Neuroanatomy Practice Questions

Q: The lateral surface of the cerebral hemisphere is primarily supplied by which artery?

Middle cerebral artery. The blood supply to the cerebral cortex is a high-yield topic for NEET-PG, following the "Rule of Surfaces." [1] **Explanation of the Correct Answer:** The **Middle Cerebral Artery (MCA)**, the largest branch of the internal carotid artery, is the primary vessel for the **lateral (superolateral) surface** of the cerebral hemisphere. It travels through the lateral sulcus and fans out to supply the majority of the temporal, parietal, and frontal lobes. Crucially, it supplies the primary motor and sensory areas for the entire body **except** the lower limb and perineum. **Analysis of Incorrect Options:** * **Anterior Cerebral Artery (ACA):** This artery primarily supplies the **medial surface** of the cerebral hemisphere (up to the parieto-occipital sulcus) and a thin strip (about 1 inch) of the lateral surface along the superior border. [1] * **Posterior Cerebral Artery (PCA):** This artery supplies the **inferior surface** of the temporal lobe and the **occipital lobe** (both medial and lateral aspects), including the primary visual cortex. **High-Yield Clinical Pearls for NEET-PG:** 1. **Motor Homunculus:** An MCA stroke typically results in contralateral hemiplegia and hemisensory loss affecting the **face and upper limb** more than the leg. 2. **Aphasia:** Since the MCA supplies the lateral surface of the dominant hemisphere, it covers **Broca’s area** (frontal) and **Wernicke’s area** (temporal); thus, MCA infarcts often present with global or specific aphasias. 3. **Macular Sparing:** In PCA strokes involving the visual cortex, the macula is often spared because the occipital pole receives a collateral supply from the MCA.

Q: The facial nerve lies with which cranial nerve within the internal auditory meatus?

Vestibulocochlear nerve. ### Explanation **Correct Answer: C. Vestibulocochlear nerve** The **Internal Auditory Meatus (IAM)** is a canal in the petrous part of the temporal bone that serves as a conduit for structures passing between the posterior cranial fossa and the inner ear. The primary contents of the IAM are: 1. **Facial Nerve (CN VII)** 2. **Vestibulocochlear Nerve (CN VIII)** [1] 3. **Nervus Intermedius** (Sensory root of the facial nerve) 4. **Labyrinthine artery** (Branch of AICA) The facial nerve and vestibulocochlear nerve enter the IAM together. Within the meatus, the facial nerve occupies the **anterosuperior** quadrant, while the vestibulocochlear nerve divides into the cochlear and vestibular branches occupying the remaining quadrants [1]. **Analysis of Incorrect Options:** * **A. Trigeminal nerve (CN V):** Exits the brainstem at the pons and enters the **Meckel’s cave** (trigeminal cave) near the apex of the petrous temporal bone. * **B. Abducent nerve (CN VI):** Enters the **Dorello’s canal** and passes through the cavernous sinus. * **D. Hypoglossal nerve (CN XII):** Exits the skull via the **Hypoglossal canal** in the occipital bone. **High-Yield Clinical Pearls for NEET-PG:** * **Bill’s Bar:** A vertical bony crest in the IAM that separates the facial nerve (anterior) from the superior vestibular nerve (posterior). * **Acoustic Neuroma (Vestibular Schwannoma):** A tumor arising from the Schwann cells of CN VIII within the IAM. Early symptoms include hearing loss and tinnitus, but as it grows, it can compress the adjacent **Facial nerve**, leading to facial weakness. * **Zygomatic branch of CN VII:** This is the most common nerve injured during parotid surgeries, but within the IAM, it is the main trunk of CN VII that is at risk.

Q: A 62-year-old male patient presented with paraplegia, bilateral thermoanesthesia and analgesia below the level of the umbilicus, and loss of bowel and bladder movements. Proprioception and vibration senses are intact. Spinal angiography revealed a thrombus in the anterior spinal artery. Which of the following regions of the spinal cord is likely to be affected?

Anterior two-thirds of the spinal cord. ### Explanation **Concept Overview:** The spinal cord is supplied by one **Anterior Spinal Artery (ASA)** and two **Posterior Spinal Arteries (PSA)**. The ASA originates from the vertebral arteries and runs in the anterior median fissure. It supplies the **anterior two-thirds** of the spinal cord, which includes the anterior horns (motor), lateral corticospinal tracts (motor), and lateral spinothalamic tracts (pain and temperature). **Why Option C is Correct:** The patient presents with **Anterior Spinal Artery Syndrome**. The clinical features align perfectly with the structures supplied by the ASA: * **Paraplegia:** Damage to the lateral corticospinal tracts [1]. * **Thermoanesthesia and Analgesia:** Damage to the lateral spinothalamic tracts. * **Autonomic Dysfunction:** Loss of bowel/bladder control due to involvement of descending autonomic pathways. * **Intact Proprioception/Vibration:** These are carried by the **Dorsal Columns**, which are supplied by the **Posterior Spinal Arteries**, thus remaining spared. **Why Other Options are Incorrect:** * **Option A:** A whole segment involvement (Transverse Myelitis) would result in the loss of *all* modalities, including proprioception and vibration. * **Options B & D:** These are anatomically incorrect proportions. The ASA consistently supplies the anterior two-thirds, while the PSAs supply the posterior one-third. **NEET-PG High-Yield Pearls:** * **Artery of Adamkiewicz:** The largest radicular artery (usually on the left at T9-L2); its occlusion during aortic surgery often leads to ASA syndrome. * **Sparing of Dorsal Columns:** This is the "hallmark" of ASA syndrome, distinguishing it from a complete cord transection. * **Level of Umbilicus:** Corresponds to the **T10** dermatome. * **Vulnerability:** The thoracic segment (T4-T8) is a "watershed area" and is most susceptible to ischemic injury.

Q: Osler's nodes are seen at?

Tip of palm and sole. Osler’s nodes are a classic clinical sign of Infective Endocarditis (IE). They are characterized as small, tender, raised, erythematous (red) nodules with a pale center. Why Option C is correct: Osler’s nodes are typically found on the pulp of the fingers and toes (tips of palms and soles). Pathophysiologically, they are caused by immune complex deposition (Type III hypersensitivity) in the skin, leading to localized vasculitis. Their hallmark feature is that they are painful/tender, which distinguishes them from other cutaneous manifestations of IE. Why the other options are incorrect: * Option A (Head): While IE can cause neurological complications (like embolic strokes), Osler’s nodes do not manifest on the scalp or face. * Option B (Knee joint): Joint pain (arthralgia) can occur in IE, but the specific nodular lesions of Osler are restricted to distal extremities. * Option D (Anterior abdominal wall): This is not a site for immune-complex mediated nodules in IE; however, splenomegaly is a common abdominal finding in these patients. High-Yield Clinical Pearls for NEET-PG: * Janeway Lesions: Unlike Osler’s nodes, these are painless, hemorrhagic macules found on the palms and soles, caused by septic emboli (not immune complexes). * Roth Spots: Retinal hemorrhages with central clearing seen on fundoscopy in IE. * Splinter Hemorrhages: Linear dark-red streaks under the nail beds. * Mnemonic: Osler nodes = Ouch (Painful). Janeway = Just fine (Painless).

Q: The Vein of Galen drains into which of the following venous structures?

Straight sinus. **Explanation:** The **Great Cerebral Vein (Vein of Galen)** is a short, thick venous trunk formed by the union of the two **Internal Cerebral Veins** and the two **Basal Veins (of Rosenthal)**. It is located in the quadrigeminal cistern. The Vein of Galen travels posteriorly and superiorly to join the **Inferior Sagittal Sinus** at the junction of the falx cerebri and tentorium cerebelli. This union forms the **Straight Sinus (Sinus Rectus)**, which then drains into the confluence of sinuses. **Analysis of Options:** * **Option C (Straight Sinus):** This is the direct continuation of the Vein of Galen after it merges with the inferior sagittal sinus. * **Option A & B (Internal/External Jugular Veins):** These are major neck veins. While the internal jugular vein is the ultimate destination for all dural venous sinuses (via the sigmoid sinus), it is not the immediate structure the Vein of Galen drains into. * **Option D (Superior Sagittal Sinus):** This sinus runs along the superior border of the falx cerebri and receives blood from the superior cerebral veins, not the deep venous system represented by the Vein of Galen. **High-Yield Clinical Pearls for NEET-PG:** * **Vein of Galen Malformation (VOGM):** An arteriovenous malformation in neonates that can lead to high-output heart failure and hydrocephalus. * **Deep Venous System:** Remember the sequence: *Internal Cerebral Veins + Basal Veins → Vein of Galen → Straight Sinus.* * **Location:** The Vein of Galen is situated beneath the splenium of the corpus callosum.

Q: Which of the following statements is FALSE regarding the fourth cranial nerve (trochlear nerve)?

It innervates the superior oblique muscle.. The **Trochlear Nerve (CN IV)** is a high-yield topic in neuroanatomy due to its unique anatomical characteristics. ### **Explanation of the Correct Option** The question asks for the **FALSE** statement. However, the provided options contain a repetition (A and B). In the context of CN IV, the statement "It innervates the superior oblique muscle" is actually **TRUE**. *Note: If this were a standard NEET-PG question, the false statement would typically be related to its origin (it is the only nerve to emerge from the **dorsal** aspect of the brainstem) or its decussation (it is the only CN that completely decussates before exiting).* ### **Analysis of Options** * **Option A & B (True):** CN IV provides motor innervation to the **Superior Oblique (SO)** muscle. Remember the mnemonic **LR6SO4**, which stands for Lateral Rectus (CN VI) and Superior Oblique (CN IV). * **Option C (True):** The trochlear nerve travels in the **lateral wall** of the cavernous sinus, positioned between the oculomotor nerve (above) and the ophthalmic division of the trigeminal nerve (below). * **Option D (True):** It enters the orbit via the **superior orbital fissure (SOF)**. Specifically, it passes **outside** the common tendinous ring (Annulus of Zinn). ### **High-Yield Clinical Pearls for NEET-PG** 1. **Longest Intracranial Course:** CN IV has the longest intracranial (subarachnoid) path, making it highly susceptible to shear injuries during head trauma. 2. **Smallest Cranial Nerve:** It contains the fewest number of axons. 3. **Dorsal Exit:** It is the only cranial nerve to exit from the posterior aspect of the brainstem (midbrain). 4. **Clinical Deficit:** Paralysis of CN IV leads to **diplopia (double vision)**, which worsens when looking down (e.g., reading or walking down stairs). Patients often present with a **compensatory head tilt** to the opposite side.

Q: A lesion in the occipital lobe will cause which of the following visual field defects?

Homonymous hemianopia with macular sparing. **Explanation:** A lesion in the **occipital lobe** (specifically the primary visual cortex or Brodmann area 17) typically results in **contralateral homonymous hemianopia with macular sparing** [1]. The hallmark of this condition is **macular sparing**, which occurs due to two main reasons: 1. **Dual Blood Supply:** The occipital pole, which represents the macula, receives a collateral blood supply from both the **Middle Cerebral Artery (MCA)** and the **Posterior Cerebral Artery (PCA)**. If the PCA is occluded, the MCA maintains perfusion to the macular area. 2. **Large Cortical Representation:** The macula has a disproportionately large area of representation in the visual cortex, making it more resilient to small focal lesions [1]. **Analysis of Incorrect Options:** * **A. Binasal hemianopia:** This rare defect is usually caused by lateral pressure on the optic chiasm (e.g., calcified internal carotid arteries) [1]. * **B. Bitemporal hemianopia:** This is the classic "tunnel vision" caused by a lesion at the **optic chiasm** (e.g., Pituitary adenoma or Craniopharyngioma) [1]. * **C. Homonymous superior quadrantanopia:** Also known as "Pie in the sky," this results from a lesion in the **Meyer’s loop** in the temporal lobe. **NEET-PG High-Yield Pearls:** * **Congruity:** The more posterior the lesion in the visual pathway, the more **congruous** (identical in both eyes) the visual field defect. Occipital lesions produce highly congruous defects. * **Pie in the Floor:** Inferior quadrantanopia occurs due to a lesion in the **Baum’s loop** (Parietal lobe). * **Optic Tract Lesion:** Causes contralateral homonymous hemianopia but **without** macular sparing and may present with Wernicke’s hemianopic pupil [1].

Q: Which of the following is NOT a feature of unilateral 3rd Cranial nerve nuclear injury?

Unilateral Ptosis. To understand this question, one must distinguish between a **3rd Nerve Trunk (Nerve) lesion** and a **3rd Nerve Nuclear lesion**. [1] ### 1. Why "Unilateral Ptosis" is the Correct Answer In a **nuclear** lesion of the 3rd nerve, **unilateral ptosis is anatomically impossible**. The Levator Palpebrae Superioris (LPS) muscles are supplied by a **single, midline subnucleus** (the Central Caudal Nucleus) that provides bilateral innervation. Therefore, a lesion at the nuclear level will always result in **Bilateral Ptosis**. Unilateral ptosis is a hallmark of a peripheral nerve trunk lesion, not a nuclear one. ### 2. Analysis of Incorrect Options * **A. Bilateral incomplete Ptosis:** This is a characteristic feature of a nuclear lesion because the single midline subnucleus for LPS is affected, impacting both eyelids. * **B & C. Weakness of Ipsilateral and Contralateral Superior Rectus:** The subnucleus for the Superior Rectus (SR) is unique; its fibers **decussate** within the midbrain to supply the **contralateral** eye. However, because these fibers pass through the opposite SR nucleus, a unilateral nuclear lesion typically destroys both the resident neurons (supplying the opposite eye) and the axons passing through from the other side. Thus, a unilateral nuclear lesion results in **bilateral SR weakness**. ### 3. NEET-PG High-Yield Pearls * **Rule of 3s for Nuclear Lesions:** A unilateral 3rd nerve nuclear lesion causes: 1. **Ipsilateral** weakness of MR, IR, and IO. 2. **Contralateral** weakness of SR. 3. **Bilateral** Ptosis (due to the single midline nucleus). * **Mnemonic:** "Nuclear is Near the Middle" — affecting shared structures like the LPS midline nucleus. * **Clinical Distinction:** If a patient has 3rd nerve palsy with **normal** contralateral SR function and **unilateral** ptosis, the lesion is in the **nerve trunk**, not the nucleus. [1]

Q: Which gyrus is not located on the lateral aspect of the cerebral hemisphere?

Cingulate gyrus. ### Explanation The cerebral hemisphere is divided into lateral, medial, and inferior surfaces. Understanding the topographical anatomy of these surfaces is crucial for localizing cortical functions and lesions. **Why Cingulate Gyrus is the Correct Answer:** The **Cingulate gyrus** is located exclusively on the **medial surface** of the cerebral hemisphere. It lies immediately superior to the corpus callosum, separated from it by the callosal sulcus, and is bounded superiorly by the cingulate sulcus. It is a key component of the **limbic system**, involved in emotional processing and memory. **Analysis of Incorrect Options:** * **Superior Temporal Gyrus (A):** Located on the lateral surface of the temporal lobe, just below the lateral sulcus. It contains the primary auditory cortex (Heschl’s gyri) and Wernicke’s area [1]. * **Middle Frontal Gyrus (B):** Situated on the lateral surface of the frontal lobe between the superior and inferior frontal sulci. It houses the frontal eye field (Brodmann area 8). * **Inferior Frontal Gyrus (D):** Located on the lateral surface of the frontal lobe. In the dominant hemisphere, its posterior part (pars opercularis and pars triangularis) constitutes **Broca’s motor speech area**. **High-Yield Clinical Pearls for NEET-PG:** * **Broca’s Area:** Located in the inferior frontal gyrus (Brodmann areas 44, 45). Damage leads to expressive aphasia. * **Wernicke’s Area:** Located in the posterior part of the superior temporal gyrus (Brodmann area 22). Damage leads to receptive aphasia [1]. * **Papez Circuit:** The cingulate gyrus is a vital link in this circuit, which is essential for the cortical control of emotions. * **Paracentral Lobule:** Another high-yield medial surface structure; it represents the motor and sensory areas for the lower limb and perineum.

Question 1

The lateral surface of the cerebral hemisphere is primarily supplied by which artery?

Accepted Answer

Middle cerebral artery

Answer

Anterior cerebral artery

Answer

Posterior cerebral artery

Answer

None of the above

Question 2

The facial nerve lies with which cranial nerve within the internal auditory meatus?

Accepted Answer

Vestibulocochlear nerve

Answer

Trigeminal nerve

Answer

Abducent nerve

Answer

Hypoglossal nerve

Question 3

A 62-year-old male patient presented with paraplegia, bilateral thermoanesthesia and analgesia below the level of the umbilicus, and loss of bowel and bladder movements. Proprioception and vibration senses are intact. Spinal angiography revealed a thrombus in the anterior spinal artery. Which of the following regions of the spinal cord is likely to be affected?

Accepted Answer

Anterior two-thirds of the spinal cord

Answer

Whole segment of the spinal cord

Answer

Anterior one-third of the spinal cord

Answer

Anterior one-half of the spinal cord

Question 4

Osler's nodes are seen at?

Accepted Answer

Tip of palm and sole

Answer

Head

Answer

Knee joint

Answer

Anterior abdominal wall

Question 5

The Vein of Galen drains into which of the following venous structures?

Accepted Answer

Straight sinus

Answer

Internal Jugular vein

Answer

External Jugular vein

Answer

Superior sagittal sinus

Question 6

In the central nervous system, which cell scavenges the debris created after the breakdown of an axon and its myelin?

Accepted Answer

Microglia

Answer

Macrophages

Answer

Astrocytes

Answer

Neutrophils

Question 7

Which of the following statements is FALSE regarding the fourth cranial nerve (trochlear nerve)?

Accepted Answer

It innervates the superior oblique muscle.

Answer

It runs along the lateral wall of the cavernous sinus.

Answer

It enters the orbit through the superior orbital fissure.

Question 8

A lesion in the occipital lobe will cause which of the following visual field defects?

Accepted Answer

Homonymous hemianopia with macular sparing

Answer

Binasal hemianopia

Answer

Bitemporal hemianopia

Answer

Homonymous superior quadrantanopia

Question 9

Which of the following is NOT a feature of unilateral 3rd Cranial nerve nuclear injury?

Accepted Answer

Unilateral Ptosis

Answer

Bilateral incomplete Ptosis

Answer

Weakness of the ipsilateral superior rectus muscles

Answer

Weakness of the contralateral superior rectus muscles

Question 10

Which gyrus is not located on the lateral aspect of the cerebral hemisphere?

Accepted Answer

Cingulate gyrus

Answer

Superior temporal gyrus

Answer

Middle frontal gyrus

Answer

Inferior frontal gyrus

Neuroanatomy — MCQs

Neuroanatomy — MCQs

On this page

Practice by Chapter

Want unlimited practice?