Brain and Neuroanatomy Practice Questions

Q: Which of the following is not a branch of the cerebral part of the internal carotid artery?

Posterior cerebral artery.. The **Internal Carotid Artery (ICA)** is divided into four segments: Cervical, Petrous, Cavernous, and Cerebral (Supraclinoid). Understanding the branches of the cerebral segment is crucial for mastering the Circle of Willis. ### Why Option C is Correct The **Posterior Cerebral Artery (PCA)** is typically the terminal branch of the **Basilar Artery**, which is part of the vertebrobasilar (posterior) circulation. While the PCA is connected to the ICA via the posterior communicating artery, it does not originate from the ICA itself. ### Analysis of Incorrect Options The cerebral part of the ICA begins where the vessel pierces the dura mater. Its branches can be remembered by the mnemonic **"O PAMA"**: * **A. Ophthalmic Artery:** The first branch of the cerebral ICA, entering the orbit through the optic canal. * **D. Anterior Choroidal Artery:** A long, slender branch that supplies the internal capsule and choroid plexus. * **Posterior Communicating Artery:** Connects the ICA to the PCA. * **B. Anterior Cerebral Artery (ACA):** One of the two terminal branches of the ICA. * **Middle Cerebral Artery (MCA):** The larger terminal branch of the ICA (often considered the direct continuation). ### High-Yield Clinical Pearls for NEET-PG * **Circle of Willis:** The ICA provides the anterior circulation, while the Basilar artery provides the posterior circulation. * **Stroke Localization:** Occlusion of the **Anterior Choroidal Artery** leads to a classic triad: contralateral hemiplegia, hemianesthesia, and homonymous hemianopia. * **Aneurysms:** The most common site for berry aneurysms in the ICA system is the junction of the ICA and the **Posterior Communicating Artery**, often presenting with **3rd Nerve Palsy** (mydriasis and ptosis). * **Terminal Bifurcation:** The ICA terminates by dividing into the ACA and MCA lateral to the optic chiasm.

Q: The bulb of the posterior horn of the lateral ventricle is formed by which structure?

Forceps major. **Explanation:** The **bulb of the posterior horn** is a distinct elevation on the medial wall of the posterior horn of the lateral ventricle. It is produced by the fibers of the **forceps major**, which are the large bundle of commissural fibers from the splenium of the corpus callosum that sweep backward into the occipital lobe. **Analysis of Options:** * **Forceps major (Correct):** These fibers bulge into the medial wall of the posterior horn, creating the "bulb." * **Calcarine sulcus (Incorrect):** This sulcus produces a separate elevation on the medial wall of the posterior horn, situated just below the bulb, known as the **Calcar avis**. * **Collateral sulcus (Incorrect):** This sulcus produces an elevation on the floor of the **inferior horn** (not the posterior horn) called the **collateral eminence**. * **Stria terminalis (Incorrect):** This is a bundle of nerve fibers located in the floor of the body and the roof of the inferior horn of the lateral ventricle, running between the thalamus and the caudate nucleus. **High-Yield Clinical Pearls for NEET-PG:** * **Medial Wall of Posterior Horn:** Features two elevations—the **Bulb** (superior, formed by forceps major) and the **Calcar avis** (inferior, formed by calcarine sulcus). * **Floor of Inferior Horn:** Features the **Hippocampus** (medially) and the **Collateral eminence** (laterally). * **Roof of Inferior Horn:** Contains the tail of the caudate nucleus, stria terminalis, and the amygdaloid body. * **The "Trigone" (Atrium):** The area where the body, posterior horn, and inferior horn meet; it contains the largest part of the choroid plexus (glomus choroideum) [1].

Q: Which cranial nerve carries parasympathetic fibers?

Vagus nerve. ### Explanation The parasympathetic nervous system (craniosacral outflow) involves four specific cranial nerves: **III (Oculomotor), VII (Facial), IX (Glossopharyngeal), and X (Vagus).** [1] **Why Vagus Nerve (CN X) is Correct:** The Vagus nerve provides the most extensive parasympathetic innervation in the body [1]. Its preganglionic fibers originate in the **Dorsal Nucleus of the Vagus** and the **Nucleus Ambiguus**. It supplies parasympathetic control to the thoracic and abdominal viscera (heart, lungs, and digestive tract) up to the splenic flexure of the colon. **Why Other Options are Incorrect:** * **Trigeminal Nerve (CN V):** This is primarily a sensory nerve for the face and motor nerve for muscles of mastication. While parasympathetic fibers from other nerves often "hitchhike" along branches of CN V to reach their targets (e.g., CN VII fibers on the Lingual nerve), the Trigeminal nerve itself has **no** parasympathetic nuclei or outflow. * **Hypoglossal Nerve (CN XII):** This is a purely motor nerve supplying the intrinsic and extrinsic muscles of the tongue (except the Palatoglossus). * **Abducent Nerve (CN VI):** This is a purely motor nerve supplying only the Lateral Rectus muscle of the eye. **High-Yield NEET-PG Pearls:** 1. **Mnemonic for Parasympathetic CNs:** Remember the year **1973** (CN **10**, **9**, **7**, **3**). 2. **Associated Ganglia:** * CN III → Ciliary ganglion (Pupillary constriction). * CN VII → Pterygopalatine & Submandibular ganglia (Lacrimation/Salivation). * CN IX → Otic ganglion (Parotid secretion). * CN X → Terminal ganglia (Visceral function). 3. **Nucleus Ambiguus:** This is a shared motor nucleus for CN IX, X, and XI; it provides special visceral efferent (SVE) fibers to the muscles of the larynx and pharynx.

Q: The dorsal surface of the pons is related with which cranial nerve nucleus?

Facial nucleus. **Explanation:** The dorsal surface of the pons forms the upper part of the floor of the **fourth ventricle**. The correct answer is the **Facial nucleus** because of its unique anatomical relationship with the Abducens nucleus on the pontine floor. The axons of the facial nerve (CN VII) originate from the motor nucleus, loop dorsally around the Abducens (CN VI) nucleus, and create a visible elevation on the dorsal surface of the pons known as the **Facial Colliculus**. This "internal genu" of the facial nerve is a landmark high-yield feature of the pontine anatomy. **Analysis of Incorrect Options:** * **A. Trochlear nucleus (CN IV):** Located in the **midbrain** at the level of the inferior colliculus. It is the only cranial nerve to emerge from the dorsal aspect of the brainstem, but it is not related to the dorsal surface of the pons. * **B. Motor nucleus of Vagus (CN X):** Located in the **medulla oblongata**. It forms the vagal triangle (ala cinerea) in the lower part of the floor of the fourth ventricle. * **C. Hypoglossal nucleus (CN XII):** Also located in the **medulla**. It forms the hypoglossal triangle, situated medially in the floor of the fourth ventricle, inferior to the stria medullaris. **High-Yield Clinical Pearls for NEET-PG:** * **Millard-Gubler Syndrome:** A pontine stroke affecting the facial nerve fibers and abducens nucleus, leading to ipsilateral facial palsy, ipsilateral inward deviation of the eye, and contralateral hemiplegia. * **Facial Colliculus Lesion:** A lesion here results in **ipsilateral facial paralysis** AND **ipsilateral lateral rectus palsy** (due to involvement of the underlying CN VI nucleus).

Q: The lunate sulcus is present in which lobe of the cerebrum?

Occipital lobe. ### Explanation **Correct Answer: D. Occipital Lobe** The **lunate sulcus** (also known as the simian sulcus) is a small, semilunar-shaped groove located on the lateral surface of the **occipital lobe**, just in front of the occipital pole [1]. It serves as the boundary between the primary visual cortex (Brodmann area 17) and the secondary visual cortex (Brodmann area 18). In humans, it is often considered a vestigial structure and is highly variable in its presence and depth, whereas it is very prominent in non-human primates. [1] **Why other options are incorrect:** * **Frontal Lobe:** This lobe is characterized by the precentral sulcus, superior/inferior frontal sulci, and the olfactory sulcus on its inferior surface. It does not contain the lunate sulcus. * **Parietal Lobe:** Key landmarks here include the postcentral sulcus and the intraparietal sulcus, which divides the lobe into superior and inferior parietal lobules. * **Temporal Lobe:** This lobe features the superior and inferior temporal sulci, which run parallel to the lateral sulcus. **High-Yield Facts for NEET-PG:** * **Visual Cortex Landmark:** The lunate sulcus represents the lateral limit of the **stria of Gennari** (a band of myelinated fibers in the visual cortex) [1]. * **Calcarine Sulcus:** Located on the medial surface of the occipital lobe; it is the primary landmark for the visual cortex [1]. * **Pre-occipital Notch:** A small indentation on the inferolateral border of the hemisphere, located about 5 cm in front of the occipital pole, used to demarcate the temporal and occipital lobes. * **Clinical Correlation:** Lesions in the occipital lobe near these sulci typically result in **contralateral homonymous hemianopia** with or without macular sparing. [1]

Q: Virchow-Robin’s space is a space of which of the following?

Subarachnoid space. **Explanation:** **Virchow-Robin spaces (VRS)**, also known as perivascular spaces, are immunological and fluid-filled compartments that surround the walls of small blood vessels (arteries, arterioles, veins, and venules) as they pierce the brain parenchyma from the surface. 1. **Why Subarachnoid Space is Correct:** As blood vessels dive into the brain from the subarachnoid space, they carry a "sleeve" or invagination of the **leptomeninges** (pia mater and arachnoid mater) with them. The Virchow-Robin space is technically an extension of the **subarachnoid space**, containing interstitial fluid (and some CSF), acting as a drainage pathway for the brain's "glymphatic system." 2. **Why Other Options are Incorrect:** * **Epidural Space:** This is a potential space between the dura mater and the skull [2]. It is not involved in the deep penetration of vessels into the brain tissue. * **Subdural Space:** This is a potential space between the dura and arachnoid mater [2]. While it contains bridging veins, it does not form the perivascular sleeves characteristic of VRS. * **Fourth Ventricle:** This is a large, CSF-filled cavity within the brainstem/cerebellum. While it is part of the ventricular system, it is not a perivascular space. **High-Yield Clinical Pearls for NEET-PG:** * **Glymphatic System:** VRS are now recognized as key components of the brain’s waste clearance system. * **MRI Appearance:** On MRI, they appear as small, well-defined "punched-out" lesions that follow CSF intensity (T1 dark, T2 bright). * **Pathology:** Dilated Virchow-Robin spaces (état criblé) are often associated with aging, hypertension, and dementia [1]. * **Cryptococcosis:** In cases of Cryptococcal meningitis, the fungus can fill and dilate these spaces, leading to a "soap bubble" appearance on imaging.

Question 1

Which of the following is not a branch of the cerebral part of the internal carotid artery?

Accepted Answer

Posterior cerebral artery.

Answer

Ophthalmic artery.

Answer

Anterior cerebral artery.

Answer

Anterior choroidal artery.

Question 2

Which of the following is NOT true regarding the optic chiasma?

Accepted Answer

Inferonasal fibers of the optic nerve are related to the posterior portion of the chiasma.

Answer

It lies superior to the tuberculum sellae.

Answer

A tumor compressing the chiasma can cause visual field defects.

Answer

Decussation of fibers from the medial half of each retina occurs at the chiasma.

Question 3

The bulb of the posterior horn of the lateral ventricle is formed by which structure?

Accepted Answer

Forceps major

Answer

Collateral sulcus

Answer

Calcarine sulcus

Answer

Stria terminalis

Question 4

Which cranial nerve carries parasympathetic fibers?

Accepted Answer

Vagus nerve

Answer

Trigeminal nerve

Answer

Hypoglossal nerve

Answer

Abducent nerve

Question 5

The dorsal surface of the pons is related with which cranial nerve nucleus?

Accepted Answer

Facial nucleus

Answer

Trochlear nucleus

Answer

Motor nucleus of vagus

Answer

Hypoglossal nucleus

Question 6

The middle cerebellar peduncle primarily transmits fibers of which pathway?

Accepted Answer

Ponto cerebellar pathway

Answer

Tectospinal pathway

Answer

Spinocerebellar pathway

Answer

Olivo cerebellar pathway

Question 7

The lunate sulcus is present in which lobe of the cerebrum?

Accepted Answer

Occipital lobe

Answer

Frontal lobe

Answer

Parietal lobe

Answer

Temporal lobe

Question 8

Third-nerve palsy can result from pathology at all of the following locations, EXCEPT:

Accepted Answer

None of the above

Answer

Brainstem

Answer

Subarachnoid space

Answer

Cavernous sinus

Question 9

Virchow-Robin’s space is a space of which of the following?

Accepted Answer

Subarachnoid space

Answer

Epidural space

Answer

Subdural space

Answer

Fourth ventricle

Question 10

Venous drainage from the neurohypophysis occurs through which of the following pathways EXCEPT?

Accepted Answer

Superior hypophyseal veins to ventricular tanycytes

Answer

Portal vessels to the adenohypophysis

Answer

Inferior hypophyseal veins to dural venous sinuses

Answer

Capillaries to the median eminence and hypothalamus

Brain and Neuroanatomy — MCQs

Brain and Neuroanatomy — MCQs

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