Brainstem — MCQs
Which part of the brain, when lesioned, primarily affects horizontal movements of the eye?
Patient presented with following features: - ipsilateral loss of pain and temperature sensation in the face - Contralateral loss of pain and temperature sensation in the body - Horner's syndrome - Dysphagia and hoarseness - Ataxia and vertigo Which artery is involved in syndrome based on above clinical features?
Which syndrome is associated with posterior inferior cerebellar artery thrombosis?
Which part of the brainstem regulates autonomic functions such as heart rate and breathing?
Mark the false statement regarding nucleus of facial nerve :
The following USG scan should prompt you to screen for which of the following disorders?
Which of the following nuclei of the vagus receives special and general visceral afferents?
What is the primary function of the superior cervical ganglion?
Inferior cerebellar peduncle has all of the following tracts, except which one?
The vein of Galen is formed by which structure?
Brainstem Indian Medical PG Practice Questions and MCQs
Question 1: Which part of the brain, when lesioned, primarily affects horizontal movements of the eye?
- A. Cerebellum
- B. Midbrain
- C. Cerebrum
- D. Pons (Correct Answer)
Explanation: **Pons** - The **paramedian pontine reticular formation (PPRF)**, located in the pons, is responsible for generating horizontal eye movements. - A lesion in the pons can interrupt the neural pathways to the **abducens nucleus** and internuclear neurons, leading to deficits in conjugate horizontal gaze. *Cerebellum* - The cerebellum plays a crucial role in coordinating and fine-tuning **eye movements**, particularly for smooth pursuit and gaze holding [3]. - However, direct lesions primarily cause **nystagmus** or impaired smooth pursuit rather than a primary deficit in the generation of horizontal movements. *Midbrain* - The midbrain contains structures involved in **vertical gaze** (e.g., rostral interstitial nucleus of the medial longitudinal fasciculus) and the integration of eye movements. - Lesions here typically affect vertical eye movements or cause disorders like **Parinaud's syndrome**, not primarily horizontal gaze palsy [1]. *Cerebrum* - The frontal eye fields in the cerebrum initiate voluntary **saccadic eye movements** and exert supranuclear control over gaze [2]. - While cerebral lesions can cause **gaze preference** or transient gaze palsies, the direct generation of horizontal movements is orchestrated in the brainstem, not the cerebrum itself.
Question 2: Patient presented with following features: - ipsilateral loss of pain and temperature sensation in the face - Contralateral loss of pain and temperature sensation in the body - Horner's syndrome - Dysphagia and hoarseness - Ataxia and vertigo Which artery is involved in syndrome based on above clinical features?
- A. Posterior inferior cerebellar artery (Correct Answer)
- B. Basilar artery.
- C. Superior cerebellar artery
- D. Anterior inferior cerebellar artery
Explanation: ***Posterior inferior cerebellar artery*** - The constellation of **ipsilateral facial numbness**, **contralateral body numbness**, **Horner's syndrome**, **dysphagia**, **hoarseness**, **ataxia**, and **vertigo** is characteristic of Wallenberg syndrome, also known as **lateral medullary syndrome**, which results from occlusion of the **posterior inferior cerebellar artery (PICA)** [1]. - This artery supplies the **lateral medulla** and **inferior cerebellum**, affecting the **spinal trigeminal nucleus and tract**, **spinothalamic tract**, **descending sympathetic fibers**, **nucleus ambiguus**, and **inferior cerebellar peduncle** [1], [2]. *Basilar artery* - **Basilar artery occlusions** typically cause more extensive deficits, including **quadriplegia**, **locked-in syndrome**, and **cranial nerve palsies**, due to its supply to the brainstem and cerebellum. - While it can affect the PICA territory, a sole PICA occlusion does not result in the widespread deficits seen with a **main basilar artery occlusion**. *Superior cerebellar artery* - Occlusion of the **superior cerebellar artery (SCA)** typically causes **ipsilateral cerebellar ataxia**, **dysarthria**, and sometimes **contralateral spinothalamic deficits** and **Horner's syndrome**, but usually spares the dysphagia and hoarseness associated with the nucleus ambiguus. - The SCA supplies the **superior cerebellum** and parts of the **pons**, which would generally not produce the full symptom complex described. *Anterior inferior cerebellar artery* - Occlusion of the **anterior inferior cerebellar artery (AICA)** typically results in **ipsilateral hearing loss/tinnitus**, **facial paralysis**, and **cerebellar ataxia**, often with **contralateral pain and temperature loss in the body**. - While it shares some features, the prominent dysphagia and hoarseness are less common with AICA strokes than with **PICA strokes**, as the AICA primarily supplies the **lateral pontine region** and **labyrinthine artery**.
Question 3: Which syndrome is associated with posterior inferior cerebellar artery thrombosis?
- A. Wallenberg syndrome (Correct Answer)
- B. Medial medullary syndrome
- C. Inferior alternating syndrome
- D. Dejerine syndrome
Explanation: No specific references from the provided list reached the relevance threshold (score >= 7) to be cited in the explanation. The original text remains unchanged. ***Wallenberg syndrome*** - Also known as **lateral medullary syndrome**, it is caused by **thrombosis of the posterior inferior cerebellar artery (PICA)** or its branches. - Symptoms include ipsilateral **ataxia**, **vertigo**, **nystagmus**, dysphagia, and contralateral loss of pain and temperature sensation. *Medial medullary syndrome* - This syndrome results from occlusion of the **anterior spinal artery** and paramedian branches of the **vertebral artery**. - Clinical features include contralateral **hemiparesis**, ipsilateral **tongue deviation**, and loss of position and vibration sensation. *Inferior alternating syndrome* - This is another name for **medial medullary syndrome**, caused by a lesion in the **medulla oblongata**. - It is characterized by ipsilateral cranial nerve signs and contralateral long tract signs, differentiating it from Wallenberg syndrome. *Dejerine syndrome* - Also known as **medial medullary syndrome**, it is linked to occlusion of the **anterior spinal artery**. - Symptoms primarily involve the **pyramidal tract**, **medial lemniscus**, and **hypoglossal nerve**.
Question 4: Which part of the brainstem regulates autonomic functions such as heart rate and breathing?
- A. Midbrain
- B. Pons
- C. Thalamus
- D. Medulla oblongata (Correct Answer)
Explanation: ***Medulla oblongata*** - The **medulla oblongata** contains vital centers that regulate essential **autonomic functions** such as heart rate, breathing, blood pressure, and reflexes like vomiting, coughing, and sneezing. - It serves as a crucial relay station for nerve signals between the brain and the spinal cord, controlling many of the automatic processes necessary for life. *Midbrain* - The **midbrain** primarily functions in motor control, **visual** and **auditory processing**, and contains structures like the substantia nigra, crucial for movement. - While it plays a role in some reflexes, it is not the primary regulator of fundamental autonomic functions like heart rate and respiration. *Pons* - The **pons** is involved in regulating **breathing rhythm**, sleep, and relaying sensory information between the cerebellum and cerebrum. - While it contributes to respiration, the medulla oblongata holds the primary control centers for this and other vital autonomic processes. *Thalamus* - The **thalamus** is a relay station for **sensory and motor signals** to the cerebral cortex and is involved in consciousness, sleep, and alertness. - It is part of the diencephalon, not the brainstem, and does not directly regulate basic autonomic functions.
Question 5: Mark the false statement regarding nucleus of facial nerve :
- A. Bilateral innervation of forehead preserves its function in supranuclear lesions
- B. Motor nucleus of facial nerve is situated in pons
- C. Upper part of the nucleus receives fibres from both the cerebral hemispheres
- D. Lower part of nucleus gets uncrossed fibres from ipsilateral hemisphere (Correct Answer)
Explanation: ***Lower part of nucleus gets uncrossed fibres from ipsilateral hemisphere*** - This statement is false because the **lower part of the facial nucleus**, which innervates the muscles of the lower face, primarily receives **crossed fibers from the contralateral cerebral hemisphere** [1]. - It does not receive uncrossed fibers from the ipsilateral hemisphere. *Bilateral innervation of forehead preserves its function in supranuclear lesions* - The **upper part of the facial nucleus**, responsible for innervating the muscles of the forehead and upper face, receives **bilateral innervation** from both cerebral hemispheres [1]. - Therefore, in a **supranuclear lesion** (e.g., stroke affecting the motor cortex), the forehead muscles are spared due to this bilateral input, while the lower face is paralyzed [1]. *Motor nucleus of facial nerve is situated in pons* - The main **motor nucleus of the facial nerve (CN VII)** is indeed located in the **pontine tegmentum** of the brainstem [1]. - It is one of the distinct nuclei associated with the facial nerve, along with the superior salivatory and lacrimal nuclei. *Upper part of the nucleus receives fibres from both the cerebral hemispheres* - The **upper part of the facial motor nucleus** receives **corticonuclear fibers from both the ipsilateral and contralateral cerebral hemispheres** [1]. - This bilateral innervation is crucial for preserving upper facial muscle function in unilateral upper motor neuron lesions [1].
Question 6: The following USG scan should prompt you to screen for which of the following disorders?
- A. Neural tube defect
- B. Aneuploidy (Correct Answer)
- C. Achondroplasia
- D. Artifact on routine scans
Explanation: ***Aneuploidy*** - The ultrasound image shows increased nuchal translucency (indicated by the red arrow), which is a key marker for **chromosomal abnormalities** like Down syndrome (Trisomy 21). - Increased nuchal translucency combined with other features like **absent nasal bone** (not clearly visible in this image but often associated) warrants further screening for aneuploidy. *Neural tube defect* - Neural tube defects are characterized by abnormalities of the brain and spine, such as **anencephaly** or **spina bifida**, which are not directly indicated by increased nuchal translucency. - While some chromosomal abnormalities can be associated with neural tube defects, nuchal translucency specifically points more strongly to aneuploidy. *Achondroplasia* - Achondroplasia is a form of **dwarfism** recognized by disproportionately short limbs and macrocephaly, which are typically identified later in pregnancy during detailed anatomical surveys. - Increased nuchal translucency is not a primary screening marker for achondroplasia. *Artifact on routine scans* - While artifacts can occur, increased nuchal translucency is a well-established and **clinically significant finding** that requires specific measurements and interpretation in screening for fetal abnormalities. - This measurement is a standard part of the **first-trimester screening** for chromosomal disorders.
Question 7: Which of the following nuclei of the vagus receives special and general visceral afferents?
- A. Nucleus of Solitary Tract (Correct Answer)
- B. Dorsal Nucleus of Vagus
- C. Nucleus Ambiguous
- D. Spinal nucleus of trigeminal nerve
Explanation: ### Nucleus of Solitary Tract - The **nucleus of the solitary tract** (NST) is the primary sensory nucleus for **general visceral afferents** (GVA) and **special visceral afferents** (SVA) from the vagus nerve (CN X) [1], [2]. - It receives taste sensation from the **epiglottis** and upper esophagus (SVA) and general sensation from the pharynx, larynx, and thoracic/abdominal viscera (GVA) [1], [2]. *Dorsal Nucleus of Vagus* - The **dorsal nucleus of the vagus** is primarily an **efferent (motor)** nucleus, providing **preganglionic parasympathetic innervation** to thoracic and abdominal viscera. - While it plays a role in visceral function, it is not the primary recipient of **afferent sensory information** from the vagus nerve. *Nucleus Ambiguous* - The **nucleus ambiguous** is a **motor nucleus** that provides **branchiomotor innervation** to muscles of the pharynx and larynx via the vagus nerve. - It is involved in processes like swallowing and speech, but it does **not receive visceral afferent input**. *Spinal nucleus of trigeminal nerve* - The **spinal nucleus of the trigeminal nerve** processes **pain and temperature sensation** for the face and oral cavity, primarily from the trigeminal nerve (CN V). - It is **not associated with the vagus nerve's visceral afferent functions**.
Question 8: What is the primary function of the superior cervical ganglion?
- A. Is the largest cervical ganglion
- B. Supplies sympathetic fibers to the dilator pupillae muscle (Correct Answer)
- C. Deep petrosal nerve of pterygopalatine ganglion is derived from plexus around internal carotid artery
- D. Left superior cervical cardiac branch goes to deep cardiac plexus
Explanation: Supplies sympathetic fibers to the dilator pupillae muscle - The superior cervical ganglion is the primary source of postganglionic sympathetic fibers to the head and neck. - One of its key functions is providing sympathetic innervation to the dilator pupillae muscle [1] via the long ciliary nerves, causing mydriasis (pupil dilation) [2]. - This represents a clear physiological function of the ganglion in autonomic control of the eye. Is the largest cervical ganglion - While the superior cervical ganglion is indeed the largest of the three cervical sympathetic ganglia, this is an anatomical characteristic, not a function. - Size is a structural feature, not a physiological role. Left superior cervical cardiac branch goes to deep cardiac plexus - The superior cervical ganglion does contribute cardiac branches to the cardiac plexus for sympathetic innervation of the heart. - However, this describes an anatomical pathway rather than the primary function itself, and specifying "left" and "deep cardiac plexus" makes it overly specific rather than addressing overall function. Deep petrosal nerve of pterygopalatine ganglion is derived from plexus around internal carotid artery - The superior cervical ganglion does send postganglionic fibers forming a plexus around the internal carotid artery, which contributes to the deep petrosal nerve. - However, this is an anatomical derivation/pathway, not a functional description of what the ganglion does physiologically.
Question 9: Inferior cerebellar peduncle has all of the following tracts, except which one?
- A. Olivocerebellar
- B. Spinocerebellar
- C. Pontocerebellar (Correct Answer)
- D. Vestibulocerebellar
Explanation: ***Pontocerebellar*** - The **pontocerebellar tracts** originate from the **pontine nuclei** and project to the contralateral cerebellum exclusively through the **middle cerebellar peduncle** (NOT the inferior cerebellar peduncle). - These tracts are crucial for carrying information about voluntary movements initiated by the cerebral cortex to the cerebellum for motor coordination. - The middle cerebellar peduncle is the largest cerebellar peduncle and consists almost entirely of pontocerebellar fibers. *Olivocerebellar* - The **olivocerebellar tracts** originate from the **inferior olivary nucleus** and pass through the **inferior cerebellar peduncle** to reach the contralateral cerebellar cortex [1]. - These fibers are crucial for motor learning, coordination, and error correction [1]. *Spinocerebellar* - The **posterior spinocerebellar tract** is a major component of the **inferior cerebellar peduncle**, conveying **unconscious proprioception** from the lower limb and lower trunk [1]. - This information helps the cerebellum coordinate posture and movement [1]. *Vestibulocerebellar* - **Vestibulocerebellar tracts** transmit essential information from the **vestibular nuclei** and organs to the cerebellum through the **inferior cerebellar peduncle** [1]. - These fibers contribute to balance, posture, and vestibulo-ocular reflexes [1].
Question 10: The vein of Galen is formed by which structure?
- A. Internal cerebral veins (Correct Answer)
- B. Basal veins of Rosenthal
- C. Inferior sagittal sinus
- D. Superior sagittal sinus
Explanation: ***Internal cerebral veins*** - The **great cerebral vein of Galen** is formed by the union of two **internal cerebral veins** and two **basal veins of Rosenthal**. - It plays a crucial role in draining the deep venous system of the brain, including the **thalamus**, **basal ganglia**, and **choroid plexus**. - While both internal cerebral veins and basal veins contribute to its formation, "internal cerebral veins" is the most commonly tested answer. *Basal veins of Rosenthal* - The **basal veins of Rosenthal** also contribute to forming the great cerebral vein of Galen along with the internal cerebral veins. - However, in most examination contexts, the internal cerebral veins are considered the primary answer. - The basal veins primarily drain structures in the midbrain, thalamus, and insula. *Inferior sagittal sinus* - The **inferior sagittal sinus** does not form the great cerebral vein. - Instead, it merges with the **great cerebral vein** to form the **straight sinus**. - The inferior sagittal sinus runs along the lower border of the falx cerebri. *Superior sagittal sinus* - The **superior sagittal sinus** does not form the great cerebral vein. - It drains into the **confluence of sinuses** (torcular Herophili), which then connects to the transverse sinuses. - It runs along the superior border of the falx cerebri and drains the superior aspects of the cerebral hemispheres.
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