Neuroanatomy Practice Questions

Q: Facial nerve does not supply which structure of the face?

Parotid gland. ***Parotid gland*** - While the facial nerve (CN VII) passes *through* the parotid gland, it does not provide motor innervation to the gland itself. - The parotid gland receives parasympathetic innervation for **salivation** primarily from the **glossopharyngeal nerve (CN IX)** via the otic ganglion. *Posterior belly of digastric muscle* - The **facial nerve (CN VII)** provides motor innervation to the posterior belly of the digastric muscle. - This muscle is involved in **depressing the mandible** and **elevating the hyoid bone**. *Submandibular gland* - The facial nerve (CN VII) provides parasympathetic secretomotor innervation to the submandibular gland via the **chorda tympani** and submandibular ganglion. - This innervation controls **salivation** from the submandibular gland. *Auricular muscle* - The facial nerve (CN VII) supplies the **auricular muscles**, which are muscles of facial expression around the ear. - These muscles contribute to minor **ear movements**.

Q: Which of the following nerves does not provide sensory innervation to the palate?

Hypoglossal nerve. ***Hypoglossal nerve*** - The **hypoglossal nerve (CN XII)** is primarily a **motor nerve** that innervates the intrinsic and extrinsic muscles of the tongue, controlling tongue movement. - It plays no role in the **sensory innervation of the palate**. *Facial nerve* - The **facial nerve (CN VII)** provides **taste sensation to the soft palate** via the **greater petrosal nerve**, which arises from the geniculate ganglion. - The greater petrosal nerve also carries **parasympathetic fibers** to the palatine glands and contributes to the sensory innervation of the palate. - While primarily known for facial muscle innervation, it also has important sensory and parasympathetic functions related to the oral cavity. *Glossopharyngeal nerve* - The **glossopharyngeal nerve (CN IX)** provides general sensation and taste to the posterior third of the tongue and contributes to the **sensory innervation of the soft palate** and pharynx. - Specifically, it innervates the soft palate's posterior aspect and the fauces. *Maxillary division of trigeminal nerve* - The **maxillary division of the trigeminal nerve (CN V2)** provides general sensory innervation to the hard and soft palates. - This is primarily carried through the **greater, lesser, and nasopalatine nerves**, which are branches of V2.

Q: Which of the following muscles is supplied by the cranial part of the accessory nerve?

Levator veli palatini. ***Levator veli palatini*** - The **cranial part of the accessory nerve (CN XI)** sends fibers that join the **vagus nerve (CN X)** and are distributed via the **pharyngeal plexus** - These fibers supply the **levator veli palatini** muscle along with other pharyngeal muscles - This muscle is crucial for **elevating the soft palate** during swallowing and speech - This is the **correct answer** as it receives innervation from cranial accessory fibers via the vagus *Cricothyroid* - The **cricothyroid** muscle is supplied by the **external laryngeal nerve**, a branch of the **superior laryngeal nerve** from the vagus - It does NOT receive fibers from the cranial accessory nerve - Functions to **tense the vocal cords** and control pitch *Stylopharyngeus* - The **stylopharyngeus** muscle is uniquely innervated by the **glossopharyngeal nerve (CN IX)** - NOT supplied by the accessory nerve - Involved in **elevating the pharynx and larynx** during swallowing *Tensor veli palati* - The **tensor veli palati** muscle is innervated by the **mandibular nerve (CN V3)**, a branch of the trigeminal nerve - NOT supplied by the accessory nerve - Primary role is to **tense the soft palate** and open the eustachian tube

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: Which nerve is the masseteric nerve a branch of?

Mandibular division of the trigeminal nerve. ***Mandibular division of the trigeminal nerve*** - The **masseteric nerve** is a branch of the **anterior trunk** of the mandibular division (V3) of the trigeminal nerve. - It supplies motor innervation to the **masseter muscle**, which is one of the muscles of mastication. *Buccal nerve* - The **buccal nerve** is primarily a **sensory nerve** that provides sensation to the skin of the cheek, the buccal mucosa, and the gingiva of the mandibular molars. - While it is also a branch of the mandibular division of the trigeminal nerve, it does not directly give rise to the masseteric nerve. *Maxillary nerve* - The **maxillary nerve** (V2) is the second division of the trigeminal nerve and is **purely sensory**. - It provides sensation to the midface, upper teeth, and palate, and does not innervate muscles of mastication. *Facial nerve* - The **facial nerve** (CN VII) is responsible for motor innervation of the **muscles of facial expression**, not the muscles of mastication. - Damage to the facial nerve would affect facial movements like smiling or frowning, not chewing.

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.

Q: What is the nerve supply of the angle of the jaw?

Greater auricular nerve. Greater auricular nerve - The greater auricular nerve, a branch of the cervical plexus (C2, C3), supplies cutaneous sensation to the skin over the angle of the mandible, the parotid gland, and the mastoid process. - This nerve is often involved in conditions like parotid surgery or neck dissections, leading to numbness in its distribution. Mandibular nerve - The mandibular nerve (V3) provides sensory innervation to the lower teeth, chin, lower lip, and part of the cheek, and motor innervation to the muscles of mastication. - While it innervates areas close to the jaw, its primary cutaneous distribution does not include the skin directly over the angle of the jaw. Maxillary nerve - The maxillary nerve (V2) is responsible for sensory innervation to the midface, upper teeth, nasal cavity, and hard palate. - Its cutaneous distribution is primarily above the lower jaw, specifically the nose, upper lip, and cheekbone area. Lesser occipital nerve - The lesser occipital nerve, another branch of the cervical plexus (C2), primarily supplies sensation to the skin over the mastoid process and the posterosuperior aspect of the auricle. - Its innervation is mainly posterior to the ear and does not extend to the angle of the jaw.

Q: All of the following muscles are supplied by the accessory nerve except:

Stylopharyngeus. ***Stylopharyngeus*** - The stylopharyngeus muscle is supplied by the **glossopharyngeal nerve (CN IX)**, making it the exception. - This muscle is responsible for **elevating the pharynx and larynx** during swallowing. - **All other options are pharyngeal muscles supplied by the vagus nerve (CN X) via the pharyngeal plexus, NOT by the accessory nerve.** *Palatopharyngeus* - The palatopharyngeus muscle is supplied by the **vagus nerve (CN X)** via the **pharyngeal plexus**. - It depresses the **soft palate** and elevates the **pharynx and larynx**. - **Note:** The accessory nerve does NOT supply pharyngeal muscles. *Palatoglossus* - The palatoglossus muscle is supplied by the **vagus nerve (CN X)** via the **pharyngeal plexus**. - It elevates the **posterior part of the tongue** and depresses the **soft palate**. - **Note:** The accessory nerve does NOT supply pharyngeal muscles. *Musculus uvulae* - The musculus uvulae is supplied by the **vagus nerve (CN X)** via the **pharyngeal plexus**. - This muscle **shortens and elevates the uvula**. - **Note:** The accessory nerve does NOT supply pharyngeal muscles. **Clinical Pearl:** The accessory nerve (CN XI) actually supplies the **sternocleidomastoid** and **trapezius** muscles, not pharyngeal muscles. The cranial part of CN XI joins the vagus but does not independently innervate pharyngeal musculature.

Q: What does right 12th cranial nerve damage lead to?

Tongue deviation to right on protrusion. ***Tongue deviation to right on protrusion*** - Damage to the **right 12th cranial nerve (hypoglossal nerve)** causes weakness or paralysis of the **right genioglossus muscle**. - When the tongue is protruded, the **unopposed action of the left genioglossus muscle** pushes the tongue to the **right**, towards the side of the lesion. *Tongue deviation to left on protrusion* - This symptom would occur with damage to the **left 12th cranial nerve**, as the unopposed right genioglossus muscle would push the tongue to the left. - The **genioglossus muscle** is primarily responsible for tongue protrusion and moving the tongue to the opposite side. *Nasal twang to voice* - A **nasal twang** or **hypernasality** is typically associated with **palatal weakness**, often due to damage to the **vagus nerve (CN X)** or a **velopharyngeal insufficiency**. - The **hypoglossal nerve** (CN XII) does not directly control the muscles involved in soft palate movement or phonation in this manner. *Scanning speech defects* - **Scanning speech**, characterized by a slow, hesitant, and dysarthric pattern with abnormally long pauses, is a classic sign of **cerebellar dysfunction**. - It is not directly caused by isolated damage to the **hypoglossal nerve**, which primarily affects tongue movement and articulation.

Question 1

Facial nerve does not supply which structure of the face?

Accepted Answer

Parotid gland

Answer

Posterior belly of digastric muscle

Answer

Submandibular gland

Answer

Auricular muscle

Question 2

Which of the following nerves does not provide sensory innervation to the palate?

Accepted Answer

Hypoglossal nerve

Answer

Glossopharyngeal nerve

Answer

Maxillary division of trigeminal nerve

Answer

Facial nerve

Question 3

Which of the following muscles is supplied by the cranial part of the accessory nerve?

Accepted Answer

Levator veli palatini

Answer

Cricothyroid

Answer

Stylopharyngeus

Answer

Tensor veli palati

Question 4

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 5

Which nerve is the masseteric nerve a branch of?

Accepted Answer

Mandibular division of the trigeminal nerve

Answer

Buccal nerve

Answer

Maxillary nerve

Answer

Facial nerve

Question 6

Schirmer's test detects abnormality of which nerve?

Accepted Answer

Facial

Answer

Oculomotor

Answer

Hypoglossal

Answer

Glossopharyngeal

Question 7

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

Accepted Answer

Stylopharyngeus

Answer

Cricopharyngeus

Answer

Palatopharyngeus

Answer

Salpingopharyngeus

Question 8

What is the nerve supply of the angle of the jaw?

Accepted Answer

Greater auricular nerve

Answer

Mandibular nerve

Answer

Maxillary nerve

Answer

Lesser occipital nerve

Question 9

All of the following muscles are supplied by the accessory nerve except:

Accepted Answer

Stylopharyngeus

Answer

Palatopharyngeus

Answer

Musculus uvulae

Answer

Palatoglossus

Question 10

What does right 12th cranial nerve damage lead to?

Accepted Answer

Tongue deviation to right on protrusion

Answer

Scanning speech defects

Answer

Tongue deviation to left on protrusion

Answer

Nasal twang to voice

Neuroanatomy — MCQs

Neuroanatomy — MCQs

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