Brain and Neuroanatomy — MCQs

Brain and Neuroanatomy Indian Medical PG Practice Questions and MCQs

Question 401: During surgery for meningioma, the left paracentral lobule was injured. It would lead to paresis of:

A. Left face
B. Right shoulder & trunk
C. Right face
D. Right Leg and perineum (Correct Answer)

Explanation: Right Leg and perineum - The **paracentral lobule** is located in the medial aspect of the cerebral hemispheres and contains the cortical representations for the leg and perineum. [1] - Injury to the **left paracentral lobule** would therefore affect motor control on the contralateral side, specifically the **right leg and perineum**. *Left face* - Motor control for the face is primarily located in the **lateral aspects of the precentral gyrus**, not the paracentral lobule. - A left-sided lesion affecting the face would typically cause **contralateral (right) facial weakness**, not ipsilateral (left). *Right shoulder & trunk* - The motor cortex for the shoulder and trunk is located more **superior and lateral** in the precentral gyrus, distal to the paracentral lobule. - Injury to the paracentral lobule specifically spares these regions. *Right face* - As mentioned, the motor control for the face resides in the **lateral precentral gyrus**. - While this is the contralateral side, the specific anatomical location of the paracentral lobule does not typically involve the face.

Question 402: Fibers reaching directly to Purkinje cells of cerebellum arise from which of the following:

A. Locus ceruleus
B. Inferior olivary nucleus (Correct Answer)
C. Vestibular nucleus
D. Raphe nucleus

Explanation: ***Inferior olivary nucleus*** - The **inferior olivary nucleus** gives rise to **climbing fibers**, which form powerful **excitatory synapses** directly onto the **Purkinje cells** of the cerebellum [1]. - Each Purkinje cell receives input from a single climbing fiber, which produces a characteristic **complex spike** response [1]. *Locus ceruleus* - The **locus ceruleus** is a nucleus in the pons that is the primary source of **noradrenaline** in the brain. - Its fibers project widely throughout the cerebrum, cerebellum, and spinal cord, modulating neuronal activity rather than forming direct, primary excitatory synapses on Purkinje cells. *Vestibular nucleus* - The **vestibular nuclei** send mossy fiber inputs to the cerebellum, particularly to the **flocculonodular lobe** and uvula, influencing balance and eye movements [2]. - These are **mossy fibers**, not climbing fibers, and they synapse indirectly via granule cells onto Purkinje cells, not directly [1]. *Raphe nucleus* - The **raphe nuclei** are a group of serotonin-producing nuclei located in the brainstem. - They project widely throughout the central nervous system, including the cerebellum, impacting mood, sleep, and pain perception, but their fibers do not directly synapse on Purkinje cells in the manner of climbing fibers.

Question 403: Cranial nerve that is involved in olfaction:

A. Hypoglossal
B. Trigeminal (Correct Answer)
C. Glossopharyngeal
D. Vagus

Explanation: ***Trigeminal*** - The **trigeminal nerve (CN V)** carries sensory information from the face and contributes to olfactory perception through its **ophthalmic (V1) and maxillary (V2) divisions** [1]. - These divisions detect **chemical irritants, pungency, cooling, and warming sensations** in the nasal cavity (chemesthesis), contributing to the overall perception of smells. - Examples include the stinging sensation of **ammonia**, cooling of **menthol**, and burning of **capsaicin** - all part of the smell experience. - This is distinct from true olfaction (CN I) but is an essential component of how we perceive "smell" in daily life. *Hypoglossal* - The **hypoglossal nerve (CN XII)** is purely a **motor nerve** that controls the intrinsic and extrinsic muscles of the **tongue**. - It is essential for **speech, swallowing, and tongue movement** but has **no role in olfaction or smell perception**. *Glossopharyngeal* - The **glossopharyngeal nerve (CN IX)** mediates **taste sensation from the posterior third of the tongue**, swallowing, and salivation. - While important for taste, it has **no role in olfactory pathways or smell detection**. *Vagus* - The **vagus nerve (CN X)** has extensive **parasympathetic functions** and carries taste sensation from the **epiglottis and pharynx**. - It innervates thoracic and abdominal organs but is **not involved in olfactory perception**.

Question 404: Arrange the sequence of auditory pathway from peripheral to central: Inferior colliculus, Cochlear nucleus, Auditory cortex, Medial geniculate body

A. B>A>D>C (Correct Answer)
B. A>D>B>C
C. C>A>B>D
D. B>D>C>A

Explanation: ***B>A>D>C*** - This sequence represents the correct path of auditory information from the cochlea to the brain: **Cochlear nucleus** (B), then **Inferior colliculus** (A), followed by the **Medial geniculate body** (D), and finally the **Auditory cortex** (C) [1]. - This pathway allows for processing and integration of sound as it ascends through various brainstem and thalamic nuclei before reaching the cortex [1]. *A>D>B>C* - This sequence incorrectly places the **Inferior colliculus** (A) before the **Cochlear nucleus** (B) and the **Medial geniculate body** (D) before the Inferior colliculus, disrupting the normal ascending pathway. - The auditory signal originates from the cochlea and first synapses in the cochlear nucleus, not the inferior colliculus [1]. *C>A>B>D* - This sequence starts with the **Auditory cortex** (C), which is the final destination, indicating an inverted or incorrect order of information flow. - It also places the **Cochlear nucleus** (B) after the **Inferior colliculus** (A), which is the reverse of the true ascending pathway. *B>D>C>A* - This sequence correctly starts with the **Cochlear nucleus** (B) but then skips directly to the **Medial geniculate body** (D), omitting the **Inferior colliculus** (A) as an essential intermediate relay [1]. - It also places the **Auditory cortex** (C) before the Inferior colliculus, which is incorrect.

Question 405: Which of the following DOESN'T supply dura mater?

A. Middle meningeal artery
B. Meningeal branch of internal carotid artery in posterior cranial fossa (Correct Answer)
C. Anterior and posterior ethmoidal arteries
D. Accessory meningeal artery

Explanation: ***Meningeal branch of internal carotid artery in posterior cranial fossa*** - The **internal carotid artery** does give off meningeal branches (cavernous branches, tentorial branches), but these supply the dura mater in the **anterior** and **middle cranial fossae**, NOT the **posterior cranial fossa**. - The **posterior cranial fossa** dura is primarily supplied by meningeal branches from the **vertebral artery**, **ascending pharyngeal artery**, and **occipital artery**. - Therefore, a "meningeal branch of internal carotid artery in posterior cranial fossa" does not exist as a typical arterial supply to the dura mater. *Middle meningeal artery* - The **middle meningeal artery** is the **major blood supply** to the dura mater of the **middle cranial fossa**. - It enters the cranial cavity through the **foramen spinosum** and branches extensively over the lateral surface of the dura. - This is the most important meningeal artery clinically (often involved in epidural hematomas). *Anterior and posterior ethmoidal arteries* - The **anterior and posterior ethmoidal arteries** are branches of the **ophthalmic artery** that pass through the anterior and posterior ethmoidal foramina. - While they primarily supply the **nasal cavity** and **ethmoid sinuses**, they also contribute to the blood supply of the **dura mater** in the **anterior cranial fossa**, particularly around the **cribriform plate** region. - Therefore, these arteries DO supply dura mater. *Accessory meningeal artery* - The **accessory meningeal artery** typically originates from the **maxillary artery** (or sometimes the middle meningeal artery). - It enters the cranium via the **foramen ovale** and supplies the dura mater in the **middle cranial fossa**, particularly around the trigeminal ganglion and foramen ovale region.

Question 406: Which lobe of the brain is most involved in auditory processing?

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

Explanation: ***Temporal lobe*** - The **primary auditory cortex**, responsible for processing sounds, is located within the **temporal lobe** [1]. - It plays a crucial role in the interpretation of **speech** and other auditory stimuli [1]. *Parietal lobe* - Primarily involved in processing **sensory information** (touch, temperature, pain) and **spatial awareness**. - While it integrates sensory data, its direct role in initial auditory processing is minimal. *Occipital lobe* - This lobe is predominantly responsible for **visual processing**, containing the primary visual cortex. - It has no direct role in the initial processing of auditory information. *Frontal lobe* - The frontal lobe is involved in **executive functions**, **voluntary movement**, and **planning**. - Although it may process auditory information at a higher cognitive level, it is not the primary site for initial auditory processing.

Question 407: Which structure is NOT present in the floor of the inferior horn of the lateral ventricle?

A. Tail of the caudate nucleus (Correct Answer)
B. Fimbria
C. Hippocampus
D. Collateral eminence

Explanation: ***Tail of the caudate nucleus*** - The **tail of the caudate nucleus** is located in the **roof** of the inferior horn of the lateral ventricle, not in the floor. - It courses along the lateral aspect of the inferior horn, terminating in the **amygdaloid body** [1]. *Fimbria* - The **fimbria** is a prominent white matter bundle that forms part of the **floor** of the inferior horn of the lateral ventricle. - It consists of efferent fibers from the hippocampus, converging to form the **crus of the fornix**. *Hippocampus* - The **hippocampus** is a major structure in the **floor** of the inferior horn of the lateral ventricle, forming a distinctive bulge [1]. - It plays a critical role in **memory formation** and extends throughout the length of the inferior horn [1]. *Collateral eminence* - The **collateral eminence** is an elevation in the **floor** of the inferior horn, lateral to the hippocampus. - It is formed by the indentation of the collateral sulcus on the inferior surface of the temporal lobe.

Question 408: What does the foramen of Monro connect?

A. Subarachnoid space
B. Central canal
C. Third to fourth ventricle
D. Lateral ventricles to the third ventricle (Correct Answer)

Explanation: ***Lateral ventricles to the third ventricle*** - The **foramen of Monro**, also known as the interventricular foramen, serves as the communication pathway between each **lateral ventricle** and the **third ventricle**. - This connection allows for the flow of **cerebrospinal fluid (CSF)** from the lateral ventricles into the third ventricle [2]. *Subarachnoid space* - The **subarachnoid space** surrounds the brain and spinal cord and is connected to the ventricular system primarily via the **foramina of Luschka** and **Magendie**, not the foramen of Monro [1], [2]. - CSF flows from the fourth ventricle into the subarachnoid space, where it is eventually reabsorbed [2]. *Central canal* - The **central canal** is a cerebrospinal fluid-filled channel that runs through the spinal cord, and it is a caudal extension of the fourth ventricle. - It does not directly connect to the lateral or third ventricles via the foramen of Monro. *Third to fourth ventricle* - The connection between the **third ventricle** and the **fourth ventricle** is established by the **cerebral aqueduct** (also known as the aqueduct of Sylvius), not the foramen of Monro [3]. - The foramen of Monro connects the lateral ventricles to the third ventricle.

Question 409: Which artery supplies most of the lateral cerebral cortex?

A. Posterior cerebral
B. Anterior cerebral
C. Basilar artery
D. Middle cerebral (Correct Answer)

Explanation: ***Middle cerebral artery*** - The **middle cerebral artery (MCA)** is the largest of the three major arteries that supply the cerebral hemispheres and is a direct continuation of the **internal carotid artery** - It supplies blood to the **lateral surface** of the frontal, parietal, and temporal lobes, including areas responsible for motor and sensory functions of the **contralateral upper limb and face**, as well as **speech centers (Broca's and Wernicke's areas)** [1] - This represents the **largest territory** of any cerebral artery *Posterior cerebral artery* - The **posterior cerebral artery (PCA)** primarily supplies the **occipital lobe**, inferior temporal lobe, and parts of the thalamus and midbrain - It is responsible for **visual processing** and the medial temporal structures - It does **not** supply the lateral cortex [1] *Anterior cerebral artery* - The **anterior cerebral artery (ACA)** mainly supplies the **medial surface** of the frontal and parietal lobes, as well as the superior margin of the lateral surface [1] - It is crucial for motor and sensory function of the **contralateral lower limb** - It supplies a much **smaller portion** of the lateral cortex compared to the MCA *Basilar artery* - The **basilar artery** is formed by the union of the two vertebral arteries and supplies the **brainstem** and cerebellum - It terminates by dividing into the two posterior cerebral arteries - It does **not directly supply** the cerebral cortex but is part of the posterior circulation

Question 410: Which part of the brain is involved in regulating balance and coordination?

A. Cerebellum (Correct Answer)
B. Thalamus
C. Medulla
D. Cerebrum

Explanation: ***Cerebellum*** - The **cerebellum** plays a crucial role in coordinating voluntary movements, maintaining balance, and regulating muscle tone [1]. - It receives sensory input from the spinal cord and other parts of the brain and integrates this information to control fine motor skills and posture [1]. *Thalamus* - The **thalamus** primarily acts as a relay station for sensory information, sending it to the cerebral cortex for processing [2]. - It does not directly control balance or coordination, though it processes sensory data critical for these functions [2]. *Medulla* - The **medulla oblongata** primarily controls vital autonomic functions like breathing, heart rate, and blood pressure. - While it helps maintain posture, its primary role is not in the fine-tuning of balance and coordination. *Cerebrum* - The **cerebrum** is responsible for higher-level functions such as thought, voluntary movement, language, and perception. - While it initiates voluntary movements, the **cerebellum** is responsible for refining and coordinating these movements for balance and precision [1].

Practice by Chapter

Cerebral Hemispheres

Practice Questions

Diencephalon

Practice Questions

Brainstem

Practice Questions

Cerebellum

Practice Questions

Basal Ganglia

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Limbic System

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Ventricular System and CSF

Practice Questions

Blood Supply of the Brain

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Cranial Nerves and Nuclei

Practice Questions

Functional Systems and Pathways

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Applied Neuroanatomy

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Neuroimaging Correlations

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