Neuroanatomy Practice Questions

Q: Nucleus intercalatus is seen in which part of the brain?

Medulla. Medulla - The **nucleus intercalatus** is a small nucleus located in the **dorsal part of the medulla oblongata**, specifically near the midline and caudal to the facial nucleus. - It forms part of the **vestibular complex** and is involved in processing vestibular information, contributing to postural control and eye movements [1]. *Frontal lobe* - The **frontal lobe** is part of the **forebrain** and is primarily involved in executive functions, motor control, and language, not vestibular processing [4]. - It houses structures like the **motor cortex** and **prefrontal cortex**, which are distinct from brainstem nuclei [4]. *Temporal lobe* - The **temporal lobe** is involved in auditory processing, memory, and emotion, containing structures like the **hippocampus** and **amygdala** [2]. - It is a part of the **cerebral cortex**, located far from the brainstem where the nucleus intercalatus is found. *Midbrain* - The **midbrain** is the smallest part of the brainstem, located caudal to the diencephalon and rostral to the pons. - It contains structures like the **substantia nigra** and **red nucleus**, involved in motor control and visual/auditory reflexes, but not the nucleus intercalatus [3].

Q: Which of the following cells is not present in the cerebellum?

Pyramidal cells. ### Pyramidal cells - Pyramidal cells are **excitatory neurons** found in the **cerebral cortex** and **hippocampus**, characterized by their triangular cell bodies and prominent apical dendrites. - They are not present in the cerebellum, which has its own distinct neuronal architecture. *Purkinje cells* - **Purkinje cells** [1] are large, flask-shaped neurons with extensive dendritic trees located in the **cerebellar cortex** [1]. - They are the **sole output neurons** of the cerebellar cortex, providing inhibitory projections to the deep cerebellar nuclei [1]. *Stellate cells* - **Stellate cells** are small **inhibitory interneurons** located in the **molecular layer** of the cerebellar cortex [1]. - They synapse onto the dendrites of Purkinje cells, modulating their activity [1]. *Basket cells* - **Basket cells** are another type of **inhibitory interneuron** found in the **molecular layer** of the cerebellar cortex [1]. - They form characteristic **basket-like plexuses** around the cell bodies of Purkinje cells, exerting powerful inhibition [1].

Q: The facial nerve's first branch is?

Greater petrosal nerve. ***Greater petrosal nerve*** - The **greater petrosal nerve** is the **first major branch** of the facial nerve, emerging from the geniculate ganglion. - It carries **preganglionic parasympathetic fibers** to the pterygopalatine ganglion, which innervates the lacrimal gland and glands of the nasal and palatal mucosa. *Lesser petrosal nerve* - The **lesser petrosal nerve** originates from the **glossopharyngeal nerve (CN IX)**, not the facial nerve. - It carries parasympathetic fibers to the **otic ganglion**, supplying the parotid gland. *Chorda tympani nerve* - The **chorda tympani nerve** is a branch of the facial nerve that arises within the **temporal bone**, but it is not the *first* branch. - It carries **taste fibers** from the anterior two-thirds of the tongue and **preganglionic parasympathetic fibers** to the submandibular and sublingual glands. *Nerve to stapedius* - The **nerve to stapedius** branches off the facial nerve within the facial canal, innervating the **stapedius muscle**. - It is a very small motor branch and arises **after** the greater petrosal nerve.

Q: A 64-year-old man presented to the clinic with a severely painful rash and skin eruptions localized entirely on one side of his body, closely following the dermatome level of spinal nerve C7, and was diagnosed with herpes zoster virus. In which structure has the virus most likely proliferated to cause the patient's current condition?

The dorsal root ganglion of the C7 spinal nerve. ***The dorsal root ganglion of the C7 spinal nerve*** - After primary infection (chickenpox), the **varicella-zoster virus (VZV)** lies dormant in the **dorsal root ganglia** [1]. - Reactivation occurs in these ganglia, leading to viral proliferation and axonal transport down the sensory nerves to the skin, causing the characteristic **dermatomal rash** of herpes zoster [1]. *The sympathetic chain* - The sympathetic chain primarily contains **autonomic postganglionic neurons** and is not the site of VZV latency or reactivation. - Reactivation in the sympathetic chain would lead to autonomic dysfunction, not the dermatomal rash seen in herpes zoster. *The lateral horn of the C7 spinal cord segment* - The **lateral horn** contains **preganglionic sympathetic neurons** and is part of the autonomic nervous system. - Herpes zoster specifically affects **sensory neurons**, not autonomic neurons located in the lateral horn. *The posterior cutaneous branch of the dorsal ramus of C7* - This nerve branch is a peripheral nerve that carries **sensory information** from the skin but is not the primary site of viral latency or initial reactivation. - The virus travels *to* this branch from the dorsal root ganglion to produce the rash.

Q: Which tract fibers pass through the genu of the internal capsule?

Corticonuclear tract. ***Corticonuclear tract*** - The **corticonuclear tract** (also known as the corticobulbar tract) conveys motor commands from the cerebral cortex to the motor nuclei of the **cranial nerves** in the brainstem [1]. These fibers precisely pass through the **genu of the internal capsule** [1]. - Damage to the corticonuclear tract at the genu can result in **contralateral weakness** or paralysis of the face, tongue, and pharyngeal muscles. *Optic radiation* - The **optic radiation** transmits visual information from the lateral geniculate nucleus to the primary visual cortex in the occipital lobe [3]. - These fibers typically course through the **retrolenticular** and **sublenticular parts** of the internal capsule, not the genu. *Corticospinal* - The **corticospinal tract** is responsible for voluntary motor control of the body, and its fibers pass through the **posterior limb of the internal capsule** [2]. - Lesions affecting the corticospinal tract in the posterior limb lead to **contralateral hemiparesis or hemiplegia** [1]. *Corticorubral tract* - The **corticorubral tract** connects the cerebral cortex to the red nucleus, which is involved in motor coordination and learning. - These fibers typically travel through the **midbrain**, separate from the internal capsule's genu.

Q: The afferent component of the corneal reflex is mediated by:

Trigeminal nerve. ***Trigeminal nerve*** - The **afferent arc** of the corneal reflex is mediated by the **ophthalmic division (V1)** of the **trigeminal nerve**. - Stimulation of the cornea sends sensory signals via this nerve to the **pons**. *Vagus nerve* - The **vagus nerve (cranial nerve X)** is primarily responsible for parasympathetic innervation to most organs below the head and neck. - It has no role in the corneal reflex. *Facial nerve* - The **facial nerve (cranial nerve VII)** mediates the **efferent arc** of the corneal reflex, causing bilateral eyelid closure (orbicularis oculi muscle). - It is not involved in the sensory (afferent) detection of corneal stimulation. *Glossopharyngeal nerve* - The **glossopharyngeal nerve (cranial nerve IX)** provides sensory innervation to the posterior third of the tongue, pharynx, and middle ear. - It is not involved in the corneal reflex.

Q: Paralysis of the 3rd, 4th, and 6th nerves, with involvement of the ophthalmic division of the 5th nerve, localizes the lesion to:

Cavernous sinus. ***Cavernous sinus*** - The **cavernous sinus** contains cranial nerves **III (oculomotor)**, **IV (trochlear)**, **VI (abducens)**, and the **ophthalmic (V1)** and **maxillary (V2)** divisions of the trigeminal nerve (V). - A lesion here would therefore affect the function of most **extraocular muscles** and cause sensory disturbances in the distribution of V1, precisely matching the symptoms described. *Apex of orbit* - The **apex of the orbit** also contains cranial nerves III, IV, VI, the nasociliary branch of V1, and the optic nerve (II). - While it explains the CN III, IV, VI, and ophthalmic V involvement, a lesion at the apex of the orbit is more likely to also cause **optic neuropathy**, which is not mentioned. *Brainstem* - Lesions in the **brainstem** can affect these cranial nerves, but typically also involve long tracts (e.g., corticospinal, sensory pathways) leading to **contralateral weakness** or specific brainstem syndromes, which are not described. - Furthermore, brainstem lesions would not selectively affect the **ophthalmic division of the 5th nerve** in isolation without more widespread sensory or motor deficits in the face or body. *Base of skull* - Lesions at the **base of the skull** are broad and can affect multiple cranial nerves, but are generally less specific than a cavernous sinus lesion for this exact combination. - Involvement of CN III, IV, VI, and V1 together points more precisely to the anatomical confines of the **cavernous sinus** rather than a general base of skull lesion, which might affect other adjacent cranial nerves as well.

Q: Sensory fibers from the taste buds in the back of the tongue and soft palate travel along:

Glossopharyngeal nerve. ***Glossopharyngeal nerve*** - The **glossopharyngeal nerve** (cranial nerve IX) innervates the **posterior one-third of the tongue** for general sensation and taste, as well as the **palatoglossal arch** and **soft palate** [1]. - This nerve carries taste sensations from taste buds located in these regions to the brainstem [1]. *Trigeminal nerve* - The **trigeminal nerve** (cranial nerve V) is primarily responsible for **general sensation** from the face, oral cavity, and anterior two-thirds of the tongue, but it does **not** carry taste fibers. - It also provides motor innervation to the muscles of mastication. *Facial nerve* - The **facial nerve** (cranial nerve VII) carries taste sensation from the **anterior two-thirds of the tongue** via the chorda tympani, not the posterior tongue or soft palate. - It also controls the muscles of facial expression. *Vagus nerve* - The **vagus nerve** (cranial nerve X) plays a minor role in taste, primarily innervating taste buds in the **epiglottis** and **pharynx**, which are not specified in this question [1]. - Its main functions include parasympathetic innervation to many visceral organs.

Question 1

Nucleus intercalatus is seen in which part of the brain?

Accepted Answer

Medulla

Answer

Frontal lobe

Answer

Temporal lobe

Answer

Midbrain

Question 2

Which of the following cells is not present in the cerebellum?

Accepted Answer

Pyramidal cells

Answer

Stellate cells

Answer

Basket cells

Answer

Purkinje cells

Question 3

The facial nerve's first branch is?

Accepted Answer

Greater petrosal nerve

Answer

Lesser petrosal nerve

Answer

Chorda tympani nerve

Answer

Nerve to stapedius

Question 4

A 64-year-old man presented to the clinic with a severely painful rash and skin eruptions localized entirely on one side of his body, closely following the dermatome level of spinal nerve C7, and was diagnosed with herpes zoster virus. In which structure has the virus most likely proliferated to cause the patient's current condition?

Accepted Answer

The dorsal root ganglion of the C7 spinal nerve

Answer

The sympathetic chain

Answer

The lateral horn of the C7 spinal cord segment

Answer

The posterior cutaneous branch of the dorsal ramus of C7

Question 5

Which tract fibers pass through the genu of the internal capsule?

Accepted Answer

Corticonuclear tract

Answer

Optic radiation

Answer

Corticospinal

Answer

Corticorubral tract

Question 6

The afferent component of the corneal reflex is mediated by:

Accepted Answer

Trigeminal nerve

Answer

Vagus nerve

Answer

Facial nerve

Answer

Glossopharyngeal nerve

Question 7

Paralysis of the 3rd, 4th, and 6th nerves, with involvement of the ophthalmic division of the 5th nerve, localizes the lesion to:

Accepted Answer

Cavernous sinus

Answer

Apex of orbit

Answer

Brainstem

Answer

Base of skull

Question 8

What will be the consequence if the left optic nerve is severed?

Accepted Answer

Left eye complete blindness with loss of ipsilateral direct reflex and loss of contralateral consensual reflex.

Answer

Left eye complete blindness with no effect on light reflexes.

Answer

Bitemporal hemianopia due to optic chiasm involvement.

Answer

Left eye complete blindness with intact direct reflex but loss of consensual reflex.

Question 9

Sensory fibers from the taste buds in the back of the tongue and soft palate travel along:

Accepted Answer

Glossopharyngeal nerve

Answer

Facial nerve

Answer

Trigeminal nerve

Answer

Vagus nerve

Neuroanatomy — MCQs

Neuroanatomy — MCQs

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