion gives bilateral weakness and pain loss with preserved dorsal columns.
Question 4 · Easy
During a routine examination in the medicine OPD, a tap on the patellar tendon of a 30-year-old man produces a brisk extension of the knee. Which receptor is stimulated first in this reflex?
1. ARuffini ending in the joint
2. BMuscle spindle
3. CPacinian corpuscle in the skin
4. DGolgi tendon organ
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Answer: B · Muscle spindle
The tap briefly stretches the quadriceps, stimulating the primary (annulospiral) endings of its muscle spindles. Group Ia afferents synapse directly on alpha motor neurons in the L3-L4 segments, making this a monosynaptic stretch reflex. Gamma motor neurons set the sensitivity of the spindle, which is why reflexes are brisk in upper motor neuron lesions and can be reinforced by the Jendrassik manoeuvre.
- A: Joint receptors signal position but do not trigger the stretch reflex.
- C: Skin receptors are not the afferent limb of a tendon reflex.
- D: Golgi tendon organs sense tension and mediate inhibition of the same muscle, not the jerk.
Question 5 · Medium
A 30-year-old woman with irreversible pulpitis of a molar has had throbbing toothache for two days, worse at night, although she stopped noticing her new ring within minutes of putting it on. Which property of nociceptors explains why her pain persists?
1. AThey are inhibited by bradykinin and prostaglandins
2. BThey adapt very little and can become sensitised
3. CThey send their signals in thick A-beta fibres
4. DThey are rapidly adapting encapsulated endings
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Answer: B · They adapt very little and can become sensitised
Nociceptors are free nerve endings that adapt very little, so pain continues as long as the damaging stimulus lasts, which keeps warning the body of injury. In inflamed tissue, bradykinin, prostaglandins and other mediators lower their threshold (sensitisation, hyperalgesia), so the pain may even increase with time. Touch receptors such as those signalling the ring adapt quickly and stop firing to a steady stimulus. NSAIDs relieve inflammatory pain partly by preventing prostaglandin sensitisation.
- A: Bradykinin and prostaglandins excite and sensitise nociceptors rather than inhibiting them.
- C: Pain travels in thin A-delta and C fibres, not A-beta fibres.
- D: Rapidly adapting encapsulated endings, such as Pacinian corpuscles, serve touch and vibration.
Question 6 · Medium
A 9-year-old boy bangs his elbow on a desk in class and immediately rubs it hard, which eases the pain within seconds. Which mechanism best explains the relief?
1. AConduction block of the C fibres by local pressure
2. BDescending inhibition from the periaqueductal grey
3. CRelease of beta-endorphin into the blood from the pituitary
4. DA-beta input activating inhibitory dorsal horn interneurons
Answer and explanation in LearnFree account
Question 7 · Medium
A 70-year-old hypertensive woman suddenly develops wild, flinging movements of her left arm and leg that continue even at rest. MRI shows a small lacunar infarct. Where is the infarct most likely?
1. ALeft subthalamic nucleus
2. BRight subthalamic nucleus
3. CRight cerebellar hemisphere
4. DRight caudate nucleus
Answer and explanation in LearnFree account
Question 8 · Medium
A 34-year-old schoolteacher says she no longer feels whether her tea glass is hot and has found small scars on her fingers she cannot account for. Pin-prick and temperature sensation are lost from C4 to T2 on both sides, while light touch, vibration and joint position sense are normal. MRI shows a cavity in the centre of the cervical cord. Damage to which fibres explains this pattern?
1. ALateral corticospinal tract fibres
2. BDorsal root ganglia of the cervical segments
3. CCrossing fibres in the anterior white commissure
4. DDorsal column fibres of the cervical cord
Answer and explanation in LearnFree account
Question 9 · Medium
A 40-year-old man has jerky, dance-like involuntary movements, irritability and declining memory. His father had a similar illness from about the same age. MRI shows atrophy of both caudate nuclei. Loss of which neurons best explains the involuntary movements?
1. ACholinergic neurons of the nucleus basalis
2. BDopaminergic neurons of the substantia nigra
3. CGlutamatergic neurons of the subthalamic nucleus
4. DGABAergic striatal neurons of the indirect pathway
Answer and explanation in LearnFree account
Question 10 · Medium
A 45-year-old woman with a slowly worsening headache has an intention tremor of the right hand, overshoots the target to the right on finger-nose testing and cannot perform rapid alternating movements with the right hand. Power and sensation are normal. Where is the lesion?
1. ARight cerebellar hemisphere
2. BLeft cerebellar hemisphere
3. CLeft precentral gyrus
4. DLeft lentiform nucleus
Answer and explanation in LearnFree account
Question 11 · Medium
A 60-year-old man had a left internal capsule infarct 3 months ago and has right hemiparesis. Which of these findings would you expect in his right limbs now? 1. Fasciculations 2. Clasp-knife spasticity 3. Marked muscle wasting within weeks 4. Extensor plantar response
1. A1 and 3 only
2. B2 and 4 only
3. C1, 2, 3 and 4
4. D1, 2 and 4 only
Answer and explanation in LearnFree account
Question 12 · Easy
A 58-year-old man with long-standing diabetes cannot feel the buzz of a 128 Hz tuning fork placed on his big toes, although he still feels a wisp of cotton. Input from which receptor has been lost?
1. ARuffini endings
2. BFree nerve endings
3. CMerkel discs
4. DPacinian corpuscles
Answer and explanation in LearnFree account
Question 13 · Hard
A 55-year-old truck driver has unsteadiness that is worse in the dark, and episodes of sudden stabbing pains in the legs. Standing with feet together he sways and nearly falls when he closes his eyes. Pupils are small and irregular and constrict on near effort but not to light. Knee and ankle jerks are absent; power is normal. Serum VDRL is reactive. Damage to which structures causes his unsteadiness?
1. AAnterior horn cells of the lumbar cord
2. BLateral corticospinal tracts
3. CVermis of the cerebellum
4. DDorsal roots and dorsal columns
Answer and explanation in LearnFree account
Question 14 · Hard
A 48-year-old lifelong vegetarian from Gujarat has tingling in the feet and an unsteady gait for 6 months. Vibration and joint position sense are lost in both legs, Romberg sign is positive, knee jerks are brisk and both plantars are extensor. Hb 8.9 g/dL, MCV 112 fL, and the smear shows hypersegmented neutrophils. Which pair of spinal cord pathways is affected?
1. ASpinothalamic and lateral corticospinal tracts
2. BDorsal columns and lateral corticospinal tracts
3. CDorsal columns and lateral spinothalamic tracts
4. DSpinocerebellar tracts and anterior horn cells
Answer and explanation in LearnFree account
Question 15 · Medium
A 22-year-old man has a complete spinal cord transection at T6 after falling from a coconut tree. Two days later both legs are flaccid, with absent knee and ankle jerks and no plantar response. What best explains the absent reflexes?
1. ADamage to the anterior horn cells of L2 to S1
2. BAssociated injury to the cauda equina
3. CSpinal shock from loss of descending facilitation
4. DLoss of the dorsal root afferents to the legs
Answer and explanation in LearnFree account
Question 16 · Medium
A 19-year-old student in the surgical ward has acute appendicitis. His pain began as a vague ache around the umbilicus and moved to the right iliac fossa 12 hours later. Why was the early pain felt around the umbilicus?
1. AThe inflamed appendix lies against the parietal peritoneum at the umbilicus
2. BEarly inflammation irritates the anterior abdominal wall muscles
3. CAppendiceal pain travels in the vagus to the periumbilical skin
4. DVisceral and T10 skin afferents converge on shared dorsal horn neurons
Answer and explanation in LearnFree account
Question 17 · Medium
A 52-year-old man with 25 years of heavy drinking walks on a wide base and cannot walk heel to toe, but his finger-nose testing, speech and eye movements are almost normal. Which part of the cerebellum is mainly damaged?
1. ADentate nuclei
2. BFlocculonodular lobe
3. CAnterior superior vermis
4. DLateral cerebellar hemispheres
Answer and explanation in LearnFree account
Question 18 · Medium
A 66-year-old retired clerk has a pill-rolling tremor at rest, cogwheel rigidity and a slow, shuffling gait. Loss of striatal dopamine produces his slowness of movement mainly through which change?
1. AIncreased excitatory drive from cortex to the putamen
2. BDecreased inhibitory output from the GPi to the thalamus
3. CLoss of excitatory cerebellar output to the motor cortex
4. DIncreased inhibitory output from the GPi to the thalamus
Answer and explanation in LearnFree account

Sensory and motor systems, reflexes

A 62-year-old man has right-sided weakness after a stroke. Stroking the outer sole of his right foot makes the big toe extend and the other toes fan out. Damage to which tract does this sign indicate?

A 25-year-old man with a severe head injury from a road accident is in the neurosurgery ICU with rising intracranial pressure. To a painful stimulus, his arms and legs stiffen in extension with the arms pronated and the neck arched. What lesion and mechanism produce this posture?

During a routine examination in the medicine OPD, a tap on the patellar tendon of a 30-year-old man produces a brisk extension of the knee. Which receptor is stimulated first in this reflex?

A 30-year-old woman with irreversible pulpitis of a molar has had throbbing toothache for two days, worse at night, although she stopped noticing her new ring within minutes of putting it on. Which property of nociceptors explains why her pain persists?

A 9-year-old boy bangs his elbow on a desk in class and immediately rubs it hard, which eases the pain within seconds. Which mechanism best explains the relief?

A 70-year-old hypertensive woman suddenly develops wild, flinging movements of her left arm and leg that continue even at rest. MRI shows a small lacunar infarct. Where is the infarct most likely?

A 40-year-old man has jerky, dance-like involuntary movements, irritability and declining memory. His father had a similar illness from about the same age. MRI shows atrophy of both caudate nuclei. Loss of which neurons best explains the involuntary movements?

A 45-year-old woman with a slowly worsening headache has an intention tremor of the right hand, overshoots the target to the right on finger-nose testing and cannot perform rapid alternating movements with the right hand. Power and sensation are normal. Where is the lesion?

A 60-year-old man had a left internal capsule infarct 3 months ago and has right hemiparesis. Which of these findings would you expect in his right limbs now? 1. Fasciculations 2. Clasp-knife spasticity 3. Marked muscle wasting within weeks 4. Extensor plantar response

A 58-year-old man with long-standing diabetes cannot feel the buzz of a 128 Hz tuning fork placed on his big toes, although he still feels a wisp of cotton. Input from which receptor has been lost?

A 22-year-old man has a complete spinal cord transection at T6 after falling from a coconut tree. Two days later both legs are flaccid, with absent knee and ankle jerks and no plantar response. What best explains the absent reflexes?

A 19-year-old student in the surgical ward has acute appendicitis. His pain began as a vague ache around the umbilicus and moved to the right iliac fossa 12 hours later. Why was the early pain felt around the umbilicus?

A 52-year-old man with 25 years of heavy drinking walks on a wide base and cannot walk heel to toe, but his finger-nose testing, speech and eye movements are almost normal. Which part of the cerebellum is mainly damaged?

A 66-year-old retired clerk has a pill-rolling tremor at rest, cogwheel rigidity and a slow, shuffling gait. Loss of striatal dopamine produces his slowness of movement mainly through which change?