Head — MCQs

Head Indian Medical PG Practice Questions and MCQs

Question 361: The angle of the mandible is supplied by which nerve?

A. Greater Auricular nerve (Correct Answer)
B. Lesser occipital nerve
C. Auriculotemporal nerve
D. None of the above

Explanation: ### Explanation The sensory innervation of the face is primarily provided by the three divisions of the **Trigeminal nerve (CN V)**. However, there is a classic anatomical exception: the skin overlying the **angle of the mandible** and the parotid gland. **1. Why Greater Auricular Nerve is Correct:** The **Greater Auricular nerve** (C2, C3) is a branch of the **Cervical Plexus**. While most of the face is supplied by CN V, the area over the angle of the mandible is supplied by this spinal nerve. This is a high-yield "boundary" area where the cervical plexus meets the trigeminal distribution. **2. Analysis of Incorrect Options:** * **Lesser Occipital Nerve (C2):** This branch of the cervical plexus supplies the skin of the scalp posterior and superior to the auricle. It does not descend far enough anteriorly to reach the mandible. * **Auriculotemporal Nerve (V3):** A branch of the Mandibular division of the Trigeminal nerve. It supplies the TMJ, the tragus of the ear, and the temple region. While it is a "mandibular" branch, it specifically spares the angle. * **None of the above:** Incorrect, as the Greater Auricular nerve is the definitive supply. **3. NEET-PG High-Yield Pearls:** * **Hilton’s Law Application:** The nerve supplying a joint also supplies the muscles moving the joint and the skin over it. However, the angle of the mandible is a frequent "trap" question because it deviates from the expected V3 distribution. * **Parotid Gland:** The skin over the parotid gland is also supplied by the Greater Auricular nerve. * **Referred Pain:** Pain from the cervical spine (C2-C3) can sometimes be referred to the angle of the jaw, mimicking dental or TMJ issues. * **The "V" Shape:** Remember that the Trigeminal nerve supplies the face in a "V" shape, but the "jawline" near the ear is the territory of the Cervical Plexus.

Question 362: Which nerves supply the pinna?

A. Vagus nerve
B. Auriculotemporal nerve
C. Greater auricular nerve
D. All of the above (Correct Answer)

Explanation: The sensory nerve supply of the pinna (auricle) is a high-yield topic in NEET-PG Anatomy, as it involves a complex contribution from both cranial and spinal nerves. ### **Explanation of the Correct Answer** The pinna is supplied by multiple nerves derived from the cervical plexus and various cranial nerves. The correct answer is **"All of the above"** because: 1. **Greater Auricular Nerve (C2, C3):** This is the primary nerve supplying the majority of the pinna, specifically the lower part of both the lateral and medial surfaces (including the lobule and helix). 2. **Auriculotemporal Nerve (Branch of V3):** This supplies the upper part of the lateral surface of the pinna, including the tragus and the anterior crus of the helix. 3. **Vagus Nerve (Arnold’s Nerve):** The auricular branch of the vagus supplies the concha (the deepest depression) and the posterior wall of the external auditory canal. ### **Additional Nerve Supply** * **Lesser Occipital Nerve (C2):** Supplies the upper part of the medial (cranial) surface. * **Facial Nerve (CN VII):** Provides minor sensory twigs to the concha and retroauricular area. ### **Clinical Pearls for NEET-PG** * **Arnold’s Reflex (Ear-Cough Reflex):** Stimulation of the external auditory canal (e.g., cleaning with a bud or syringing) can stimulate the Vagus nerve, leading to a reflex cough or, rarely, bradycardia/fainting. * **Ramsay Hunt Syndrome:** Herpes Zoster infection of the geniculate ganglion (CN VII) often presents with painful vesicles on the concha and external canal, reflecting the facial nerve's sensory distribution here. * **Referred Otalgia:** Pain in the ear can be referred from the teeth or tongue (via CN V), the oropharynx/tonsils (via CN IX), or the larynx/hypopharynx (via CN X).

Question 363: Which of the following muscles is supplied by the third cranial nerve?

A. Superior oblique
B. Inferior oblique (Correct Answer)
C. Lateral rectus
D. Dilator pupillae

Explanation: The **Oculomotor nerve (CN III)** is the primary motor nerve for the extraocular muscles. It supplies all extraocular muscles except for the Superior Oblique and the Lateral Rectus. [2] ### **Explanation of Options:** * **Inferior Oblique (Correct):** This muscle is supplied by the **inferior division** of the Oculomotor nerve. [2] CN III also supplies the Superior Rectus, Inferior Rectus, Medial Rectus, and the Levator Palpebrae Superioris (LPS). [2] * **Superior Oblique (Incorrect):** This muscle is supplied by the **Trochlear nerve (CN IV)**. [2] It is the only muscle supplied by CN IV. * **Lateral Rectus (Incorrect):** This muscle is supplied by the **Abducens nerve (CN VI)**. [2] It is responsible for abduction of the eye. [2] * **Dilator Pupillae (Incorrect):** This muscle is under **sympathetic** control (from the superior cervical ganglion). In contrast, the Sphincter pupillae and Ciliary muscles are supplied by parasympathetic fibers traveling with the Oculomotor nerve. [1] ### **High-Yield NEET-PG Pearls:** 1. **The Formula:** A classic mnemonic to remember extraocular nerve supply is **LR6(SO4)3**. (Lateral Rectus = VI; Superior Oblique = IV; All others = III). 2. **Functional Anatomy:** The Inferior Oblique is the only extraocular muscle that originates from the **floor of the orbit** (anteriorly); all others originate from the common tendinous ring (Annulus of Zinn) at the orbital apex. 3. **Clinical Sign:** A complete CN III palsy results in **"Down and Out"** eye position, ptosis (due to LPS paralysis), and a dilated, non-reactive pupil (mydriasis).

Question 364: Which of the following is the commonest source of extradural hemorrhage?

A. Middle meningeal artery (Correct Answer)
B. Subdural venous sinus
C. Charcot's artery
D. Middle cerebral artery

Explanation: **Explanation:** **Extradural Hemorrhage (EDH)** [1], also known as epidural hemorrhage, occurs due to the accumulation of blood between the inner table of the skull and the endosteal layer of the dura mater. 1. **Why Middle Meningeal Artery (MMA) is correct:** The MMA is the most common source of EDH (involved in ~85% of cases). It is a branch of the maxillary artery that enters the skull through the **foramen spinosum**. It is particularly vulnerable at the **pterion**—the H-shaped junction of the frontal, parietal, temporal, and sphenoid bones—where the skull is thinnest. A fracture at this point can lacerate the artery, leading to rapid arterial bleeding that strips the dura away from the bone. 2. **Why other options are incorrect:** * **Subdural venous sinus:** These (along with bridging veins) are typically associated with **Subdural Hemorrhage (SDH)** [1], not extradural. * **Charcot’s artery (Lenticulostriate artery):** This is a branch of the Middle Cerebral Artery. Rupture of these microaneurysms leads to **intracerebral hemorrhage** (specifically in the basal ganglia), often associated with chronic hypertension. * **Middle cerebral artery:** Rupture of this artery or its branches typically results in **intracerebral hemorrhage** [2] or **Subarachnoid Hemorrhage (SAH)** [2] if an aneurysm is involved. **High-Yield Clinical Pearls for NEET-PG:** * **Radiology:** EDH presents as a **biconvex (lentiform/lemon-shaped)** hyperdensity on CT because the blood is limited by cranial sutures where the dura is firmly attached. * **Clinical Feature:** The classic **"Lucid Interval"** (initial loss of consciousness followed by a period of recovery before rapid deterioration) is highly characteristic of EDH. * **Nerve Involvement:** Expanding EDH can cause uncal herniation, leading to an **ipsilateral dilated pupil** (3rd nerve palsy) and contralateral hemiparesis.

Question 365: All of the following are superficial relations of the hyoglossus muscle except?

A. Hypoglossal nerve
B. Lingual nerve
C. Styloglossus muscle
D. Stylohyoid ligament (Correct Answer)

Explanation: The **hyoglossus muscle** is a key landmark in the submandibular region, often referred to as the "key muscle of the floor of the mouth." Understanding its relations is high-yield for NEET-PG, as structures are categorized by whether they pass superficial (lateral) or deep (medial) to it. ### **Why Stylohyoid Ligament is the Correct Answer** The **stylohyoid ligament** is a **deep relation** of the hyoglossus. It passes deep to the muscle along with the glossopharyngeal nerve (CN IX) and the lingual artery. Since the question asks for "superficial relations except," the stylohyoid ligament is the correct choice. ### **Analysis of Superficial Relations (Incorrect Options)** The following structures lie **superficial (lateral)** to the hyoglossus: * **Hypoglossal nerve (CN XII):** Accompanied by the vena comitans, it runs across the lower part of the muscle. * **Lingual nerve:** Located in the upper part, it loops around the submandibular duct. * **Styloglossus muscle:** This muscle originates from the styloid process and passes superficial to the hyoglossus to interdigitate with it. * **Submandibular ganglion and duct:** Both are also superficial relations. ### **High-Yield Clinical Pearls for NEET-PG** * **Deep Relations Mnemonic (GLS):** **G**lossopharyngeal nerve, **L**ingual artery, **S**tylohyoid ligament. * **The Lingual Artery:** This is the most important deep relation. To ligate the lingual artery (to control bleeding in tongue surgeries), the hyoglossus muscle must be divided. * **The "Sandwich" Concept:** The hyoglossus separates the lingual nerve and hypoglossal nerve (superficial) from the lingual artery (deep).

Question 366: Which nerve provides sensory innervation to the angle of the jaw?

A. Great auricular nerve (Correct Answer)
B. Posterior auricular nerve
C. Auriculotemporal nerve
D. Lesser petrosal nerve

Explanation: The sensory innervation of the face is primarily provided by the Trigeminal nerve (CN V), with one notable exception: the **angle of the mandible**. ### **Explanation of the Correct Answer** The **Great Auricular Nerve** (C2, C3) is a branch of the **Cervical Plexus**. While the Trigeminal nerve covers most of the face, the skin overlying the angle of the jaw and the parotid gland is supplied by the Great Auricular nerve. This is a high-yield anatomical "exception" often tested in NEET-PG. It emerges from the posterior border of the Sternocleidomastoid muscle (at Erb’s point) and ascends toward the ear. ### **Analysis of Incorrect Options** * **B. Posterior Auricular Nerve:** This is a motor branch of the **Facial Nerve (CN VII)** that supplies the auricularis posterior muscle and the occipital belly of the occipitofrontalis. It does not provide cutaneous sensation to the jaw. * **C. Auriculotemporal Nerve:** A branch of the Mandibular nerve (V3). It provides sensory innervation to the tragus, upper part of the external pinna, and the temple region. It also carries postganglionic parasympathetic fibers to the parotid gland. * **D. Lesser Petrosal Nerve:** This is a preganglionic parasympathetic nerve derived from the **Glossopharyngeal nerve (CN IX)**. It carries secretomotor fibers to the parotid gland via the otic ganglion; it has no sensory cutaneous function. ### **High-Yield Clinical Pearls** * **Hilton’s Law:** The nerve supplying a joint also supplies the muscles moving the joint and the skin over the insertion of those muscles. * **Erb’s Point:** The location on the posterior border of the Sternocleidomastoid where four cutaneous branches of the cervical plexus emerge (Great auricular, Lesser occipital, Transverse cervical, and Supraclavicular nerves). * **Referred Pain:** Pain from the parotid gland (e.g., mumps) is often referred to the ear via the Great Auricular and Auriculotemporal nerves.

Question 367: Which of the following structures does NOT pass through the internal auditory meatus?

A. Nerve of Wrisberg
B. Anterior inferior cerebellar artery (Correct Answer)
C. Superior vestibular nerve
D. Cochlear nerve

Explanation: The **internal auditory meatus (IAM)** is a bony canal in the petrous part of the temporal bone that transmits several neurovascular structures from the posterior cranial fossa to the inner ear and face. ### **Why Option B is Correct** The **Anterior Inferior Cerebellar Artery (AICA)** typically originates from the basilar artery and travels in the cerebellopontine angle. While it is closely related to the IAM, it **does not** actually pass through the canal. Instead, it gives off a specific branch called the **Labyrinthine artery** (Internal Auditory artery), which enters the IAM to supply the inner ear. In NEET-PG, this distinction is a frequent "trap": the parent artery (AICA) stays outside, while its branch (Labyrinthine artery) enters the meatus. ### **Why Other Options are Incorrect** The IAM is divided into four quadrants by the falciform crest and Bill’s bar. The structures passing through it include: * **Nerve of Wrisberg (Option A):** Also known as the **nervus intermedius**, it is the sensory/parasympathetic root of the Facial nerve (CN VII). It enters the IAM alongside the motor root. * **Superior Vestibular Nerve (Option C):** Occupies the **posterosuperior** quadrant of the IAM. * **Cochlear Nerve (Option D):** Occupies the **anteroinferior** quadrant of the IAM. ### **High-Yield Clinical Pearls for NEET-PG** * **Mnemonic for IAM contents:** "7 up, Coke down" (CN **7** is **up**per/superior; **Coch**lear is **down**/inferior). * **Bill’s Bar:** A vertical bony ridge in the IAM that separates the Facial nerve (anterior) from the Superior Vestibular nerve (posterior). * **Acoustic Neuroma (Vestibular Schwannoma):** Usually arises from the vestibular nerves within the IAM, leading to tinnitus, hearing loss, and eventually facial nerve palsy as the canal becomes crowded.

Question 368: Which cranial nerve supplies the lateral rectus muscle?

A. Oculomotor nerve (III)
B. Trochlear nerve (IV)
C. Trigeminal nerve (V)
D. Abducens nerve (VI) (Correct Answer)

Explanation: The movement of the eyeball is controlled by six extraocular muscles, which are innervated by three cranial nerves (III, IV, and VI). ### **Why Option D is Correct** The **Abducens nerve (CN VI)** is the correct answer because it specifically supplies the **Lateral Rectus (LR)** muscle [1]. The name "abducens" is derived from its function: the lateral rectus muscle **abducts** the eye (moves it away from the midline/towards the temple) [1]. ### **Why Other Options are Incorrect** * **Option A: Oculomotor nerve (III):** This nerve supplies the majority of the extraocular muscles, including the Superior Rectus, Inferior Rectus, Medial Rectus, and Inferior Oblique, as well as the Levator Palpebrae Superioris (which lifts the eyelid) [1]. * **Option B: Trochlear nerve (IV):** This nerve supplies only the **Superior Oblique (SO)** muscle [1]. It is the only cranial nerve that exits from the dorsal aspect of the brainstem. * **Option C: Trigeminal nerve (V):** This is a sensory nerve for the face and motor nerve for the muscles of mastication; it does not supply any extraocular muscles. ### **NEET-PG High-Yield Pearls** * **Mnemonic (LR6SO4)3:** This is the gold standard for remembering ocular innervation: **L**ateral **R**ectus is by CN **6**; **S**uperior **O**blique is by CN **4**; all **others** are by CN **3** [1]. * **Clinical Correlation:** A lesion of the Abducens nerve results in **medial strabismus** (convergent squint) because the medial rectus acts unopposed, pulling the eye inward [1]. Patients will present with **horizontal diplopia** (double vision). * **Longest Intracranial Course:** The Abducens nerve has a long intracranial course, making it highly susceptible to damage in cases of **increased intracranial pressure (ICP)**, often acting as a "false localizing sign."

Question 369: The tip of the spine of the sphenoid bone is related to which of the following structures?

A. Auriculotemporal nerve
B. Posterior fibres of Tensor veli palatini
C. Auditory tube
D. Sphenomandibular ligament (Correct Answer)

Explanation: The **spine of the sphenoid** is a sharp bony projection located at the posterior extremity of the greater wing of the sphenoid bone. It serves as a critical anatomical landmark in the infratemporal fossa. **Why the Correct Answer is Right:** The **Sphenomandibular ligament** is a primary accessory ligament of the temporomandibular joint (TMJ). It originates from the **tip of the spine of the sphenoid** and descends to attach to the **lingula** of the mandibular foramen. It is a remnant of the perichondrium of Meckel’s cartilage (1st branchial arch). **Analysis of Incorrect Options:** * **A. Auriculotemporal nerve:** This nerve is related to the **lateral** aspect of the spine of the sphenoid, not the tip. It typically loops around the middle meningeal artery near this region. * **B. Posterior fibres of Tensor veli palatini:** This muscle originates from the **scaphoid fossa** and the **medial** aspect of the spine of the sphenoid, rather than the tip. * **C. Auditory tube (Eustachian tube):** The cartilaginous part of the auditory tube lies in a groove (sulcus tubae) located **medial** to the spine of the sphenoid. **NEET-PG High-Yield Pearls:** 1. **Foramen Spinosum:** Located just anterior to the spine; it transmits the **Middle Meningeal Artery** and the **Nervus Spinosus** (meningeal branch of the mandibular nerve). 2. **Chorda Tympani:** This nerve passes through the Petrotympanic fissure, which lies **medial** to the spine of the sphenoid. 3. **Meckel’s Cartilage Derivatives:** The spine of the sphenoid, the sphenomandibular ligament, and the malleus/incus all share a common embryological origin from the **1st Pharyngeal Arch**.

Question 370: A patient has loss of sensation at the angle of the mandible and the parotid area. Which of the following nerves is most likely to be injured?

A. Mandibular nerve
B. Auriculotemporal nerve
C. Lesser occipital nerve
D. Greater auricular nerve (Correct Answer)

Explanation: ### Explanation The correct answer is **Greater auricular nerve (C2, C3)**. **1. Why the Correct Answer is Right:** The **Greater auricular nerve** is a branch of the **cervical plexus**. It ascends vertically across the superficial surface of the Sternocleidomastoid muscle towards the parotid gland. It provides sensory innervation to the skin over the **angle of the mandible**, the **parotid gland fascia**, and both surfaces of the lower part of the **auricle**. A high-yield anatomical fact is that while the Mandibular nerve (V3) supplies most of the lower face, the skin over the angle of the mandible is a notable exception, as it is supplied by the spinal nerves (C2, C3) via the Greater auricular nerve. **2. Why Incorrect Options are Wrong:** * **Mandibular nerve (V3):** While it supplies the lower teeth and chin, it specifically **spares** the angle of the mandible. * **Auriculotemporal nerve:** A branch of V3 that supplies the upper part of the auricle, the external auditory meatus, and the temple region. It does not supply the angle of the mandible. * **Lesser occipital nerve (C2):** This nerve supplies the skin of the scalp posterior and superior to the auricle. **3. Clinical Pearls for NEET-PG:** * **The "Angle of Mandible" Rule:** Always remember that the angle of the mandible is the "boundary" where cranial nerve territory (Trigeminal) ends and spinal nerve territory (Cervical Plexus) begins. * **Parotid Surgery:** The Greater auricular nerve is the most commonly injured nerve during parotidectomy, leading to numbness in the earlobe and the area over the parotid gland. * **Erb’s Point:** This nerve emerges at the posterior border of the Sternocleidomastoid (Punctum Nervosum), along with the Lesser occipital, Transverse cervical, and Supraclavicular nerves.

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