Neuroanatomy Practice Questions

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: 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: 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: Which of the following cranial nerves is NOT involved in superior orbital fissure syndrome?

Olfactory nerve (1st cranial nerve). ***Olfactory nerve (1st cranial nerve)*** - The **olfactory nerve (CN I)** passes through the **cribriform plate** of the ethmoid bone, not the superior orbital fissure [2]. - Its involvement is not a feature of superior orbital fissure syndrome, which affects structures passing through that fissure. *Trochlear nerve (4th cranial nerve)* - The **trochlear nerve (CN IV)** passes through the **superior orbital fissure** to innervate the superior oblique muscle [1]. - Its involvement can lead to **diplopia** and impaired downward and inward eye movement [1]. *Abducens nerve (6th cranial nerve)* - The **abducens nerve (CN VI)** travels through the **superior orbital fissure** to innervate the lateral rectus muscle [1]. - Damage to this nerve results in **esotropia** (medial deviation of the eye) and **diplopia** [1]. *Oculomotor nerve (3rd cranial nerve)* - The **oculomotor nerve (CN III)** passes through the **superior orbital fissure** and controls most extraocular muscles, as well as pupillary constriction and eyelid elevation. - Injury to CN III leads to **ptosis**, **mydriasis**, and an eye that is **down and out**.

Q: Pain of stylalgia is mediated through which nerve?

9th cranial nerve. ***9th cranial nerve*** - **Stylalgia**, or Eagle syndrome, is characterized by pain along the styloid process and is often associated with an elongated styloid process or calcification of the stylohyoid ligament. - The **glossopharyngeal nerve** (9th cranial nerve) passes close to the styloid process and is frequently implicated in mediating the pain experienced in stylalgia [1]. *10th cranial nerve* - The **vagus nerve** (10th cranial nerve) primarily innervates structures in the neck, thorax, and abdomen, and is not directly responsible for pain associated with stylalgia [1]. - While it has broad sensory functions, its branches are less intimately involved with the styloid process itself compared to the glossopharyngeal nerve. *11th cranial nerve* - The **spinal accessory nerve** (11th cranial nerve) is chiefly a motor nerve, innervating the sternocleidomastoid and trapezius muscles. - It has no significant role in mediating sensory pain from the styloid process. *5th cranial nerve* - The **trigeminal nerve** (5th cranial nerve) is responsible for sensation in the face and mastication, and its branches do not directly mediate pain from the styloid process. - Though some atypical facial pain conditions exist, stylalgia pain is distinct and attributed to other cranial nerves.

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

Palsy of the right genioglossus causes

Accepted Answer

Deviation of tongue to the right due to right genioglossus paralysis

Answer

Deviation of tongue to the left due to left genioglossus paralysis

Answer

Deviation of soft palate to the right due to right genioglossus paralysis

Answer

Deviation of soft palate to the left due to left genioglossus paralysis

Question 2

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 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

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

Accepted Answer

Corticonuclear tract

Answer

Optic radiation

Answer

Corticospinal

Answer

Corticorubral tract

Question 5

Which of the following cranial nerves is NOT involved in superior orbital fissure syndrome?

Accepted Answer

Olfactory nerve (1st cranial nerve)

Answer

Abducens nerve (6th cranial nerve)

Answer

Trochlear nerve (4th cranial nerve)

Answer

Oculomotor nerve (3rd cranial nerve)

Question 6

Pain of stylalgia is mediated through which nerve?

Accepted Answer

9th cranial nerve

Answer

10th cranial nerve

Answer

11th cranial nerve

Answer

5th cranial 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

On this page

Practice by Chapter

Want unlimited practice?