Neuroanatomy Practice Questions

Q: Which of the following is NOT a division of the Vth cranial nerve?

Optic. The **Trigeminal nerve (CN V)** is the largest cranial nerve and serves as the primary sensory nerve for the face and the motor nerve for the muscles of mastication. It originates from the pons and divides into three distinct branches at the trigeminal (semilunar/Gasserian) ganglion. ### **Explanation of Options:** * **Optic Nerve (Correct Answer):** The Optic nerve is the **IInd cranial nerve**, not a division of the Vth. It is a purely sensory nerve responsible for vision, originating from the retina and transmitting impulses to the visual cortex. * **Ophthalmic (V1):** This is the first and smallest division. It exits the skull via the **superior orbital fissure** and provides sensory innervation to the forehead, upper eyelid, and cornea. * **Maxillary (V2):** This is the second division. It exits via the **foramen rotundum** and provides sensory innervation to the mid-face, upper teeth, and maxillary sinus. * **Mandibular (V3):** This is the third and largest division. It exits via the **foramen ovale**. Unlike V1 and V2, it is a **mixed nerve**, carrying sensory fibers to the lower face/teeth and motor fibers to the muscles of mastication (e.g., masseter, temporalis). ### **NEET-PG High-Yield Pearls:** 1. **Exit Foramina Mnemonic:** **S**uperior Orbital Fissure (V1), Foramen **R**otundum (V2), Foramen **O**vale (V3) — Remember "**SRO**" (Standing Room Only). 2. **Trigeminal Neuralgia:** A clinical condition characterized by episodes of intense, stabbing pain, most commonly affecting the V2 or V3 distributions. 3. **Corneal Reflex:** The afferent limb is the Ophthalmic nerve (V1), while the efferent limb is the Facial nerve (CN VII).

Q: Pseudounipolar neurons are typically found in which of the following locations?

Dorsal root ganglia. Explanation: 1. Why the Correct Answer is Right: Pseudounipolar neurons are characterized by a single process that emerges from the cell body and subsequently divides into two branches: a peripheral branch (acting as a dendrite/sensory receptor) and a central branch (acting as an axon) [1]. These neurons are the hallmark of primary sensory ganglia. The Dorsal Root Ganglia (DRG) of the spinal cord house the cell bodies of these neurons, which transmit sensory information (touch, pain, temperature) from the periphery to the central nervous system. 2. Analysis of Incorrect Options: * B. Ganglia of Cranial Nerve VIII: The Vestibulocochlear nerve (CN VIII) contains Bipolar neurons [1]. These have two distinct processes (one axon and one dendrite) extending from opposite poles of the cell body. Bipolar neurons are also found in the retina and olfactory epithelium. * C. Mesencephalic Nucleus: This is a high-yield "exception" in neuroanatomy. While it is a sensory nucleus (proprioception for muscles of mastication), it is unique because it contains pseudounipolar neurons located inside the CNS (brainstem) rather than in a peripheral ganglion. However, the question asks where they are typically found, making the DRG the primary representative site. * D. Motor neurons: These are Multipolar neurons, which possess one axon and multiple dendrites [1]. This is the most common neuronal type in the CNS. 3. NEET-PG High-Yield Pearls: * Bipolar Neurons: Remember the "Special Senses" rule—Retina (Vision), Olfactory (Smell), and CN VIII (Hearing/Balance). * Mesencephalic Nucleus of V: It is the only instance where primary sensory cell bodies are located within the CNS (effectively a "ganglion" trapped inside the midbrain). * Unipolar Neurons: True unipolar neurons (one process only) are rare in humans but are found in the mesencephalic nucleus during early embryonic development.

Q: Structure A is formed by which of the following tracts?

Pontocerebellar. ***Pontocerebellar*** - Structure A represents the **middle cerebellar peduncle (brachium pontis)**, which is exclusively formed by **pontocerebellar fibers** originating from pontine nuclei. - These fibers carry information from the **cerebral cortex** via corticopontine pathways and cross to reach the **contralateral cerebellar hemisphere**. *Olivocerebellar* - **Olivocerebellar fibers** travel through the **inferior cerebellar peduncle (restiform body)**, not the middle peduncle. - These fibers originate from the **inferior olivary nucleus** and provide **climbing fiber** input to Purkinje cells. *Vestibulocerebellar* - **Vestibulocerebellar fibers** also pass through the **inferior cerebellar peduncle**, connecting vestibular nuclei to the cerebellum. - These pathways are crucial for **balance and equilibrium** but do not form the middle cerebellar peduncle. *Anterior spinocerebellar* - **Anterior spinocerebellar tract** fibers travel through the **superior cerebellar peduncle (brachium conjunctivum)** after crossing twice. - This tract carries **unconscious proprioceptive information** from the lower limbs to the cerebellar cortex.

Q: Which of the following tracts is seen in the posterior column of the spinal cord?

Fasciculus gracilis. **Explanation:** The spinal cord white matter is organized into three columns (funiculi): anterior, lateral, and posterior. The **posterior column** (dorsal column) is exclusively composed of ascending sensory fibers that carry fine touch, conscious proprioception, and vibratory sense [1]. **Why Fasciculus Gracilis is Correct:** The posterior column consists of two major tracts: the **Fasciculus Gracilis** (medial) and the **Fasciculus Cuneatus** (lateral) [1]. The Fasciculus Gracilis carries sensory information from the lower limbs and lower trunk (below T6). These fibers synapse in the medulla (nucleus gracilis), decussate as internal arcuate fibers, and ascend as the medial lemniscus [1]. **Analysis of Incorrect Options:** * **A. Lateral spinothalamic tract:** Located in the **lateral column**. It carries pain and temperature sensations [1]. * **C. Corticospinal tract:** The lateral corticospinal tract (the major motor pathway) is located in the **lateral column**, while the anterior corticospinal tract is in the **anterior column** [2]. * **D. Posterior spinocerebellar tract:** Despite the name "posterior," this tract is located on the periphery of the **lateral column**. It carries unconscious proprioception to the cerebellum. **NEET-PG High-Yield Pearls:** * **Rule of T6:** Fasciculus Gracilis is present at all spinal levels, but Fasciculus Cuneatus (carrying upper limb data) only appears at and above the **T6 level**. * **Clinical Correlation:** Damage to the posterior columns results in **Tabes Dorsalis** (syphilis) or Subacute Combined Degeneration (B12 deficiency), leading to loss of vibration sense and a positive **Romberg’s sign**. * **Decussation:** Unlike the spinothalamic tract (which decussates at the spinal level), the posterior column pathway decussates in the **medulla** [1].

Q: All of the following are parts of the optic nerve except?

Intracavernous part. The optic nerve (Cranial Nerve II) is a unique extension of the brain, rather than a peripheral nerve [1]. It measures approximately 45–50 mm in length and is divided into four distinct segments. **Explanation of the Correct Answer:** **Option D (Intracavernous part)** is the correct answer because the optic nerve **does not** pass through the cavernous sinus [1]. After exiting the optic canal, the optic nerve enters the middle cranial fossa to form the optic chiasm. The nerves that do traverse the cavernous sinus include CN III, IV, V1, V2 (in the lateral wall), and CN VI (within the sinus). **Explanation of Incorrect Options:** * **A. Intraorbital part:** This is the longest segment (~25 mm). It has a "S-shaped" curve to allow for eye movements without tension. It is surrounded by all three meningeal layers (dura, arachnoid, and pia). * **B. Intracanalicular part:** This segment (~5–9 mm) passes through the optic canal within the lesser wing of the sphenoid, accompanied by the ophthalmic artery. * **C. Cisternal segment:** Also known as the intracranial part (~10 mm), it extends from the optic canal to the optic chiasm, passing through the subarachnoid space (suprasellar cistern). **High-Yield Clinical Pearls for NEET-PG:** * **Meningeal Sheaths:** Because the optic nerve is an outgrowth of the diencephalon, it is covered by all three meninges. This explains why increased intracranial pressure (ICP) is transmitted to the optic disc, causing **papilledema** [3]. * **Myelination:** It is myelinated by **oligodendrocytes**, not Schwann cells [2]. This makes it susceptible to Multiple Sclerosis (Optic Neuritis). * **Blood Supply:** The intraorbital part is primarily supplied by the **central retinal artery**, a branch of the ophthalmic artery.

Q: What is Charcot's artery?

Striate branch of the middle cerebral artery. **Explanation:** **Charcot’s Artery** (also known as the **Artery of Cerebral Hemorrhage**) refers to the **lateral striate branches** of the **Middle Cerebral Artery (MCA)**. These are long, thin, thin-walled perforating vessels that supply the internal capsule, basal ganglia (putamen and caudate nucleus), and thalamus. 1. **Why Option B is Correct:** The lateral striate arteries (specifically the largest one) are the most common site for hypertensive intracerebral hemorrhage [1]. Due to their right-angled origin from the MCA and high pressure, they are prone to forming **Charcot-Bouchard aneurysms**, which can rupture and lead to strokes involving the motor fibers of the internal capsule [2]. 2. **Why Other Options are Incorrect:** * **Option A:** The medial striate branch of the Anterior Cerebral Artery (ACA) is known as the **Recurrent Artery of Heubner**. It supplies the head of the caudate nucleus and the anterior limb of the internal capsule. * **Options C & D:** The Fronto-polar and Calloso-marginal arteries are cortical branches of the ACA. They supply the medial surface of the frontal and parietal lobes, not the deep subcortical structures associated with Charcot’s artery. **High-Yield Clinical Pearls for NEET-PG:** * **Commonest site of hypertensive bleed:** Putamen (supplied by Charcot’s artery) [1]. * **Charcot-Bouchard Aneurysms:** Micro-aneurysms in small perforating arteries (associated with chronic hypertension); distinct from Berry aneurysms (Circle of Willis) [3]. * **Clinical Presentation:** Rupture typically results in contralateral hemiplegia due to involvement of the posterior limb of the internal capsule [2].

Q: Vertebral arteries of both sides unite to form which of the following arteries?

Basilar artery. ### Explanation The vertebral arteries are the first branches of the subclavian arteries. They ascend through the foramina transversaria of the upper six cervical vertebrae, enter the cranium via the foramen magnum, and run on the ventral surface of the medulla. **Why the Correct Answer is Right:** At the **lower border of the pons** (pontomedullary junction), the two vertebral arteries converge and unite in the midline to form the **Basilar artery**. This artery then travels in the basilar groove of the pons and eventually terminates by dividing into the two posterior cerebral arteries. This system is known as the Vertebro-basilar system, which supplies the brainstem, cerebellum, and posterior part of the cerebrum. **Analysis of Incorrect Options:** * **A. Anterior spinal artery:** This is formed by the union of two small branches, one from each vertebral artery, but it descends along the anterior median fissure of the spinal cord rather than forming the main trunk. * **B. Posterior spinal artery:** These usually arise from the vertebral artery (or the posterior inferior cerebellar artery) and descend on the posterior surface of the spinal cord. They do not unite to form a single large vessel. * **C. Medullary artery:** These are small, segmental branches that supply the medulla oblongata; they do not represent the union of the main vertebral trunks. **High-Yield Facts for NEET-PG:** * **PICA (Posterior Inferior Cerebellar Artery):** The largest branch of the vertebral artery. Occlusion leads to **Wallenberg Syndrome** (Lateral Medullary Syndrome). * **Circle of Willis:** The basilar artery contributes to this circle via its terminal branches (Posterior Cerebral) and the Posterior Communicating arteries. * **Top of the Basilar Syndrome:** Embolic occlusion at the bifurcation of the basilar artery, affecting the midbrain and thickness.

Question 1

A neurological examination of a 47-year-old woman reveals a normal corneal reflex in her right eye, but no consensual corneal reflex in her left eye. Which of the following additional findings might be expected?

Accepted Answer

Hyperacusis of the left ear

Answer

Absence of pupillary light reflex of the left eye

Answer

Inability to abduct the right eye

Answer

Loss of pain and temperature of the left face

Question 2

Which of the following is NOT a division of the Vth cranial nerve?

Accepted Answer

Optic

Answer

Ophthalmic

Answer

Mandibular

Answer

Maxillary

Question 3

Pseudounipolar neurons are typically found in which of the following locations?

Accepted Answer

Dorsal root ganglia

Answer

Ganglia of Cranial Nerve VIII

Answer

Mesencephalic Nucleus

Answer

Motor neurons

Question 4

Structure A is formed by which of the following tracts?

Accepted Answer

Pontocerebellar

Answer

Olivocerebellar

Answer

Vestibulocerebellar

Answer

Anterior spinocerebellar

Question 5

In a lesion of the right hypoglossal nucleus, which way does the tip of the tongue turn on protrusion?

Accepted Answer

To the right side because of the unopposed action of the left geniglossus muscle.

Answer

To the left side because of paralysis of the left side tongue muscles.

Answer

To the right side because of paralysis of the right side tongue muscles.

Answer

To the left side because of the unopposed action of the left geniglossus muscle.

Question 6

Which of the following tracts is seen in the posterior column of the spinal cord?

Accepted Answer

Fasciculus gracilis

Answer

Lateral spinothalamic tract

Answer

Corticospinal tract

Answer

Posterior spinocerebellar

Question 7

All of the following are parts of the optic nerve except?

Accepted Answer

Intracavernous part

Answer

Intraorbital part

Answer

Intracanalicular part

Answer

Cisternal segment

Question 8

After graft repair of a thoraco-abdominal aneurysm, a patient is unable to move both lower limbs. What is the most probable cause?

Accepted Answer

Insufficiency of the arteria magna radicularis

Answer

Damage to the thoracic splanchnic nerve

Answer

Damage to lumbar spinal nerves

Answer

Ischemia of the lower limbs

Question 9

What is Charcot's artery?

Accepted Answer

Striate branch of the middle cerebral artery

Answer

Medial striate branch of the anterior cerebral artery

Answer

Fronto-polar artery

Answer

Calloso-marginal artery

Question 10

Vertebral arteries of both sides unite to form which of the following arteries?

Accepted Answer

Basilar artery

Answer

Anterior spinal artery

Answer

Posterior spinal artery

Answer

Medullary artery

Neuroanatomy — MCQs

Neuroanatomy — MCQs

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