Brain and Neuroanatomy — MCQs

Brain and Neuroanatomy Indian Medical PG Practice Questions and MCQs

Question 11: The lateral ventricle is connected to the third ventricle by which foramen?

A. Foramen of Monro (Correct Answer)
B. Foramen of Luschka
C. Foramen of Magendie
D. Median foramen

Explanation: The ventricular system of the brain is a series of communicating cavities filled with cerebrospinal fluid (CSF). The **Foramen of Monro** (also known as the interventricular foramen) is the correct answer because it serves as the anatomical conduit between the paired **lateral ventricles** (located in the cerebral hemispheres) and the midline **third ventricle** (located in the diencephalon). **Analysis of Incorrect Options:** * **Foramen of Luschka (B):** These are two **lateral** apertures in the fourth ventricle that allow CSF to flow into the subarachnoid space (specifically the pontine cistern) [1]. *Mnemonic: **L**uschka = **L**ateral.* * **Foramen of Magendie (C):** This is a single **median** aperture in the roof of the fourth ventricle that drains CSF into the cisterna magna [2]. *Mnemonic: **M**agendie = **M**edian.* * **Median Foramen (D):** This is simply another name for the Foramen of Magendie; it does not connect the lateral and third ventricles. **High-Yield Clinical Pearls for NEET-PG:** 1. **Flow of CSF:** Lateral Ventricle → *Foramen of Monro* → 3rd Ventricle → *Aqueduct of Sylvius* → 4th Ventricle → *Foramina of Luschka/Magendie* → Subarachnoid space [2]. 2. **Obstruction:** Narrowing or blockage of the Foramen of Monro (e.g., by a colloid cyst) leads to **non-communicating hydrocephalus**, causing dilation of the lateral ventricles while the third and fourth ventricles remain normal in size [1]. 3. **Boundaries:** The Foramen of Monro is bounded anteriorly by the column of the fornix and posteriorly by the anterior end of the thalamus.

Question 12: A 48-year-old woman presented with self-inflicted injuries, auditory hallucinations, and delusional disorder. A routine MRI revealed a tumor involving the posterior limb of the internal capsule and the structure medial to it. Which of the following structures are likely to be affected?

A. Globus pallidus
B. Putamen
C. Thalamus (Correct Answer)
D. Caudate nucleus

Explanation: Explanation: The **internal capsule** is a vital white matter structure containing projection fibers. To answer this question, one must understand the precise anatomical relations of its **posterior limb**. 1. **Why Thalamus is Correct:** The posterior limb of the internal capsule is bounded **medially by the Thalamus** and **laterally by the Lentiform nucleus** (comprising the Putamen and Globus Pallidus). Therefore, a tumor involving the posterior limb and the structure medial to it directly implicates the Thalamus. Clinically, the Thalamus acts as a sensory relay station [1]; however, lesions in the mediodorsal nucleus of the thalamus are also associated with neuropsychiatric symptoms like those described in the vignette. 2. **Why Incorrect Options are Wrong:** * **Globus Pallidus & Putamen (Options A & B):** These structures form the Lentiform nucleus [2], which lies **lateral** to the posterior limb of the internal capsule. * **Caudate Nucleus (Option D):** The head of the caudate nucleus is located **medial** to the **anterior limb** of the internal capsule, not the posterior limb. **High-Yield NEET-PG Pearls:** * **Anterior Limb Relations:** Medial = Caudate Head; Lateral = Lentiform Nucleus. * **Posterior Limb Relations:** Medial = Thalamus; Lateral = Lentiform Nucleus. * **Blood Supply:** The posterior limb is primarily supplied by the **Lenticulostriate arteries** (branches of MCA) and the **Anterior Choroidal artery**. * **Clinical Correlation:** A stroke in the posterior limb typically presents with **pure motor hemiplegia** because it carries the corticospinal tract [3].

Question 13: Which sulcus is also known as the operculated sulcus?

A. Central Sulcus
B. Lunate Sulcus (Correct Answer)
C. Collateral Sulcus
D. Calcarine Sulcus

Explanation: The **Lunate Sulcus** is a small, vertically oriented sulcus located on the lateral surface of the occipital lobe, just in front of the occipital pole. It is termed an **operculated sulcus** because its anterior lip (the operculum) overlaps the posterior part, burying the transition between the primary visual cortex (Area 17) and the visual association cortex (Area 18). It is more prominent in non-human primates and is often used as a landmark for the primary visual area. ### Explanation of Options: * **A. Central Sulcus (of Rolando):** This is a **limiting sulcus** that separates the motor cortex (precentral gyrus) from the sensory cortex (postcentral gyrus). It does not have an operculated structure. * **C. Collateral Sulcus:** This is a **ventral sulcus** located on the inferior surface of the temporal and occipital lobes. It is a **complete sulcus** because it produces an elevation (the collateral eminence) in the lateral ventricle. * **D. Calcarine Sulcus:** This is an **axial sulcus** located on the medial surface of the occipital lobe [1]. It is also a **complete sulcus**, as it produces the *calcar avis* in the posterior horn of the lateral ventricle. ### NEET-PG High-Yield Pearls: * **Types of Sulci:** * **Limiting Sulcus:** Separates two functionally different areas (e.g., Central Sulcus). * **Axial Sulcus:** Develops along the long axis of a functional area (e.g., Calcarine Sulcus) [1]. * **Operculated Sulcus:** One lip overlaps the other (e.g., Lunate Sulcus). * **Complete Sulcus:** Deep enough to cause an elevation in the ventricular cavity (e.g., Collateral and Calcarine sulci). * The Lunate sulcus marks the lateral boundary of the **Primary Visual Cortex (Brodmann Area 17)**.

Question 14: The indusium griseum is a thin layer of grey matter located on the superior surface of the corpus callosum. What is its anatomical relationship to the corpus callosum?

A. Lateral to the corpus callosum
B. Dorsal to the corpus callosum (Correct Answer)
C. Ventral to the corpus callosum
D. Medial to the corpus callosum

Explanation: Explanation: The **indusium griseum** (also known as the supracallosal gyrus) is a thin vestigial layer of grey matter that covers the **superior (dorsal) surface** of the corpus callosum. It is a component of the limbic system and represents the superior extension of the hippocampus. 1. **Why Option B is Correct:** In anatomical terminology, "dorsal" refers to the back or upper surface of a structure in the brain. Since the indusium griseum sits directly on top of the corpus callosum, it is positioned **dorsally**. Embedded within this layer are two longitudinal bundles of white matter fibers known as the **medial and lateral striae of Lancisi**. 2. **Why Other Options are Incorrect:** * **Lateral (A):** The indusium griseum is a midline structure covering the roof of the corpus callosum, not situated to its sides. * **Ventral (C):** The ventral (inferior) surface of the corpus callosum is related to the septum pellucidum and the fornix, not the indusium griseum. * **Medial (D):** As the indusium griseum is already a midline structure covering the entire width of the corpus callosum's superior surface, "medial" is an inaccurate description of its relative vertical position. **High-Yield NEET-PG Pearls:** * **Embryological Origin:** It is a vestigial part of the **hippocampal formation**. * **Continuity:** Anteriorly, it continues around the genu of the corpus callosum as the **paraterminal gyrus**. Posteriorly, it continues around the splenium as the **fasciolar gyrus**, which eventually leads into the dentate gyrus. * **White Matter Association:** Remember the **Striae of Lancisi**; these are the white matter tracts found within the indusium griseum.

Question 15: Which cranial nerve is involved in Weber syndrome?

A. II
B. III (Correct Answer)
C. IV
D. V

Explanation: **Explanation:** **Weber Syndrome** (Superior Alternating Hemiplegia) is a midbrain stroke syndrome typically caused by an occlusion of the paramedian branches of the **posterior cerebral artery**. **1. Why Option B is Correct:** The lesion involves the **ventral (anterior) midbrain**. This area contains the **oculomotor nerve (CN III) fascicles** [1] and the **cerebral peduncle** (containing the corticospinal and corticobulbar tracts). Damage to the CN III fibers results in an **ipsilateral** (same side) third nerve palsy, characterized by ptosis, a "down and out" eye, and a dilated pupil [1]. **2. Why Incorrect Options are Wrong:** * **Option A (CN II):** The optic nerve is part of the diencephalon and is not located in the midbrain. Lesions here cause visual field defects, not brainstem syndromes. * **Option C (CN IV):** The trochlear nerve nuclei are in the lower midbrain, but the nerve exits posteriorly. It is involved in syndromes affecting the dorsal midbrain (e.g., Parinaud syndrome), not the ventral aspect. * **Option D (CN V):** The trigeminal nerve nuclei span the brainstem, but the nerve exits at the level of the **pons**. Lesions here would suggest Millard-Gubler or Foville syndrome. **3. Clinical Pearls for NEET-PG:** * **The "Alternating" Rule:** Brainstem syndromes are "alternating" because they present with **ipsilateral** cranial nerve deficits and **contralateral** hemiplegia (due to damage to the corticospinal tract before it decussates in the medulla). * **Weber vs. Benedikt:** Both involve CN III. However, Weber involves the cerebral peduncle (hemiparesis), while **Benedikt syndrome** involves the red nucleus/substantia nigra (resulting in tremors/ataxia). * **Classic Presentation:** Ipsilateral CN III palsy [1] + Contralateral spastic paralysis.

Question 16: Which of the following are association fibers?

A. Uncinate fasciculus
B. Cingulum
C. Superior longitudinal fasciculus
D. Corpus callosum (Correct Answer)

Explanation: ### 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 the Correct Answer is Right:** * **Corpus Callosum (Option D):** This is the largest **commissural fiber** bundle in the brain [1]. Commissural fibers connect corresponding cortical areas between the **two different hemispheres** (left and right) [1]. Since the question asks for association fibers, and the Corpus Callosum is a commissural fiber, it stands out as the distinct category (Note: In many MCQ formats, the "correct" answer is the one that does *not* belong to the group mentioned in the stem). **2. Why the Other Options are Incorrect:** Association fibers connect different cortical areas within the **same hemisphere**. * **Uncinate Fasciculus (Option A):** A short association fiber connecting the orbitofrontal cortex to the anterior temporal lobe. * **Cingulum (Option B):** A long association fiber located within the cingulate gyrus, connecting the frontal and parietal lobes to the parahippocampal gyrus. * **Superior Longitudinal Fasciculus (Option C):** The longest association fiber, connecting the frontal, parietal, occipital, and temporal lobes. Its subset, the *arcuate fasciculus*, is vital for language (connecting Broca’s and Wernicke’s areas). **High-Yield Clinical Pearls for NEET-PG:** * **Corpus Callosum Parts:** From anterior to posterior: Rostrum, Genu, Body, and Splenium. * **Forceps Minor:** Fibers of the Genu connecting the frontal lobes. * **Forceps Major:** Fibers of the Splenium connecting the occipital lobes. * **Tapetum:** Fibers of the corpus callosum forming the roof and lateral wall of the posterior and inferior horns of the lateral ventricle. * **Clinical Correlation:** Lesions of the arcuate fasciculus lead to **Conduction Aphasia** (intact comprehension and speech, but inability to repeat words).

Question 17: Which Brodmann areas constitute Wernicke's area of speech?

A. 41, 42, 22
B. 22, 42, 39
C. 42, 41, 44
D. 22, 39, 40 (Correct Answer)

Explanation: ### Explanation **Wernicke’s area** is the sensory speech area responsible for the interpretation and comprehension of spoken and written language [1]. It is located in the dominant hemisphere (usually the left) at the junction of the temporal and parietal lobes [2]. **1. Why Option D is Correct:** Traditionally, Wernicke’s area is associated with the posterior part of the **Superior Temporal Gyrus (Brodmann Area 22)**. However, modern neuroanatomy and clinical practice include the adjacent regions of the inferior parietal lobule—specifically the **Supramarginal Gyrus (Area 40)** and the **Angular Gyrus (Area 39)**—as they are essential for processing complex linguistic information and reading [1]. Therefore, the combination of **22, 39, and 40** constitutes the functional Wernicke’s complex. **2. Analysis of Incorrect Options:** * **Option A & C:** Include **Areas 41 and 42**, which represent the **Primary Auditory Cortex** (Heschl’s gyri). While these areas receive sound, they do not interpret its linguistic meaning. * **Option C:** Also includes **Area 44**, which is part of **Broca’s area** (motor speech), located in the frontal lobe. * **Option B:** Includes Area 42 (auditory) but misses Area 40, making it an incomplete description of the sensory speech complex. **3. Clinical Pearls for NEET-PG:** * **Wernicke’s Aphasia (Sensory/Receptive):** Characterized by "word salad"—speech is fluent and effortless but lacks meaning [1]. The patient has poor comprehension and is often unaware of their deficit (**anosognosia**). * **Arcuate Fasciculus:** The white matter tract connecting Wernicke’s to Broca’s area [1]. Damage here leads to **Conduction Aphasia** (impaired repetition). * **Blood Supply:** Wernicke’s area is supplied by the **inferior division of the Middle Cerebral Artery (MCA)**.

Question 18: The posterior cerebral artery supplies all of the following except?

A. Pons (Correct Answer)
B. Midbrain
C. Thalamus
D. Striate cortex

Explanation: ### Explanation The **Posterior Cerebral Artery (PCA)** is the terminal branch of the basilar artery. It primarily supplies the posterior aspects of the brain, including the midbrain, thalamus, and the visual cortex. **Why Pons is the correct answer:** The **Pons** is supplied by the **Basilar artery** itself through its paramedian, short circumflex, and long circumflex (including the Superior Cerebellar Artery and AICA) branches. The PCA originates at the superior border of the pons but does not provide its primary blood supply. **Analysis of Incorrect Options:** * **Midbrain:** The PCA gives off small perforating branches (paramedian and circumflex) that supply the midbrain, particularly the cerebral peduncles and the tectum. * **Thalamus:** The PCA provides the **thalamoperforating** and **thalamogeniculate** arteries, which are the major blood supply to the posterior and lateral parts of the thalamus. * **Striate Cortex:** This is the primary visual area (Brodmann area 17) located in the occipital lobe. The **calcarine artery**, a major branch of the PCA, is the specific vessel supplying this region. **High-Yield Clinical Pearls for NEET-PG:** * **Macular Sparing:** In PCA territory infarcts, there is often contralateral homonymous hemianopia with **macular sparing** because the macular representation in the occipital pole receives a dual blood supply from both the PCA and the Middle Cerebral Artery (MCA). * **Weber’s Syndrome:** Often involves branches of the PCA/Basilar tip supplying the midbrain, leading to ipsilateral CN III palsy and contralateral hemiplegia. * **Thalamic Syndrome (Dejerine-Roussy):** Results from occlusion of the thalamogeniculate branches of the PCA, characterized by contralateral sensory loss followed by agonizing burning pain.

Question 19: What is the representation of the body in the cerebrum called?

A. Horizontal
B. Vertical (Correct Answer)
C. Tandem
D. Oblique

Explanation: The representation of the body in the cerebrum (specifically in the primary motor and sensory cortices) is described as **Vertical** because the body parts are mapped along the vertical axis of the precentral and postcentral gyri. This mapping is famously known as the **Homunculus** (Motor and Sensory) [1]. 1. **Why Vertical is Correct:** The body is represented in an **inverted (upside-down)** manner along the vertical extent of the cortex [1]. The head and face are represented at the lower (inferior/lateral) part of the gyrus, while the trunk and upper limbs are in the middle. The lower limbs and perineum are represented on the medial surface of the hemisphere (within the paracentral lobule) [1]. This vertical arrangement reflects the topographical organization of the cortex. 2. **Why Incorrect Options are Wrong:** * **Horizontal/Oblique:** These do not describe the anatomical orientation of the homunculus. The mapping follows the vertical curvature of the cerebral hemisphere from the lateral fissure up to the longitudinal fissure. * **Tandem:** This term refers to a "one-behind-the-other" arrangement (like tandem gait), which is irrelevant to cortical mapping. **High-Yield Clinical Pearls for NEET-PG:** * **The Homunculus is disproportionate:** The size of the cortical area is proportional to the **complexity of function** (e.g., fine motor control of fingers/lips) rather than the physical size of the body part [1]. * **Blood Supply Correlation:** The lateral aspect (face/upper limb) is supplied by the **Middle Cerebral Artery (MCA)**, while the medial aspect (lower limb/perineum) is supplied by the **Anterior Cerebral Artery (ACA)**. * **Paracentral Lobule:** This is the specific site for the "foot and micturition" centers on the medial surface.

Question 20: Mitral cells and periglomerular cells are seen in which part of the brain?

A. Medulla
B. Olfactory bulb (Correct Answer)
C. Primary visual cortex
D. Geniculate body

Explanation: **Explanation:** The correct answer is **B. Olfactory bulb**. The olfactory bulb is the primary relay station for the sense of smell. It contains a specialized structure called the **olfactory glomerulus**, where the axons of olfactory sensory neurons synapse with the dendrites of second-order neurons [2]. * **Mitral cells:** These are the primary output neurons of the olfactory bulb [2]. Their dendrites receive input within the glomeruli, and their axons form the olfactory tract, which travels to the primary olfactory cortex [2]. * **Periglomerular cells:** These are inhibitory interneurons that surround the glomeruli [4]. They play a crucial role in lateral inhibition, helping to sharpen the discrimination between different odors [4]. * **Tufted cells:** Another type of output neuron found in the olfactory bulb, similar to mitral cells but located more superficially [2]. **Why other options are incorrect:** * **Medulla:** Contains nuclei for cranial nerves (IX, X, XI, XII) and vital centers (respiratory/cardiovascular), but lacks the glomerular organization of the olfactory system. * **Primary visual cortex (V1):** Characterized by the "Stria of Gennari" and organized into six layers (notably a thick Layer IV), but does not contain mitral cells. * **Geniculate body:** The Lateral Geniculate Body (LGB) is for vision and the Medial Geniculate Body (MGB) is for hearing. They consist of layered relay neurons, not mitral or periglomerular cells. **High-Yield Facts for NEET-PG:** * **Olfactory Pathway:** It is the only sensory pathway that reaches the cerebral cortex without a mandatory relay in the **thalamus** [3]. * **Bowman’s Glands:** Located in the olfactory mucosa (not the bulb), these secrete mucus to dissolve odorants [1]. * **Regeneration:** Olfactory receptor neurons are unique as they are among the few neurons in the body that undergo continuous replacement throughout life [1].

Practice by Chapter

Cerebral Hemispheres

Practice Questions

Diencephalon

Practice Questions

Brainstem

Practice Questions

Cerebellum

Practice Questions

Basal Ganglia

Practice Questions

Limbic System

Practice Questions

Ventricular System and CSF

Practice Questions

Blood Supply of the Brain

Practice Questions

Cranial Nerves and Nuclei

Practice Questions

Functional Systems and Pathways

Practice Questions

Applied Neuroanatomy

Practice Questions

Neuroimaging Correlations

Practice Questions

Want unlimited practice?

Get full access to all questions, explanations, and performance tracking.

Start For Free