Neuroanatomy Practice Questions

Q: Where are mitral cells primarily located?

Olfactory bulb. Olfactory bulb - **Mitral cells** are the primary projection neurons in the **olfactory bulb**, receiving extensive input from olfactory sensory neurons [1]. - They play a crucial role in processing and transmitting **olfactory information** from the nose to higher brain regions [1]. *Kidney* - The kidney contains various specialized cells for filtration and reabsorption (e.g., **podocytes**, **tubular cells**), but no mitral cells. - Its primary function is maintaining **fluid and electrolyte balance** and waste excretion, unrelated to olfaction. *Mitral valve* - The **mitral valve** is located in the heart, separating the left atrium and left ventricle. - It consists of connective tissue and endothelial cells and is essential for regulating **blood flow**, not scent perception. *Optic nerve* - The **optic nerve** transmits visual information from the retina to the brain and is composed of retinal ganglion cell axons [2]. - Its function is entirely distinct from olfaction, involving **light perception** and visual processing [2].

Q: A boy presents with his eye deviated laterally and slightly downward, and he has impaired upward gaze and is unable to medially rotate his eye. Which cranial nerve is most likely involved?

III. Cranial nerve III (oculomotor nerve) innervates most extraocular muscles, including the medial rectus, superior rectus, inferior rectus, and inferior oblique [1]. Damage to CN III causes the eye to deviate laterally and slightly downward (due to unopposed action of the lateral rectus and superior oblique muscles), impaired upward gaze, and inability to medially rotate the eye [1]. Cranial nerve IV (trochlear nerve) innervates the superior oblique muscle, which is responsible for intorsion, depression, and abduction of the eye [1]. Damage to CN IV would primarily result in vertical diplopia and upward eye deviation, especially when looking down and in, which is not the primary presentation here. This option is incorrect because the constellation of symptoms—lateral and downward deviation, impaired upward gaze, and inability to medially rotate the eye—is highly specific for oculomotor nerve (CN III) palsy [2].

Q: Which of the following Brodmann areas is primarily associated with Broca's motor aphasia?

44. ***Brodmann Area 44*** - **Brodmann area 44**, also known as **Broca's area**, is located in the inferior frontal gyrus and is critical for **speech production**. - Damage to this area typically leads to **Broca's motor aphasia** (also called expressive aphasia), characterized by **non-fluent speech**, difficulty forming words, and impaired grammar while comprehension remains relatively intact. *Brodmann Area 4* - **Brodmann area 4** corresponds to the **primary motor cortex**, responsible for executing voluntary movements. - While essential for motor control, it is not directly involved in the cognitive aspects of language production that define Broca's aphasia. *Brodmann Area 22* - **Brodmann area 22** is primarily associated with **Wernicke's area**, which is located in the superior temporal gyrus and is crucial for **language comprehension**. - Damage to this area results in **Wernicke's aphasia** (receptive aphasia), characterized by fluent but meaningless speech and impaired comprehension. *Brodmann Area 17* - **Brodmann area 17** is the **primary visual cortex**, responsible for processing visual information. - It plays no direct role in language processing or speech production; damage here would primarily cause visual field deficits.

Q: Abnormal regeneration of which nerve is the cause of crocodile tears?

Facial Nerve. Facial Nerve - **Crocodile tears**, or Bogorad's syndrome, result from aberrant regeneration of the **facial nerve (CN VII)** after injury, often occurring after Bell's palsy or trauma. - During regeneration, parasympathetic secretomotor fibers that should reinnervate salivary glands mistakenly regrow to innervate the **lacrimal gland**, leading to tearing (lacrimation) during salivation or eating. - The mechanism involves misdirected regeneration of fibers from the **greater petrosal nerve** or **chorda tympani** branches of CN VII. *Mandibular Nerve (V3)* - The mandibular nerve is a branch of the **trigeminal nerve (CN V)** and is primarily responsible for motor innervation to the muscles of mastication and sensory innervation to the lower face and mouth. - Its fibers are not involved in **lacrimal gland innervation** nor does its aberrant regeneration lead to crocodile tears. *Vagus Nerve (CN X)* - The vagus nerve is responsible for extensive innervation of the **visceral organs**, including the heart, lungs, and gastrointestinal tract, and plays a role in swallowing and speech. - It does not contain fibers that innervate the **lacrimal gland** or significantly contribute to facial gland secretion. *Glossopharyngeal Nerve* - The glossopharyngeal nerve (CN IX) primarily provides **sensory innervation** to the posterior tongue and pharynx, and motor innervation to the stylopharyngeus muscle. - It also carries parasympathetic fibers to the **parotid salivary gland**, but its aberrant regeneration does not cause lacrimation with salivation.

Q: Which of the following is an example of a non-macroglial cell?

None of the options. ***None of the options*** - All three listed cell types (Schwann cells, oligodendrocytes, and astrocytes) are **macroglial cells** [1]. - **Macroglia** refers to glial cells of **ectodermal origin** and includes both CNS glia (astrocytes, oligodendrocytes, ependymal cells) and PNS glia (Schwann cells) [1]. - **Non-macroglial cells** would include **microglia**, which are derived from mesodermal/hematopoietic lineage and function as immune cells of the CNS [1]. *Schwann cells* - Schwann cells are **macroglial cells** of the peripheral nervous system (PNS) [1]. - They are derived from neural crest (ectodermal origin) and responsible for myelinating axons in the PNS [1], [3]. - They are the PNS equivalent of oligodendrocytes in the CNS [2]. *Oligodendrocytes* - Oligodendrocytes are **macroglial cells** in the central nervous system (CNS) [1]. - Their primary function is to myelinate multiple axons within the CNS [2], [3]. *Astrocytes* - Astrocytes are the most abundant type of **macroglial cell** in the CNS [1]. - They provide structural support, maintain the blood-brain barrier, and provide metabolic support for neurons.

Q: When a patient says "Ah" and the uvula deviates to the right, which nerve is damaged?

Left X CN. ***Left X CN*** - The **vagus nerve (CN X)** innervates the muscles of the soft palate, including the **levator veli palatini**, which elevates the soft palate and uvula. - When one side of the vagus nerve is damaged, the intact side pulls the uvula towards the **healthy side** during phonation ("Ah"). Therefore, if the uvula deviates to the right, the **left vagus nerve** is paretic. *Right X CN* - If the **right vagus nerve** were damaged, the uvula would deviate to the **left side**, as the intact left vagus nerve would pull it in that direction. - This option incorrectly identifies the side of the lesion that would cause rightward deviation. *Left XII CN* - The **left hypoglossal nerve (CN XII)** primarily controls the muscles of the **tongue**, not the soft palate or uvula. - Damage to this nerve would cause deviation of the tongue, not the uvula, to the **affected side** (left). *Right XII CN* - The **right hypoglossal nerve (CN XII)** also controls the muscles of the tongue. - Damage to this nerve would cause the tongue to deviate to the **right side** upon protrusion, but would not affect uvular movement.

Q: An anterolateral cordotomy relieving pain in the right leg is effective because it interrupts the

Left lateral spinothalamic tract. ***Left lateral spinothalamic tract*** - An **anterolateral cordotomy** intentionally damages the **spinothalamic tracts**, which are responsible for transmitting **pain** and temperature sensations. - The **lateral spinothalamic tract** decussates (crosses over) in the spinal cord upon entry; thus, pain from the **right leg** is carried by the **left lateral spinothalamic tract**. *Left dorsal column* - The **dorsal column** (also known as the posterior column-medial lemniscus pathway) transmits **fine touch**, **vibration**, and **proprioception**, not pain. - While it mediates sensory information from the left side of the body, its interruption would not relieve pain. *Left ventral spinothalamic tract* - The **ventral (anterior) spinothalamic tract** primarily transmits crude touch and pressure, and a small portion of diffuse pain, not the focused, localized pain typically targeted by cordotomy. - Although it is on the left side, it is not the primary pathway for pain from the contralateral limb. *Right lateral spinothalamic tract* - The **right lateral spinothalamic tract** carries pain and temperature sensation from the **left side of the body** due to its decussation in the spinal cord. - Interrupting this tract would relieve pain in the left leg, not the right leg.

Q: Schirmer's test detects abnormality of which nerve?

Facial. Facial - Schirmer's test measures **tear production**, which is primarily innervated by the **lacrimal gland** through parasympathetic fibers originating from the facial nerve (CN VII). - Abnormalities in tear production, as detected by this test, can indicate dysfunction of the facial nerve or its associated pathways. Oculomotor - The oculomotor nerve (CN III) is responsible for controlling most **extraocular muscles** and **pupillary constriction**, not tear production. - Damage to this nerve typically causes symptoms like **ptosis**, **diplopia**, and **mydriasis**. Hypoglossal - The hypoglossal nerve (CN XII) primarily controls the **movements of the tongue**. - Dysfunction of this nerve would manifest as difficulties with **speech** and **swallowing**, not tear deficiency. Glossopharyngeal - The glossopharyngeal nerve (CN IX) is involved in **taste**, **salivation**, and controlling muscles of the **pharynx**. - It does not have a direct role in lacrimal gland function or tear production.

Q: Muscles spared by complete transection of the cranial part of the accessory nerve are:

Stylopharyngeus. ***Stylopharyngeus*** - The stylopharyngeus muscle is innervated by the **glossopharyngeal nerve (CN IX)**, not the cranial part of the accessory nerve. - Therefore, a complete transection of the cranial accessory nerve would spare its function. *Cricopharyngeus* - The cricopharyngeus muscle is innervated by the **pharyngeal plexus**, which receives input from the **vagus nerve (CN X)** and the cranial part of the accessory nerve. - Damage to the cranial accessory nerve would likely affect its function. *Palatopharyngeus* - The palatopharyngeus muscle is innervated by the **pharyngeal plexus**, which receives contributions from the **vagus nerve (CN X)** and the cranial part of the accessory nerve. - Its function would be compromised by a complete transection of the cranial accessory nerve. *Salpingopharyngeus* - The salpingopharyngeus muscle is innervated by the **pharyngeal plexus**, which includes fibers from the **vagus nerve (CN X)** and the cranial part of the accessory nerve. - Transection of the cranial accessory nerve would therefore affect this muscle.

Question 1

Where are mitral cells primarily located?

Accepted Answer

Olfactory bulb

Answer

Kidney

Answer

Mitral valve

Answer

Optic nerve

Question 2

A boy presents with his eye deviated laterally and slightly downward, and he has impaired upward gaze and is unable to medially rotate his eye. Which cranial nerve is most likely involved?

Accepted Answer

III

Answer

IV

Answer

V

Answer

None of the options

Question 3

Which of the following Brodmann areas is primarily associated with Broca's motor aphasia?

Accepted Answer

44

Answer

4

Answer

22

Answer

17

Question 4

What is the primary function of the hypoglossal nerve?

Accepted Answer

Motor innervation to the intrinsic and extrinsic muscles of the tongue (except palatoglossus)

Answer

Sensory innervation to the posterior third of the tongue

Answer

Sensory innervation to the anterior two-thirds of the tongue

Answer

Taste sensation from the posterior one-third of the tongue

Question 5

Abnormal regeneration of which nerve is the cause of crocodile tears?

Accepted Answer

Facial Nerve

Answer

Glossopharyngeal Nerve

Answer

Mandibular Nerve (V3)

Answer

Vagus Nerve (CN X)

Question 6

Which of the following is an example of a non-macroglial cell?

Accepted Answer

None of the options

Answer

Schwann cells

Answer

Oligodendrocytes

Answer

Astrocytes

Question 7

When a patient says "Ah" and the uvula deviates to the right, which nerve is damaged?

Accepted Answer

Left X CN

Answer

Left XII CN

Answer

Right X CN

Answer

Right XII CN

Question 8

An anterolateral cordotomy relieving pain in the right leg is effective because it interrupts the

Accepted Answer

Left lateral spinothalamic tract

Answer

Left dorsal column

Answer

Right lateral spinothalamic tract

Answer

Left ventral spinothalamic tract

Question 9

Schirmer's test detects abnormality of which nerve?

Accepted Answer

Facial

Answer

Oculomotor

Answer

Hypoglossal

Answer

Glossopharyngeal

Question 10

Muscles spared by complete transection of the cranial part of the accessory nerve are:

Accepted Answer

Stylopharyngeus

Answer

Cricopharyngeus

Answer

Palatopharyngeus

Answer

Salpingopharyngeus

Neuroanatomy — MCQs

Neuroanatomy — MCQs

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