Neuroanatomy Practice Questions

Q: What is the drug of choice for supraventricular tachycardia?

Verapamil. **Explanation:** **Supraventricular Tachycardia (SVT)**, specifically Paroxysmal SVT (PSVT), is most commonly caused by a re-entry circuit involving the Atrioventricular (AV) node. To terminate the arrhythmia, the conduction through the AV node must be slowed or blocked. **Why Verapamil is the Correct Answer:** Verapamil is a **Class IV antiarrhythmic** (Non-dihydropyridine Calcium Channel Blocker). It acts by blocking L-type calcium channels, which are the primary drivers of depolarization in the SA and AV nodes. By increasing the refractory period and slowing conduction velocity at the AV node, Verapamil effectively breaks the re-entry circuit. While **Adenosine** is technically the first-line drug of choice for acute termination in emergency settings, Verapamil remains a classic "drug of choice" in exam scenarios for both termination and prophylaxis of PSVT. **Analysis of Incorrect Options:** * **B. Diltiazem:** Also a Class IV CCB, but it has less potent AV nodal blocking effects compared to Verapamil and is more commonly used for rate control in Atrial Fibrillation. * **C. Digoxin:** While it slows AV conduction via vagomimetic effects, its onset of action is too slow for the acute termination of SVT. It is primarily used for rate control in chronic heart failure with Atrial Fibrillation. * **D. Phenytoin:** A Class IB antiarrhythmic primarily used for **Digitalis-induced arrhythmias** (specifically ventricular arrhythmias), not for standard PSVT. **High-Yield Clinical Pearls for NEET-PG:** * **Adenosine** is the drug of choice for *acute* termination of PSVT (short half-life <10 seconds). * **Verapamil** is contraindicated in patients with Wide QRS Tachycardia or Wolff-Parkinson-White (WPW) syndrome with Atrial Fibrillation, as it may precipitate Ventricular Fibrillation [1]. * **Side effect:** A common side effect of Verapamil is constipation and gingival hyperplasia.

Q: A lesion at the spinal sensory nucleus of the trigeminal nerve leads to loss of which sensation?

Ipsilateral temperature. **Explanation:** The **Spinal Sensory Nucleus of the Trigeminal Nerve (CN V)** is functionally analogous to the dorsal horn of the spinal cord. It primarily processes **pain and temperature** sensations from the face. 1. **Why Option D is Correct:** Primary afferent fibers for pain and temperature enter the pons and descend via the **Spinal Trigeminal Tract** to synapse in the Spinal Nucleus (which extends down to the C2-C3 spinal levels). Because these fibers have not yet decussated (crossed over) at the level of the nucleus, a lesion here results in the loss of **ipsilateral** (same side) pain and temperature sensation. 2. **Why Other Options are Incorrect:** * **Touch (A):** Fine touch and pressure are primarily processed by the **Main (Principal) Sensory Nucleus** of CN V located in the pons. * **Position Sensation (B):** Proprioception (position sense) from the muscles of mastication and TMJ is processed by the **Mesencephalic Nucleus** of CN V. * **Contralateral Pain (C):** Pain sensation becomes contralateral only *after* synapsing in the spinal nucleus and crossing the midline to form the Ventral Trigeminothalamic Tract. A lesion of the nucleus itself affects the incoming ipsilateral fibers. **High-Yield Clinical Pearls for NEET-PG:** * **Wallenberg Syndrome (PICA Infarct):** A classic exam favorite where a lateral medullary lesion involves the Spinal Trigeminal Nucleus, causing **ipsilateral** loss of pain/temp on the face and **contralateral** loss on the body (due to Lateral Spinothalamic Tract involvement). * **Nucleus Organization:** The Spinal Nucleus is arranged somatotopically like an "onion skin," where the most central parts of the face are represented superiorly and the peripheral parts inferiorly.

Q: Gustatory cortex is situated in which of the following locations?

Inferior parietal gyrus. **Explanation:** The **Gustatory Cortex** (Primary Taste Area) is responsible for the perception of taste. It is primarily located in the **anterior insula** and the **frontal operculum**. In the context of cortical anatomy, this region corresponds to the **inferior parietal gyrus** (specifically the parietal operculum) and the lower part of the postcentral gyrus (Brodmann area 43) [1]. **Why the correct answer is right:** * **Brodmann Area 43:** This area is situated at the base of the postcentral gyrus, extending into the **parietal operculum** (part of the inferior parietal lobule/gyrus). It receives taste sensations from the ventral posteromedial (VPM) nucleus of the thalamus [1]. **Why the incorrect options are wrong:** * **Superior temporal gyrus:** This contains the **Primary Auditory Cortex** (Heschl’s gyri, Areas 41 and 42) and Wernicke’s area (Area 22). * **Inferior frontal gyrus:** This contains **Broca’s Motor Speech Area** (Areas 44 and 45) in the dominant hemisphere. * **Superior frontal gyrus:** This is primarily involved in higher cognitive functions, motor planning (Supplementary Motor Area), and working memory. **High-Yield Facts for NEET-PG:** * **Taste Pathway:** Receptors → Cranial Nerves VII, IX, X → Nucleus Tractus Solitarius (NTS) → VPM Nucleus of Thalamus → Primary Gustatory Cortex (Area 43) [1]. * **Insula:** Often considered the "fifth lobe" of the brain; it is hidden deep within the lateral sulcus and is the primary site for visceral and gustatory integration. * **Ageusia:** The clinical term for the loss of taste sensation.

Q: Which of the following is a complete sulcus?

Collateral sulcus. ### Explanation In neuroanatomy, a **complete sulcus** is defined as a deep groove that is so profound it causes a corresponding elevation or inward bulging in the wall of the lateral ventricle. **Why Collateral Sulcus is correct:** The **collateral sulcus** is located on the tentorial surface of the brain, separating the parahippocampal gyrus from the medial occipitotemporal gyrus. It is a classic example of a complete sulcus because its depth produces a longitudinal elevation on the floor of the temporal horn of the lateral ventricle, known as the **collateral eminence**. **Analysis of Incorrect Options:** * **A. Central sulcus:** This is a limiting sulcus (separating motor and sensory areas) but does not indent the ventricular system. * **B. Paracentral sulcus:** This is a minor sulcus on the medial surface of the hemisphere and does not reach the ventricular wall. * **D. Post-calcarine sulcus:** While the **calcarine sulcus** itself is a complete sulcus (producing the *calcar avis* in the posterior horn of the lateral ventricle), the *post-calcarine* portion is generally considered a continuation that does not consistently produce a ventricular indentation in the same manner as the main trunk or the collateral sulcus. **High-Yield Facts for NEET-PG:** * **The Two Main Complete Sulci:** 1. **Collateral Sulcus** $\rightarrow$ produces **Collateral Eminence**. 2. **Calcarine Sulcus** $\rightarrow$ produces **Calcar Avis** (Hippocampus minor). * **Limiting Sulcus:** A sulcus that separates two different functional/histological areas (e.g., Central Sulcus). * **Operculated Sulcus:** A sulcus whose lips contain a third area hidden in its depths (e.g., Lunate sulcus). * **Crucial Landmark:** The collateral sulcus begins near the occipital pole and runs forward, parallel to the calcarine sulcus.

Q: Which cranial nerve, possessing a motor component, is most frequently damaged?

Facial. The **Facial Nerve (CN VII)** is the most frequently paralyzed peripheral nerve in the human body. This high incidence of injury is primarily due to its complex and longest intraosseous course through the narrow facial canal (Fallopian canal) in the temporal bone. Any inflammation or edema within this rigid bony tunnel leads to nerve compression, resulting in **Bell’s Palsy** (idiopathic lower motor neuron facial paralysis), which is the most common cause of spontaneous facial paralysis. **Analysis of Options:** * **Facial Nerve (Correct):** Beyond Bell’s Palsy, it is highly susceptible to trauma (temporal bone fractures), middle ear infections (otitis media), and surgical injury (parotid gland surgery). * **Oculomotor Nerve (A):** While commonly affected by aneurysms (Posterior Communicating Artery) or diabetes, it is far less frequently damaged than the facial nerve in general clinical practice. * **Trigeminal Nerve (B):** Though it can be involved in Trigeminal Neuralgia, it is less prone to complete motor paralysis compared to the facial nerve. * **Glossopharyngeal Nerve (D):** Isolated lesions of CN IX are clinically rare due to its protected deep anatomical position. **NEET-PG High-Yield Pearls:** * **Longest Intracranial Course:** Trochlear Nerve (CN IV). * **Longest Intraosseous Course:** Facial Nerve (CN VII). * **Most Common Nerve Injured in Midshaft Humerus Fracture:** Radial Nerve. * **Most Common Cranial Nerve Injured in Head Trauma:** Olfactory Nerve (CN I), followed by the Abducens Nerve (CN VI) due to its long intracranial course. However, among those with a **motor component** and general clinical frequency, the **Facial Nerve** remains the most common.

Q: Which of the following structures is not considered a part of the basal ganglia?

Thalamus. **Explanation:** The **basal ganglia** (or basal nuclei) are a group of subcortical gray matter structures located deep within the cerebral hemispheres, primarily involved in the control and refinement of motor movements [1]. **Why Thalamus is the Correct Answer:** The **Thalamus** is a massive collection of nuclei located in the diencephalon [2]. While it is functionally interconnected with the basal ganglia (acting as the "relay station" for the motor loop back to the cortex), it is anatomically and embryologically distinct. It is **not** considered a component of the basal ganglia [1]. **Analysis of Incorrect Options:** * **Caudate Nucleus:** A C-shaped structure that forms the lateral wall of the lateral ventricle. It is a primary component of the **Striatum** [1]. * **Lenticular Nucleus:** A lens-shaped mass consisting of the **Putamen** (lateral part) and the **Globus Pallidus** (medial part) [1]. * **Globus Pallidus:** Divided into internal (GPi) and external (GPe) segments, it serves as the major output nucleus of the basal ganglia system [1]. **High-Yield NEET-PG Pearls:** 1. **Corpus Striatum:** Comprises the Caudate nucleus and the Lenticular nucleus [1]. 2. **Neostriatum (Striatum):** Caudate nucleus + Putamen [1]. 3. **Paleostriatum:** Globus Pallidus. 4. **Functional Components:** Although not part of the "anatomical" basal ganglia, the **Subthalamic Nucleus** (diencephalon) and **Substantia Nigra** (midbrain) are functionally essential parts of the system [1]. 5. **Clinical Correlation:** Lesions in the basal ganglia lead to movement disorders like **Parkinson’s disease** (Substantia Nigra) and **Hemiballismus** (Subthalamic Nucleus).

Q: Which of the following foramina allows cerebrospinal fluid to pass directly from the ventricular system into the subarachnoid space?

Foramen of Magendie. ### Explanation The ventricular system is a series of communicating cavities within the brain where cerebrospinal fluid (CSF) is produced. For CSF to fulfill its protective and metabolic functions, it must exit the internal ventricular system and enter the **subarachnoid space**. **Why Option A is Correct:** The **Foramen of Magendie** (median aperture) is a midline opening in the roof of the fourth ventricle. Along with the two **Foramina of Luschka** (lateral apertures), it serves as the primary exit point for CSF to pass from the fourth ventricle into the **cisterna magna** (subarachnoid space) [2]. **Why the Other Options are Incorrect:** * **Option B (Aqueduct of Sylvius):** Also known as the cerebral aqueduct, it connects the third ventricle to the fourth ventricle. It is an *internal* conduit and does not communicate with the subarachnoid space. * **Options C & D (Third and Lateral Ventricles):** These are internal components of the ventricular system. CSF flows from the lateral ventricles to the third ventricle via the *Foramina of Monro*, remaining entirely within the brain's internal cavities. **NEET-PG High-Yield Pearls:** * **Mnemonic for Apertures:** **M**agendie is **M**edian (midline); **L**uschka is **L**ateral. * **Flow Sequence:** Lateral Ventricles → Foramen of Monro → 3rd Ventricle → Aqueduct of Sylvius → 4th Ventricle → Foramina of Luschka/Magendie → Subarachnoid Space. * **Clinical Correlation:** Obstruction at any of these foramina (e.g., by a tumor or congenital stenosis) leads to **non-communicating (obstructive) hydrocephalus**, causing increased intracranial pressure [1]. * **Absorption:** CSF is ultimately reabsorbed into the dural venous sinuses via **arachnoid granulations** [2].

Q: In children, the spinal cord typically terminates at the lower border of which vertebral level?

L3. ### Explanation The spinal cord terminates at different levels depending on the age of the individual due to the differential growth rates of the vertebral column and the spinal cord (a phenomenon known as the **"ascent of the cord"**). **1. Why L3 is Correct:** In **neonates and infants**, the spinal cord ends at the level of the **L3 vertebra**. During early fetal development, the spinal cord occupies the entire length of the vertebral canal. However, as the vertebral column grows much faster than the neural tissue, the distal end of the cord (conus medullaris) appears to "move up." By birth, it typically reaches the lower border of L3. **2. Analysis of Incorrect Options:** * **A & B (L1/L2):** These are the termination levels in **adults** [1]. In most adults, the spinal cord ends at the lower border of **L1** or the L1-L2 intervertebral disc [1]. Choosing these for a child would be incorrect and clinically dangerous during procedures. * **D (L4):** This level is too low for a term infant. While the cord is at the sacral level in early fetal life (8 weeks), it has already ascended past L4 by the time of birth. **3. Clinical Pearls & High-Yield Facts:** * **Lumbar Puncture (LP) Safety:** To avoid needle injury to the spinal cord, an LP is performed at the **L3-L4 or L4-L5** space in adults, but must be performed lower (usually **L4-L5 or L5-S1**) in infants. * **Subarachnoid Space:** While the cord ends at L1 (adult) or L3 (child), the subarachnoid space (dural sac) ends at **S2** in both [1]. * **Filum Terminale:** The fibrous extension of the pia mater that anchors the cord to the coccyx is called the filum terminale [1]. * **Tethered Cord Syndrome:** A clinical condition where the conus medullaris is abnormally low, often associated with spina bifida.

Question 1

What is the drug of choice for supraventricular tachycardia?

Accepted Answer

Verapamil

Answer

Diltiazem

Answer

Digoxin

Answer

Phenytoin

Question 2

A lesion at the spinal sensory nucleus of the trigeminal nerve leads to loss of which sensation?

Accepted Answer

Ipsilateral temperature

Answer

Touch

Answer

Position sensation

Answer

Contralateral pain

Question 3

Gustatory cortex is situated in which of the following locations?

Accepted Answer

Inferior parietal gyrus

Answer

Superior temporal gyrus

Answer

Inferior frontal gyrus

Answer

Superior frontal gyrus

Question 4

Which of the following is a complete sulcus?

Accepted Answer

Collateral sulcus

Answer

Central sulcus

Answer

Paracentral sulcus

Answer

Post calcarine sulcus

Question 5

Which cranial nerve, possessing a motor component, is most frequently damaged?

Accepted Answer

Facial

Answer

Occulomotor

Answer

Trigeminal

Answer

Glossopharyngeal

Question 6

Which of the following structures is not considered a part of the basal ganglia?

Accepted Answer

Thalamus

Answer

Caudate nucleus

Answer

Lenticular nucleus

Answer

Globus pallidus

Question 7

Which of the following foramina allows cerebrospinal fluid to pass directly from the ventricular system into the subarachnoid space?

Accepted Answer

Foramen of Magendie

Answer

Aqueduct of Sylvius

Answer

Third ventricle

Answer

Lateral ventricle

Question 8

Examination of a patient demonstrates foot drop with weakness of the anterior tibial, posterior tibial, and peroneal muscles. Sensory loss is demonstrated over the anterior shin and dorsal foot. These findings suggest a radiculopathy at which of the following cord levels?

Accepted Answer

L-5

Answer

C-7

Answer

S-3

Answer

T-9

Question 9

Which of the following arteries provides blood supply to the lateral geniculate body?

Accepted Answer

Posterior cerebral artery

Answer

Anterior cerebral artery

Answer

Middle cerebral artery

Answer

Posterior communicating artery

Question 10

In children, the spinal cord typically terminates at the lower border of which vertebral level?

Accepted Answer

L3

Answer

L1

Answer

L2

Answer

L4

Neuroanatomy — MCQs

Neuroanatomy — MCQs

On this page

Practice by Chapter

Want unlimited practice?