Neuroanatomy Practice Questions

Q: Otic ganglia are related to which cranial nerve?

9th nerve. ### Explanation The **Otic ganglion** is a peripheral parasympathetic ganglion functionally associated with the **Glossopharyngeal nerve (9th cranial nerve)**. It serves as the relay station for secretomotor fibers to the parotid gland. **Why the 9th Nerve is Correct:** The pathway begins in the **inferior salivatory nucleus** of the medulla. Pre-ganglionic parasympathetic fibers travel via the 9th nerve, its tympanic branch (Jacobson’s nerve), and the **lesser petrosal nerve** to synapse in the otic ganglion. Post-ganglionic fibers then hitchhike along the **auriculotemporal nerve** (a branch of V3) to reach the parotid gland. **Why Other Options are Incorrect:** * **10th Nerve (Vagus):** Primarily supplies parasympathetic innervation to thoracic and abdominal viscera (up to the splenic flexure). It does not relay in the otic ganglion. * **8th Nerve (Vestibulocochlear):** A purely special sensory nerve for hearing and equilibrium; it carries no autonomic fibers. * **7th Nerve (Facial):** While it carries parasympathetic fibers, it is associated with the **Submandibular ganglion** (via chorda tympani) and the **Pterygopalatine ganglion** (via greater petrosal nerve), not the otic ganglion. **High-Yield Clinical Pearls for NEET-PG:** * **Topographical Relation:** Anatomically, the otic ganglion is situated just below the **foramen ovale**, medial to the mandibular nerve (V3). * **Frey’s Syndrome:** Results from injury to the auriculotemporal nerve. During regeneration, parasympathetic fibers (originally for the parotid) mistakenly grow into sympathetic pathways supplying sweat glands, leading to "gustatory sweating." * **Mnemonic (Ganglia & Nerves):** * **C**iliary – **3**rd Nerve * **P**terygopalatine – **7**th Nerve * **S**ubmandibular – **7**th Nerve * **O**tic – **9**th Nerve

Q: The posterior cerebral artery supplies all of the following except?

Pons. The **Posterior Cerebral Artery (PCA)** is the terminal branch of the basilar artery. It primarily supplies the posterior aspects of the brain, including the occipital lobe, inferior temporal lobe, and deep structures of the diencephalon and midbrain. **Why Pons is the correct answer:** The **Pons** is supplied by the **Basilar Artery** via its paramedian, short circumflex, and long circumflex (including the Superior Cerebellar Artery and Anterior Inferior Cerebellar Artery) branches. The PCA originates at the superior border of the pons but does not contribute to its blood supply. **Analysis of Incorrect Options:** * **Thalamus:** The PCA gives off the **thalamoperforating** and **thalamogeniculate** arteries, which are the primary blood supply to the thalamus. * **Midbrain:** As the PCA winds around the midbrain, it provides direct branches to the **tectum** and **cerebral peduncles**. * **Lentiform Nucleus:** While the Middle Cerebral Artery (MCA) is the main supply via lenticulostriate arteries, the **posterior part** of the lentiform nucleus receives supply from the PCA (specifically the medial branch of the posterior choroidal artery). **NEET-PG High-Yield Pearls:** 1. **Visual Field Deficits:** Occlusion of the PCA typically results in **contralateral homonymous hemianopia with macular sparing** (due to collateral supply to the occipital pole from the MCA). 2. **Weber’s Syndrome:** A midbrain stroke involving the PCA branches can lead to ipsilateral CN III palsy and contralateral hemiplegia. 3. **Thalamic Syndrome (Dejerine-Roussy):** PCA territory infarcts involving the thalamus can cause severe chronic pain and sensory loss.

Q: What types of nerve fibres does the facial nerve contain?

Motor and sensory root. The facial nerve (CN VII) is a mixed nerve consisting of two distinct roots: a large **motor root** and a smaller **sensory root**, also known as the **nervus intermedius (of Wrisberg)**. ### Why the Correct Answer is Right: The facial nerve is anatomically and functionally divided into: 1. **Motor Root:** Contains Special Visceral Efferent (SVE) fibers that supply the muscles of facial expression (derived from the 2nd branchial arch). 2. **Sensory Root (Nervus Intermedius):** Despite its name, it carries both: * **Sensory fibers:** Special Visceral Afferent (SVA) for taste from the anterior 2/3 of the tongue and General Somatic Afferent (GSA) for the external ear. * **Parasympathetic fibers:** General Visceral Efferent (GVE) fibers for the submandibular, sublingual, and lacrimal glands. ### Why Other Options are Wrong: * **Option A:** Incorrect because it ignores the significant sensory and autonomic components carried by the nervus intermedius. * **Option C & D:** While the facial nerve does carry parasympathetic fibers, it **does not** carry sympathetic fibers in its primary roots. Sympathetic supply to the face travels via plexuses around the internal and external carotid arteries. ### High-Yield Clinical Pearls for NEET-PG: * **Nuclei:** The facial nerve arises from four nuclei: Motor nucleus (SVE), Superior salivatory nucleus (GVE), Lacrimatory nucleus (GVE), and Nucleus tractus solitarius (SVA/GSA). * **Course:** It enters the internal acoustic meatus, passes through the facial canal (the longest bony canal for any nerve), and exits via the **stylomastoid foramen**. * **Bell’s Palsy:** Lower motor neuron lesion of the facial nerve resulting in ipsilateral paralysis of facial muscles, loss of taste (anterior 2/3), and hyperacusis (due to paralysis of the stapedius muscle).

Q: What is true about the fourth ventricle?

The rhomboid fossa forms its floor.. ### Explanation **1. Why Option A is Correct:** The fourth ventricle is a tent-shaped cavity located between the brainstem (anteriorly) and the cerebellum (posteriorly). Its **floor** is formed by the posterior surfaces of the pons and the upper part of the medulla oblongata. This floor is diamond-shaped and is anatomically referred to as the **rhomboid fossa**. It contains vital structures such as the facial colliculus, hypoglossal triangle, and vagal triangle. **2. Why the Other Options are Incorrect:** * **Option B:** The **choroid plexus** of the fourth ventricle is located in its **roof** (specifically the lower part of the roof formed by the inferior medullary velum), not the floor. * **Option C:** The fourth ventricle connects the cerebral aqueduct (of Sylvius) superiorly to the central canal of the spinal cord inferiorly. The connection between the two cerebral hemispheres is facilitated by the **corpus callosum**, while the **third ventricle** lies between the two thalami. * **Option D:** The fourth ventricle lies **medial** to the cerebellar peduncles. The inferior cerebellar peduncles actually form the lower part of the lateral boundaries of the rhomboid fossa. **3. High-Yield Clinical Pearls for NEET-PG:** * **Foramina:** CSF exits the fourth ventricle into the subarachnoid space via three openings: the median **Foramen of Magendie** and two lateral **Foramina of Luschka** [1] (*Mnemonic: **M**agendie is **M**idline; **L**uschka is **L**ateral*). Fluid also accumulates proximal to the block and distends the ventricles when these foramina are obstructed [1]. * **Facial Colliculus:** Found in the floor (pons part), it is formed by the fibers of the facial nerve hooking around the abducens nucleus. * **Area Postrema:** Located in the inferolateral part of the floor (near the obex), it lacks a blood-brain barrier and serves as the **chemoreceptor trigger zone (CTZ)** for vomiting.

Q: Which of the following structures is involved in the auditory pathway?

Inferior colliculus. The auditory pathway is a complex multisynaptic chain that transmits sound signals from the cochlea to the auditory cortex. [1] **Explanation of the Correct Answer:** **A. Inferior Colliculus:** This is a major auditory center located in the midbrain. It receives input from the lateral lemniscus and acts as a critical integration hub for sound localization and frequency analysis. [1] From here, fibers project via the brachium of the inferior colliculus to the Medial Geniculate Body (MGB) of the thalamus. [1] **Explanation of Incorrect Options:** * **B. Lateral Geniculate Body (LGB):** This is part of the **visual pathway**, receiving input from the optic tract and projecting to the primary visual cortex. (Mnemonic: **L**GB for **L**ight; **M**GB for **M**usic). * **C. Inferior Olivary Nucleus:** This structure is located in the medulla and is primarily involved in **motor control** and cerebellar coordination. It should not be confused with the *Superior* Olivary Nucleus, which is indeed part of the auditory pathway. * **D. Medial Lemniscus:** This is part of the **DCML pathway** (Dorsal Column-Medial Lemniscus), responsible for carrying fine touch, vibration, and conscious proprioception. The auditory counterpart is the *Lateral* Lemniscus. [1] **High-Yield Facts for NEET-PG:** * **Pathway Mnemonic (ECOLI):** **E**ighth nerve → **C**ochlear nuclei → **O**live (Superior Olivary Nucleus) → **L**ateral Lemniscus → **I**nferior Colliculus. [1] * **Primary Auditory Cortex:** Located in the **Heschl’s gyri** (Brodmann areas 41 and 42) in the temporal lobe. * **Bilateral Representation:** Above the level of the cochlear nuclei, auditory information is represented bilaterally. Therefore, unilateral central lesions do not cause complete deafness in one ear.

Q: A 64-year-old male undergoing aortic bypass surgery has an accidental injury to an artery arising from the aorta at the level of the lower thoracic region. This artery provides major blood supply to the spinal cord. Which region of the spinal cord is likely to be affected?

Lower two-thirds of the spinal cord. ### Explanation The artery described in the clinical scenario is the **Artery of Adamkiewicz** (also known as the *arteria radicularis magna*). This is the largest and most significant segmental medullary artery. **1. Why the Correct Answer is Right:** The Artery of Adamkiewicz typically arises from the left side of the aorta between the levels of **T9 and T12**. It joins the anterior spinal artery to provide the primary blood supply to the **lower two-thirds of the spinal cord** (thoracolumbar segments). Because the anterior spinal artery is relatively narrow in the mid-thoracic region (a "watershed" area), the spinal cord depends heavily on this artery. Injury during aortic surgery leads to ischemia, resulting in **Beck’s Syndrome** (Anterior Spinal Artery Syndrome), characterized by paraplegia and loss of pain/temperature sensation, while preserving dorsal column functions. **2. Why Incorrect Options are Wrong:** * **Options A & C (Upper regions):** The upper one-third and cervical spinal cord are primarily supplied by the vertebral arteries and branches of the thyrocervical trunk. These are superior to the thoracic aorta and are not affected by lower thoracic aortic injuries. * **Option D (Lower one-third):** While the artery does supply the lower one-third (conus medullaris), its territory is more extensive, covering the entire lower two-thirds of the cord starting from the lower thoracic levels. **3. NEET-PG High-Yield Pearls:** * **Origin:** Usually arises from the left posterior intercostal artery (T9-T12). * **Anterior Spinal Artery (ASA):** Supplies the anterior 2/3rds of the cord (motor and spinothalamic tracts). * **Posterior Spinal Arteries (PSA):** Usually two in number; supply the posterior 1/3rd (dorsal columns). * **Clinical Sign:** Post-aortic surgery paraplegia is a classic board-style presentation of Artery of Adamkiewicz injury.

Q: Which of the following is included in the telencephalon?

Cerebrum. **Explanation:** The brain develops from three primary vesicles: the Prosencephalon (forebrain), Mesencephalon (midbrain), and Rhombencephalon (hindbrain). The **Prosencephalon** further divides into two secondary vesicles: the **Telencephalon** and the **Diencephalon** [3]. 1. **Telencephalon (Correct Answer):** This is the most anterior part of the brain. It develops into the **Cerebrum**, which includes the cerebral cortex, underlying white matter, and the basal ganglia (corpus striatum) [1]. It also contains the lateral ventricles. 2. **Diencephalon (Options B & C):** The **Thalamus** and **Hypothalamus** (along with the epithalamus and subthalamus) are derivatives of the Diencephalon [3]. A high-yield landmark is that the Diencephalon surrounds the third ventricle. 3. **Mesencephalon (Option D):** The **Substantia nigra** is a part of the midbrain (Mesencephalon) [1]. This region does not divide further into secondary vesicles and contains the cerebral aqueduct of Sylvius. **NEET-PG High-Yield Pearls:** * **Derivatives Mnemonic:** Remember that "T" in **T**elencephalon stands for **T**op (Cerebrum), while **D**iencephalon contains structures ending in "-thalamus." * **Rhombencephalon:** Divides into the **Metencephalon** (Pons and Cerebellum) and **Myelencephalon** (Medulla oblongata). * **Clinical Correlation:** Holoprosencephaly is a failure of the Telencephalon to divide into two hemispheres, often associated with Sonic Hedgehog (SHH) signaling pathway defects [2].

Q: Purkinje cells of the cerebellum are connected to which of the following?

All of the above. The Purkinje cell is the functional centerpiece of the cerebellar cortex. Understanding its connections is vital for mastering cerebellar neuroanatomy. [1] **1. Why "All of the above" is correct:** The Purkinje cell acts as the sole output channel of the cerebellar cortex. Its complex dendritic tree and long axon facilitate multiple connections: * **Input (Afferent):** Purkinje cells receive inhibitory input from **Basket cells** and **Stellate cells** (interneurons located in the molecular layer). [1] These cells use GABA to provide "lateral inhibition," sharpening the focus of Purkinje cell activity. * **Output (Efferent):** The axons of Purkinje cells project downward through the granular layer to synapse primarily upon the **Deep Cerebellar Nuclei** (Dentate, Emboliform, Globose, and Fastigial). **2. Analysis of Options:** * **Basket & Stellate Cells:** These are inhibitory interneurons of the molecular layer. Stellate cells synapse on the dendritic shafts, while Basket cells wrap around the Purkinje cell soma (cell body). [1] * **Deep Cerebellar Nuclei:** This is the primary target for Purkinje axons. Notably, Purkinje cells are **inhibitory (GABAergic)**; they modulate the output of the deep nuclei rather than exciting them. **3. High-Yield Clinical Pearls for NEET-PG:** * **Sole Output:** Purkinje cells are the *only* cells whose axons leave the cerebellar cortex. [1] * **Neurotransmitter:** They are always **GABAergic** (inhibitory). [1] * **Climbing Fibers:** These originate from the **Inferior Olivary Nucleus** and wrap directly around Purkinje cell dendrites (one-to-one relationship), providing the strongest excitatory synapse in the CNS. [1] * **Clinical Correlation:** Alcohol-induced cerebellar degeneration primarily affects Purkinje cells, leading to truncal ataxia.

Q: What is the length of the optic nerve?

50 mm. The optic nerve (Cranial Nerve II) is a vital structure for vision, extending from the lamina cribrosa of the sclera to the optic chiasm. Its total length is approximately **50 mm**, which is a high-yield fact for NEET-PG. ### **Breakdown of the Optic Nerve Segments** The correct answer is **50 mm** because the nerve is divided into four distinct anatomical segments: 1. **Intraocular (1 mm):** The shortest part, where the nerve fibers exit the globe through the lamina cribrosa. 2. **Intraorbital (25–30 mm):** The longest segment. It has an "S-shaped" redundancy to allow for free movement of the eyeball without putting tension on the nerve. 3. **Intracanalicular (6–9 mm):** The portion passing through the optic canal, accompanied by the ophthalmic artery. 4. **Intracranial (10–15 mm):** The segment extending from the optic canal to the optic chiasm. ### **Analysis of Incorrect Options** * **A (20 mm) & B (30 mm):** These values are too short for the total length. 25–30 mm specifically represents only the **intraorbital** portion. * **C (40 mm):** While closer, it underestimates the combined length of the intracranial and intracanalicular segments. ### **Clinical Pearls for NEET-PG** * **Morphology:** The optic nerve is not a true peripheral nerve; it is an outgrowth of the diencephalon. * **Myelination:** It is myelinated by **oligodendrocytes**, not Schwann cells. This explains why it is affected in Multiple Sclerosis. * **Blood Supply:** The central artery of the retina (a branch of the ophthalmic artery) enters the nerve approximately 12 mm behind the eyeball. * **Papilledema:** Increased intracranial pressure is transmitted through the subarachnoid space surrounding the nerve, leading to swelling of the optic disc.

Question 1

Otic ganglia are related to which cranial nerve?

Accepted Answer

9th nerve

Answer

10th nerve

Answer

8th nerve

Answer

7th nerve

Question 2

A 50-year-old patient presented with attacks of intractable nausea, vomiting, and hiccups that did not subside even after medication. Which of the following statements about the involved structure is FALSE?

Accepted Answer

It is a poorly vascularized structure with high permeability for circulating blood signals.

Answer

It is a bilaterally paired structure, located at the caudal limit of the floor of the fourth ventricle.

Answer

It is a chemoreceptive area that triggers vomiting in response to the presence of emetic substances in the blood.

Answer

Along with the nucleus tractus solitarius and the dorsal motor nucleus of the vagus, it makes up the so-called dorsal vagal complex.

Question 3

The posterior cerebral artery supplies all of the following except?

Accepted Answer

Pons

Answer

Thalamus

Answer

Midbrain

Answer

Lentiform nucleus

Question 4

What types of nerve fibres does the facial nerve contain?

Accepted Answer

Motor and sensory root

Answer

Motor root only

Answer

Motor and sympathetic fibres

Answer

Motor, sympathetic, and parasympathetic fibres

Question 5

What is true about the fourth ventricle?

Accepted Answer

The rhomboid fossa forms its floor.

Answer

The choroid plexus lies at its floor.

Answer

It forms a connection between the two cerebral hemispheres.

Answer

It lies inferior to the inferior cerebellar peduncle.

Question 6

Which of the following structures is involved in the auditory pathway?

Accepted Answer

Inferior colliculus

Answer

Lateral geniculate body

Answer

Inferior olivary nucleus

Answer

Medial lemniscus

Question 7

A 64-year-old male undergoing aortic bypass surgery has an accidental injury to an artery arising from the aorta at the level of the lower thoracic region. This artery provides major blood supply to the spinal cord. Which region of the spinal cord is likely to be affected?

Accepted Answer

Lower two-thirds of the spinal cord

Answer

Upper two-thirds of the spinal cord

Answer

Upper one-third of the spinal cord

Answer

Lower one-third of the spinal cord

Question 8

Which of the following is included in the telencephalon?

Accepted Answer

Cerebrum

Answer

Thalamus

Answer

Hypothalamus

Answer

Substantia nigra

Question 9

Purkinje cells of the cerebellum are connected to which of the following?

Accepted Answer

All of the above

Answer

Basket cells

Answer

Stellate cells

Answer

Deep cerebellar nuclei

Question 10

What is the length of the optic nerve?

Accepted Answer

50 mm

Answer

20 mm

Answer

30 mm

Answer

40 mm

Neuroanatomy — MCQs

Neuroanatomy — MCQs

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