Neuroanatomy Practice Questions

Q: Which artery is the major supply of the medial surface of the cerebral hemisphere?

Anterior cerebral artery. ***Anterior cerebral artery*** - The **anterior cerebral artery (ACA)** is a primary branch of the internal carotid artery and is responsible for supplying blood to the **medial surface** of the frontal and parietal lobes of the cerebral hemispheres [1]. - It also supplies the **corpus callosum**, the superior aspect of the frontal and parietal lobes, and parts of the basal ganglia [1]. *Posterior cerebral artery* - The **posterior cerebral artery (PCA)** primarily supplies the **occipital lobe** and the inferior part of the **temporal lobe** [1]. - It also provides blood to parts of the midbrain and the **thalamus** [1]. *Middle cerebral artery* - The **middle cerebral artery (MCA)** is the largest cerebral artery and supplies most of the **lateral surface** of the cerebral hemispheres [1]. - It is crucial for the blood supply to the **motor and sensory cortices** for the face and upper limb, as well as language areas (Broca's and Wernicke's). *Posterior inferior cerebellar artery* - The **posterior inferior cerebellar artery (PICA)** is a branch of the **vertebral artery** and exclusively supplies the **cerebellum** and the lateral medulla. - It is not involved in the blood supply to the cerebral hemispheres.

Q: Which of the following is pure sensory nerve?

Olfactory. ***Olfactory*** - The **olfactory nerve (Cranial Nerve I)** is exclusively responsible for the sense of **smell**, making it a pure **sensory nerve** [1]. - It transmits impulses from the **olfactory receptors** in the nasal cavity to the brain. *Trigeminal* - The **trigeminal nerve (Cranial Nerve V)** is a **mixed nerve**. - It has both **sensory functions** (face sensation) and **motor functions** (mastication). *Abducent* - The **abducent nerve (Cranial Nerve VI)** is a **motor nerve**. - It innervates the **lateral rectus muscle**, responsible for moving the eye laterally. *Trochlear* - The **trochlear nerve (Cranial Nerve IV)** is primarily a **motor nerve**. - It innervates the **superior oblique muscle**, which depresses and intorts the eyeball.

Q: Secretomotor fibers to parotid gland are through?

Tympanic plexus. This is an easy question, and the expected Bloom's level is low (L1) with an expectation of just remembering the right answer. ***Tympanic plexus*** - The secretomotor fibers to the parotid gland originate from the inferior **salivatory nucleus**, travel via the **glossopharyngeal nerve (CN IX)** to the tympanic plexus. - From the tympanic plexus, these preganglionic parasympathetic fibers form the **lesser petrosal nerve**, which synapses in the otic ganglion, and postganglionic fibers then join the **auriculotemporal nerve** to reach the parotid gland. *Greater petrosal nerve* - The **greater petrosal nerve** carries preganglionic parasympathetic fibers that primarily innervate the **lacrimal gland** and glands of the nasal cavity and palate, not the parotid gland. - It is a branch of the **facial nerve (CN VII)**, whereas secretomotor innervation to the parotid is from the glossopharyngeal nerve (CN IX). *Geniculate ganglion* - The **geniculate ganglion** is a sensory ganglion of the **facial nerve (CN VII)**, containing cell bodies for taste sensation from the anterior two-thirds of the tongue. - It is not directly involved in transmitting secretomotor fibers to the parotid gland. *None of the options* - As the **tympanic plexus** is the correct conduit for the secretomotor fibers to the parotid gland, this option is incorrect. - The pathway involves a specific sequence of nerves and ganglia, which includes the tympanic plexus as a key relay point.

Q: The nerve which has the longest intracranial course is:

Trochlear nerve (Fourth cranial nerve). The nerve which has the longest intracranial course is: ***Trochlear nerve (Fourth cranial nerve)*** - This nerve has the **longest intracranial course** of all the cranial nerves, emerging from the dorsal aspect of the midbrain. - Its long path makes it particularly susceptible to **injury** from head trauma or increased intracranial pressure. *Oculomotor nerve (Third cranial nerve)* - While significant in length, the **oculomotor nerve** does not have the longest intracranial course; it emerges from the ventral midbrain. [1] - It controls most of the **extraocular muscles**, but its intracranial path is shorter than that of the trochlear nerve. *Abducens nerve (Sixth cranial nerve)* - The **abducens nerve** has a relatively long course within the pons and across the clivus but is not the longest. - It is often impacted in conditions causing **elevated intracranial pressure** or skull base fractures due to its path. *Trigeminal nerve (Fifth cranial nerve)* - The **trigeminal nerve** has a large sensory ganglion and extensive peripheral branches but its intracranial course is comparatively short, emerging from the pons. - It is primarily responsible for **facial sensation** and mastication.

Q: Which of the following structures is seen in the cavernous sinus?

Internal carotid artery. ***Internal carotid artery*** - The **internal carotid artery** passes directly through the body of the **cavernous sinus**, making it highly vulnerable to injury or compression in this region. - This artery is surrounded by venous blood within the sinus and is a common site for **carotid-cavernous fistulas** if damaged. *Mandibular division of the trigeminal nerve (V3)* - The **mandibular division (V3)** of the trigeminal nerve does not pass through the cavernous sinus itself; it exits the skull via the **foramen ovale**. - Only the **ophthalmic (V1)** and **maxillary (V2)** divisions are found in the lateral wall of the cavernous sinus. *Facial nerve* - The **facial nerve (CN VII)** has a long and complex course but does not pass through the cavernous sinus. - It travels through the **internal auditory meatus** and then exits the skull via the **stylomastoid foramen**. *Optic nerve (CN II)* - The **optic nerve (CN II)** enters the skull via the **optic canal** and is surrounded by meninges, but it does not traverse the cavernous sinus. - It is located superior and medial to the cavernous sinus, passing into the **middle cranial fossa** to join the optic chiasm.

Q: Largest cranial nerve is:

Trigeminal. ***Trigeminal*** - The **trigeminal nerve (CN V)** is the largest cranial nerve, both in terms of its overall diameter and the number of fibers it contains. - It has three major divisions: **ophthalmic, maxillary, and mandibular**, providing extensive sensory innervation to the face and motor innervation to the muscles of mastication. *Trochlear* - The **trochlear nerve (CN IV)** is the smallest cranial nerve in terms of diameter and number of axons. - It primarily innervates a single muscle, the **superior oblique muscle** of the eye. *Oculomotor* - The **oculomotor nerve (CN III)** is responsible for innervating several extrinsic eye muscles and plays a role in pupil constriction. - While significant, it is not the largest cranial nerve. *Vagus* - The **vagus nerve (CN X)** has the longest anatomical course among all cranial nerves, extending into the abdomen, but it is not the largest in terms of overall size or fiber count. - It carries extensive **parasympathetic fibers** and has broad effects on visceral organs.

Q: Nerve supply of stapedius is:

Facial nerve (7th nerve). ***Facial nerve (7th nerve)*** - The **facial nerve** is responsible for innervating the **stapedius muscle**, which helps to dampen loud sounds by pulling the stapes away from the oval window. - A lesion in the facial nerve can lead to **hyperacusis** due to the paralysis of the stapedius muscle. *Oculomotor nerve (3rd nerve)* - The **oculomotor nerve** primarily controls **eye movements** and **pupil constriction**. - It does not have any direct involvement in the innervation of middle ear muscles. *Trigeminal nerve (5th nerve)* - The **trigeminal nerve** is responsible for **sensation of the face** and innervates the **muscles of mastication**. - It provides motor supply to the **tensor tympani muscle**, not the stapedius. *Glossopharyngeal nerve (9th nerve)* - The **glossopharyngeal nerve** is primarily involved in **taste sensation** from the posterior tongue, **swallowing**, and mediating the **gag reflex**. - It does not innervate any muscles of the middle ear.

Q: Oculomotor nucleus is located in -

Midbrain. ***Midbrain*** - The **oculomotor nucleus** (cranial nerve III) and the Edinger-Westphal nucleus (parasympathetic component) are both located in the **ventral gray matter** near the cerebral aqueduct in the **midbrain** [1]. - This position allows the oculomotor nerve to exit from the interpeduncular fossa of the midbrain [1]. *Forebrain* - The **forebrain** primarily contains structures like the cerebral hemispheres, thalamus, and hypothalamus, which are involved in higher cognitive functions and sensory processing. - No cranial nerve nuclei are located within the forebrain itself; they are largely concentrated in the brainstem. *Pons* - The **pons** contains nuclei for cranial nerves V (trigeminal), VI (abducens), VII (facial), and VIII (vestibulocochlear), but not the oculomotor nucleus. - It is located inferior to the midbrain and superior to the medulla. *Medulla* - The **medulla oblongata** houses nuclei for cranial nerves IX (glossopharyngeal), X (vagus), XI (accessory), and XII (hypoglossal). - It is the most caudal part of the brainstem, inferior to the pons, and is not where the oculomotor nucleus is found.

Q: Downward and outward movement of eye is affected in injury of?

3rd nerve. The 3rd cranial nerve (oculomotor nerve) controls most extraocular muscles including the superior rectus, inferior rectus, medial rectus, and inferior oblique, as well as the levator palpebrae superioris. Injury to the 3rd nerve results in paralysis of these muscles, leaving only the lateral rectus (6th nerve) and superior oblique (4th nerve) functioning. This causes the classic "down and out" position of the eye at rest due to the unopposed action of these two muscles [1]. The eye is pulled downward by the superior oblique and outward by the lateral rectus [1]. Additional features include ptosis (drooping eyelid), dilated pupil, and diplopia (double vision) [1][2]. The patient loses the ability to move the eye upward, downward (via inferior rectus), and medially. Incorrect Option: 4th nerve - The 4th cranial nerve (trochlear nerve) innervates the superior oblique muscle. The superior oblique primarily causes depression (downward), intorsion, and abduction of the eye [1]. However, its action is most effective for downward and INWARD movement when the eye is adducted. - 4th nerve palsy results in vertical diplopia (especially when looking down and inward, like reading or descending stairs), hypertropia (upward deviation), and head tilt to the opposite side. This does NOT produce a "down and out" position. Incorrect Option: 5th nerve - The 5th cranial nerve (trigeminal nerve) provides sensory innervation to the face and motor innervation to the muscles of mastication. It has no role in eye movements. Incorrect Option: 6th nerve - The 6th cranial nerve (abducens nerve) innervates the lateral rectus muscle, responsible for abduction (outward movement) of the eye [1]. 6th nerve palsy causes inability to abduct the eye, resulting in esotropia (inward deviation) and horizontal diplopia.

Q: Which nerve carries the motor component of the light reflex?

3rd nerve. ***3rd nerve*** - The **oculomotor nerve** (3rd cranial nerve) carries the **efferent motor pathway** of the pupillary light reflex [1]. - It innervates the **sphincter pupillae muscle**, causing pupillary constriction (miosis) [1]. *1st nerve* - The **olfactory nerve** (1st cranial nerve) is responsible for the sense of **smell**. - It is not involved in vision or the pupillary light reflex. *2nd nerve* - The **optic nerve** (2nd cranial nerve) carries the **afferent sensory pathway** of the pupillary light reflex, detecting light [1]. - While essential for the reflex, it is not the motor component that causes pupillary constriction [1]. *4th nerve* - The **trochlear nerve** (4th cranial nerve) innervates the **superior oblique muscle** of the eye [2]. - Its primary function is eye movement, specifically depression and intorsion, and it has no role in the pupillary light reflex [2].

Question 1

Which artery is the major supply of the medial surface of the cerebral hemisphere?

Accepted Answer

Anterior cerebral artery

Answer

Posterior cerebral artery

Answer

Middle cerebral artery

Answer

Posterior inferior cerebellar artery

Question 2

Which of the following is pure sensory nerve?

Accepted Answer

Olfactory

Answer

Trigeminal

Answer

Abducent

Answer

Trochlear

Question 3

Secretomotor fibers to parotid gland are through?

Accepted Answer

Tympanic plexus

Answer

Greater petrosal nerve

Answer

Geniculate ganglion

Answer

None of the options

Question 4

The nerve which has the longest intracranial course is:

Accepted Answer

Trochlear nerve (Fourth cranial nerve)

Answer

Oculomotor nerve (Third cranial nerve)

Answer

Abducens nerve (Sixth cranial nerve)

Answer

Trigeminal nerve (Fifth cranial nerve)

Question 5

Which of the following structures is seen in the cavernous sinus?

Accepted Answer

Internal carotid artery

Answer

Facial nerve

Answer

Mandibular division of the trigeminal nerve (V3)

Answer

Optic nerve (CN II)

Question 6

Largest cranial nerve is:

Accepted Answer

Trigeminal

Answer

Trochlear

Answer

Oculomotor

Answer

Vagus

Question 7

Nerve supply of stapedius is:

Accepted Answer

Facial nerve (7th nerve)

Answer

Oculomotor nerve (3rd nerve)

Answer

Trigeminal nerve (5th nerve)

Answer

Glossopharyngeal nerve (9th nerve)

Question 8

Oculomotor nucleus is located in -

Accepted Answer

Midbrain

Answer

Forebrain

Answer

Pons

Answer

Medulla

Question 9

Downward and outward movement of eye is affected in injury of?

Accepted Answer

3rd nerve

Answer

4th nerve

Answer

5th nerve

Answer

6th nerve

Question 10

Which nerve carries the motor component of the light reflex?

Accepted Answer

3rd nerve

Answer

1st nerve

Answer

2nd nerve

Answer

4th nerve

Neuroanatomy — MCQs

Neuroanatomy — MCQs

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