Neuroanatomy Practice Questions

Q: All of the following are concerned with the auditory pathway except?

Genu of internal capsule. **Explanation:** The auditory pathway (the **ECOLI** pathway) follows a specific sequence of structures from the cochlea to the primary auditory cortex [1]. The correct answer is **Genu of internal capsule** because it is not involved in the transmission of auditory signals. **1. Why Genu of internal capsule is the correct answer:** The internal capsule is divided into several parts. The **Genu** (the "knee") contains **corticobulbar fibers** (upper motor neurons for cranial nerves). Auditory radiations, however, travel through the **sublentiform part** of the posterior limb of the internal capsule to reach the Superior Temporal Gyrus (Heschl’s gyrus). **2. Analysis of incorrect options (Auditory structures):** * **Trapezoid Body:** Located in the lower pons, this consists of decussating fibers from the ventral cochlear nuclei. it is the first site where binaural localization of sound occurs. * **Medial Geniculate Body (MGB):** Located in the thalamus, the MGB acts as the "sensory relay station" for hearing [1]. (Mnemonic: **M** for **M**usic/Medial; **L** for **L**ight/Lateral). * **Lateral Lemniscus:** This is the main ascending auditory tract in the brainstem, connecting the superior olivary complex to the inferior colliculus [1]. **NEET-PG High-Yield Pearls:** * **Mnemonic for Auditory Pathway (ECOLI):** **E**xternal ear → **C**ochlear nuclei → **O**livary complex (Superior) → **L**ateral lemniscus → **I**nferior colliculus → **M**GB → **A**uditory cortex [1]. * The **Inferior Colliculus** is the principal midbrain nucleus of the auditory pathway [1]. * **Primary Auditory Cortex:** Brodmann areas 41 and 42. * Unilateral lesions proximal to the cochlear nuclei do not cause total deafness because auditory fibers ascend bilaterally.

Q: Which of the following statements about the cerebellum is incorrect?

Mossy fibers directly inhibit Purkinje cells.. ### Explanation The cerebellum functions through a complex circuit of excitatory and inhibitory signals. Understanding the histology and connectivity of the cerebellar cortex is high-yield for NEET-PG [1]. **Why Option C is Incorrect (The Correct Answer):** Mossy fibers are **excitatory**, not inhibitory [1]. They originate from the spinal cord and brainstem nuclei (e.g., spinocerebellar, pontocerebellar tracts). Crucially, they do not contact Purkinje cells directly. Instead, they synapse on **Granule cells**, which then give rise to parallel fibers that excite Purkinje cells [1]. Therefore, the mossy fiber pathway is an indirect excitatory input. **Analysis of Other Options:** * **Option A:** This is a classic "3-4-5" rule of cerebellar anatomy. It has **3 layers** (Molecular, Purkinje, Granular), **4 deep nuclei** (Dentate, Emboliform, Globose, Fastigial), and **5 cell types** (Purkinje, Granule, Stellate, Basket, and Golgi) [1]. * **Option B:** Climbing fibers (originating from the **Inferior Olivary Nucleus**) and Mossy fibers are the two primary afferent (input) systems to the cerebellum [2]. * **Option D:** Climbing fibers are highly excitatory. A single climbing fiber wraps around a single Purkinje cell, creating one of the most powerful excitatory synapses in the CNS (producing "complex spikes") [2]. **High-Yield Clinical Pearls for NEET-PG:** * **All output** from the cerebellar cortex is via **Purkinje cells**, which are **inhibitory (GABAergic)** to the deep cerebellar nuclei [1]. * **Granule cells** are the only **excitatory** neurons within the cerebellar cortex; the other four (Purkinje, Golgi, Stellate, Basket) are inhibitory [1]. * **Lesion Localization:** Midline lesions (vermis) cause truncal ataxia/gait instability; lateral lesions (hemispheres) cause limb ataxia and dysmetria [1].

Q: Occlusion of which of the following blood vessels can result in hemiplegia?

Middle cerebral artery. **Explanation:** **Middle Cerebral Artery (MCA)** is the correct answer because it supplies the majority of the **primary motor cortex** (Precentral gyrus) and the **internal capsule** (via lenticulostriate branches). The motor cortex contains the upper motor neurons responsible for voluntary movement. Specifically, the MCA supplies the areas representing the face and upper limbs [2]. Occlusion leads to contralateral hemiplegia (paralysis) and hemisensory loss, typically affecting the face and arm more than the leg [4]. **Analysis of Incorrect Options:** * **Anterior Cerebral Artery (ACA):** While ACA occlusion can cause motor deficits, it primarily affects the medial aspect of the motor cortex (paracentral lobule), which represents the **lower limb**. It results in monoplegia or hemiplegia where the leg is more affected than the arm/face. * **Posterior Cerebral Artery (PCA):** This vessel primarily supplies the occipital lobe (visual cortex) and the inferior temporal lobe. Occlusion typically results in **visual field defects** (e.g., contralateral homonymous hemianopia with macular sparing) rather than motor paralysis. * **Posterior Communicating Artery:** This is a component of the Circle of Willis that connects the ICA and PCA systems. While an aneurysm here can cause a **CN III (Oculomotor) nerve palsy**, its occlusion does not directly cause hemiplegia [3]. **High-Yield NEET-PG Pearls:** * **Most common site of stroke:** Middle Cerebral Artery [2]. * **Lenticulostriate Arteries:** Branches of the MCA known as the "arteries of stroke/cerebral hemorrhage," frequently involved in hypertensive bleeds affecting the internal capsule [1]. * **Total MCA Syndrome:** Presents with "Global Aphasia" (if dominant hemisphere), contralateral hemiplegia, and hemianesthesia.

Q: Two internal cerebral veins fuse to form which of the following?

Great cerebral vein. **Explanation** The **Great Cerebral Vein (of Galen)** is a short, thick venous trunk formed by the union of the **two internal cerebral veins**. This union occurs just below and behind the splenium of the corpus callosum. The Great Cerebral Vein then travels posteriorly to join the inferior sagittal sinus, together forming the **Straight Sinus**. **Analysis of Options:** * **Great Cerebral Vein (Correct):** It is a key deep venous structure. It receives the two internal cerebral veins and the two basal veins (of Rosenthal). * **Middle Cerebral Vein (Incorrect):** This is divided into superficial and deep parts. The superficial middle cerebral vein runs in the lateral sulcus and drains into the cavernous sinus, while the deep middle cerebral vein joins the anterior cerebral vein to form the basal vein. * **Anterior Cerebral Vein (Incorrect):** This vein accompanies the anterior cerebral artery and joins the deep middle cerebral vein to form the Basal Vein of Rosenthal. * **Inferior Cerebral Vein (Incorrect):** These are small veins on the inferior surface of the hemispheres that drain into the cavernous and transverse sinuses. **NEET-PG High-Yield Pearls:** 1. **Formation of Straight Sinus:** Great Cerebral Vein + Inferior Sagittal Sinus = Straight Sinus. 2. **Basal Vein of Rosenthal:** Formed by the union of the Anterior Cerebral Vein, Deep Middle Cerebral Vein, and Inferior Striate Veins. 3. **Internal Cerebral Veins:** Formed at the interventricular foramen (of Monro) by the union of the **Thalamostriate vein** and the **Choroid vein**. 4. **Clinical Significance:** Obstruction or malformations (Vein of Galen Malformation) can lead to high-output heart failure in neonates or hydrocephalus [1].

Q: Which one of the following is a branch of the facial nerve?

Greater superficial petrosal nerve. ### Explanation The **Facial Nerve (CN VII)** gives off several branches within the temporal bone (intrapetrosal branches). The **Greater Superficial Petrosal Nerve (GSPN)** is the first branch of the facial nerve, arising from the **geniculate ganglion**. It carries preganglionic parasympathetic fibers destined for the pterygopalatine ganglion, eventually supplying the lacrimal gland and nasal/palatine mucosa. #### Analysis of Options: * **Greater Superficial Petrosal Nerve (Correct):** It arises at the geniculate ganglion, exits the petrous temporal bone via its own hiatus, and joins the deep petrosal nerve to form the **nerve of the pterygoid canal (Vidian nerve)**. * **Deep Petrosal Nerve (Incorrect):** This is a **sympathetic** nerve arising from the internal carotid plexus (postganglionic fibers from the superior cervical ganglion). * **Lesser Superficial Petrosal Nerve (Incorrect):** This is a branch of the **Glossopharyngeal nerve (CN IX)** via the tympanic plexus. It carries parasympathetic fibers to the parotid gland via the otic ganglion. * **External Petrosal Nerve (Incorrect):** This is an inconsistent sympathetic branch from the internal carotid plexus to the geniculate ganglion; it is not a primary branch of the facial nerve. #### NEET-PG High-Yield Pearls: * **Schirmer’s Test:** Used to evaluate GSPN function by measuring lacrimation. If the facial nerve lesion is proximal to the geniculate ganglion, lacrimation is lost. * **Vidian Nerve Composition:** GSPN (Parasympathetic) + Deep Petrosal Nerve (Sympathetic). * **Intrapetrosal Branches of CN VII:** 1. GSPN, 2. Nerve to Stapedius, 3. Chorda Tympani. * **Hyperacusis:** Occurs if the branch to the stapedius muscle is paralyzed, leading to an inability to dampen loud sounds.

Q: Which cells are not present in the cerebral cortex?

Purkinje cells. The cerebral cortex is organized into six distinct histological layers (neocortex) containing specific neuronal types. Understanding the localization of these cells is a high-yield topic for NEET-PG. **Why Purkinje cells are the correct answer:** **Purkinje cells** are exclusively found in the **cerebellar cortex**, not the cerebral cortex [1]. They constitute the middle layer (Purkinje cell layer) of the cerebellum and represent the sole output from the cerebellar cortex, sending inhibitory (GABAergic) projections to the deep cerebellar nuclei [1]. **Analysis of incorrect options:** * **Pyramidal cells:** These are the most abundant neurons in the cerebral cortex. They are found in all layers except Layer I and are especially prominent in Layer III (External Pyramidal) and Layer V (Internal Pyramidal). The giant cells of Betz in the motor cortex are a specialized type of pyramidal cell. * **Stellate (Granule) cells:** These are small, star-shaped interneurons found throughout the cerebral cortex, particularly concentrated in Layer IV (Internal Granular layer), which receives sensory input from the thalamus. * **Cajal-Retzius cells:** These are spindle-shaped cells located in the most superficial layer (**Layer I - Molecular layer**) of the cerebral cortex. They play a critical role during embryonic development in organizing cortical lamination. **High-Yield NEET-PG Pearls:** 1. **Betz Cells:** Largest pyramidal cells, found in Layer V of the primary motor cortex (Area 4). 2. **Layers of Cerebral Cortex:** Remember the sequence: Molecular (I), External Granular (II), External Pyramidal (III), Internal Granular (IV), Internal Pyramidal (V), and Multiform (VI). 3. **Afferents:** Thalamocortical fibers [2] primarily terminate in **Layer IV**. 4. **Efferents:** **Layer V** gives rise to long projection fibers (Corticospinal tract) [3], while **Layer VI** sends feedback to the thalamus.

Q: The gustatory nucleus is part of which of the following nuclei?

Solitary nucleus. The **Solitary Nucleus (Nucleus Tractus Solitarius - NTS)** is a vertical column of grey matter located in the dorsolateral medulla [1]. It is the primary sensory nucleus for visceral and taste fibers. ### Why the Correct Answer is Right: The Solitary Nucleus is functionally divided into two parts: * **Rostral Part (Gustatory Nucleus):** Receives special visceral afferent (SVA) fibers for **taste** from the anterior 2/3 of the tongue (CN VII), posterior 1/3 of the tongue (CN IX), and the epiglottis (CN X) [1]. * **Caudal Part:** Receives general visceral afferent (GVA) fibers from the thoracic and abdominal viscera (CN IX and X), regulating cardiovascular and respiratory reflexes [2]. ### Why the Other Options are Wrong: * **Hypoglossal Nucleus:** A motor nucleus (GSE) that supplies all intrinsic and extrinsic muscles of the tongue (except the palatoglossus) [2]. It has no role in taste. * **Nucleus Ambiguus:** A motor nucleus (SVE) that supplies the muscles of the larynx, pharynx, and palate via CN IX, X, and XI [2]. * **Dorsal Motor Nucleus:** A parasympathetic (GVE) nucleus of the Vagus nerve (CN X) that supplies the heart, lungs, and gastrointestinal tract [2]. ### NEET-PG High-Yield Facts: * **Taste Pathway:** 1st order neurons are in the Geniculate (VII), Petrosal (IX), and Nodose (X) ganglia. They terminate in the **rostral NTS** [1]. * **Second-order neurons** from the NTS project to the **VPM nucleus of the Thalamus** (ipsilaterally). * **Cortical Area:** Taste is perceived in the **Insular cortex** and the frontal operculum (Area 43). * **Mnemonic:** "S" for Solitary is for "S"ensation (Taste/Visceral), while "A"mbiguus is for "A"ction (Motor).

Question 1

All of the following are concerned with the auditory pathway except?

Accepted Answer

Genu of internal capsule

Answer

Trapezoid body

Answer

Medial geniculate body

Answer

Lateral lemniscus

Question 2

Which of the following features differentiates hydranencephaly from hydrocephalus?

Accepted Answer

Cerebral cortex is deficient or hypoplastic in hydranencephaly.

Answer

Hydranencephaly is static, whilst hydrocephalus continues to increase in size.

Answer

Hydranencephaly does not increase in head size.

Answer

All of the above.

Question 3

Which of the following statements about the cerebellum is incorrect?

Accepted Answer

Mossy fibers directly inhibit Purkinje cells.

Answer

It has 3 layers, 4 nuclei, and 5 main cell types.

Answer

Climbing fibers represent afferent inputs to the cerebellar cortex.

Answer

Climbing fibers excite Purkinje cells.

Question 4

Occlusion of which of the following blood vessels can result in hemiplegia?

Accepted Answer

Middle cerebral artery

Answer

Anterior cerebral artery

Answer

Posterior cerebral artery

Answer

Posterior communicating artery

Question 5

Which of the following eye muscles is supplied by the contralateral nerve nucleus?

Accepted Answer

Superior rectus

Answer

Inferior rectus

Answer

Medial rectus

Answer

Inferior oblique

Question 6

Two internal cerebral veins fuse to form which of the following?

Accepted Answer

Great cerebral vein

Answer

Middle cerebral vein

Answer

Anterior cerebral vein

Answer

Inferior cerebral vein

Question 7

Which one of the following is a branch of the facial nerve?

Accepted Answer

Greater superficial petrosal nerve

Answer

Deep petrosal nerve

Answer

Lesser superficial petrosal nerve

Answer

External petrosal nerve

Question 8

How many lobes are present in the cerebellum?

Accepted Answer

6

Answer

2

Answer

4

Answer

8

Question 9

Which cells are not present in the cerebral cortex?

Accepted Answer

Purkinje cells

Answer

Stellate cells

Answer

Cajal cells

Answer

Pyramidal cells

Question 10

The gustatory nucleus is part of which of the following nuclei?

Accepted Answer

Solitary nucleus

Answer

Hypoglossal nucleus

Answer

Nucleus ambiguous

Answer

Dorsal motor nucleus

Neuroanatomy — MCQs

Neuroanatomy — MCQs

On this page

Practice by Chapter

Want unlimited practice?