Neuroanatomy Practice Questions

Q: Which of the following is considered a nucleus of the basal ganglia?

Caudate. The **Basal Ganglia** (or Basal Nuclei) are a group of subcortical nuclei situated deep within the cerebral hemispheres, primarily involved in the control of voluntary motor movements, procedural learning, and habit formation [1]. **Why Caudate is Correct:** The **Caudate nucleus** is a major component of the basal ganglia [1]. Together with the Putamen, it forms the **Striatum** (Neostriatum) [1]. Anatomically, it is C-shaped and closely related to the lateral ventricles. It plays a vital role in the "cognitive" loop of motor control, processing information from the association cortex. **Analysis of Incorrect Options:** * **A. Dentate:** This is the largest of the **deep cerebellar nuclei**. It is located in the cerebellum and is involved in the planning and initiation of voluntary movements, not the basal ganglia [1]. * **B. Thalamus:** While the thalamus is a major relay station that works closely with the basal ganglia (via the thalamic fasciculus), it is a **diencephalic structure** and is not classified as part of the basal ganglia itself [3]. * **D. Red Nucleus:** Located in the **midbrain tegmentum**, it is part of the extrapyramidal system (rubrospinal tract) but is not considered a primary nucleus of the basal ganglia [2]. **High-Yield NEET-PG Pearls:** 1. **Components of Basal Ganglia:** Caudate, Putamen, Globus Pallidus (Internal & External), Subthalamic Nucleus, and Substantia Nigra [1]. 2. **Corpus Striatum:** Caudate + Putamen + Globus Pallidus [1]. 3. **Lentiform Nucleus:** Putamen + Globus Pallidus (wedge-shaped) [1]. 4. **Clinical Correlation:** Degeneration of dopaminergic neurons in the Substantia Nigra pars compacta leads to **Parkinson’s Disease**, while atrophy of the Caudate nucleus is the hallmark of **Huntington’s Chorea** [4].

Q: A lesion of the optic radiation involving Meyer's loop causes which of the following visual field defects?

Superior quadrantanopia. ### Explanation **Underlying Medical Concept:** The optic radiation (geniculocalcarine tract) carries visual information from the Lateral Geniculate Body (LGB) to the primary visual cortex. It is divided into two distinct bundles [1]: 1. **Meyer’s Loop (Inferior Fibers):** These fibers loop forward into the **temporal lobe** before heading back to the lingual gyrus. They carry information from the **inferior retina**, which corresponds to the **superior visual field** [1]. 2. **Baum’s Loop (Superior Fibers):** These fibers travel directly through the **parietal lobe** to the cuneus gyrus. They carry information from the **superior retina**, corresponding to the **inferior visual field** [1]. Because the optic radiation is post-chiasmatic, a lesion on one side affects the contralateral visual field [2]. Therefore, a lesion in Meyer’s loop results in a **Contralateral Superior Quadrantanopia** (often called "Pie in the Sky" defect). **Analysis of Options:** * **B (Correct):** Meyer’s loop (temporal lobe) = Superior visual field defect. * **A (Incorrect):** **Homonymous hemianopia** occurs with complete destruction of the optic tract or the entire optic radiation [2]. * **C (Incorrect):** **Inferior quadrantanopia** ("Pie on the Floor") is caused by a lesion in the parietal lobe (Baum’s loop). * **D (Incorrect):** **Central scotoma** is typically associated with macular degeneration or lesions of the optic nerve/macular fibers. **High-Yield Clinical Pearls for NEET-PG:** * **Temporal Lobe Lesion:** Superior Quadrantanopia ("Pie in the Sky"). * **Parietal Lobe Lesion:** Inferior Quadrantanopia ("Pie on the Floor"). * **Macular Sparing:** Seen in Posterior Cerebral Artery (PCA) strokes affecting the visual cortex, as the macula has a dual blood supply (PCA + Middle Cerebral Artery) [2]. * **Mnemonic:** **M**eyer’s = **M**id-brain/Temporal = **M**ountain (Sky/Superior). **P**arietal = **P**it (Floor/Inferior).

Q: Lynch syndrome is associated with which of the following cancers?

Colon, endometrium, ovary. **Explanation:** **Lynch Syndrome**, also known as Hereditary Non-Polyposis Colorectal Cancer (HNPCC), is an autosomal dominant condition caused by germline mutations in **DNA Mismatch Repair (MMR) genes** (primarily *MLH1, MSH2, MSH6,* and *PMS2*) [2], [4]. This leads to microsatellite instability (MSI) and a significantly increased risk of various malignancies [1]. **Why Option D is Correct:** The hallmark of Lynch syndrome is the high risk of **Colorectal cancer** (often right-sided) [2]. However, it is a multi-organ cancer syndrome. In women, the risk of **Endometrial cancer** is exceptionally high, often equaling or exceeding the risk of colon cancer [3], [4]. **Ovarian cancer** is the third most common associated malignancy. Therefore, the triad of Colon, Endometrium, and Ovary represents the core clinical spectrum of the syndrome. **Why Other Options are Incorrect:** * **Options A, B, and C:** These options include **Breast cancer**. While some studies suggest a slightly elevated risk, breast cancer is **not** a classic component of the Lynch syndrome diagnostic criteria (Amsterdam II or Bethesda criteria). Breast cancer is more typically associated with *BRCA1/2* mutations or Li-Fraumeni syndrome [1], [4]. **High-Yield Clinical Pearls for NEET-PG:** * **Inheritance:** Autosomal Dominant [2]. * **Most common mutation:** *MLH1* and *MSH2* [1], [2]. * **Amsterdam II Criteria (3-2-1 Rule):** 3 relatives with Lynch-associated cancer, 2 successive generations, 1 diagnosed before age 50 [3]. * **Other associated cancers:** Gastric, small bowel, hepatobiliary, and transitional cell carcinoma of the ureter/renal pelvis [4]. * **Muir-Torre Syndrome:** A variant of Lynch syndrome associated with sebaceous gland tumors and keratoacanthomas.

Q: The optic nerve is a tract of the diencephalon that is not completely myelinated until when?

3 months after birth. The optic nerve is unique because it is not a true peripheral nerve but rather an **outgrowth of the diencephalon**. Unlike peripheral nerves, which are myelinated by Schwann cells, the optic nerve is myelinated by **oligodendrocytes** [1] and is encased in the three layers of the meninges (dura, arachnoid, and pia mater). [3] **Why Option D is correct:** Myelination of the optic nerve begins centrally at the optic chiasm during the 7th month of fetal life and progresses distally toward the eyeball. At birth, myelination usually reaches the level of the lamina cribrosa. However, the process is not functionally complete until approximately **3 months after birth**, coinciding with the development of visual acuity and fixation in infants. **Analysis of Incorrect Options:** * **Options A & B (5 years and 2 years):** These timeframes are too late. While the brain undergoes significant synaptic pruning and refinement during these years, the structural myelination of the primary visual pathway is established much earlier. * **Option C (1 year):** While some complex association tracts in the brain continue to myelinate until the end of the first year (and beyond), the optic nerve completes its primary myelination phase by the end of the first trimester of infancy. **NEET-PG High-Yield Pearls:** * **Origin:** The optic nerve is a tract of the **CNS**, not a PNS nerve. * **Myelination:** It is myelinated by **oligodendrocytes**, which explains why it is affected in **Multiple Sclerosis** (a CNS demyelinating disease) but spared in Guillain-Barré Syndrome. [1],[2] * **Clinical Sign:** Myelinated nerve fibers can sometimes extend beyond the lamina cribrosa into the retina, appearing as white, feathery patches on fundoscopy; this is usually a benign finding. * **Pressure:** Because it is surrounded by the subarachnoid space, increased intracranial pressure (ICP) is transmitted to the optic nerve head, leading to **papilledema**.

Q: Which of the following statements best describes the sulcus limitans?

It is located between the alar and basal plates. ### Explanation **Correct Answer: B. It is located between the alar and basal plates** The **sulcus limitans** is a longitudinal groove in the lateral wall of the developing neural tube. Its primary embryological function is to demarcate the neural tube into two functional zones: 1. **Alar Plate (Dorsal):** Gives rise to **sensory** neurons. 2. **Basal Plate (Ventral):** Gives rise to **motor** neurons. In the adult brainstem, as the fourth ventricle opens up (the "open medulla" and pons), the alar plates are pushed laterally and the basal plates remain medial. Therefore, the sulcus limitans persists in the floor of the fourth ventricle, separating the medial **motor nuclei** (e.g., hypoglossal eminence) from the lateral **sensory nuclei** (e.g., vestibular area). **Analysis of Incorrect Options:** * **Option A:** The interpeduncular fossa is located on the ventral surface of the midbrain between the cerebral peduncles; it contains the exit point of the oculomotor nerve, not the sulcus limitans. * **Option C:** The medulla and pons are separated by the **ponto-medullary sulcus** (transverse), where the 6th, 7th, and 8th cranial nerves emerge. * **Option D:** The hypothalamus and thalamus are separated by the **hypothalamic sulcus**, which is a separate anatomical landmark in the third ventricle. **High-Yield NEET-PG Pearls:** * **Functional Rule:** Medial to sulcus limitans = Motor; Lateral to sulcus limitans = Sensory. * **Midbrain Landmark:** In the midbrain, the sulcus limitans separates the **tegmentum** (ventral/motor) from the **tectum** (dorsal/sensory). * **Clinical Correlation:** Developmental defects in the alar/basal plate differentiation can lead to complex congenital neurological syndromes involving dissociated sensory and motor deficits.

Q: Which of the following are association fibers?

All of the above. White matter fibers in the cerebrum are classified into three types: **Association**, **Commissural**, and **Projection** fibers. **Association fibers** are bundles of axons that connect different cortical areas within the **same hemisphere**. They are further divided into short association fibers (connecting adjacent gyri) and long association fibers (connecting distant lobes) [1]. * **Uncinate Fasciculus:** A long association fiber bundle that connects the orbitofrontal cortex with the anterior temporal lobe. It is hook-shaped and passes across the bottom of the lateral fissure. * **Cingulum:** A curved bundle of association fibers located within the cingulate gyrus. It connects the frontal and parietal lobes with the parahippocampal gyrus and adjacent temporal cortical regions, forming a key part of the limbic system. * **Superior Longitudinal Fasciculus:** The largest association bundle, connecting the frontal, parietal, occipital, and temporal lobes. A specialized component, the **Arcuate fasciculus**, specifically connects Broca’s area to Wernicke’s area. Since all three options represent fibers connecting regions within the same hemisphere, **Option D** is the correct answer. **High-Yield Facts for NEET-PG:** 1. **Arcuate Fasciculus Clinical Correlation:** Damage to these fibers results in **Conduction Aphasia**, characterized by poor repetition but intact comprehension and fluent speech. 2. **Commissural Fibers:** Connect corresponding areas of the two hemispheres (e.g., Corpus Callosum, Anterior Commissure). 3. **Projection Fibers:** Connect the cerebral cortex with lower centers like the brainstem or spinal cord (e.g., Internal Capsule). 4. **Corpus Callosum** is the largest commissural fiber bundle in the brain.

Q: The trigeminal ganglion is?

Homologous with the dorsal root ganglion.. ### Explanation The **Trigeminal (Gasserian or Semilunar) ganglion** is the large, sensory ganglion of the 5th cranial nerve, located in the Meckel’s cave of the middle cranial fossa. **1. Why Option C is Correct:** The trigeminal ganglion is **homologous with the dorsal root ganglion (DRG)** of spinal nerves. Both contain the cell bodies of **pseudounipolar primary sensory neurons**. Just as the DRG carries sensory information from the body to the spinal cord, the trigeminal ganglion carries somatosensory information (touch, pain, temperature) from the face and head to the brainstem. **2. Why the Other Options are Incorrect:** * **Option A:** It is a **purely sensory** ganglion. While the trigeminal nerve (CN V) has a motor component, the motor fibers do not synapse or reside in the ganglion; they bypass it entirely. * **Option B:** It is composed of **pseudounipolar cells**, not bipolar cells. Bipolar cells are typically found in specialized sensory systems like the retina or the vestibulocochlear nerve (CN VIII). * **Option D:** The motor root of the trigeminal nerve passes **deep (inferior)** to the ganglion and joins the mandibular division (V3) at the foramen ovale. It does not "enter" the posterior concavity of the ganglion. **High-Yield Clinical Pearls for NEET-PG:** * **Location:** It sits on the **trigeminal impression** on the apex of the petrous temporal bone. * **Dural Relation:** It is enclosed in a pouch of dura mater called **Meckel’s cave**. * **Clinical Correlation:** **Trigeminal Neuralgia** (Tic Douloureux) involves this pathway; surgical decompression or glycerol injection often targets this ganglion. * **Herpes Zoster:** The virus can remain latent in the trigeminal ganglion, manifesting as Herpes Zoster Ophthalmicus when reactivated.

Q: A lesion in which of the following areas will affect left-sided lateral gaze?

Right frontal lobe. ### Explanation The control of horizontal conjugate gaze involves a complex pathway originating in the **Frontal Eye Fields (FEF)**, located in the posterior part of the middle frontal gyrus (Brodmann area 8). **Mechanism of the Correct Answer (A):** The FEF controls **voluntary saccadic eye movements to the contralateral side** [1]. When the **Right Frontal Lobe** (specifically the Right FEF) fires, it sends signals that decussate (cross over) in the lower pons to stimulate the **Left Parapontine Reticular Formation (PPRF)**. The Left PPRF then activates the Left Abducens nucleus (CN VI) to move the left eye laterally and the Right Oculomotor nucleus (CN III) via the medial longitudinal fasciculus (MLF) to move the right eye medially. Therefore, a lesion in the **Right Frontal Lobe** results in an inability to perform a **left-sided lateral gaze**. **Analysis of Incorrect Options:** * **B & C (Occipital Lobes):** The occipital cortex (specifically the visual association areas) is primarily involved in **smooth pursuit** movements (tracking a moving object) rather than voluntary saccadic gaze [1]. * **D (Left Frontal Lobe):** A lesion here would impair the ability to look toward the **right** side. **Clinical Pearls for NEET-PG:** 1. **"Gaze preference":** In a destructive cortical lesion (e.g., stroke), the eyes "look toward the lesion" because the opposing FEF is unopposed. Thus, a Right FEF lesion causes the eyes to deviate to the **right**. 2. **Pons vs. Cortex:** While a cortical lesion causes the eyes to look *away* from the hemiparesis, a **Pontine lesion** (PPRF) causes the eyes to look *toward* the hemiparesis (away from the lesion). 3. **Destructive vs. Irritative:** A destructive lesion (stroke) causes gaze toward the lesion; an irritative lesion (seizure) causes gaze away from the lesion.

Q: Which cranial nerve is related to the apex of the petrous temporal bone?

VI. The correct answer is **VI (Abducens nerve)**. This relationship is a high-yield anatomical landmark in neuroanatomy. **Why Option C is Correct:** The Abducens nerve (CN VI) has a long intracranial course. After leaving the pons, it ascends along the clivus and enters **Dorello’s Canal**. This canal is located between the **apex of the petrous temporal bone** and the petrosphenoid ligament (Gruber’s ligament). At this specific point, the nerve makes a sharp bend to enter the cavernous sinus, making it highly vulnerable to pathological processes at the petrous apex. **Why Other Options are Incorrect:** * **Options A (VIII) and B (VII):** Both the Facial (VII) and Vestibulocochlear (VIII) nerves enter the **internal acoustic meatus**, which is located on the posterior surface of the petrous temporal bone, but not at its apex. * **Option D (IX):** The Glossopharyngeal nerve exits the skull through the **jugular foramen**, which lies between the petrous temporal bone and the occipital bone, well inferior to the apex. **Clinical Pearls for NEET-PG:** * **Gradenigo’s Syndrome:** This is a classic triad resulting from **petrous apicitis** (inflammation of the petrous apex). It presents with: 1. **Abducens nerve palsy** (Diplopia due to involvement at the apex). 2. **Trigeminal nerve pain** (Retro-orbital pain due to involvement of the Trigeminal ganglion at Meckel’s cave). 3. **Otorrhea** (Persistent ear discharge/Otitis media). * The Abducens nerve is the most common cranial nerve involved in **raised intracranial pressure (ICP)** because of its long course and the sharp turn it takes over the petrous apex.

Q: Which of the following does NOT supply the posterior limb of the internal capsule?

Anterior cerebral artery. The internal capsule is a vital white matter structure, and its blood supply is a frequent high-yield topic in NEET-PG. The **Posterior Limb** of the internal capsule is strategically located between the thalamus and the lentiform nucleus, receiving a rich collateral blood supply from several major arteries [1]. ### Why the Anterior Cerebral Artery (ACA) is the Correct Answer: The **Anterior Cerebral Artery (ACA)**, specifically its branch the **Medial Striate Artery (Recurrent Artery of Heubner)**, primarily supplies the **Anterior Limb** and the **Genu** of the internal capsule. It does not extend far enough posteriorly to supply the posterior limb. ### Analysis of Other Options: * **Middle Cerebral Artery (MCA):** The **Lateral Striate (Lenticulostriate) arteries** arising from the M1 segment of the MCA supply the superior half of the posterior limb. These are often called the "arteries of stroke." * **Anterior Choroidal Artery (AChA):** A branch of the Internal Carotid Artery, it supplies the inferior half of the posterior limb, as well as the retrolentiform and sublentiform parts. * **Posterior Cerebral Artery (PCA):** Through its posterolateral central (thalamogeniculate) branches, the PCA contributes to the supply of the posterior limb, particularly the part adjacent to the thalamus. ### High-Yield Clinical Pearls: * **Recurrent Artery of Heubner (ACA):** Supplies the Anterior Limb + Genu. * **Charcot’s Artery of Cerebral Hemorrhage:** A specific large lenticulostriate branch of the MCA often implicated in hypertensive bleeds affecting the internal capsule. * **Clinical Presentation:** A stroke in the posterior limb typically presents with **pure motor hemiplegia** (due to involvement of corticospinal tracts) and **contralateral sensory loss** (due to thalamocortical fibers).

Question 1

Which of the following is considered a nucleus of the basal ganglia?

Accepted Answer

Caudate

Answer

Dentate

Answer

Thalamus

Answer

Red nucleus

Question 2

A lesion of the optic radiation involving Meyer's loop causes which of the following visual field defects?

Accepted Answer

Superior quadrantanopia

Answer

Homonymous hemianopia

Answer

Inferior quadrantanopia

Answer

Central scotoma

Question 3

Lynch syndrome is associated with which of the following cancers?

Accepted Answer

Colon, endometrium, ovary

Answer

Breast, colon, ovary

Answer

Breast, endometrium, ovary

Answer

Breast, colon, endometrium

Question 4

The optic nerve is a tract of the diencephalon that is not completely myelinated until when?

Accepted Answer

3 months after birth

Answer

5 years after birth

Answer

2 years after birth

Answer

1 year after birth

Question 5

Which of the following statements best describes the sulcus limitans?

Accepted Answer

It is located between the alar and basal plates

Answer

It is found in the interpeduncular fossa

Answer

It separates the medulla from the pons

Answer

It separates the hypothalamus from the thalamus

Question 6

Which of the following are association fibers?

Accepted Answer

All of the above

Answer

Uncinate fasciculus

Answer

Cingulum

Answer

Superior longitudinal fasciculus

Question 7

The trigeminal ganglion is?

Accepted Answer

Homologous with the dorsal root ganglion.

Answer

A motor and sensory ganglion of the trigeminal nerve.

Answer

Made up of unipolar and bipolar cells.

Answer

Receives the motor root at its posterior concavity.

Question 8

A lesion in which of the following areas will affect left-sided lateral gaze?

Accepted Answer

Right frontal lobe

Answer

Right occipital lobe

Answer

Left occipital lobe

Answer

Left frontal lobe

Question 9

Which cranial nerve is related to the apex of the petrous temporal bone?

Accepted Answer

VI

Answer

VIII

Answer

VII

Answer

IX

Question 10

Which of the following does NOT supply the posterior limb of the internal capsule?

Accepted Answer

Anterior cerebral artery

Answer

Middle cerebral artery

Answer

Anterior choroidal artery

Answer

Posterior cerebral artery

Neuroanatomy — MCQs

Neuroanatomy — MCQs

On this page

Practice by Chapter

Want unlimited practice?