Brain and Neuroanatomy — MCQs

Brain and Neuroanatomy Indian Medical PG Practice Questions and MCQs

Question 381: Match the following: A) Glossopharyngeal nerve B) Spinal accessory nerve C) Facial nerve D) Mandibular nerve 1) Shrugging of shoulder 2) Touch sensation from the posterior one-third of the tongue 3) Chewing 4) Taste from the anterior two-thirds of the tongue

A. A-3 , B-1 , C-4 , D-2
B. A-2 , B-3 , C-4 , D-1
C. A-4 , B-1 , C-2 , D-3
D. A-2 , B-1 , C-4 , D-3 (Correct Answer)

Explanation: ***A-2 , B-1 , C-4 , D-3*** - **A) Glossopharyngeal nerve (CN IX)** is responsible for **general sensation and taste from the posterior one-third of the tongue** [1]. (2). - **B) Spinal Accessory nerve (CN XI)** innervates the **sternocleidomastoid** and **trapezius muscles**, which are involved in shrugging the shoulders (1). - **C) Facial nerve (CN VII)** carries **taste sensation from the anterior two-thirds of the tongue** [1] (4) via the chorda tympani. - **D) Mandibular nerve (V3)**, a branch of the trigeminal nerve, innervates the muscles of mastication, enabling **chewing** (3). *A-3 , B-1 , C-4 , D-2* - This option incorrectly associates the **glossopharyngeal nerve** with chewing, which is a function of the mandibular nerve (V3). - It also incorrectly associates the **mandibular nerve** with touch sensation from the posterior one-third of the tongue, which is a function of the glossopharyngeal nerve [1]. *A-2 , B-3 , C-4 , D-1* - This option incorrectly links the **spinal accessory nerve** with chewing; this nerve primarily controls shoulder and neck movements. - It also incorrectly assigns shrugging of the shoulder to the **mandibular nerve** instead of the spinal accessory nerve. *A-4 , B-1 , C-2 , D-3* - This choice incorrectly attributes **taste from the anterior two-thirds of the tongue** to the glossopharyngeal nerve, which supplies the posterior one-third [1]. - It also incorrectly links **touch sensation from the posterior one-third of the tongue** to the facial nerve, which is involved in taste from the anterior two-thirds [1].

Question 382: What is the correct sequence of the auditory pathway?

A. Spiral Ganglion → Cochlea → Cochlear Nerve → Superior Olivary N
B. Spiral Ganglion → Cochlear Nerve → Cochlea → Superior Olivary N
C. Cochlea → Spiral Ganglion → Cochlear Nerve → Superior Olivary N (Correct Answer)
D. Cochlear Nerve → Spiral Ganglion → Cochlea → Superior Olivary N

Explanation: ***Cochlea → Spiral Ganglion → Cochlear Nerve → Superior Olivary N*** - Sound vibrations are first transduced into electrical signals by the **hair cells** in the **cochlea** [2]. These signals are then transmitted to the **spiral ganglion**. - Neurons in the **spiral ganglion** generate action potentials, which are carried by the **cochlear nerve** to the brainstem, specifically the **superior olivary nucleus**, for further processing [1]. *Spiral Ganglion → Cochlea → Cochlear Nerve → Superior Olivary N* - This sequence is incorrect because the **cochlea** is where the initial mechanical-to-electrical transduction of sound occurs, *before* the signal reaches the **spiral ganglion** neurons [2]. - The spiral ganglion consists of the cell bodies of the neurons that innervate the cochlea's hair cells, meaning the cochlea must process the sound first. *Spiral Ganglion → Cochlear Nerve → Cochlea → Superior Olivary N* - This order is incorrect as the **cochlea** is the organ that processes sound input *prior* to the involvement of the **spiral ganglion** and the **cochlear nerve** [2]. - The flow of information begins at the peripheral sensory organ (cochlea) and then moves centrally. *Cochlear Nerve → Spiral Ganglion → Cochlea → Superior Olivary N* - This sequence is incorrect because the **cochlea** is the initial site of sound detection and signal generation, *before* the **cochlear nerve** transmits the signal. - The **spiral ganglion** contains the cell bodies of the neurons whose axons form the cochlear nerve, so the signal must pass through the ganglion before going down the nerve.

Question 383: Fibers from the marked structure terminate at which of the following?

A. Red nucleus (Correct Answer)
B. Subthalamus
C. Inferior olivary nucleus
D. Fastigial nucleus

Explanation: ***Red nucleus*** - The arrow points to the **superior cerebellar peduncle**, which contains efferent fibers from the **dentate nucleus** of the cerebellum. - A major projection of the superior cerebellar peduncle is to the **contralateral red nucleus**, forming part of the **dentato-rubro-thalamic pathway**. *Subthalamus* - The subthalamus is part of the **diencephalon** and is involved in motor control as part of the **basal ganglia circuit**. - It does not receive direct efferent projections from the cerebellum via the superior cerebellar peduncle. *Inferior olivary nucleus* - The inferior olivary nucleus is a major source of **climbing fibers** to the cerebellum, providing **afferent input** for motor learning and coordination. - It does not receive direct efferent output from the cerebellum's deep nuclei via the superior cerebellar peduncle. *Fastigial nucleus* - The fastigial nucleus is one of the **deep cerebellar nuclei**, located medially. - Its primary efferent projections are via the **inferior cerebellar peduncle** to the vestibular nuclei and reticular formation, not typically receiving fibers from the superior cerebellar peduncle.

Question 384: Which structure connects Broca's area and Wernicke's area?

A. Fornix
B. Anterior commissure
C. Corpus callosum
D. Arcuate fasciculus (Correct Answer)

Explanation: ***Arcuate fasciculus*** - The **arcuate fasciculus** is a bundle of **association fibers** that connects the **Broca's area** (speech production) and **Wernicke's area** (speech comprehension) in the brain [1]. - Damage to this pathway can lead to **conduction aphasia**, where speech comprehension and production are relatively preserved, but repetition is severely impaired. *Fornix* - The **fornix** is a C-shaped bundle of nerve fibers in the brain that acts as the primary efferent (output) pathway of the **hippocampus**, a crucial structure for memory. - It carries signals from the hippocampus to the mammillary bodies and other subcortical structures, playing a key role in **episodic memory** and **spatial navigation**. *Anterior commissure* - The **anterior commissure** is a bundle of nerve fibers, located in front of the columns of the fornix, that connects the two **temporal lobes** and plays a role in pain sensation and memory. - It specifically connects parts of the **pyriform cortex** and **amygdalar nuclei** of the two hemispheres. *Corpus callosum* - The **corpus callosum** is a large, C-shaped nerve fiber bundle found beneath the cerebral cortex in the brain, connecting the **two cerebral hemispheres**. - It facilitates **interhemispheric communication**, allowing for the transfer of motor, sensory, and cognitive information between both sides of the brain [1].

Question 385: Most medial nucleus of cerebellum is:

A. Dentate
B. Emboliform
C. Globose
D. Fastigial (Correct Answer)

Explanation: ***Fastigial*** - The **fastigial nucleus** is located most **medially** within the cerebellum, closest to the midline in the roof of the fourth ventricle [1]. - It is the most medial of the four deep cerebellar nuclei and is primarily associated with the **vestibulocerebellum** (flocculonodular lobe) [1]. - Functions: Maintains **balance, posture, and coordinated eye movements** via connections to vestibular nuclei and reticular formation [1]. *Dentate* - The **dentate nucleus** is the **largest and most lateral** of the cerebellar nuclei, with a characteristic crumpled sac-like appearance (resembling an olive). - Located deep within the **lateral cerebellar hemisphere** white matter [1]. - Associated with the **neocerebellum** (cerebrocerebellum) and involved in **planning and initiating voluntary movements** via the ventrolateral thalamus to motor cortex [1]. *Emboliform* - The **emboliform nucleus** is elongated and located **medial to the dentate** but **lateral to the globose** nucleus. - Together with the globose nucleus, forms the **interposed nuclei**. - Associated with the **spinocerebellum** and involved in **modulating limb movements** and adjusting ongoing motor activity [1]. *Globose* - The **globose nucleus** consists of rounded cell masses located **medial to emboliform** and **lateral to fastigial** nucleus. - Part of the **interposed nuclei** along with emboliform nucleus. - Functions in **fine-tuning and coordinating ongoing movements**, particularly of distal limbs.

Question 386: Which of the following nerves transmits impulses originating from the vestibular apparatus?

A. Cranial nerve XI
B. Cranial nerve VIII (Correct Answer)
C. Cranial nerve VII
D. Cranial nerve II

Explanation: ***Cranial nerve VIII*** - The **vestibulocochlear nerve (CN VIII)** is responsible for transmitting both auditory (cochlear branch) and balance (vestibular branch) information to the brain [1], [2]. - The **vestibular apparatus** in the inner ear detects head movements and position, and its impulses are carried by the vestibular part of CN VIII [2]. *Cranial nerve XI* - **Cranial nerve XI (Accessory nerve)** primarily controls the **sternocleidomastoid** and **trapezius muscles**, involved in head and shoulder movement. - It has no role in transmitting sensory information from the vestibular apparatus or the inner ear. *Cranial nerve VII* - **Cranial nerve VII (Facial nerve)** innervates the **muscles of facial expression**, carries taste sensation from the anterior two-thirds of the tongue, and supplies several glands. - It is not involved in transmitting impulses related to balance from the vestibular apparatus. *Cranial nerve II* - **Cranial nerve II (Optic nerve)** is responsible for **vision**, transmitting visual information from the retina to the brain. - It has no function related to the vestibular system or balance.

Question 387: 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 388: Aphasia is most likely associated with a lesion in

A. Broca's area (Correct Answer)
B. Primary motor area
C. Sensory area
D. Visual area

Explanation: ***Broca's area*** - Lesions in Broca's area lead to **Broca's aphasia**, characterized by **non-fluent speech** and difficulty with **language production**. [1] - This area is located in the **frontal lobe** and is critical for the motor aspects of speech. [1] *Primary motor area* - Damage to the primary motor area primarily causes **weakness** or **paralysis** of voluntary movements. [1] - While it can affect the musculature used for speech, it does not directly cause an **aphasia** where language comprehension or production is impaired at a cognitive level. [1] *Sensory area* - Lesions in the sensory cortex (e.g., primary somatosensory cortex) result in **sensory deficits** like numbness, tingling, or impaired proprioception. [2] - While **Wernicke's aphasia** relates to a sensory language area (Wernicke's area), the term "sensory area" alone is too general and does not specifically pinpoint a region for aphasia. *Visual area* - Damage to the visual cortex (e.g., primary visual cortex in the occipital lobe) leads to **visual field deficits** or blindness. - It does not cause aphasia, which is a disorder of language processing. [1]

Question 389: Cerebello pontine angle tumour is most commonly:

A. Cholesteatoma
B. Acoustic neuroma (Correct Answer)
C. Epidermoid cyst
D. Meningioma

Explanation: Acoustic neuroma - Also known as vestibular schwannoma, it originates from the vestibulocochlear nerve (VIII cranial nerve). - It is by far the most common tumor in the cerebellopontine angle, accounting for about 80% of all CPA tumors. - Typically presents with progressive unilateral hearing loss, tinnitus, and vertigo. Meningioma - Meningiomas are the second most common tumor in the CPA (10-15%), originating from the arachnoid cells of the meninges [1]. - They tend to have a broader attachment base to the dura and demonstrate distinct radiographic features compared to acoustic neuromas. - More common in middle-aged women. Epidermoid cyst - Epidermoid cysts (also called cholesteatomas when congenital) account for about 5% of CPA tumors. - These are benign congenital lesions arising from ectodermal inclusion during neural tube closure. - Characteristically appear as pearly white tumors and show restricted diffusion on MRI. Cholesteatoma - While an acquired cholesteatoma can occur in the skull base and potentially extend to the CPA, it is fundamentally a benign growth of squamous epithelium within the middle ear or mastoid. - It is a less common primary tumor of the CPA compared to acoustic neuroma and typically presents with a history of chronic ear infections and conductive hearing loss.

Question 390: Visual processing center is located in -

A. Occipital lobe (Correct Answer)
B. Frontal lobe
C. Parietal lobe
D. Temporal lobe

Explanation: ***Occipital lobe*** - The **occipital lobe** houses the **primary visual cortex**, which is responsible for processing and interpreting visual information received from the eyes [1]. - Damage to this lobe can lead to various visual deficits, including **cortical blindness** or **visual agnosia** [2], [3]. *Frontal lobe* - The **frontal lobe** is primarily involved in **executive functions**, such as decision-making, problem-solving, planning, and voluntary movement. - It also plays a key role in **personality** and social behavior. *Parietal lobe* - The **parietal lobe** integrates sensory information from various parts of the body, including touch, temperature, pain, and pressure. - It also plays a crucial role in **spatial awareness** and navigation. *Temporal lobe* - The **temporal lobe** is mainly associated with **auditory processing**, memory, and language comprehension. - It contains the **primary auditory cortex** and structures vital for forming memories, such as the hippocampus.

Practice by Chapter

Cerebral Hemispheres

Practice Questions

Diencephalon

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Brainstem

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Cerebellum

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Basal Ganglia

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Limbic System

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Ventricular System and CSF

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Blood Supply of the Brain

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Cranial Nerves and Nuclei

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Functional Systems and Pathways

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Applied Neuroanatomy

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Neuroimaging Correlations

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