Neuroanatomy Practice Questions

Q: A young girl presents with symptoms of nasal and palatal dryness. Which ganglion is likely affected?

Pterygopalatine ganglion. ***Pterygopalatine ganglion*** - The **pterygopalatine ganglion** is the primary source of **parasympathetic innervation** for the **nasal** and **palatal mucosa**, including their glands that produce secretions for moisture. - Damage to this ganglion would impair the secretomotor function, leading to **dryness in these regions**. *Nodose ganglion* - The **nodose ganglion** is a **sensory ganglion of the vagus nerve (CN X)**, primarily involved in visceral sensation from the thoracic and abdominal organs. - It does not directly innervate glands of the nasal or palatal mucosa, so its damage would not cause dryness in these areas. *Otic ganglion* - The **otic ganglion** provides **parasympathetic innervation** to the **parotid gland**, controlling saliva production from this gland. - Lesion to the otic ganglion would primarily affect parotid gland function, leading to symptoms like dry mouth, but not specifically nasal or palatal dryness. *Submandibular ganglion* - The **submandibular ganglion** provides **parasympathetic secretomotor innervation** to the **submandibular** and **sublingual salivary glands**. - Damage would lead to reduced saliva production from these glands, causing dry mouth, but not specifically nasal or palatal dryness.

Q: The fibers from the contralateral nasal hemiretina project to the following layers of the lateral geniculate nucleus:

Layers 1, 4 & 6.. ***Layers 1, 4 & 6.*** - The **contralateral nasal hemiretina** projects to layers 1, 4, and 6 of the lateral geniculate nucleus (LGN) [1]. - These layers receive input from the **magnocellular (layer 1)** and **parvocellular (layers 4 and 6)** pathways originating from the contralateral eye. *Layers 2, 3 & 5.* - This option incorrectly combines layers from both contralateral and ipsilateral projections. - Layers 2, 3, and 5 receive input from the **ipsilateral temporal hemiretina**, not the contralateral nasal hemiretina [1]. *Layers 1, 2 & 6.* - While layers 1 and 6 receive contralateral input, layer 2 specifically receives input from the **ipsilateral eye**. - This combination is not exclusively for contralateral nasal hemiretinal projection. *Layers 4, 5 & 6.* - This option includes layer 5, which receives input from the **ipsilateral temporal hemiretina**. - Layers 4 and 6 do receive contralateral input, but layer 5 makes this answer incorrect for an exclusive contralateral projection.

Q: Which of the following statements regarding chorda tympani is false?

Contains motor nerves that supply facial muscles. ***Contains motor nerves that supplies facial muscles*** - The chorda tympani carries special visceral afferent fibers for **taste from the anterior two-thirds of the tongue** [1] and preganglionic parasympathetic fibers to the **submandibular and sublingual glands**. - It does not contain **motor nerves that supply facial muscles**; those are supplied directly by the main trunk of the facial nerve (CN VII) after it exits the stylomastoid foramen. *Contains secretomotor nerves that supply salivary gland* - The chorda tympani contains **preganglionic parasympathetic fibers** that synapse in the submandibular ganglion. - These postganglionic fibers then innervate the **submandibular and sublingual salivary glands**, promoting saliva production. *Passes through the petrotympanic fissure* - The chorda tympani nerve exits the temporal bone via the **petrotympanic fissure (Glaserian fissure)**. - This is its exit point from the middle ear cavity to join the **lingual nerve**. *Contains sensory neurons that supply anterior 2/3rd of tongue* - The chorda tympani carries **special visceral afferent (taste) fibers** from the taste buds on the anterior two-thirds of the tongue [1]. - These fibers are part of the **facial nerve (CN VII)** pathway for taste sensation [1].

Q: What is the primary function of the superior cervical ganglion?

Supplies sympathetic fibers to the dilator pupillae muscle. Supplies sympathetic fibers to the dilator pupillae muscle - The superior cervical ganglion is the primary source of postganglionic sympathetic fibers to the head and neck. - One of its key functions is providing sympathetic innervation to the dilator pupillae muscle [1] via the long ciliary nerves, causing mydriasis (pupil dilation) [2]. - This represents a clear physiological function of the ganglion in autonomic control of the eye. Is the largest cervical ganglion - While the superior cervical ganglion is indeed the largest of the three cervical sympathetic ganglia, this is an anatomical characteristic, not a function. - Size is a structural feature, not a physiological role. Left superior cervical cardiac branch goes to deep cardiac plexus - The superior cervical ganglion does contribute cardiac branches to the cardiac plexus for sympathetic innervation of the heart. - However, this describes an anatomical pathway rather than the primary function itself, and specifying "left" and "deep cardiac plexus" makes it overly specific rather than addressing overall function. Deep petrosal nerve of pterygopalatine ganglion is derived from plexus around internal carotid artery - The superior cervical ganglion does send postganglionic fibers forming a plexus around the internal carotid artery, which contributes to the deep petrosal nerve. - However, this is an anatomical derivation/pathway, not a functional description of what the ganglion does physiologically.

Q: Which of the following cranial nerves does not have a parasympathetic component?

Abducens nerve. Abducens nerve - The abducens nerve (CN VI) is a purely motor nerve, primarily responsible for innervating the lateral rectus muscle of the eye. - Its function is to cause abduction (outward movement) of the eye, and it does not carry any parasympathetic fibers. Oculomotor nerve - The oculomotor nerve (CN III) contains parasympathetic fibers that control the pupillary constrictor muscles and the ciliary muscles [1]. - These fibers originate from the Edinger-Westphal nucleus and cause pupillary constriction (miosis) and accommodation [1]. Facial nerve - The facial nerve (CN VII) has parasympathetic components that innervate the submandibular and sublingual salivary glands, as well as the lacrimal glands. - These fibers are crucial for tear production and salivation. Vagus nerve - The vagus nerve (CN X) is a major parasympathetic nerve, carrying widespread innervation to the thoracic and abdominal viscera. - It regulates heart rate, digestion, respiration, and other autonomic functions in organs like the heart, lungs, and gastrointestinal tract.

Q: Following a head injury, a man lost his tears from both eyes. Absence of lacrimation is due to injury to which structure?

Greater petrosal nerve. ***Greater petrosal nerve*** - The **greater petrosal nerve** carries **parasympathetic preganglionic fibers** from the facial nerve (CN VII) that are destined for the **lacrimal gland**. - Damage to this nerve before it synapses in the **pterygopalatine ganglion** would result in the loss of **lacrimation**. *Supraorbital nerve* - The **supraorbital nerve** is a branch of the **ophthalmic division of the trigeminal nerve (CN V1)** and provides **sensory innervation** to the forehead, upper eyelid, and scalp. - It does not carry fibers for lacrimal gland function. *Tympanic plexus* - The **tympanic plexus** is formed by branches of the **glossopharyngeal nerve (CN IX)** and provides **parasympathetic innervation to the parotid gland** for salivation. - It plays no role in lacrimal gland function. *Nasociliary nerve* - The **nasociliary nerve** is a branch of the **ophthalmic division of the trigeminal nerve (CN V1)** and provides **sensory innervation** to the eyeball, conjunctiva, and part of the nasal mucosa. - It does not carry fibers for lacrimal gland secretion.

Q: Lacrimal gland receives postganglionic innervation through?

Pterygopalatine ganglion. ***Pterygopalatine ganglion*** - The **lacrimal gland** receives **secretomotor parasympathetic innervation** from the pterygopalatine ganglion [2]. - The **postganglionic fibers** from this ganglion travel with the **zygomatic nerve** and then join the **lacrimal nerve** to reach the lacrimal gland [2]. *Submandibular ganglion* - This ganglion primarily provides **postganglionic parasympathetic innervation** to the **submandibular and sublingual salivary glands** [2]. - Its fibers are involved in saliva production, not tear secretion. *Otic ganglion* - The otic ganglion supplies **postganglionic parasympathetic innervation** to the **parotid salivary gland** [2]. - It is involved in mumps and is not associated with lacrimal gland function. *Ciliary ganglion* - The ciliary ganglion innervates the **sphincter pupillae** and **ciliary muscle** of the eye, controlling pupil constriction and accommodation [1], [2]. - It does not have a role in the innervation of the lacrimal gland.

Q: What is the primary function of Schwann cells?

Form myelin sheath. ***Form myelin sheath*** - **Schwann cells** are glial cells found in the **peripheral nervous system** that wrap around axons to form the myelin sheath [1], [3]. - The **myelin sheath** acts as an electrical insulator, increasing the speed of nerve impulse conduction via **saltatory conduction** [2]. - This is the **primary and most characteristic function** of Schwann cells in the PNS [3]. *Part of the central nervous system* - Schwann cells are exclusively found in the **peripheral nervous system (PNS)**, not the CNS [4]. - In the **central nervous system (CNS)**, **oligodendrocytes** are responsible for myelin formation [1], [4]. *Derived from neural crest cells* - While Schwann cells are indeed derived from **neural crest cells**, this describes their **embryological origin**, not their function. - Many other cell types (melanocytes, neurons of peripheral ganglia) are also neural crest derivatives. *Present in both myelinated and unmyelinated nerve fibers* - While Schwann cells are associated with both fiber types, this describes their **distribution**, not their primary function [1], [3]. - In unmyelinated fibers, Schwann cells envelop multiple axons without forming concentric myelin layers [1].

Q: In the central nervous system, which cells are responsible for the formation of the myelin sheath of neurons?

Oligodendroglia cells. ***Oligodendroglia cells*** - **Oligodendroglia cells (oligodendrocytes)** are responsible for forming the **myelin sheath** around axons in the **central nervous system** (CNS) [2]. - Each oligodendrocyte can myelinate **multiple axons** (up to 50 segments), providing insulation that speeds up nerve impulse conduction via **saltatory conduction** [3], [4]. - This is a key distinguishing feature from Schwann cells in the PNS [3]. *Astrocytes* - **Astrocytes** are star-shaped glial cells that play a crucial role in providing **nutritional support** to neurons, regulating the **blood-brain barrier**, and maintaining the **extracellular environment**. - They do not form myelin; instead, they are involved in structural support, repair within the CNS, and neurotransmitter recycling [1]. *Schwann cells* - **Schwann cells** are the myelin-forming cells of the **peripheral nervous system** (PNS) [2]. - Unlike oligodendrocytes, each Schwann cell typically myelinates only a **single segment of one axon** [3], [4]. - This is the key anatomical difference between CNS and PNS myelination. *Microglia* - **Microglia** are the resident **immune cells** of the CNS, derived from mesoderm [1]. - They act as macrophages, responding to injury and infection, but play no role in myelin formation [1], [3]. - They are involved in immune surveillance and phagocytosis of debris [1].

Q: A patient presents with a brachial plexus injury and exhibits signs of Horner's syndrome. Which nerve root level is primarily involved?

T1. ***T1*** - Involvement of the **T1 nerve root** is crucial because it carries **preganglionic sympathetic fibers** that ascend to the superior cervical ganglion [1]. - Damage to these fibers at the T1 level, often due to a **lower brachial plexus injury (Klumpke's palsy)**, interrupts the sympathetic pathway to the head, leading to **Horner's syndrome** [1]. *C5* - The **C5 nerve root** primarily contributes to the **upper trunk** of the brachial plexus and innervates muscles like the deltoid and biceps. - Injury to C5 typically results in deficits related to **shoulder abduction** and **elbow flexion**, not Horner's syndrome. *C6* - The **C6 nerve root** also contributes to the upper and middle trunks, innervating muscles responsible for **wrist extension** and **elbow flexion**. - Damage to C6 would primarily cause weakness in these movements and sensory loss in the thumb and index finger. *C7* - The **C7 nerve root** forms the middle trunk and innervates muscles like the triceps and wrist flexors. - Injury to C7 would lead to deficits in **elbow extension** and **wrist flexion**, and sensory loss in the middle finger.

Question 1

A young girl presents with symptoms of nasal and palatal dryness. Which ganglion is likely affected?

Accepted Answer

Pterygopalatine ganglion

Answer

Otic ganglion

Answer

Nodose ganglion

Answer

Submandibular ganglion

Question 2

The fibers from the contralateral nasal hemiretina project to the following layers of the lateral geniculate nucleus:

Accepted Answer

Layers 1, 4 & 6.

Answer

Layers 4, 5 & 6.

Answer

Layers 2, 3 & 5.

Answer

Layers 1, 2 & 6.

Question 3

Which of the following statements regarding chorda tympani is false?

Accepted Answer

Contains motor nerves that supply facial muscles

Answer

Contains secretomotor nerves that supply salivary gland

Answer

Passes through the petrotympanic fissure

Answer

Contains sensory neurons that supply anterior 2/3rd of tongue

Question 4

What is the primary function of the superior cervical ganglion?

Accepted Answer

Supplies sympathetic fibers to the dilator pupillae muscle

Answer

Is the largest cervical ganglion

Answer

Deep petrosal nerve of pterygopalatine ganglion is derived from plexus around internal carotid artery

Answer

Left superior cervical cardiac branch goes to deep cardiac plexus

Question 5

Which of the following cranial nerves does not have a parasympathetic component?

Accepted Answer

Abducens nerve

Answer

Oculomotor nerve

Answer

Facial nerve

Answer

Vagus nerve

Question 6

Following a head injury, a man lost his tears from both eyes. Absence of lacrimation is due to injury to which structure?

Accepted Answer

Greater petrosal nerve

Answer

Supraorbital nerve

Answer

Tympanic plexus

Answer

Nasociliary nerve

Question 7

Lacrimal gland receives postganglionic innervation through?

Accepted Answer

Pterygopalatine ganglion

Answer

Submandibular ganglion

Answer

Otic ganglion

Answer

Ciliary ganglion

Question 8

What is the primary function of Schwann cells?

Accepted Answer

Form myelin sheath

Answer

Part of the central nervous system

Answer

Derived from neural crest cells

Answer

Present in both myelinated and unmyelinated nerve fibers

Question 9

In the central nervous system, which cells are responsible for the formation of the myelin sheath of neurons?

Accepted Answer

Oligodendroglia cells

Answer

Astrocytes

Answer

Schwann cells

Answer

Microglia

Question 10

A patient presents with a brachial plexus injury and exhibits signs of Horner's syndrome. Which nerve root level is primarily involved?

Accepted Answer

T1

Answer

C5

Answer

C6

Answer

C7

Neuroanatomy — MCQs

Neuroanatomy — MCQs

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