Structure and functions of brain stem MCQs With Answer

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Structure and functions of brain stem MCQs With Answer

The brain stem — composed of the midbrain, pons and medulla oblongata — controls vital functions such as respiration, cardiovascular regulation, cranial nerve reflexes and arousal. For B.Pharm students, mastering the structure and functions of brain stem is essential for understanding drug effects on respiratory centers, autonomic pathways, cranial nerve pharmacology and clinical syndromes like locked‑in state or Wallenberg infarct. These MCQs focus on anatomy, nuclei, ascending/descending tracts, blood supply and pharmacological relevance, with clinical correlations to improve diagnostic and therapeutic insight. Clear, targeted practice of these topics will strengthen exam readiness and practical pharmacology knowledge. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. Which three major parts make up the brain stem?

  • Cerebrum, cerebellum, medulla
  • Midbrain, pons, medulla oblongata
  • Thalamus, hypothalamus, midbrain
  • Pons, cerebellum, spinal cord

Correct Answer: Midbrain, pons, medulla oblongata

Q2. Which is the most rostral (superior) component of the brain stem?

  • Pons
  • Medulla oblongata
  • Midbrain
  • Cerebellar peduncle

Correct Answer: Midbrain

Q3. The oculomotor nucleus that controls most extraocular muscles is located in which part of the brain stem?

  • Pons
  • Midbrain
  • Medulla oblongata
  • Cerebellum

Correct Answer: Midbrain

Q4. Where does the pyramidal (corticospinal) decussation occur?

  • At the level of the midbrain
  • In the upper pons
  • At the cervicomedullary junction (lower medulla)
  • Within the spinal cord at T1

Correct Answer: At the cervicomedullary junction (lower medulla)

Q5. Which region contains the primary respiratory centers controlling rhythm and rate?

  • Midbrain tectum
  • Pons only
  • Medulla oblongata
  • Thalamus

Correct Answer: Medulla oblongata

Q6. The cardiac center that modulates heart rate is mainly located in which structure?

  • Pons
  • Medulla oblongata
  • Midbrain
  • Cingulate gyrus

Correct Answer: Medulla oblongata

Q7. Which function is a primary role of the reticular formation in the brain stem?

  • Fine motor coordination of fingers
  • Arousal and maintenance of consciousness
  • Sensory transduction in the cochlea
  • Long‑term memory consolidation

Correct Answer: Arousal and maintenance of consciousness

Q8. The inferior colliculus in the midbrain is primarily associated with which sensory modality?

  • Vision
  • Olfaction
  • Audition (hearing)
  • Somatic touch

Correct Answer: Audition (hearing)

Q9. The superior colliculus is primarily involved in which function?

  • Visual reflexes and eye movements
  • Auditory processing
  • Respiratory rhythm generation
  • Facial expression

Correct Answer: Visual reflexes and eye movements

Q10. Which cranial nerve motor nucleus is located in the pons and controls muscles of mastication?

  • Facial nucleus
  • Trigeminal motor nucleus
  • Hypoglossal nucleus
  • Accessory nucleus

Correct Answer: Trigeminal motor nucleus

Q11. The nucleus ambiguus, which contains motor neurons for swallowing and phonation, is located in which brain stem region?

  • Midbrain
  • Pons
  • Medulla oblongata
  • Cerebellum

Correct Answer: Medulla oblongata

Q12. The dorsal motor nucleus of the vagus nerve, providing parasympathetic output, is found where?

  • Pons
  • Medulla oblongata
  • Midbrain
  • Hypothalamus

Correct Answer: Medulla oblongata

Q13. Vestibular nuclei that process balance information are located in which regions?

  • Only in the midbrain
  • In the pons and medulla
  • In the thalamus
  • Only in the cerebellum

Correct Answer: In the pons and medulla

Q14. Lateral medullary (Wallenberg) syndrome is most commonly due to infarction of which artery?

  • Anterio r spinal artery
  • Posterior inferior cerebellar artery (PICA)
  • Posterior cerebral artery
  • Middle cerebral artery

Correct Answer: Posterior inferior cerebellar artery (PICA)

Q15. Which artery is the primary blood supply to the ventral pons?

  • Basilar artery
  • Posterior cerebral artery
  • Superior cerebellar artery
  • Anterior communicating artery

Correct Answer: Basilar artery

Q16. The oculocephalic reflex (doll’s eye maneuver) tests the integrity of which neural structures?

  • Cerebellum only
  • Brain stem (midbrain and pons) pathways
  • Spinal cord tracts only
  • Basal ganglia

Correct Answer: Brain stem (midbrain and pons) pathways

Q17. Vertical gaze centers are located primarily in which part of the brain stem?

  • Medulla oblongata
  • Midbrain
  • Pons
  • Spinal cord

Correct Answer: Midbrain

Q18. The corticospinal tract in the midbrain is located within which structure?

  • Superior colliculus
  • Cerebral peduncles (basis pedunculi)
  • Inferior olivary nucleus
  • Reticular formation

Correct Answer: Cerebral peduncles (basis pedunculi)

Q19. The Edinger-Westphal nucleus participates in which reflex?

  • Pupillary light reflex (parasympathetic pupillary constriction)
  • Corneal blink reflex
  • Jaw-jerk reflex

Correct Answer: Pupillary light reflex (parasympathetic pupillary constriction)

Q20. The paramedian pontine reticular formation (PPRF) is primarily involved in controlling:

  • Vertical eye movements
  • Horizontal gaze
  • Pupillary constriction
  • Auditory localization

Correct Answer: Horizontal gaze

Q21. A lesion in the PPRF would most likely cause:

  • Vertical gaze palsy
  • Horizontal gaze palsy toward the side of the lesion
  • Loss of pupillary light reflex
  • Contralateral hemianopia

Correct Answer: Horizontal gaze palsy toward the side of the lesion

Q22. Opioid-induced respiratory depression primarily acts on receptors located in which brain area?

  • Cerebellum
  • Medullary respiratory centers (brain stem)
  • Basal ganglia
  • Spinal dorsal horn

Correct Answer: Medullary respiratory centers (brain stem)

Q23. The area postrema, a chemoreceptor trigger zone for vomiting, is located in which part of the brain stem?

  • Midbrain
  • Pons
  • Medulla oblongata
  • Hypothalamus

Correct Answer: Medulla oblongata

Q24. The reticular activating system (RAS) influences which of the following functions?

  • Auditory transduction in the cochlea
  • Wakefulness and attention
  • Motor unit recruitment in muscle
  • Short-term memory storage

Correct Answer: Wakefulness and attention

Q25. Complete ventral pontine infarction most classically produces which syndrome?

  • Wallenberg syndrome
  • Locked‑in syndrome
  • Horner syndrome only
  • Benedikt’s syndrome

Correct Answer: Locked‑in syndrome

Q26. The facial nucleus that controls muscles of facial expression is located in which part of the brain stem?

  • Medulla oblongata
  • Pons
  • Midbrain
  • Spinal cord

Correct Answer: Pons

Q27. Which ascending tract carries unconscious proprioceptive information to the cerebellum via the brain stem?

  • Corticospinal tract
  • Dorsal column medial lemniscus
  • Spinocerebellar tracts
  • Spinothalamic tract

Correct Answer: Spinocerebellar tracts

Q28. The gracile and cuneate nuclei, which relay fine touch and proprioception to the thalamus, are located in:

  • Rostral midbrain
  • Dorsal medulla
  • Pons ventrolateral tegmentum
  • Cerebellar cortex

Correct Answer: Dorsal medulla

Q29. The superior cerebellar peduncle primarily connects the cerebellum to which brain stem structure?

  • Medulla
  • Pons
  • Midbrain
  • Spinal cord

Correct Answer: Midbrain

Q30. The middle cerebellar peduncle is derived largely from input originating in which structure?

  • Pons (pontocerebellar fibers)
  • Medulla (olivocerebellar fibers)
  • Midbrain (tectocerebellar fibers)
  • Spinal cord (spinocerebellar fibers)

Correct Answer: Pons (pontocerebellar fibers)

Q31. The inferior cerebellar peduncle transmits which major input to the cerebellum?

  • Corticospinal projections
  • Spinal and vestibular inputs (including olivary fibers)
  • Visual projections from the superior colliculus
  • Auditory fibers from the inferior colliculus

Correct Answer: Spinal and vestibular inputs (including olivary fibers)

Q32. The locus coeruleus, a major noradrenergic nucleus involved in arousal, is located in which brain stem region?

  • Midbrain
  • Pons
  • Medulla
  • Hypothalamus

Correct Answer: Pons

Q33. Which brain stem nuclei are the principal source of serotonergic projections affecting mood and pain modulation?

  • Raphe nuclei
  • Edinger-Westphal nuclei
  • Lateral geniculate nuclei
  • Nucleus ambiguus

Correct Answer: Raphe nuclei

Q34. The nucleus of the solitary tract (NTS) primarily receives which types of afferent input?

  • Somatic motor commands
  • Taste and visceral afferents (cardiorespiratory inputs)
  • Visual inputs from retina
  • Proprioceptive signals from limbs

Correct Answer: Taste and visceral afferents (cardiorespiratory inputs)

Q35. Parasympathetic preganglionic neurons that constrict the pupil originate in which nucleus?

  • Edinger‑Westphal nucleus (midbrain)
  • Superior salivatory nucleus (pons)
  • Dorsal motor nucleus of vagus (medulla)
  • Nucleus ambiguus (medulla)

Correct Answer: Edinger‑Westphal nucleus (midbrain)

Q36. Which cranial nerve uniquely exits from the dorsal surface of the brain stem?

  • Trochlear nerve (CN IV)
  • Oculomotor nerve (CN III)
  • Hypoglossal nerve (CN XII)
  • Accessory nerve (CN XI)

Correct Answer: Trochlear nerve (CN IV)

Q37. Which cranial nerves emerge at the pontomedullary junction?

  • Olfactory and optic
  • Facial (VII) and vestibulocochlear (VIII)
  • Trochlear and oculomotor
  • Hypoglossal and glossopharyngeal only

Correct Answer: Facial (VII) and vestibulocochlear (VIII)

Q38. The medullary dorsal respiratory group (DRG) primarily influences which aspect of respiration?

  • Expiration forcefulness only
  • Inspiratory rhythm and basic drive to inspiratory muscles
  • Voluntary breath holding
  • Pulmonary vasoconstriction

Correct Answer: Inspiratory rhythm and basic drive to inspiratory muscles

Q39. The pneumotaxic center in the pons modulates respiration by:

  • Directly activating diaphragm motor neurons
  • Shortening inspiratory time and regulating respiratory rate
  • Controlling peripheral chemoreceptors in the carotid body
  • Inhibiting the cough reflex only

Correct Answer: Shortening inspiratory time and regulating respiratory rate

Q40. Damage to the nucleus solitarius would most likely impair which reflex?

  • Pupillary light reflex
  • Baroreceptor reflex (blood pressure regulation)
  • Deep tendon reflexes of the limb
  • Optokinetic reflex

Correct Answer: Baroreceptor reflex (blood pressure regulation)

Q41. Corticobulbar fibers primarily terminate in which locations?

  • Spinal anterior horn cells
  • Brain stem cranial nerve motor nuclei
  • Cerebellar deep nuclei
  • Thalamic sensory nuclei

Correct Answer: Brain stem cranial nerve motor nuclei

Q42. A lesion of the lateral pontine tegmentum that affects the facial nerve nucleus would produce:

  • Contralateral hemiplegia only
  • Ipsilateral facial paralysis (upper and lower face)
  • Isolated loss of proprioception in the leg
  • Loss of visual acuity

Correct Answer: Ipsilateral facial paralysis (upper and lower face)

Q43. Superior alternating hemiplegia (Weber syndrome) is due to a lesion in the ventral midbrain affecting which structures?

  • Corticospinal fibers and oculomotor nerve fascicles
  • Facial nucleus and vestibulocochlear nerve
  • Nucleus ambiguus and spinal trigeminal nucleus
  • Cerebellar peduncles only

Correct Answer: Corticospinal fibers and oculomotor nerve fascicles

Q44. The inferior olivary nucleus, involved in motor learning, is located in which brain stem region?

  • Pons
  • Medulla oblongata
  • Midbrain
  • Thalamus

Correct Answer: Medulla oblongata

Q45. Posterior inferior cerebellar artery (PICA) infarction commonly causes which combination of sensory deficits?

  • Ipsilateral loss of facial pain and temperature, contralateral loss of body pain and temperature
  • Bilateral loss of vibration sense in the legs
  • Isolated loss of proprioception of ipsilateral arm only
  • Complete ipsilateral hemianopia

Correct Answer: Ipsilateral loss of facial pain and temperature, contralateral loss of body pain and temperature

Q46. Anatomically, the brain stem can be divided into which transverse zones?

  • Tectum, tegmentum, and basis (basilar) regions
  • Corona radiata, internal capsule, external capsule
  • Anterior horn, lateral horn, posterior horn
  • Hippocampus, amygdala, septum

Correct Answer: Tectum, tegmentum, and basis (basilar) regions

Q47. The cerebral peduncles are located in which brain stem segment?

  • Rostral midbrain (ventral aspect)
  • Pons dorsal surface
  • Medulla dorsal column
  • Cerebellar vermis

Correct Answer: Rostral midbrain (ventral aspect)

Q48. The area postrema is distinctive because it:

  • Has an intact blood‑brain barrier preventing toxin access
  • Lacks a normal blood‑brain barrier and detects bloodborne toxins to trigger vomiting
  • Is the main respiratory chemoreceptor in the cortex
  • Is located in the midbrain periaqueductal gray

Correct Answer: Lacks a normal blood‑brain barrier and detects bloodborne toxins to trigger vomiting

Q49. Which nucleus is the primary relay for baroreceptor afferents and integrates cardiovascular reflexes in the brain stem?

  • Nucleus ambiguus
  • Nucleus tractus solitarius (NTS)
  • Edinger‑Westphal nucleus
  • Inferior olivary nucleus

Correct Answer: Nucleus tractus solitarius (NTS)

Q50. Which class of drugs is most directly associated with marked respiratory depression via action on opioid receptors in medullary respiratory centers?

  • Benzodiazepines
  • Opioids (e.g., morphine, fentanyl)
  • Anticholinergics
  • Beta blockers

Correct Answer: Opioids (e.g., morphine, fentanyl)

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