Brain and Neuroanatomy Practice Questions

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.

Q: The marked extraocular muscle has a cranial nerve nucleus. At what level in the brain is the nucleus located? (AIIMS May 2018)

Facial colliculus. ***Facial colliculus*** - The image shows the **lateral rectus muscle** (indicated by the arrow), which controls abduction of the eye. - The lateral rectus muscle is innervated by the **abducens nerve (CN VI)**, and its nucleus is located at the **facial colliculus** in the pons. - The facial colliculus is a bulge on the dorsal surface of the pons, formed by the **facial nerve (CN VII) fibers** wrapping around the **abducens nucleus (CN VI)**. - This is the only extraocular muscle whose nucleus is located at the facial colliculus. *Superior colliculus* - The superior colliculus is located in the **midbrain** and is involved in visual reflexes and saccadic eye movements. - The **oculomotor nucleus (CN III)** is located ventral to the superior colliculus in the periaqueductal gray at the level of the superior colliculus. - CN III innervates the superior rectus, inferior rectus, medial rectus, and inferior oblique muscles, but not the muscle shown in the image. *Superior olivary nucleus* - The superior olivary nucleus is located in the **pons** and is a critical component of the auditory pathway, involved in sound localization. - It has no role in the innervation of extraocular muscles. *Inferior colliculus* - The inferior colliculus is situated in the **midbrain** and is a major relay center in the auditory pathway. - The **trochlear nucleus (CN IV)** is located at the level of the inferior colliculus and innervates the superior oblique muscle. - However, the inferior colliculus itself does not contain nuclei for extraocular muscle innervation.

Q: Which disease occurs due to involvement of the structure marked in red? (AIIMS May 2018)

Paralysis agitans. ***Paralysis agitans*** - The red circle points to the **substantia nigra**, a key brain structure involved in producing **dopamine**. - **Paralysis agitans**, also known as **Parkinson's disease**, is characterized by the degeneration of dopaminergic neurons in the substantia nigra, leading to motor symptoms like tremor, rigidity, and bradykinesia. *Depression* - Depression is a mood disorder associated with imbalances in various **neurotransmitters** (e.g., serotonin, norepinephrine, dopamine) and often involves brain regions such as the prefrontal cortex and limbic system, not primarily the substantia nigra. - While dopamine pathways can be implicated in motivation and reward, the primary pathology of major depression is not direct degeneration of the substantia nigra. *Alzheimer's disease* - Alzheimer's disease is a neurodegenerative disorder primarily characterized by the accumulation of **amyloid plaques** and **neurofibrillary tangles**, leading to neuronal loss and brain atrophy, particularly in the hippocampus and cerebral cortex, not the substantia nigra. - It results in progressive **memory loss** and cognitive decline, distinct from the motor symptoms seen in Parkinson's. *Huntington's chorea* - Huntington's chorea is a hereditary neurodegenerative disease caused by the degeneration of GABAergic neurons in the **striatum** (caudate and putamen). - It is characterized by **involuntary movements** (chorea), cognitive decline, and psychiatric symptoms, which result from basal ganglia dysfunction but not specifically originating from the substantia nigra.

Q: Identify the structure shown. (Recent NEET Pattern 2019)

Cerebellum. ***Cerebellum*** - The arrow in the sagittal MRI view points to the posterior cranial fossa, where the **cerebellum** is located, characterized by its distinctive folia and fissures. - The cerebellum is critical for **motor control**, balance, coordination, and learning motor skills. *Pons* - The **pons** is located anterior to the cerebellum, appearing as a prominent bulge on the brainstem, superior to the medulla. - It primarily acts as a communication bridge between the **cerebrum and cerebellum** and contains nuclei important for sleep, respiration, and bladder control. *Medulla* - The **medulla oblongata** is the lowest part of the brainstem, continuous with the spinal cord, situated inferior to the pons. - It contains vital autonomic centers for **cardiac, respiratory, and vasomotor functions**. *Occipital cortex* - The **occipital cortex** is part of the cerebrum, located at the posterior pole of the brain, superior to the cerebellum, and is responsible for **visual processing**. - It is identifiable by its characteristic gyri and sulci, distinctly different from the highly folded cerebellar folia.

Q: Occlusion of blood supply of the area marked in red will lead to all of the following except:

Apraxia (Constructional). ***Apraxia (Constructional)*** - The area marked in red represents the **medial portion of the precentral gyrus (motor cortex)** and **postcentral gyrus (sensory cortex)**, as well as the **paracentral lobule**, which are supplied by the **anterior cerebral artery (ACA)**. - Constructional apraxia is typically associated with **posterior parietal lobe lesions**, particularly in the non-dominant hemisphere, which is supplied by the posterior cerebral artery and middle cerebral artery branches, not the ACA. *Urinary incontinence* - The **paracentral lobule**, located in the area supplied by the ACA (marked in red), contains centers for **bladder control** and voluntary micturition. - Damage to this region can lead to **urinary incontinence** due to disrupted cortical control over bladder function. *Rectal incontinence* - Similar to bladder control, the **paracentral lobule** also plays a role in **voluntary bowel control**. - Ischemia in this region due to ACA occlusion can therefore result in **rectal incontinence**. *Peri-anal anaesthesia* - The **somatosensory cortex** representing the lower limbs and perineum is located in the **paracentral lobule** (postcentral gyrus part). - Occlusion of the ACA, supplying this region, can lead to **sensory deficits**, including **anaesthesia** in the peri-anal area.

Q: What is the name of the marked blood vessel in the Circle of Willis?

Posterior communicating artery. ***Posterior communicating artery*** - The image displays the Circle of Willis, and the vessel marked with 'X' is connecting the **internal carotid artery** (which branches into the middle and anterior cerebral arteries) to the **posterior cerebral artery**. - This connecting artery is the **posterior communicating artery**, an essential component of the Circle of Willis, ensuring collateral blood flow to the brain. *Middle cerebral artery* - The **middle cerebral artery** branches off the internal carotid artery and typically extends laterally into the Sylvian fissure, supplying a large part of the lateral cerebral cortex. - The marked vessel is clearly connecting proximal arteries within the Circle of Willis, not extending into the cerebral cortex peripherally. *Internal carotid artery* - The **internal carotid artery** enters the skull and gives rise to several branches, including the middle cerebral artery and the posterior communicating artery. - While it's part of the supply to the Circle of Willis, the 'X' points specifically to the **communicating segment** connecting the anterior and posterior circulations, not the main trunk of the internal carotid. *Posterior cerebral artery* - The **posterior cerebral artery** is formed by the bifurcation of the basilar artery and supplies the occipital lobe and parts of the temporal lobe. - The marked vessel is connecting to the posterior cerebral artery, but it is not the posterior cerebral artery itself; rather, it is the vessel **communicating** with it from the anterior circulation.

Q: What is the name of the marked blood vessel shown in brain circulation?

Posterior communicating artery. ***Posterior communicating artery*** - The arrow points to a vessel connecting the **anterior circulation** (internal carotid artery system) with the **posterior circulation** (vertebrobasilar system) within the **Circle of Willis**. - This specific location and function are characteristic of the **posterior communicating artery**, which typically arises from the internal carotid and joins the posterior cerebral artery. *Middle cerebral artery* - The middle cerebral artery is a large artery that branches off the **internal carotid artery** and typically extends laterally and superiorly to supply a large part of the **cerebral hemispheres**. - It would appear more prominent and more laterally positioned, not forming a direct "communicating" link in the central Circle of Willis as shown. *Internal carotid artery* - The internal carotid artery ascends from the neck into the skull and bifurcates into the **anterior and middle cerebral arteries**. - While visible in the image, the arrow is pointing to a smaller anastomotic branch, not the main trunk of the internal carotid artery. *Anterior communicating artery* - The **anterior communicating artery** connects the two **anterior cerebral arteries** at the anterior aspect of the Circle of Willis. - This is a distinct location from that indicated by the arrow, which shows a vessel connecting anterior to posterior circulation, not linking the two anterior cerebral arteries.

Q: Identify the image given below.

3rd ventricle. ***3rd ventricle*** - The arrow points to a midline fluid-filled structure located superior to the **brainstem** and anterior to the **cerebellum** on this sagittal MRI image. - This anatomical position is characteristic of the **third ventricle**, which is a narrow cavity between the two thalami. *Lateral ventricle* - The **lateral ventricles** are much larger and are located more superiorly within the cerebral hemispheres, not in the midline position indicated. - They are connected to the third ventricle via the **foramina of Monro**. *Corpus callosum* - The **corpus callosum** is a thick band of white matter connecting the two cerebral hemispheres, located superior to the third ventricle. - It appears as a solid structure on MRI, not a fluid-filled space. *4th ventricle* - The **fourth ventricle** is located inferior to the third ventricle, anterior to the **cerebellum**, and posterior to the **pons** and **medulla**. - It leads into the central canal of the spinal cord and is distinctly inferior to the structure indicated by the arrow.

Q: The glymphatic system is the lymphatic-like structure of which system?

Central Nervous System. ***Central Nervous System*** - The **glymphatic system** is a specialized waste clearance pathway unique to the **central nervous system (CNS)**. - It facilitates the removal of metabolic waste products, including **amyloid-beta**, from the brain, playing a crucial role in CNS health. *Gastro-intestinal* - The gastrointestinal system has its own extensive lymphatic network, including **Peyer's patches** and **mesenteric lymph nodes**, for immune surveillance and lipid absorption. - These structures differ significantly in function and anatomy from the brain's glymphatic system. *Respiratory* - The respiratory system is equipped with **bronchial lymphatics** and **pulmonary lymph nodes** that drain fluid and immune cells from the lungs. - This system is involved in immune responses and fluid balance in the lungs, not directly related to brain waste clearance. *Renal* - The renal system has lymphatic drainage associated with the kidneys, which helps in the return of interstitial fluid and immune cells [1]. - This system is distinct from the glymphatic system and primarily involved in kidney function and fluid balance [1].

Question 1

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 2

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

Question 3

The marked extraocular muscle has a cranial nerve nucleus. At what level in the brain is the nucleus located? (AIIMS May 2018)

Accepted Answer

Facial colliculus

Answer

Superior colliculus

Answer

Superior olivary nucleus

Answer

Inferior colliculus

Question 4

Which disease occurs due to involvement of the structure marked in red? (AIIMS May 2018)

Accepted Answer

Paralysis agitans

Answer

Depression

Answer

Alzheimer's disease

Answer

Huntington's chorea

Question 5

Identify the structure shown. (Recent NEET Pattern 2019)

Accepted Answer

Cerebellum

Answer

Pons

Answer

Medulla

Answer

Occipital cortex

Question 6

Occlusion of blood supply of the area marked in red will lead to all of the following except:

Accepted Answer

Apraxia (Constructional)

Answer

Urinary incontinence

Answer

Rectal incontinence

Answer

Peri-anal anaesthesia

Question 7

What is the name of the marked blood vessel in the Circle of Willis?

Accepted Answer

Posterior communicating artery

Answer

Middle cerebral artery

Answer

Internal carotid artery

Answer

Posterior cerebral artery

Question 8

What is the name of the marked blood vessel shown in brain circulation?

Accepted Answer

Posterior communicating artery

Answer

Middle cerebral artery

Answer

Internal carotid artery

Answer

Anterior communicating artery

Question 9

Identify the image given below.

Accepted Answer

3rd ventricle

Answer

Lateral ventricle

Answer

Corpus callosum

Answer

4th ventricle

Question 10

The glymphatic system is the lymphatic-like structure of which system?

Accepted Answer

Central Nervous System

Answer

Gastrointestinal

Answer

Respiratory

Answer

Renal

Brain and Neuroanatomy — MCQs

Brain and Neuroanatomy — MCQs

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