Brain and Neuroanatomy Practice Questions

Q: The pathway of light reflex is shown. Lesion of which of the following areas results in development of Argyll Robertson pupil?

Periaqueductal gray matter. ***Periaqueductal gray matter in the midbrain*** - This region is crucial for the **light reflex pathway**, as it contains interneurons that connect the pretectal nucleus (after optic afferents synapse) to the Edinger-Westphal nuclei. - A lesion here interrupts the pupillary light reflex while sparing the accommodation reflex, leading to the classic **"light-near dissociation"** seen in Argyll Robertson pupils. - Classically associated with **neurosyphilis**, though can also occur in diabetes mellitus. *Optic nerve* - Damage to the optic nerve causes a **loss of consensual and direct light reflexes** in the affected eye, resulting in a **relative afferent pupillary defect (RAPD)**. - While it affects pupillary response to light, it does not produce the light-near dissociation characteristic of Argyll Robertson pupils. *Lateral geniculate body (LGB)* - The LGB is primarily involved in **visual processing**, receiving input from the optic tracts and projecting to the visual cortex. - Lesions here would cause **visual field defects** but would not affect the pupillary light reflex, as the light reflex pathway projects to the pretectal nucleus, bypassing the LGB. *Edinger-Westphal (E-W) nuclei* - These nuclei are the **preganglionic parasympathetic component** of the oculomotor nerve, controlling pupillary constriction. - Bilateral damage to the E-W nuclei would result in **fixed, dilated pupils** (mydriasis) that do not react to light *or* accommodation, unlike the Argyll Robertson pupil which preserves the accommodation reflex.

Q: All are true about the area shown except:

Receives impulses from retinal halves of same side. ***Receives impulses from retinal halves of same side*** - The **primary visual cortex (V1)**, also known as **Brodmann area 17**, receives visual impusles from the contralateral visual field. - This means that the left V1 receives input from the right visual field (temporal half of the left retina, nasal half of the right retina), and the right V1 receives input from the left visual field (temporal half of the right retina, nasal half of the left retina). *Area 17 of Brodmann* - The image shows **V1**, which corresponds to **Brodmann Area 17**, the **primary visual cortex**. - This area is responsible for processing basic visual information like edges, colors, and motion. *Located in depth of calcarine sulcus with upper lip in lingual gyrus* - The **primary visual cortex (V1)** is located primarily along the banks of the **calcarine sulcus**. - Its upper lip extends into the **cuneus gyrus** and its lower lip into the **lingual gyrus**. *Supplied by posterior cerebral artery* - The **posterior cerebral artery (PCA)** supplies the **occipital lobe**, including the **primary visual cortex (V1)**. - Infarction in the PCA territory can lead to contralateral **hemianopia** with **macular sparing**.

Q: Which of the following depicts insula in the cross section of the brain?

C. ***C*** - The image illustrates a **coronal section of the brain**. The letter C points to the **insula**, a cortical region buried deep within the lateral sulcus, covered by the opercula of the frontal, parietal, and temporal lobes. - The insula is involved in various functions including **consciousness**, emotion, homeostasis, and perception (e.g., taste, pain). *A* - The letter A indicates the **corpus callosum**, a large bundle of nerve fibers connecting the two cerebral hemispheres. - Its primary function is to integrate motor, sensory, and cognitive performances between the cerebral cortex on one side of the brain to the same region on the other side. *B* - The letter B points to the **third ventricle**, a narrow, C-shaped cavity filled with cerebrospinal fluid (CSF) that lies in the midline of the brain, between the two thalami. - It plays a crucial role in the production and circulation of **CSF**, which cushions the brain and spinal cord. *D* - The letter D is pointing to the **putamen**, which is part of the basal ganglia. - The putamen is involved in **motor control** and learning, particularly in the regulation of voluntary movement.

Q: Identify the artery labelled with black arrow in the given diagram.

Superior cerebellar artery. ***Superior cerebellar artery*** - The superior cerebellar artery (SCA) typically originates from the **distal basilar artery**, just before its bifurcation into the posterior cerebral arteries. - In the provided image, the artery indicated by the black arrow is seen branching off the **basilar artery** (labeled H) and curving over the superior aspect of the cerebellum/brainstem, consistent with the SCA. *Posterior communicating artery* - The posterior communicating artery (PCOM) connects the **internal carotid artery** to the **posterior cerebral artery**. - This artery is part of the **Circle of Willis** and is located more anteriorly in relation to the basilar artery and cerebellum, and is not shown by the arrow. *Anterior inferior cerebellar artery* - The anterior inferior cerebellar artery (AICA) originates from the **lower third of the basilar artery** and supplies the anterior and inferior aspects of the cerebellum. - Its position is typically more caudal than the artery indicated by the black arrow, which is seen at a higher level with respect to the brainstem. *Basilar artery* - The basilar artery (labeled H) is a large, midline artery formed by the union of the two **vertebral arteries** and runs along the ventral surface of the pons. - The black arrow points to a vessel branching off the main basilar artery, not the basilar artery itself.

Q: The structure marked as $X$ is:

Internal capsule. ***Internal capsule*** - The arrow points to a white matter structure composed of ascending and descending tracts, located between the **thalamus** and the **basal ganglia**. - Its characteristic 'V' shape on axial imaging, with an anterior and posterior limb, confirms it as the **internal capsule**. *Genu of corpus callosum* - The **genu of the corpus callosum** is the anterior-most part of the large commissural fiber bundle connecting the cerebral hemispheres. - It would be located more anteriorly and medially, forming the anterior wall of the lateral ventricles. *Splenium of corpus callosum* - The **splenium of the corpus callosum** is the posterior-most part of the corpus callosum. - It would be seen more posteriorly, caudal to the pineal gland. *Thalamus* - The **thalamus** is a large, ovoid mass of gray matter located deep within the brain, superior to the brainstem. - It forms the lateral wall of the third ventricle and is adjacent to the internal capsule, but the arrow points specifically to the white matter tract.

Q: The structure marked by arrow is:

Fourth ventricle. ***Fourth ventricle*** - The arrow points to a **CSF-filled space** located between the pons/medulla anteriorly and the cerebellum posteriorly, which is characteristic of the fourth ventricle. - On this **axial T2-weighted MRI** image, CSF appears bright, clearly delineating the ventricular space. *Clivus* - The clivus is a **bony structure** forming the anterior boundary of the posterior cranial fossa, situated anterior to the brainstem. - It would appear as a **dark, cortical bone signal** on T2-weighted images and is not pointing to the fluid space as indicated. *Massa intermedia* - The massa intermedia (or interthalamic adhesion) is a band of **gray matter connecting the two thalami**, located within the third ventricle. - This structure is found much more **superiorly** in the brain, not at the level of the brainstem and cerebellum shown. *Pineal gland* - The pineal gland is a **small endocrine gland** located in the epithalamus, near the center of the brain, positioned posterior to the third ventricle. - It is located **superior to the cerebellum** and brainstem in anatomical context, not within the fourth ventricle.

Q: The area marked in CT scan is?

Pons. ***Pons*** - The arrow (X) points to the **pons**, which is characterized by its **ventral bulge** on the brainstem and its position superior to the medulla oblongata and inferior to the midbrain. - On a sagittal CT scan view, the pons is distinctly visible as a prominent, rounded structure forming the central part of the **brainstem**. *Mammillary body* - The mammillary bodies are small, paired structures located on the **inferior surface of the hypothalamus**, near the midline. - They are much smaller than the structure indicated by the arrow and are situated more anteriorly and inferiorly relative to the midbrain. *Tectum* - The tectum is the **dorsal part of the midbrain**, consisting of the superior and inferior colliculi. - It lies posterior to the cerebral aqueduct, whereas the arrow points to a ventral brainstem structure. *Midbrain* - The midbrain is superior to the pons, and while part of the brainstem, the arrow specifically indicates the **pons**, which is the section immediately inferior to the midbrain and has a more bulbous appearance. - The midbrain would be located just above the structure indicated by the arrow, characterized by structures like the cerebral peduncles ventrally and the tectum dorsally.

Q: Which is the structure marked here?

Pons. **Pons** - The image provided is a **sagittal view of an MRI of the brain**, and the arrow labeled 'X' points directly to the pons, a key part of the **brainstem**. - The pons is characterized by its **bulbous shape**, located anterior to the cerebellum and superior to the medulla oblongata, clearly visible in this anatomical plane. *Corpus callosum* - The **corpus callosum** is a large, C-shaped nerve fiber bundle found beneath the cerebral cortex and connects the two cerebral hemispheres. - It is located **superior to the structure indicated** by the arrow in this sagittal view. *Mammillary body* - The **mammillary bodies** are a pair of small, rounded prominences forming part of the posterior hypothalamus. - They are located **anterior and inferior to the region indicated** by the arrow. *Pineal gland* - The **pineal gland** is a small endocrine gland that produces melatonin and is located in the epithalamus, near the center of the brain. - It is situated **posterior and superior to the structure indicated**, typically nestled between the superior colliculi.

Q: The structure marked as $X$ in the below shown MR venography of the brain is:

Sigmoid sinus. ***Sigmoid sinus*** - The image shows a **venogram**, highlighting the venous structures of the brain. The structure marked 'X' exhibits the characteristic **S-shaped curve** that defines the sigmoid sinus. - The sigmoid sinus is a continuation of the **transverse sinus** and drains into the **internal jugular vein**. *Transverse sinus* - The transverse sinuses are typically observed as straight, elongated structures running horizontally along the posterior aspect of the brain, a path distinct from the curved structure marked 'X'. - They receive blood from the superior sagittal sinus and often from the inferior sagittal sinus via the straight sinus, converging at the **confluence of sinuses (torcular herophili)**. *Basal vein of Rosenthal* - The basal vein of Rosenthal is a deep cerebral vein, typically running anterior to the brainstem and draining into the **great cerebral vein of Galen**. - Its location and appearance are different from structure 'X', which is a large superficial dural venous sinus. *Torcular herophili* - The torcular herophili, also known as the **confluence of sinuses**, is the junction point of the superior sagittal, straight, and transverse sinuses. - It would appear as a central convergence point at the back of the skull, not a distinct, curved sinus like 'X'.

Q: Which structure is marked with a red arrow in the image shown below? (AIIMS May 2018)

Mammillary bodies. ***Mammillary bodies*** - The image shows an **axial view** of the brain, and the red arrow points to a rounded structure anterior to the pons, consistent with the location of the **mammillary bodies**. - These are part of the **limbic system** and play a crucial role in memory formation through their connections with the hippocampus and thalamus. *Hippocampus* - The hippocampus is located in the **medial temporal lobe**, deeper and more posterior than the structure indicated by the arrow on this axial slice. - It has a characteristic elongated, curved shape, quite distinct from the **paired, rounded structures** shown. *Habenular nuclei* - The **habenular nuclei** are located in the **epithalamus**, superior to the midbrain and posterior to the thalamus, not in the anterior brainstem region indicated. - They are much smaller and are involved in modulating various brain circuits, including those related to pain, stress, and reward. *Amygdala* - The amygdala is an **almond-shaped structure** located deep within the temporal lobe, anterior to the hippocampus. - While close to the region shown, its shape and exact position differ from the **mammillary bodies**, particularly in this axial plane where the mammillary bodies are seen as distinct, round structures near the midline.

Question 1

The pathway of light reflex is shown. Lesion of which of the following areas results in development of Argyll Robertson pupil?

Accepted Answer

Periaqueductal gray matter

Answer

Lateral geniculate body

Answer

Edinger-Westphal nuclei

Answer

Optic nerve

Question 2

All are true about the area shown except:

Accepted Answer

Receives impulses from retinal halves of same side

Answer

Area 17 of Brodmann

Answer

Located in depth of calcarine sulcus with upper lip in cuneus gyrus

Answer

Supplied by posterior cerebral artery

Question 3

Which of the following depicts insula in the cross section of the brain?

Accepted Answer

C

Answer

A

Answer

B

Answer

D

Question 4

Identify the artery labelled with black arrow in the given diagram.

Accepted Answer

Superior cerebellar artery

Answer

Posterior communicating artery

Answer

Anterior inferior cerebellar artery

Answer

Basilar artery

Question 5

The structure marked as $X$ is:

Accepted Answer

Internal capsule

Answer

Genu of corpus callosum

Answer

Splenium of corpus callosum

Answer

Thalamus

Question 6

The structure marked by arrow is:

Accepted Answer

Fourth ventricle

Answer

Clivus

Answer

Massa intermedia

Answer

Pineal gland

Question 7

The area marked in CT scan is?

Accepted Answer

Pons

Answer

Mammillary body

Answer

Tectum

Answer

Midbrain

Question 8

Which is the structure marked here?

Accepted Answer

Pons

Answer

Corpus callosum

Answer

Mammillary body

Answer

Pineal gland

Question 9

The structure marked as $X$ in the below shown MR venography of the brain is:

Accepted Answer

Sigmoid sinus

Answer

Transverse sinus

Answer

Basal vein of Rosenthal

Answer

Torcular herophili

Question 10

Which structure is marked with a red arrow in the image shown below? (AIIMS May 2018)

Accepted Answer

Mammillary bodies

Answer

Hippocampus

Answer

Habenular

Answer

Amygdala

Brain and Neuroanatomy — MCQs

Brain and Neuroanatomy — MCQs

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