Neuroanatomy Practice Questions

Q: Which of the following cranial nerves is a pure sensory nerve?

CN 8. ***CN 8*** - The **vestibulocochlear nerve (CN VIII)** is a pure sensory cranial nerve responsible for **hearing** and **balance** [1]. - It consists of two main branches: the **cochlear nerve** (for hearing) and the **vestibular nerve** (for balance and spatial orientation) [1], [2]. *CN 3* - The **oculomotor nerve (CN III)** is primarily a **motor nerve**, controlling most extraocular muscles and the pupil. - It also carries **parasympathetic fibers** to the pupillary sphincter and ciliary muscles, but it is not purely sensory. *CN 5* - The **trigeminal nerve (CN V)** is a **mixed nerve**, containing both sensory and motor components. - Its sensory functions include sensation from the face, while its motor component innervates the muscles of mastication. *CN 9* - The **glossopharyngeal nerve (CN IX)** is a **mixed nerve** with diverse functions. - It carries sensory information from the posterior tongue (taste and general sensation) and pharynx, and motor fibers to the stylopharyngeus muscle, as well as parasympathetic fibers to the parotid gland.

Q: Vidian nerve is also known as?

Nerve to pterygoid canal. ***Nerve to pterygoid canal*** - The **Vidian nerve** is a collective term for the nerve fibers that pass through the **pterygoid canal**, hence its alternative name. - It is formed by the union of the **greater petrosal nerve** (parasympathetic preganglionic fibers) and the **deep petrosal nerve** (sympathetic postganglionic fibers). *Superior petrosal nerve* - This is **not a recognized anatomical structure** - there is no such nerve in standard anatomical nomenclature. - The term may be confused with the **greater petrosal nerve** or the **lesser petrosal nerve**, both of which are actual cranial nerve branches, but neither is an alternative name for the Vidian nerve. *Greater petrosal nerve* - The **greater petrosal nerve** is a component of the Vidian nerve, specifically carrying **parasympathetic fibers** from the facial nerve (CN VII). - It originates from the geniculate ganglion and is one of the two main contributors to the formation of the Vidian nerve, not the Vidian nerve itself. *Auricular branch of vagus nerve* - The **auricular branch of the vagus nerve** (Arnold's nerve) innervates the external auditory canal and part of the auricle. - It is entirely unrelated to the Vidian nerve, which is involved in salivary and lacrimal gland innervation.

Q: From which structure is the deep petrosal nerve formed?

Internal carotid plexus. ***Internal carotid plexus*** - The **deep petrosal nerve** contains **postganglionic sympathetic fibers** that arise from the **superior cervical ganglion**. - These fibers ascend along the **internal carotid artery** and form the **internal carotid plexus** (sympathetic plexus around the internal carotid). - The **deep petrosal nerve** branches directly from this **internal carotid plexus**. *Greater petrosal nerve* - The **greater petrosal nerve** is a branch of the **facial nerve (CN VII)** carrying **preganglionic parasympathetic fibers**. - It joins with the **deep petrosal nerve** to form the **nerve of the pterygoid canal (Vidian nerve)**, but it does not give rise to the deep petrosal nerve. - These are two separate nerves that converge, not a source structure. *Facial nerve* - The **facial nerve (CN VII)** is primarily involved in facial expression, taste sensation, and parasympathetic innervation. - While it gives rise to the **greater petrosal nerve** (which joins with the deep petrosal nerve), it does not directly form the **deep petrosal nerve** itself. - The deep petrosal nerve carries **sympathetic** fibers, not parasympathetic from CN VII. *Glossopharyngeal* - The **glossopharyngeal nerve (CN IX)** is involved in taste, pharyngeal sensation, and parasympathetic innervation of the parotid gland. - It has no anatomical or functional connection to the formation of the **deep petrosal nerve**.

Q: Sensory afferent fibers from the fallopian tubes ascend to:

T 10. ***T 10*** - The **fallopian tubes** and **ovaries** share sensory innervation primarily through the **T10** and **T11** spinal segments. [2] - This is consistent with the **visceral pain** referral pattern often experienced in the periumbilical region during pain originating from these organs. [2] *T 8* - Sensory innervation to **T8** primarily covers the epigastric region, which is typically associated with organs higher in the abdomen, such as the stomach and gallbladder. [1] - Pain from the fallopian tubes is generally referred lower than the epigastrium. *L 2* - The **L2** spinal segment mainly innervates structures in the lower abdomen and upper thigh, like parts of the colon and the hip joint. [1] - This dermatomal level is too low to be the primary sensory afferent pathway for the fallopian tubes. *L 4* - **L4** sensory innervation is largely associated with the knee and medial calf regions. - It does not correspond to the visceral sensory pathways from pelvic organs like the fallopian tubes.

Q: Intratemporal lesion of chorda tympani nerve results in -

Loss of taste sensations from anterior 2/3rd of tongue. Loss of taste sensations from anterior 2/3rd of tongue - The chorda tympani nerve, a branch of the facial nerve (CN VII), carries special visceral afferent (taste) fibers from the anterior two-thirds of the tongue. - An intratemporal lesion of the chorda tympani will result in loss of taste sensation from the anterior two-thirds of the tongue, which is a clinically significant and easily detectable finding [1]. - The chorda tympani exits the facial canal through the petrotympanic fissure and travels through the middle ear (intratemporal course) before joining the lingual nerve. Loss of secretomotor fibers to the submandibular salivary gland - While the chorda tympani also carries parasympathetic secretomotor fibers to the submandibular and sublingual salivary glands, this function is less clinically apparent. - Although secretomotor loss does occur with an intratemporal lesion, both taste loss and secretomotor loss occur together, but the question format requires selecting the most clinically significant and testable consequence. - In standard medical examinations, taste loss from the anterior 2/3 of tongue is the classic association tested with chorda tympani lesions. Loss of taste sensations from posterior 1/3rd of tongue - Taste sensation from the posterior one-third of the tongue is carried by the glossopharyngeal nerve (CN IX), not the chorda tympani. - An intratemporal lesion of the chorda tympani would not affect this region. Loss of taste sensations from papillae of tongue - This option is too vague and non-specific. - While taste loss does affect taste papillae, this option doesn't specify which part of the tongue, making it imprecise compared to the specific anatomical distribution (anterior 2/3) affected by the chorda tympani [1].

Q: Which one of the following structures is not a part of the auditory pathway?

Medial lemniscus. ***Medial lemniscus*** - The **medial lemniscus** is a major ascending sensory pathway responsible for transmitting **fine touch, vibration, and proprioception** from the body to the cerebral cortex [2]. - It is part of the **somatosensory system** and does not play a role in auditory processing. *Lateral lemniscus* - The **lateral lemniscus** is a key ascending auditory pathway in the brainstem that transmits information from the **cochlear nuclei** to higher auditory centers [1]. - It plays a crucial role in the processing of **auditory information**, including sound localization. *Inferior colliculus* - The **inferior colliculus** is a principal nucleus in the midbrain that serves as a major integrative and relay center for virtually all **auditory information** ascending from lower brainstem nuclei [1]. - It is involved in **sound localization**, frequency discrimination, and the startle reflex. *Medial geniculate body* - The **medial geniculate body (MGB)** is the auditory nucleus of the **thalamus** that serves as a crucial relay station for auditory information between the **inferior colliculus** and the primary auditory cortex [1]. - It is involved in various aspects of auditory processing, including **sound localization** and attention.

Q: The facial nerve supplies motor fibers to which of the following muscles?

Stapedius. ***Stapedius*** - The **facial nerve (CN VII)** provides motor innervation to the **stapedius muscle**, which plays a role in dampening loud sounds by pulling the stapes away from the oval window. - Dysfunction of this innervation can lead to **hyperacusis** (increased sensitivity to sound). *Mylohyoid* - The **mylohyoid muscle** is innervated by the **nerve to mylohyoid**, which is a branch of the **inferior alveolar nerve** (a branch of the mandibular division of the trigeminal nerve, CN V3). - It forms the floor of the mouth and elevates the **hyoid bone** and tongue during swallowing and speaking. *Anterior belly of the digastric* - The **anterior belly of the digastric muscle** is innervated by the **nerve to mylohyoid**, a branch of the **inferior alveolar nerve** (CN V3). - This muscle helps in depressing the mandible and elevating the hyoid bone. *Geniohyoid* - The **geniohyoid muscle** is innervated by fibers from the **C1 spinal nerve** that travel briefly with the **hypoglossal nerve (CN XII)**. - It elevates and protracts the hyoid bone, aiding in swallowing.

Q: Which of the following nuclei of the vagus receives special and general visceral afferents?

Nucleus of Solitary Tract. ### Nucleus of Solitary Tract - The **nucleus of the solitary tract** (NST) is the primary sensory nucleus for **general visceral afferents** (GVA) and **special visceral afferents** (SVA) from the vagus nerve (CN X) [1], [2]. - It receives taste sensation from the **epiglottis** and upper esophagus (SVA) and general sensation from the pharynx, larynx, and thoracic/abdominal viscera (GVA) [1], [2]. *Dorsal Nucleus of Vagus* - The **dorsal nucleus of the vagus** is primarily an **efferent (motor)** nucleus, providing **preganglionic parasympathetic innervation** to thoracic and abdominal viscera. - While it plays a role in visceral function, it is not the primary recipient of **afferent sensory information** from the vagus nerve. *Nucleus Ambiguous* - The **nucleus ambiguous** is a **motor nucleus** that provides **branchiomotor innervation** to muscles of the pharynx and larynx via the vagus nerve. - It is involved in processes like swallowing and speech, but it does **not receive visceral afferent input**. *Spinal nucleus of trigeminal nerve* - The **spinal nucleus of the trigeminal nerve** processes **pain and temperature sensation** for the face and oral cavity, primarily from the trigeminal nerve (CN V). - It is **not associated with the vagus nerve's visceral afferent functions**.

Q: In adults, the spinal cord normally ends at what level?

Lower border of L1. ***Lower border of L1*** - In adults, the **spinal cord** typically terminates at the level of the **L1 vertebral body**, or specifically, its lower border [1]. - This marks the anatomical transition from the solid spinal cord to the **conus medullaris**, which then continues as the **cauda equina** [1]. *Lower border of L3* - While the spinal cord in **newborns** can extend as low as L3, it retracts with growth, and this level is incorrect for adults. - An adult spinal cord ending at L3 would be considered an **abnormal finding**, potentially indicating a **tethered cord syndrome**. *Lower border of S1* - The spinal cord never extends to the S1 level in healthy individuals, even in newborns. - The **sacrum (S1-S5)** is well below the normal termination point of the spinal cord. *Lower border of L5* - The spinal cord typically terminates well above L5 in adults. - The **cauda equina**, not the spinal cord itself, extends through the lumbar and sacral regions to L5 and beyond.

Question 1

Which of the following cranial nerves is a pure sensory nerve?

Accepted Answer

CN 8

Answer

CN 3

Answer

CN 5

Answer

CN 9

Question 2

Vidian nerve is also known as?

Accepted Answer

Nerve to pterygoid canal

Answer

Superior petrosal nerve

Answer

Greater petrosal nerve

Answer

Auricular branch of vagus nerve

Question 3

From which structure is the deep petrosal nerve formed?

Accepted Answer

Internal carotid plexus

Answer

Facial nerve

Answer

Glossopharyngeal

Answer

Greater petrosal nerve

Question 4

Sensory afferent fibers from the fallopian tubes ascend to:

Accepted Answer

T 10

Answer

T 8

Answer

L 2

Answer

L 4

Question 5

Intratemporal lesion of chorda tympani nerve results in -

Accepted Answer

Loss of taste sensations from anterior 2/3rd of tongue

Answer

Loss of secretomotor fibers to the submandibular salivary gland

Answer

Loss of taste sensations from posterior 1/3rd of tongue

Answer

Loss of taste sensations from papillae of tongue

Question 6

Which nerve is responsible for supplying the posterior semicircular canal?

Accepted Answer

Inferior vestibular nerve supplying posterior semicircular canal

Answer

Superior vestibular nerve supplying posterior semicircular canal

Answer

Superior vestibular nerve supplying anterior semicircular canal

Answer

Inferior vestibular nerve supplying anterior semicircular canal

Question 7

Which one of the following structures is not a part of the auditory pathway?

Accepted Answer

Medial lemniscus

Answer

Inferior colliculus

Answer

Medial geniculate body

Answer

Lateral lemniscus

Question 8

The facial nerve supplies motor fibers to which of the following muscles?

Accepted Answer

Stapedius

Answer

Mylohyoid

Answer

Anterior belly of the digastric

Answer

Geniohyoid

Question 9

Which of the following nuclei of the vagus receives special and general visceral afferents?

Accepted Answer

Nucleus of Solitary Tract

Answer

Dorsal Nucleus of Vagus

Answer

Nucleus Ambiguous

Answer

Spinal nucleus of trigeminal nerve

Question 10

In adults, the spinal cord normally ends at what level?

Accepted Answer

Lower border of L1

Answer

Lower border of L3

Answer

Lower border of S1

Answer

Lower border of L5

Neuroanatomy — MCQs

Neuroanatomy — MCQs

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