Brain and Neuroanatomy — MCQs

Brain and Neuroanatomy Indian Medical PG Practice Questions and MCQs

Question 141: Which of the following areas is located in the temporal lobe?

A. Primary visual area
B. Primary auditory area (Correct Answer)
C. Broca's area
D. Prefrontal area

Explanation: **Explanation:** The **Primary Auditory Area (Brodmann areas 41 and 42)** is located in the superior temporal gyrus of the **temporal lobe**, specifically within the transverse temporal gyri (Heschl’s gyri) [2]. It is responsible for receiving and processing auditory information from the cochlea via the medial geniculate body of the thalamus [2]. **Analysis of Incorrect Options:** * **A. Primary Visual Area (Brodmann area 17):** Located in the **occipital lobe**, specifically in the walls of the calcarine sulcus. It receives visual input from the lateral geniculate body. * **C. Broca’s Area (Brodmann areas 44 and 45):** Located in the inferior frontal gyrus of the **frontal lobe** (usually in the dominant hemisphere). It is responsible for motor speech production. * **D. Prefrontal Area:** Located in the anterior part of the **frontal lobe**. It is involved in complex cognitive behavior, personality expression, and decision-making. **High-Yield Facts for NEET-PG:** * **Wernicke’s Area (Brodmann area 22):** Also located in the posterior part of the superior temporal gyrus [1]; it is crucial for the comprehension of speech [1]. * **Meyer’s Loop:** Part of the visual radiation that passes through the **temporal lobe**; a lesion here results in "pie in the sky" appearance (superior quadrantanopia). * **Klüver-Bucy Syndrome:** Results from bilateral lesions of the anterior temporal lobes (including the amygdala), characterized by hyperorality, hypersexuality, and docility.

Question 142: All of the following cortical areas contribute fibers to the corticospinal tract, EXCEPT?

A. Primary motor cortex (precentral gyrus)
B. Premotor cortex
C. Inferior temporal cortex (Correct Answer)
D. Primary somatosensory cortex (postcentral gyrus)

Explanation: Explanation: The **corticospinal tract (CST)**, or the pyramidal tract, is the primary pathway for voluntary motor control. It originates from various areas of the cerebral cortex, descends through the internal capsule and brainstem, and synapses in the spinal cord [1]. **Why Inferior Temporal Cortex is the Correct Answer:** The **inferior temporal cortex** is primarily involved in high-level visual processing (such as object and face recognition) and language. It belongs to the "ventral stream" of visual processing and does **not** contribute motor or sensory fibers to the descending corticospinal system. **Analysis of Other Options:** * **Primary Motor Cortex (Area 4):** This is the major contributor, providing approximately **30-40%** of the CST fibers, including the large pyramidal cells of Betz [1]. * **Premotor and Supplementary Motor Areas (Area 6):** These areas contribute another **30%** of the fibers, involved in planning and sequencing complex movements [1], [2]. * **Primary Somatosensory Cortex (Areas 3, 1, 2):** Surprisingly to many students, the postcentral gyrus contributes about **30-40%** of CST fibers [1]. These fibers terminate in the dorsal horn of the spinal cord and function to modulate sensory input (sensory gating) during movement. **NEET-PG High-Yield Pearls:** 1. **Origin Breakdown:** Roughly 1/3 from Area 4, 1/3 from Area 6, and 1/3 from Areas 3, 1, 2 [1]. 2. **Betz Cells:** These giant pyramidal cells are unique to the primary motor cortex but only account for about 3% of the total CST fibers. 3. **Decussation:** 80-90% of fibers cross at the **lower medulla** to form the Lateral Corticospinal Tract; the remainder form the Anterior Corticospinal Tract [1], [3]. 4. **Internal Capsule:** CST fibers occupy the **posterior limb** of the internal capsule.

Question 143: Pure word blindness occurs due to lesion in which artery?

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

Explanation: **Explanation:** **Pure word blindness**, also known as **Alexia without Agraphia**, is a clinical syndrome where a patient can write but cannot read what they have written [1]. This occurs due to a lesion in the **Posterior Cerebral Artery (PCA)**, specifically involving the **left primary visual cortex** and the **splenium of the corpus callosum**. 1. **Why PCA is correct:** The PCA supplies the occipital lobe and the splenium [3]. A stroke in the left PCA causes a right homonymous hemianopia (loss of the right visual field) [2]. Because the splenium is also infarcted, visual information from the intact right occipital lobe cannot cross over to the language centers (Angular gyrus) in the left hemisphere [1]. Thus, the patient can see words but cannot process or "read" them. 2. **Why other options are incorrect:** * **Anterior Cerebral Artery (ACA):** Supplies the medial surface of the frontal and parietal lobes. Lesions typically result in contralateral lower limb weakness and urinary incontinence. * **Middle Cerebral Artery (MCA):** Supplies the lateral convexity of the brain, including Broca’s and Wernicke’s areas [1]. An MCA stroke would typically cause **Aphasia** (difficulty speaking or understanding) and **Agraphia** (inability to write), rather than pure word blindness. * **Spinal Artery:** Supplies the spinal cord; it has no role in higher cortical functions like reading or vision. **High-Yield Clinical Pearls for NEET-PG:** * **Dejerine Syndrome:** Another name for Alexia without Agraphia. * **Angular Gyrus Lesion:** Results in **Alexia WITH Agraphia** (Gerstmann Syndrome), usually involving the MCA territory [1]. * **Macular Sparing:** A classic sign of PCA territory infarcts due to collateral supply from the MCA to the occipital pole.

Question 144: The central sulcus is an example of which type of sulcus?

A. Limiting sulcus (Correct Answer)
B. Axial sulcus
C. Operculated sulcus
D. Complete sulcus

Explanation: The classification of cerebral sulci is based on their developmental and functional characteristics. **1. Why "Limiting Sulcus" is correct:** A **limiting sulcus** is one that separates two functionally and histologically distinct areas of the cerebral cortex. The **central sulcus (of Rolando)** is the classic example because it acts as the boundary between the **motor cortex** (Precentral gyrus, Area 4) and the **sensory cortex** (Postcentral gyrus, Areas 3, 1, 2) [1]. **2. Why other options are incorrect:** * **Axial Sulcus:** This develops along the long axis of a rapidly growing functional area. It does not separate different areas but lies within one. *Example: Posterior part of the calcarine sulcus.* * **Operculated Sulcus:** This occurs when the lips of the sulcus (opercula) hide a third area of cortex in its depths. *Example: The lunate sulcus (separating striate and parastriate areas).* * **Complete Sulcus:** This is deep enough to produce an elevation in the wall of the lateral ventricle. *Examples: Collateral sulcus (producing the collateral eminence) and the anterior part of the calcarine sulcus (producing the calcar avis).* **Clinical Pearls & High-Yield Facts for NEET-PG:** * **Central Sulcus:** It is the only sulcus that indents the superomedial border of the hemisphere [1]. It usually does not meet the lateral sulcus. * **Functional Boundary:** It separates the frontal lobe from the parietal lobe [2]. * **Development:** Most sulci appear between the 4th and 6th months of intrauterine life. * **Primary Sulci:** These are constant and develop first (e.g., Central, Lateral, and Parieto-occipital sulci).

Question 145: Dural hemorrhage is seen in which organ?

A. Brain (Correct Answer)
B. Kidney
C. Heart
D. Lung

Explanation: **Explanation:** The correct answer is **A. Brain**. **1. Why Brain is Correct:** The term "Dural" refers to the **Dura Mater**, which is the outermost, toughest, and most fibrous layer of the three meninges surrounding the brain and spinal cord [1]. Dural hemorrhages occur due to the rupture of blood vessels associated with this layer [1]. The two primary types are: * **Extradural (Epidural) Hemorrhage:** Usually caused by trauma to the pterion, leading to the rupture of the **middle meningeal artery**. It occurs between the skull bone and the dura mater [1]. * **Subdural Hemorrhage:** Caused by the tearing of **bridging veins** that drain into the dural venous sinuses [1]. It occurs between the dura mater and the arachnoid mater [2]. **2. Why Other Options are Incorrect:** * **Kidney, Heart, and Lung:** These organs are surrounded by their own specific serous membranes—the **Renal Capsule**, **Pericardium**, and **Pleura**, respectively. They do not possess a "dura mater"; therefore, a "dural hemorrhage" is anatomically impossible in these locations. **3. NEET-PG High-Yield Clinical Pearls:** * **Extradural Hemorrhage (EDH):** Characteristically shows a **biconvex (lens-shaped)** hyperdensity on a CT scan and is often associated with a **"Lucid Interval"** (a period of temporary consciousness before clinical deterioration). * **Subdural Hemorrhage (SDH):** Appears as a **crescent-shaped** (concavo-convex) hyperdensity on a CT scan [2]. It is more common in elderly patients due to cerebral atrophy stretching the bridging veins. * **Dural Venous Sinuses:** These are endothelium-lined channels located between the periosteal and meningeal layers of the dura mater, responsible for draining venous blood from the brain [1].

Question 146: The primary visual area is located in the walls of which structure?

A. Parieto-occipital sulcus
B. Superior temporal sulcus
C. Posterior part of the calcarine sulcus (Correct Answer)
D. Central sulcus

Explanation: ### Explanation **Correct Option: C. Posterior part of the calcarine sulcus** The **Primary Visual Area (Brodmann area 17)** is located on the medial surface of the occipital lobe. It occupies the upper and lower lips (walls) of the **calcarine sulcus** [1]. Specifically, the posterior part of the calcarine sulcus represents the **macula** (central vision), while the anterior part represents the peripheral visual field [1]. This area receives visual information from the lateral geniculate body via the optic radiations [2]. **Analysis of Incorrect Options:** * **A. Parieto-occipital sulcus:** This sulcus marks the boundary between the parietal and occipital lobes. While it meets the calcarine sulcus, it does not house the primary visual cortex; instead, it serves as a landmark for the precuneus and cuneus. * **B. Superior temporal sulcus:** Located in the temporal lobe, this area is involved in auditory processing and social perception (e.g., biological motion), not primary vision. * **C. Central sulcus:** This is a landmark of the lateral surface of the brain, separating the frontal lobe (Motor cortex - Area 4) from the parietal lobe (Sensory cortex - Areas 3, 1, 2) [3]. **High-Yield Clinical Pearls for NEET-PG:** * **Blood Supply:** The primary visual cortex is supplied by the **posterior cerebral artery (PCA)**. * **Macular Sparing:** In cases of PCA occlusion, the posterior part of the visual cortex (macular area) often remains functional because it receives a collateral blood supply from the **middle cerebral artery (MCA)**. * **Histology:** Area 17 is also known as the **Striate Cortex** due to the presence of the white line of Gennari (a thickened layer IV) [1]. * **Visual Association Areas:** Areas 18 and 19 surround area 17 and are responsible for the interpretation and recognition of visual stimuli.

Question 147: A lesion of which artery may cause oxygen deficiency to the medial surface of the frontal and parietal lobes of the brain, assuming collateral circulations are discounted?

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

Explanation: ***Artery C (Anterior Cerebral Artery)*** - The **anterior cerebral artery (ACA)** specifically supplies the **medial surface** of the frontal and parietal lobes, making it the correct answer for oxygen deficiency in this region. - ACA territory infarction causes **contralateral lower limb weakness** with a leg > arm pattern due to the **motor homunculus** representation on the medial surface of the precentral gyrus. *Artery A* - This likely represents the **middle cerebral artery (MCA)**, which supplies the **lateral surface** of the frontal and parietal lobes, not the medial surface. - MCA territory infarction typically causes **contralateral hemiparesis** with arm > leg weakness and **aphasia** if the dominant hemisphere is affected. *Artery B* - This could represent the **posterior cerebral artery (PCA)**, which supplies the **occipital lobe** and **inferior temporal lobe**, not the medial frontal and parietal regions. - PCA territory infarction results in **visual field defects** (homonymous hemianopia) and potential **memory impairment** if the hippocampus is involved. *Artery D* - This likely represents another cerebral vessel such as the **posterior inferior cerebellar artery (PICA)** or **vertebral artery**, which do not supply the cerebral cortex. - These arteries supply the **brainstem** and **cerebellum**, causing symptoms like **ataxia**, **vertigo**, and **cranial nerve deficits** when occluded.

Question 148: Anomic aphasia is due to a defect in which area of the brain?

A. Left inferior frontal lobe
B. Parietal lobe
C. Temporal-occipital region (Correct Answer)
D. Cerebellum

Explanation: **Explanation:** **Anomic aphasia** is characterized by a persistent inability to retrieve names for objects, people, or events, despite having fluent speech, intact repetition, and good comprehension. 1. **Why the Temporal-occipital region is correct:** The retrieval of nouns and names depends on the integration of visual recognition and language processing. The **angular gyrus** and the **junction of the temporal and occipital lobes** (specifically the inferior temporal cortex) are critical for "lexical retrieval." [1] Lesions in the temporal-occipital region disrupt the pathways that connect visual representations to their linguistic labels, leading to the isolated naming deficits seen in anomic aphasia. 2. **Analysis of Incorrect Options:** * **A. Left inferior frontal lobe:** This is the site of **Broca’s area** (Brodmann areas 44, 45). Damage here results in Broca’s aphasia, characterized by non-fluent, "telegraphic" speech and impaired repetition. [1] * **B. Parietal lobe:** While the angular gyrus is in the parietal lobe, isolated parietal lesions more commonly present with **Gerstmann Syndrome** (acalculia, agraphia, finger agnosia, right-left disorientation) rather than pure anomic aphasia. * **D. Cerebellum:** The cerebellum is primarily involved in motor coordination and balance. While it has some cognitive roles, it is not a primary site for language processing or naming. **High-Yield Clinical Pearls for NEET-PG:** * **Anomia** is the most common residual symptom of all recovering aphasias. * **Broca’s Aphasia:** Non-fluent, Repetition impaired, Comprehension intact. * **Wernicke’s Aphasia:** Fluent (word salad), Repetition impaired, Comprehension impaired. * **Conduction Aphasia:** Damage to the **arcuate fasciculus**; hallmark is severely impaired repetition with intact fluency and comprehension. [1]

Question 149: Association fibers include all of the following except?

A. Corona Radiata (Correct Answer)
B. Arcuate fasciculus
C. Cingulum
D. Uncinate fasciculus

Explanation: White matter fibers in the brain are classified into three types based on the regions they connect: **Association fibers**, **Commissural fibers**, and **Projection fibers**. 1. **Why Corona Radiata is the correct answer:** The **Corona Radiata** consists of **Projection fibers**. These fibers connect the cerebral cortex with lower centers such as the brainstem, thalamus, and spinal cord (e.g., the corticospinal tract). Because it connects the cortex to non-cortical areas rather than connecting different parts of the same hemisphere, it is not an association fiber. 2. **Analysis of Incorrect Options (Association Fibers):** Association fibers connect different cortical areas within the **same hemisphere** [1]. * **Arcuate fasciculus:** A long association fiber connecting the frontal lobe (Broca’s area) with the temporal lobe (Wernicke’s area). * **Cingulum:** A tract located within the cingulate gyrus, connecting the frontal and parietal lobes to the parahippocampal gyrus. * **Uncinate fasciculus:** A hook-shaped bundle connecting the orbital frontal cortex to the anterior temporal lobe. **High-Yield NEET-PG Pearls:** * **Short Association Fibers:** Also called "U-fibers," they connect adjacent gyri. * **Long Association Fibers:** Include the Superior/Inferior Longitudinal fasciculi, Cingulum, and Uncinate fasciculus. * **Commissural Fibers:** Connect corresponding areas of the **two hemispheres** (e.g., Corpus Callosum, Anterior Commissure). * **Clinical Correlation:** Damage to the **Arcuate fasciculus** leads to **Conduction Aphasia**, where the patient has fluent speech but poor repetition.

Question 150: Which function is primarily associated with the neocerebellum?

A. Eye movements
B. Motor planning (Correct Answer)
C. Equilibrium
D. Motor execution

Explanation: The cerebellum is functionally divided into three parts: the Vestibulocerebellum, Spinocerebellum, and Neocerebellum (Cerebrocerebellum) [1]. **1. Why "Motor Planning" is Correct:** The **Neocerebellum** (Cerebrocerebellum) consists of the lateral parts of the cerebellar hemispheres [1]. It receives its major input from the cerebral cortex via the pontine nuclei (corticopontocerebellar pathway) and sends output to the thalamus and motor cortex. Its primary role is the **planning, programming, and timing of complex, skilled movements** before they are executed [1]. **2. Why Other Options are Incorrect:** * **A & C (Eye movements and Equilibrium):** These are the primary functions of the **Vestibulocerebellum** (Flocculonodular lobe) [1]. It maintains balance and coordinates head and eye movements via connections with the vestibular nuclei [1]. * **D (Motor execution):** This is the primary function of the **Spinocerebellum** (Vermis and Paravermis) [1]. It receives sensory feedback from the spinal cord and coordinates the execution of ongoing movements by regulating muscle tone and posture [1]. **3. High-Yield Clinical Pearls for NEET-PG:** * **Lesion of Neocerebellum:** Results in **Neocerebellar Syndrome**, characterized by the "DANISH" triad: **D**ysmetria (past-pointing), **A**taxia, **N**ystagmus, **I**ntention tremor, **S**lurring of speech (scanning speech), and **H**ypotonia/Adiadochokinesia [2]. * **Evolutionary Classification:** * Archicerebellum = Vestibulocerebellum * Paleocerebellum = Spinocerebellum * Neocerebellum = Cerebrocerebellum * **Deep Nuclei:** The Neocerebellum primarily communicates through the **Dentate nucleus** (the largest and most lateral nucleus). Remember the mnemonic: **"Don't Eat Greasy Food"** (Lateral to Medial: Dentate, Emboliform, Globose, Fastigial).

Practice by Chapter

Cerebral Hemispheres

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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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