Brain and Neuroanatomy Practice Questions

Q: Identify the marked structure.

Corpus callosum. ***Corpus callosum*** - The **corpus callosum** is a prominent, thick bundle of white matter fibers that connects the two cerebral hemispheres, located just superior to the **lateral ventricles** and **septum pellucidum**. - It is typically identified in sagittal brain imaging as a C-shaped structure forming the roof of the **lateral ventricles** and contributing to the **major commissures** of the brain. *Septum pellucidum* - The **septum pellucidum** is a thin, triangular, vertical membrane that separates the anterior horns of the left and right **lateral ventricles**. - It is located inferior to the body of the **corpus callosum** and superior to the **fornix**, rather than being the large, dense band of fibers itself. *Globus pallidus* - The **globus pallidus** is a subcortical structure located deep within the cerebral hemispheres, specifically medial to the **putamen** in the **lentiform nucleus**. - It is a key component of the **basal ganglia** involved in motor control and is not part of the midline sagittal structures typically identified in this context. *Fornix* - The **fornix** is a C-shaped bundle of nerve fibers in the brain that acts as the primary output tract from the **hippocampus** to the **mammillary bodies**. - It follows an arch-like course inferior to the **septum pellucidum** and is distinct from the **corpus callosum** which lies superior to the ventricles.

Q: Identify the marked structure:

Body. ***Body*** - It is the central and largest portion of the **corpus callosum**, situated between the **genu** anteriorly and the **splenium** posteriorly. - It forms the roof of the **lateral ventricles** and connects the cortical areas of the frontal and parietal lobes across the midline. *Rostrum* - This is the thin, beak-like extension located most anteriorly and inferiorly, continuous with the **lamina terminalis**. - It represents the most anterior and inferior part of the **corpus callosum**, positioned ahead of the genu. *Splenium* - This is the thick, posterior-most bulbous part of the **corpus callosum** that overhangs the **midbrain**. - It contains fibers that primarily interconnect the **occipital lobes** and the temporal lobes. *Genu* - This is the anterior, knee-shaped bend of the **corpus callosum** that connects the two **frontal lobes**. - It is located between the rostrum and the body, serving as a distinct anatomical landmark in the midline sagittal section of the brain.

Q: Which artery supplies the deep cerebellar nuclei?

Superior cerebellar artery. **Explanation:** The **Superior Cerebellar Artery (SCA)** is the primary blood supply to the **deep cerebellar nuclei** (Dentate, Emboliform, Globose, and Fastigial). Arising from the distal part of the basilar artery, the SCA supplies the superior surface of the cerebellar cortex, the superior cerebellar peduncle, and the deep-seated nuclei before they project to the thalamus and red nucleus. **Analysis of Options:** * **Superior Cerebellar Artery (Correct):** It provides the deep penetrating branches that reach the cerebellar core and nuclei. * **Anterior Inferior Cerebellar Artery (AICA):** Supplies the anterior-inferior surface of the cerebellum, the middle cerebellar peduncle, and the CN VII and VIII nerves. It does not typically supply the deep nuclei. * **Anterior Spinal Artery:** Supplies the anterior two-thirds of the spinal cord and the medial medulla (including the pyramids and medial lemniscus). * **Posterior Cerebral Artery (PCA):** Supplies the visual cortex (occipital lobe) and the inferior surface of the temporal lobe. While it is part of the Circle of Willis, it does not supply the cerebellum. **High-Yield Facts for NEET-PG:** * **The Dentate Nucleus** is the largest and most clinically significant deep nucleus; its blood supply is almost exclusively from the **SCA**. * **PICA (Posterior Inferior Cerebellar Artery)** supplies the postero-inferior surface and the **Lateral Medulla**. Occlusion leads to **Wallenberg Syndrome**. * **AICA** occlusion leads to **Lateral Pontine Syndrome**, uniquely characterized by **ipsilateral facial paralysis and deafness** (due to involvement of CN VII, VIII, and the labyrinthine artery). * **Rule of Thumb:** The SCA supplies the "top," AICA the "middle/front," and PICA the "bottom/back" of the cerebellum.

Q: Which thalamic nucleus projects to the striatum?

Centromedian nucleus. The **Centromedian (CM) nucleus** is the largest of the **intralaminar nuclei** of the thalamus [1]. Unlike the specific relay nuclei, the intralaminar nuclei have widespread connections. The CM nucleus specifically functions as a part of the **basal ganglia circuit**, receiving inputs from the globus pallidus and projecting primarily to the **striatum** (caudate nucleus and putamen) [3]. This pathway is crucial for regulating cortical excitability and motor functions [2]. **Analysis of Incorrect Options:** * **B. Mediodorsal nucleus:** This nucleus is part of the limbic system. It receives input from the amygdala and olfactory tract and projects to the **prefrontal cortex**. It is involved in memory, emotion, and executive function. * **C. Ventral anterior (VA) nucleus:** This is a motor relay nucleus. It receives input from the basal ganglia (globus pallidus) and projects to the **premotor cortex** and supplementary motor area. * **D. Ventral lateral (VL) nucleus:** Another motor relay nucleus, it receives major input from the **cerebellum** (dentate nucleus) and projects to the **primary motor cortex** (Brodmann area 4). **High-Yield Facts for NEET-PG:** * **Mnemonic for CM:** **C**entromedian = **C**onnects to **C**audate/Striatum. * The **Ventral Postero-Lateral (VPL)** nucleus relays sensory information from the body (Spinothalamic and DCML). * The **Ventral Postero-Medial (VPM)** nucleus relays sensory information from the face (Trigeminal pathway). * **Lateral Geniculate Body (LGB)** is for Vision (**L**ight); **Medial Geniculate Body (MGB)** is for Hearing (**M**usic).

Q: Which of the following is NOT a branch of the basilar artery?

Posterior communicating artery. **Explanation:** The **basilar artery** is formed by the union of the two vertebral arteries at the lower border of the pons. It ascends in the pontine sulcus and terminates at the upper border of the pons by dividing into the two posterior cerebral arteries. **1. Why the Correct Answer is Right:** The **Posterior Communicating Artery (PCoA)** is a branch of the **Internal Carotid Artery (ICA)**. It forms a vital part of the Circle of Willis by connecting the ICA system with the posterior cerebral artery (a terminal branch of the basilar system). Since it originates from the ICA, it is not a branch of the basilar artery. **2. Analysis of Incorrect Options (Branches of the Basilar Artery):** * **Pontine Artery:** Multiple small vessels that supply the pons. * **Anterior Inferior Cerebellar Artery (AICA):** Arises from the lower part of the basilar artery to supply the anterior-inferior aspect of the cerebellum. * **Labyrinthine Artery:** Usually arises from the AICA (85% of cases) or directly from the basilar artery. It accompanies the CN VII and VIII into the internal acoustic meatus. * *Note:* The **Superior Cerebellar Artery** is also a major branch arising just before the terminal bifurcation. **3. NEET-PG High-Yield Pearls:** * **Terminal Branches:** The basilar artery ends by dividing into two **Posterior Cerebral Arteries (PCA)**. * **Clinical Correlation:** Occlusion of the basilar artery can lead to **"Locked-in Syndrome,"** where the patient is conscious but paralyzed (except for vertical eye movements). * **Aneurysm Site:** The PCoA is a common site for berry aneurysms, which can cause **third nerve palsy** (mydriasis and ptosis) due to its proximity to the oculomotor nerve.

Q: What is true about the Vein of Labbe?

Drains into the Transverse Sinus. ### Explanation The **Vein of Labbé**, also known as the **Inferior Anastomotic Vein**, is a key component of the superficial venous drainage of the cerebral cortex. **Why the correct answer is right:** The Vein of Labbé travels across the temporal lobe and connects the **Superficial Middle Cerebral Vein** (located in the Sylvian fissure) to the **Transverse Sinus**. It serves as the primary drainage pathway for the lateral temporal lobe into the dural venous sinus system [1]. **Analysis of Incorrect Options:** * **Option A:** The **Superior Sagittal Sinus** primarily receives drainage from the Superior Cerebral Veins and the Superior Anastomotic Vein (Vein of Trolard), not the Vein of Labbé. * **Option C:** The Vein of Labbé is an anastomotic channel for the **Inferior** aspect of the brain (specifically connecting the Sylvian veins to the lateral sinuses), not the Superior Cerebral Veins. * **Option D:** This describes the **Vein of Trolard** (Great Anastomotic Vein). The Vein of Trolard is the *superior* anastomotic channel (connecting to the Superior Sagittal Sinus), whereas the Vein of Labbé is the *inferior* anastomotic channel. **High-Yield NEET-PG Pearls:** 1. **Mnemonic:** **L**abbé is **L**ower (connects to Transverse Sinus); **T**rolard is **T**op (connects to Superior Sagittal Sinus). 2. **Clinical Significance:** Injury or thrombosis of the Vein of Labbé (often during temporal lobe surgery or mastoidectomy) can lead to hemorrhagic infarction of the temporal lobe, resulting in **aphasia** (if the dominant hemisphere is involved) or seizures. 3. **Sylvian Connection:** Both Trolard and Labbé provide collateral circulation for the Superficial Middle Cerebral Vein [1].

Q: A 9-year-old boy is diagnosed with multiple sclerosis (MS). Which of the following nervous structures would most likely be affected by this disease?

Optic nerve. **Explanation:** The core concept tested here is the distinction between the **Central Nervous System (CNS)** and the **Peripheral Nervous System (PNS)** based on their myelinating cells. Multiple Sclerosis (MS) is an autoimmune inflammatory disorder characterized by the demyelination of the CNS [1]. **Why Optic Nerve is Correct:** The **Optic Nerve (CN II)** is unique among cranial nerves. Embryologically, it is an outgrowth of the diencephalon (forebrain) rather than a true peripheral nerve [2]. Consequently, it is myelinated by **oligodendrocytes** (CNS myelin) and is bathed in cerebrospinal fluid. Since MS specifically targets CNS myelin produced by oligodendrocytes, the optic nerve is frequently involved, often presenting as optic neuritis. **Why Other Options are Incorrect:** * **Trigeminal Ganglion (A) & Superior Cervical Ganglion (B):** Ganglia are collections of cell bodies in the PNS. These structures are not myelinated by oligodendrocytes and are therefore spared in MS. * **Facial Nerve (D):** The Facial Nerve (CN VII) is a peripheral nerve. Like all cranial nerves except CN I and CN II, its myelin is produced by **Schwann cells**. MS does not affect Schwann cell-mediated myelination. **NEET-PG High-Yield Pearls:** * **Myelinating Cells:** CNS = Oligodendrocytes (affected in MS); PNS = Schwann cells (affected in Guillain-Barré Syndrome). * **MRI Finding:** The "Dawson Fingers" (periventricular demyelinating plaques) are a classic imaging hallmark of MS [1]. * **CSF Analysis:** Look for **Oligoclonal bands** (IgG) on electrophoresis, which are present in >90% of MS patients [2]. * **Clinical Rule:** If a cranial nerve deficit is mentioned in MS, it is almost always the **Optic Nerve** [1] or an **Internuclear Ophthalmoplegia (INO)** due to a lesion in the Medial Longitudinal Fasciculus (MLF) [2].

Q: Which of the following supplies the pineal gland?

Posterior choroidal arteries. ### Explanation The **pineal gland** (epiphysis cerebri) is a midline structure located in the epithalamus, tucked between the superior colliculi. Its blood supply is derived from the **posterior choroidal arteries**, which are branches of the **Posterior Cerebral Artery (PCA)**. #### Why the Correct Option is Right: * **Posterior Choroidal Arteries (A):** These arteries arise from the PCA and are divided into medial and lateral groups. The **medial posterior choroidal artery** specifically courses near the midbrain and provides the primary arterial supply to the pineal gland, the tectum, and the third ventricle's choroid plexus. #### Why the Other Options are Wrong: * **Tuberothalamic Arteries (B):** Also known as polar arteries, these arise from the **Posterior Communicating Artery** and supply the anterior and ventral parts of the thalamus. * **Recurrent Artery of Heubner (C):** A significant branch of the **Anterior Cerebral Artery (ACA)**, it supplies the head of the caudate nucleus and the anterior limb of the internal capsule. * **Lenticulostriate Arteries (D):** These are "stroke arteries" arising from the **Middle Cerebral Artery (MCA)**. They supply the basal ganglia (putamen, globus pallidus) and the internal capsule. #### NEET-PG High-Yield Pearls: 1. **Calcification:** The pineal gland often calcifies after age 16; a displaced calcified pineal gland on X-ray/CT can indicate a space-occupying lesion (midline shift). 2. **Melatonin:** The gland secretes melatonin, regulated by the **suprachiasmatic nucleus (SCN)** of the hypothalamus (the master circadian clock). 3. **Parinaud Syndrome:** Tumors of the pineal gland (pinealomas) can compress the superior colliculi and pretectal area, leading to **upward gaze palsy**.

Q: Which venous sinus is present over the falx cerebelli?

Occipital sinus. ### Explanation The **Occipital sinus** is the smallest of the dural venous sinuses. It is located within the attached posterior margin of the **falx cerebelli**, a small sickle-shaped fold of dura mater that separates the two cerebellar hemispheres. It begins near the foramen magnum (where it communicates with the internal vertebral venous plexus) and ascends to drain into the **confluence of sinuses** (Torcular Herophili). #### Analysis of Options: * **A. Sigmoid sinus:** This is the S-shaped continuation of the transverse sinus. It lies in a groove on the mastoid part of the temporal bone and the occipital bone, eventually exiting the skull through the jugular foramen to become the internal jugular vein. * **B. Inferior petrosal sinus:** This sinus drains the cavernous sinus into the bulb of the internal jugular vein. It runs along the petro-occipital fissure, not within a dural fold. * **C. Straight sinus:** This is formed by the union of the **Great Cerebral Vein (of Galen)** and the **Inferior Sagittal Sinus**. It is located at the junction of the **falx cerebri** and the **tentorium cerebelli**. #### High-Yield Facts for NEET-PG: * **Falx Cerebri:** Contains the Superior and Inferior Sagittal Sinuses [1]. * **Tentorium Cerebelli:** Contains the Transverse and Superior Petrosal Sinuses. * **Confluence of Sinuses:** Usually formed by the meeting of the Superior Sagittal, Straight, Transverse, and Occipital sinuses. * **Clinical Pearl:** The occipital sinus is a key landmark during posterior fossa surgeries. Because it communicates with the internal vertebral venous plexus, it provides a pathway for the spread of infections or metastases from the pelvis to the brain (Batson’s plexus).

Question 1

Identify the marked structure.

Accepted Answer

Corpus callosum

Answer

Septum pellucidum

Answer

Globus pallidus

Answer

Fornix

Question 2

Identify the marked structure:

Accepted Answer

Body

Answer

Rostrum

Answer

Splenium

Answer

Genu

Question 3

Which artery supplies the deep cerebellar nuclei?

Accepted Answer

Superior cerebellar artery

Answer

Anterior inferior cerebellar artery

Answer

Anterior spinal artery

Answer

Posterior cerebral artery

Question 4

Which thalamic nucleus projects to the striatum?

Accepted Answer

Centromedian nucleus

Answer

Mediodorsal nucleus

Answer

Ventral anterior nucleus

Answer

Ventral lateral nucleus

Question 5

Which of the following is NOT a branch of the basilar artery?

Accepted Answer

Posterior communicating artery

Answer

Labyrinthine artery

Answer

Anterior inferior cerebellar artery

Answer

Pontine artery

Question 6

What is true about the Vein of Labbe?

Accepted Answer

Drains into the Transverse Sinus

Answer

Drains into the Superior Sagittal Sinus

Answer

An anastomotic channel for Superior Cerebral Veins

Answer

Superior anastomotic channel for Superficial Middle Cerebral Vein

Question 7

A 9-year-old boy is diagnosed with multiple sclerosis (MS). Which of the following nervous structures would most likely be affected by this disease?

Accepted Answer

Optic nerve

Answer

Trigeminal ganglion

Answer

Superior cervical ganglion

Answer

Facial nerve

Question 8

The spiral ganglion innervates which of the following cells shown in the diagram?

Accepted Answer

A

Answer

B

Answer

C

Answer

D

Question 9

Which of the following supplies the pineal gland?

Accepted Answer

Posterior choroidal arteries

Answer

Tuberothalamic arteries

Answer

Recurrent artery of Heubner

Answer

Lenticulostriate arteries

Question 10

Which venous sinus is present over the falx cerebelli?

Accepted Answer

Occipital sinus

Answer

Sigmoid sinus

Answer

Inferior petrosal sinus

Answer

Straight sinus

Brain and Neuroanatomy — MCQs

Brain and Neuroanatomy — MCQs

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