Brain and Neuroanatomy Practice Questions

Q: Corpus striatum includes all of the following except?

Amygdala. The **Corpus Striatum** is a major component of the basal ganglia, located deep within the cerebral hemispheres [1]. It is functionally and anatomically divided based on its phylogenetic development and structural connections. ### **Explanation of the Correct Answer** **D. Amygdala:** While the amygdala is anatomically located in the temporal lobe near the tail of the caudate nucleus, it is functionally part of the **Limbic System**, not the corpus striatum. It is primarily involved in emotional processing and fear responses rather than the motor control functions associated with the striatum. ### **Analysis of Incorrect Options** * **A. Caudate Nucleus:** This is a C-shaped structure that forms the "Neostriatum" along with the putamen [1]. It is a core component of the corpus striatum. * **B. Putamen:** This is the larger, lateral part of the lentiform nucleus [1]. Together with the caudate, it forms the **Striatum (Neostriatum)**. * **C. Globus Pallidus:** This is the smaller, medial part of the lentiform nucleus [1]. It is referred to as the **Paleostriatum**. ### **High-Yield NEET-PG Pearls** 1. **Lentiform Nucleus:** Composed of the Putamen + Globus Pallidus [1]. 2. **Striatum (Neostriatum):** Composed of the Caudate Nucleus + Putamen [1]. 3. **Corpus Striatum:** Composed of the Caudate Nucleus + Lentiform Nucleus (Putamen + Globus Pallidus). 4. **Internal Capsule:** The white matter fibers of the internal capsule pass through the corpus striatum, giving it a "striated" or striped appearance, which is the origin of its name. 5. **Clinical Correlation:** Degeneration of the striatum (specifically GABAergic neurons) is the hallmark of **Huntington’s Disease**, whereas loss of dopaminergic input to the striatum leads to **Parkinson’s Disease** [1].

Q: Which area is involved in memory deficit following a posterior cerebral artery embolism?

Hippocampal gyrus. ### Explanation **Correct Answer: B. Hippocampal gyrus** The **Posterior Cerebral Artery (PCA)** is the primary source of blood supply to the medial aspect of the temporal lobe and the occipital lobe. The **hippocampus** and the **parahippocampal gyrus**, located in the medial temporal lobe, are critical structures for the formation of new memories (anterograde memory) and spatial navigation. [1, 5] An embolism or infarct in the PCA territory leads to ischemia of these structures, resulting in significant memory deficits. [2] **Analysis of Incorrect Options:** * **A. Prefrontal cortex:** Supplied primarily by the **Anterior Cerebral Artery (ACA)**. It is involved in executive functions, personality, and social behavior, rather than primary memory consolidation. * **C. Angular gyrus:** Located in the parietal lobe (Brodmann area 39), it is supplied by the **Middle Cerebral Artery (MCA)**. Damage here typically results in Gerstmann syndrome (acalculia, agraphia, finger agnosia, and left-right disorientation). * **D. Superior temporal gyrus:** Contains Wernicke’s area (in the dominant hemisphere) and the primary auditory cortex. It is supplied by the **MCA**. Lesions here lead to sensory aphasia, not isolated memory loss. [3] **High-Yield Clinical Pearls for NEET-PG:** * **Visual Deficits:** The most common sign of a PCA infarct is **contralateral homonymous hemianopia with macular sparing** (due to collateral supply to the occipital pole from the MCA). * **Thalamic Syndrome:** PCA occlusion can involve the thalamus, leading to contralateral sensory loss followed by agonizing burning pain (Dejerine-Roussy syndrome). * **Bilateral PCA Infarct:** Can result in **Anton syndrome**, where a patient is cortically blind but denies their blindness (confabulation).

Q: Which nucleus is primarily involved in Alzheimer's disease?

Nucleus Basalis of Meynert. **Explanation:** **1. Nucleus Basalis of Meynert (Correct Answer):** Located in the substantia innominata of the basal forebrain, the Nucleus Basalis of Meynert (NBM) is the primary source of cholinergic (acetylcholine) innervation to the entire cerebral cortex. In **Alzheimer’s disease**, there is a selective and profound degeneration of these cholinergic neurons. This loss leads to a significant deficit in acetylcholine levels [2], which is directly linked to the cognitive decline and memory impairment seen in patients. Most current pharmacological treatments (Cholinesterase inhibitors like Donepezil) aim to compensate for this loss [1]. **2. Analysis of Incorrect Options:** * **Superior Salivary Nucleus:** This is a parasympathetic nucleus of the Facial Nerve (CN VII) located in the pons. It is responsible for the secretomotor supply to the submandibular, sublingual, and lacrimal glands. It has no role in cognitive function or Alzheimer's. * **Ventromedial Nucleus of Thalamus:** This nucleus is primarily involved in motor control, acting as a relay station for the basal ganglia and cerebellum to the motor cortex. (Note: The Ventromedial nucleus of the *Hypothalamus* is the satiety center; neither is linked to Alzheimer's). **Clinical Pearls for NEET-PG:** * **Neurotransmitter involved:** Acetylcholine (ACh) is decreased in Alzheimer’s [2]. * **Histopathological Hallmarks:** Amyloid plaques (extracellular) and Neurofibrillary tangles (intracellular, composed of hyperphosphorylated Tau protein) [2]. * **Early Sign:** Atrophy of the **Hippocampus** is often the earliest radiological sign of Alzheimer’s disease. * **Other Basal Forebrain Nuclei:** The Medial Septal Nucleus also provides cholinergic input, specifically to the hippocampus.

Q: Which of the following is NOT a part of the epithalamus?

Geniculate body. The **epithalamus** is the most dorsal part of the diencephalon, forming the roof of the third ventricle [1]. It primarily connects the limbic system to other parts of the brain. ### **Why "Geniculate Body" is the Correct Answer** The **Geniculate bodies** (Lateral and Medial) are components of the **Metathalamus**, not the epithalamus. * The **Lateral Geniculate Body (LGB)** is a relay station for the visual pathway [5]. * The **Medial Geniculate Body (MGB)** is a relay station for the auditory pathway [3]. ### **Analysis of Incorrect Options (Parts of Epithalamus)** * **A. Pineal body:** An endocrine gland that secretes melatonin and regulates circadian rhythms. It is the most prominent part of the epithalamus [1]. * **C. Trigonum habenulae:** A small triangular area containing the habenular nuclei. It serves as a relay station for olfactory and visceral pathways to the brainstem. * **D. Posterior commissure:** A rounded band of white fibers crossing the midline. It is vital for the **bilateral pupillary light reflex** [4]. ### **High-Yield NEET-PG Pearls** 1. **Diencephalon Components:** Thalamus, Hypothalamus, Epithalamus, and Metathalamus [2]. 2. **Habenular Nuclei:** Known as the "reward-negative" center; it integrates smell with emotional responses. 3. **Pineal Calcification:** Often visible on X-rays/CT scans after age 17; it serves as a useful midline marker for radiologists [1]. 4. **Parinaud’s Syndrome:** Compression of the **superior colliculi and posterior commissure** (often by a pineal tumor) leads to upward gaze palsy.

Q: The phenomenon of "sparing of the macula" is due to the collateral circulation between which of the following arteries?

Middle and posterior cerebral arteries. The phenomenon of **macular sparing** occurs in patients with a **Posterior Cerebral Artery (PCA) occlusion** resulting in contralateral homonymous hemianopia [1]. Despite the loss of the rest of the visual field, the central vision (macula) remains intact. **1. Why Option A is Correct:** The primary visual cortex (Brodmann area 17) is located in the occipital lobe [2]. While the majority of the visual cortex is supplied by the **Posterior Cerebral Artery (PCA)**, the extreme posterior pole—which represents the **macula** (central vision)—is a "watershed area." It receives a dual blood supply from both the **PCA** and the **Middle Cerebral Artery (MCA)**. If the PCA is occluded, the MCA provides sufficient collateral circulation to keep the macular representation functional [1]. **2. Why Other Options are Incorrect:** * **Option B & C:** The **Anterior Cerebral Artery (ACA)** primarily supplies the medial surface of the frontal and parietal lobes (motor and sensory areas for the lower limbs). It does not reach the occipital pole or contribute to the visual cortex. * **Option D:** While all three arteries form the Circle of Willis, the specific collateralization at the occipital pole involves only the MCA and PCA. **3. Clinical Pearls for NEET-PG:** * **Lesion Site:** Macular sparing is a hallmark of **occipital lobe lesions** (vascular) [1]. * **Macular Involvement:** If a patient has homonymous hemianopia *without* macular sparing, the lesion is likely in the **optic tract** or **lateral geniculate nucleus (LGN)**, where dual supply does not exist [2]. * **Cortical Representation:** The macula occupies a disproportionately large area of the primary visual cortex (cortical magnification), making it more resilient to small focal insults [1].

Q: All of the following are true about the branches of the internal carotid artery EXCEPT:

Posterior communicating artery arises in the petrous part.. To master the branches of the **Internal Carotid Artery (ICA)**, it is essential to categorize them by the segment from which they originate. The ICA is divided into four main parts: Cervical, Petrous, Cavernous, and Cerebral. ### Why Option C is the Correct Answer The **Posterior Communicating Artery (PCoA)** arises from the **Cerebral (Supraclinoid) part** of the ICA, not the petrous part. It forms a vital link in the Circle of Willis by connecting the ICA to the Posterior Cerebral Artery. ### Analysis of Other Options * **A. Anterior choroidal artery:** This is a branch of the **Cerebral part**. It is a small but high-yield vessel that supplies the internal capsule and optic tract. * **B. Ophthalmic artery:** This is the **first branch** of the **Cerebral part**. It enters the orbit through the optic canal to supply the eye. * **D. Caroticotympanic artery:** This is a small branch that arises from the **Petrous part** within the carotid canal to supply the tympanic cavity. ### High-Yield NEET-PG Clinical Pearls * **Cervical Part:** Has **no branches** in the neck. * **Petrous Part:** Gives off the Caroticotympanic and Pterygoid (Vidian) arteries. * **Cavernous Part:** Gives off the Cavernous branches and the **Inferior Hypophyseal artery**. * **Cerebral Part:** Mnemonic **"OPAAM"** (Ophthalmic, Posterior communicating, Anterior choroidal, Anterior cerebral, and Middle cerebral arteries). * **Clinical Correlation:** An aneurysm of the **Posterior Communicating Artery** is the most common cause of **isolated 3rd Nerve Palsy** (Mydriasis + Ptosis + "Down and Out" eye).

Q: Which of the following muscles or structures is supplied by the third cranial nerve (oculomotor nerve)?

Inferior oblique muscle. The **Oculomotor nerve (CN III)** is the primary motor nerve for eye movements. It originates from the midbrain and supplies four of the six extraocular muscles, as well as the levator palpebrae superioris. [2] ### Why the Correct Answer is Right: The **Inferior Oblique muscle** is supplied by the **inferior division** of the Oculomotor nerve. [2] This nerve also supplies the Superior Rectus, Inferior Rectus, and Medial Rectus muscles. Its primary action is to elevate, abduct, and laterally rotate the eyeball. [2], [3] ### Why the Other Options are Wrong: * **A. Superior Oblique:** This muscle is supplied by the **Trochlear nerve (CN IV)**. (Mnemonic: SO4). [3] * **C. Lateral Rectus:** This muscle is supplied by the **Abducens nerve (CN VI)**. (Mnemonic: LR6). [2] * **D. Dilator Pupillae:** This muscle is under **sympathetic** control (from the superior cervical ganglion). In contrast, CN III carries *parasympathetic* fibers to the **Sphincter pupillae** and **Ciliary muscle** via the ciliary ganglion. [1] ### NEET-PG High-Yield Pearls: * **Mnemonic for Extraocular Supply:** **LR6SO4R3** (Lateral Rectus by 6, Superior Oblique by 4, Rest by 3). * **Clinical Presentation of CN III Palsy:** Characterized by **"Down and Out"** eye position, ptosis (drooping eyelid), and a dilated, non-reactive pupil (mydriasis). * **Surgical Importance:** The nerve to the inferior oblique also carries the preganglionic parasympathetic fibers to the ciliary ganglion. * **Weber’s Syndrome:** A midbrain stroke affecting the CN III fascicles and the cerebral peduncle, leading to ipsilateral CN III palsy and contralateral hemiplegia.

Q: Which layer of the retina continues as the optic nerve?

Nerve fibre layer. ### Explanation The retina consists of ten distinct layers. The formation of the optic nerve is a high-yield anatomical concept involving the innermost functional layers of the retina [1]. **Why the Nerve Fibre Layer is correct:** The **Nerve Fibre Layer (Stratum opticum)** is composed of the unmyelinated axons of the ganglion cells [3]. these axons converge at the optic disc, where they pierce the sclera (through the lamina cribrosa). Once they exit the eyeball, they acquire a myelin sheath (provided by oligodendrocytes) and collectively form the **Optic Nerve (Cranial Nerve II)**. Therefore, the nerve fibre layer is the direct anatomical precursor to the optic nerve [2]. **Analysis of Incorrect Options:** * **A. Ganglionic cell layer:** This layer contains the cell bodies of the second-order neurons of the visual pathway. While the axons *originating* here form the optic nerve, the layer itself consists of cell bodies, not the fibers that continue as the nerve [3]. * **C. Internal limiting layer:** This is the innermost layer of the retina, forming a basement membrane that separates the retina from the vitreous humor. It is formed by the expanded footplates of Müller cells. * **D. External limiting layer:** This is a fenestrated membrane situated between the photoreceptor layer and the outer nuclear layer; it does not contribute to the optic nerve. **NEET-PG High-Yield Pearls:** * **Order of Neurons:** Photoreceptors (1st order) → Bipolar cells (2nd order) → Ganglion cells (3rd order) [4]. * **Optic Disc:** Known as the "blind spot" because it lacks photoreceptors. * **Myelination:** The optic nerve is technically a tract of the CNS, not a peripheral nerve, which is why it is myelinated by **oligodendrocytes** and susceptible to Multiple Sclerosis. * **Müller Cells:** These are the principal glial cells of the retina, extending almost the entire thickness of the retina.

Question 1

Corpus striatum includes all of the following except?

Accepted Answer

Amygdala

Answer

Caudate nucleus

Answer

Putamen

Answer

Globus pallidus

Question 2

Which area is involved in memory deficit following a posterior cerebral artery embolism?

Accepted Answer

Hippocampal gyrus

Answer

Prefrontal cortex

Answer

Angular gyrus

Answer

Superior temporal gyrus

Question 3

Which nucleus is primarily involved in Alzheimer's disease?

Accepted Answer

Nucleus Basalis of Meynert

Answer

Superior salivary nucleus

Answer

Ventromedial nucleus of thalamus

Answer

All of the above

Question 4

Which of the following is NOT a part of the epithalamus?

Accepted Answer

Geniculate body

Answer

Pineal body

Answer

Trigonum habenulae

Answer

Posterior commissure

Question 5

The phenomenon of "sparing of the macula" is due to the collateral circulation between which of the following arteries?

Accepted Answer

Middle and posterior cerebral arteries

Answer

Anterior and middle cerebral arteries

Answer

Anterior and posterior cerebral arteries

Answer

Anterior, middle, and posterior cerebral arteries

Question 6

Which of the following nerve fibers are present in the genu of the internal capsule?

Accepted Answer

Sensory fibers from the thalamus to the cortex

Answer

Motor fibers from the lower limb

Answer

Motor fibers from the upper limb

Answer

Motor fibers from the trunk

Question 7

Efferents from the cochlear nucleus arise for which of the following structures?

Accepted Answer

Superior olivary nucleus

Answer

Inferior colliculus

Answer

Medial geniculate body

Answer

Lateral lemniscus

Question 8

All of the following are true about the branches of the internal carotid artery EXCEPT:

Accepted Answer

Posterior communicating artery arises in the petrous part.

Answer

Anterior choroidal artery arises in the cerebral part.

Answer

Ophthalmic artery arises in the cerebral part.

Answer

Caroticotympanic artery arises in the petrous part.

Question 9

Which of the following muscles or structures is supplied by the third cranial nerve (oculomotor nerve)?

Accepted Answer

Inferior oblique muscle

Answer

Superior oblique muscle

Answer

Lateral rectus muscle

Answer

Dilator pupillae muscle

Question 10

Which layer of the retina continues as the optic nerve?

Accepted Answer

Nerve fibre layer

Answer

Ganglionic cell layer

Answer

Internal limiting layer

Answer

External limiting layer

Brain and Neuroanatomy — MCQs

Brain and Neuroanatomy — MCQs

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