Head — MCQs

Head Indian Medical PG Practice Questions and MCQs

Question 611: The coronal suture is located between which of the following?

A. Two parietal bones
B. The two halves of the frontal bone
C. The frontal bone and the two parietal bones (Correct Answer)
D. The occipital bone and the two parietal bones

Explanation: **Explanation:** The **coronal suture** is a dense, fibrous connective tissue joint that separates the **frontal bone** from the **two parietal bones** [1]. In anatomical terms, it runs transversely across the skull, marking the boundary between the anterior and middle cranial vaults [1]. **Analysis of Options:** * **Option C (Correct):** The coronal suture joins the posterior border of the frontal bone with the anterior borders of the left and right parietal bones [1]. * **Option A (Incorrect):** The suture between the two parietal bones is the **Sagittal suture** [1]. * **Option B (Incorrect):** The suture between the two halves of the frontal bone (usually obliterated by age 6) is the **Frontal or Metopic suture** [1]. * **Option D (Incorrect):** The suture between the occipital bone and the two parietal bones is the **Lambdoid suture** [1]. **High-Yield Clinical Pearls for NEET-PG:** 1. **Bregma:** The junction where the coronal and sagittal sutures meet. It represents the site of the **Anterior Fontanelle**, which typically closes by 18–24 months of age. 2. **Pterion:** A critical clinical landmark where the frontal, parietal, temporal, and sphenoid bones meet. It overlies the **middle meningeal artery**; trauma here can lead to an extradural hematoma. 3. **Craniosynostosis:** Premature closure of the coronal suture results in a short, wide skull known as **Brachycephaly**. If only one side of the coronal suture closes prematurely, it leads to **Plagiocephaly**.

Question 612: All of the following are true regarding supernumerary teeth except:

A. May resemble normal teeth.
B. Disto molars do not resemble any other tooth.
C. Mesiodens is the most common type of supernumerary tooth.
D. More common in the mandible. (Correct Answer)

Explanation: ### Explanation Supernumerary teeth (hyperdontia) are teeth that develop in addition to the normal dental formula. Understanding their distribution and morphology is high-yield for NEET-PG. **Why Option D is the Correct Answer (The False Statement):** Supernumerary teeth are significantly **more common in the maxilla** than in the mandible (ratio of approximately 10:1). They occur most frequently in the maxillary midline, followed by the maxillary molar region. **Analysis of Other Options:** * **Option A (True):** Supernumerary teeth can be **eumorphic** (resembling a normal tooth of that series) or **dysmorphic** (conical, tuberculate, or molariform). * **Option B (True):** **Distomolars** (or distodens) are supernumerary teeth located distal to the third molar. They are typically small, rudimentary, and do not resemble the morphology of any standard tooth in the arch. * **Option C (True):** **Mesiodens** is the most common type of supernumerary tooth. It is located in the maxillary midline between the two central incisors and is usually conical in shape. **High-Yield Clinical Pearls for NEET-PG:** * **Prevalence:** More common in permanent dentition than primary dentition; more common in males (2:1). * **Associated Syndromes:** Multiple supernumerary teeth are strongly associated with **Cleidocranial Dysplasia**, **Gardner’s Syndrome**, and **Apert Syndrome**. * **Paramolar:** A supernumerary tooth situated lingually or buccally to a molar tooth. * **Complications:** They can cause delayed eruption of permanent teeth, crowding, or the formation of dentigerous cysts.

Question 613: Which of the following muscles does not elevate the jaw?

A. Temporalis
B. Masseter
C. Lateral pterygoid (Correct Answer)
D. Medial pterygoid

Explanation: The muscles of mastication are a frequent high-yield topic in NEET-PG Anatomy. To answer this question, one must distinguish between the muscles that close the jaw (elevators) and those that open it (depressors). ### **Explanation** The **Lateral Pterygoid** is the correct answer because it is the **only muscle of mastication that depresses the mandible** (opens the mouth). It has two heads; the inferior head specifically pulls the condyle of the mandible forward (protrusion) and downward along the articular eminence to initiate mouth opening. **Why the other options are incorrect:** * **Temporalis (A):** A powerful elevator of the mandible. Its anterior fibers elevate the jaw, while its posterior horizontal fibers are the primary retractors of the jaw. * **Masseter (B):** The strongest muscle of mastication. Its primary function is to elevate the mandible to close the jaw with great force. * **Medial Pterygoid (D):** Often considered the "internal counterpart" to the masseter, it forms a functional sling with the masseter to elevate the mandible. ### **Clinical Pearls for NEET-PG** * **Nerve Supply:** All four muscles of mastication are supplied by the **Mandibular Nerve (V3)**, specifically the anterior division (except the medial pterygoid, which is supplied by the main trunk of V3). * **The "Opening" Muscle:** Remember the mnemonic: **"L"** for **L**ateral Pterygoid = **L**owers the jaw. * **Side-to-side movements:** These are produced by the alternate contraction of the lateral and medial pterygoids of both sides. * **Derivation:** All muscles of mastication develop from the **First Branchial Arch**.

Question 614: Which of the following structures is associated with Bell's palsy?

A. Submandibular gland
B. Seventh cranial nerve (Correct Answer)
C. Temporomandibular joint
D. Glossopharyngeal nerve

Explanation: **Explanation:** **Bell’s palsy** is an idiopathic, acute lower motor neuron (LMN) paralysis of the **Seventh Cranial Nerve (Facial Nerve)**. It typically results from inflammation or edema of the nerve within the facial canal (stylomastoid foramen), leading to compression and subsequent dysfunction of the muscles of facial expression. * **Why Option B is Correct:** The facial nerve (CN VII) supplies all the muscles of facial expression. In Bell's palsy, patients exhibit unilateral facial drooping, inability to close the eye (lagophthalmos), loss of the nasolabial fold, and drooping of the corner of the mouth. * **Why Options A, C, and D are Incorrect:** * **Submandibular gland:** While the facial nerve (via the chorda tympani) provides parasympathetic supply to this gland, the gland itself is a salivary structure, not the site of the primary pathology. * **Temporomandibular joint (TMJ):** This is a structural joint involved in mastication; disorders here cause jaw pain or clicking, not facial muscle paralysis. * **Glossopharyngeal nerve (CN IX):** This nerve is responsible for sensory innervation of the oropharynx and posterior third of the tongue; its palsy would affect the gag reflex, not facial symmetry. **High-Yield Clinical Pearls for NEET-PG:** 1. **Bell’s Phenomenon:** When the patient attempts to close the affected eye, the eyeball rolls upwards and outwards (a normal protective reflex that becomes visible due to orbicularis oculi paralysis). 2. **Hyperacusis:** Occurs if the nerve to the stapedius is involved, leading to increased sensitivity to loud sounds. 3. **Taste Loss:** Involvement of the chorda tympani leads to loss of taste in the anterior two-thirds of the tongue. 4. **LMN vs. UMN:** In Bell’s palsy (LMN), the **entire** half of the face is affected, including the forehead. In a stroke (UMN), the forehead is spared due to bilateral cortical representation.

Question 615: In an adducted eye, what is the primary action of the superior oblique muscle?

A. Elevation of the eyeball
B. Depression of the eyeball (Correct Answer)
C. Intorsion of the eyeball
D. Extorsion of the eyeball

Explanation: **Explanation:** The action of the extraocular muscles depends on the position of the eyeball relative to the muscle’s axis of pull. The **Superior Oblique (SO)** muscle originates from the body of the sphenoid, passes through the trochlea (pulley), and inserts onto the posterolateral aspect of the sclera. 1. **Why Depression is correct:** When the eye is **adducted** (turned inward toward the nose), the visual axis aligns with the anatomical axis of the Superior Oblique tendon. In this position, the muscle pulls the back of the eye upward, which results in the front of the eye (the pupil) moving downward [1]. Therefore, **depression** is the primary action of the SO in adduction [1]. 2. **Why other options are incorrect:** * **Elevation:** This is the action of the Inferior Oblique (in adduction) and Superior Rectus (in abduction). * **Intorsion:** This is the **primary action** of the SO when the eye is in the **primary position** (looking straight ahead) or abducted. * **Extorsion:** This is the primary action of the Inferior Oblique. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic (RAD):** **R**ecti are **AD**ductors (except Lateral Rectus). **O**bliques are **AB**ductors. * **Mnemonic (SIN):** **S**uperior muscles are **IN**torsionists (Superior Oblique and Superior Rectus). * **Testing the SO:** To clinically isolate and test the Superior Oblique, ask the patient to look **"Down and In."** * **Trochlear Nerve (CN IV) Palsy:** Patients typically present with **diplopia** (double vision) and a compensatory **head tilt** toward the opposite shoulder to counteract the loss of intorsion.

Question 616: Sublingual salivary glands are drained by 8-20 excretory ducts called:

A. Bartholin's duct
B. Ducts of Rivinus (Correct Answer)
C. Wharton's duct
D. Stenson's duct

Explanation: Explanation: The **sublingual gland** is the smallest of the three major salivary glands. Unlike the parotid or submandibular glands, which primarily drain through a single large duct, the sublingual gland has a unique drainage system. It is drained by **8 to 20 small accessory ducts** known as the **Ducts of Rivinus**. These ducts open independently onto the sublingual fold (plica sublingualis) in the floor of the mouth. Analysis of Options: * **Ducts of Rivinus (Correct):** These are the multiple small ducts that drain the superior aspect of the sublingual gland. * **Bartholin’s Duct:** This is the **major sublingual duct**. In about 40% of individuals, several of the smaller ducts of Rivinus join to form a single large duct (Bartholin’s duct) that typically joins the submandibular duct (Wharton’s duct) to open at the sublingual caruncle. * **Wharton’s Duct:** This is the primary duct of the **submandibular gland**. It is approximately 5 cm long and opens at the sublingual caruncle. * **Stenson’s Duct:** This is the duct of the **parotid gland**. It pierces the buccinator muscle and opens into the vestibule of the mouth opposite the upper second molar tooth. High-Yield NEET-PG Pearls: * **Nerve Supply:** The sublingual gland receives parasympathetic supply from the **facial nerve (CN VII)** via the chorda tympani and the submandibular ganglion. * **Secretions:** It is primarily a **mucous-secreting** gland (unlike the parotid, which is purely serous). * **Clinical Correlation:** A **Ranula** is a clinical condition (mucous extravation cyst) specifically associated with the sublingual gland, often caused by the rupture of the ducts of Rivinus.

Question 617: Which of the following statements regarding the nasopharynx is true?

A. Passavant's muscle is formed by the stylopharyngeus muscle.
B. The fossa of Rosenmüller corresponds to the internal carotid artery.
C. The lower border of the nasopharynx corresponds to the upper faucial pillar.
D. The lower border of the nasopharynx lies at the level of the soft palate. (Correct Answer)

Explanation: ### Explanation The nasopharynx is the uppermost part of the pharynx, situated behind the nasal cavity and above the soft palate. **1. Why Option D is Correct:** The nasopharynx extends from the base of the skull (sphenoid and occipital bones) down to the **level of the soft palate**. During swallowing, the soft palate elevates to meet the posterior pharyngeal wall, effectively sealing the nasopharynx from the oropharynx to prevent food regurgitation. **2. Why the Other Options are Incorrect:** * **Option A:** Passavant’s muscle (or ridge) is formed by the horizontal fibers of the **palatopharyngeus muscle**, not the stylopharyngeus. It acts as a sphincter during speech and deglutition. * **Option B:** The **Fossa of Rosenmüller** (pharyngeal recess) is a slit-like depression posterior to the tubal elevation. It is the most common site for **Nasopharyngeal Carcinoma**. While it lies close to the internal carotid artery, it does not "correspond" to it; rather, the artery lies deep to its lateral wall. * **Option C:** The upper faucial pillar (palatoglossal arch) marks the boundary of the **oropharynx**, not the nasopharynx. **3. High-Yield NEET-PG Pearls:** * **Eustachian Tube:** Opens into the lateral wall of the nasopharynx; its opening is guarded by the **torus tubarius**. * **Adenoids:** Lymphoid tissue (pharyngeal tonsils) located in the roof and posterior wall; hypertrophy can lead to "adenoid facies" and mouth breathing. * **Sensory Nerve Supply:** Primarily by the **pharyngeal branch of the maxillary nerve (V2)**. * **Lining Epithelium:** Ciliated pseudostratified columnar epithelium (respiratory epithelium).

Question 618: Which cranial nerve is involved in the formation of the tympanic plexus?

A. Vagus nerve
B. Trochlear nerve
C. Glossopharyngeal nerve (Correct Answer)
D. Hypoglossal nerve

Explanation: The **tympanic plexus** is a network of nerves located on the promontory of the medial wall of the middle ear. It provides sensory innervation to the middle ear cavity, auditory tube, and mastoid air cells. **Why Glossopharyngeal nerve (CN IX) is correct:** The primary contributor to the tympanic plexus is the **tympanic nerve (Jacobson’s nerve)**, which is a branch of the Glossopharyngeal nerve. It enters the middle ear through the inferior tympanic canaliculus. Beyond providing local sensation, the fibers from this plexus eventually regroup to form the **lesser petrosal nerve**, which carries preganglionic parasympathetic fibers to the **otic ganglion** for parotid gland secretion. **Why other options are incorrect:** * **Vagus nerve (CN X):** While it has an auricular branch (Arnold’s nerve) that supplies the external auditory canal and tympanic membrane, it does not form the tympanic plexus. * **Trochlear nerve (CN IV):** This is a pure motor nerve that supplies only the superior oblique muscle of the eye. * **Hypoglossal nerve (CN XII):** This is a pure motor nerve responsible for the movements of the tongue muscles. **High-Yield Clinical Pearls for NEET-PG:** * **Jacobson’s Nerve:** A branch of CN IX; the key "inflow" to the tympanic plexus. * **Lesser Petrosal Nerve:** The "outflow" of the plexus; it exits the skull via the **foramen ovale**. * **Referred Otalgia:** Pain from the pharynx (e.g., post-tonsillectomy or malignancy) can be felt in the ear because CN IX supplies both regions. * **Components:** The plexus also receives sympathetic fibers from the **caroticotympanic nerves** (from the internal carotid plexus).

Question 619: Which of the following muscles is the primary abductor of the vocal cords?

A. Cricothyroid
B. Posterior cricoarytenoid (Correct Answer)
C. Thyroarytenoid
D. Lateral cricoarytenoid

Explanation: ### Explanation The intrinsic muscles of the larynx are responsible for controlling the tension and position of the vocal cords, thereby regulating phonation and the airway. **Correct Answer: B. Posterior cricoarytenoid** The **Posterior cricoarytenoid (PCA)** is the **only** muscle that abducts the vocal cords. It originates from the posterior surface of the cricoid lamina and inserts into the muscular process of the arytenoid cartilage. When it contracts, it rotates the arytenoid cartilages laterally, widening the rima glottidis. Because it is the sole muscle responsible for opening the airway, it is often referred to as the **"safety muscle of the larynx."** **Incorrect Options:** * **A. Cricothyroid:** This muscle tilts the cricoid cartilage upward or the thyroid cartilage downward, which **tenses and elongates** the vocal cords to increase the pitch of the voice. It is the only intrinsic muscle supplied by the **External Laryngeal Nerve**. * **C. Thyroarytenoid:** This muscle (specifically its medial part, the vocalis) **relaxes** the vocal cords, shortening them to lower the pitch. * **D. Lateral cricoarytenoid:** This is the primary **adductor** of the vocal cords. It pulls the muscular processes anteriorly, closing the rima glottidis for phonation. **NEET-PG High-Yield Pearls:** 1. **Nerve Supply:** All intrinsic muscles of the larynx are supplied by the **Recurrent Laryngeal Nerve (RLN)**, except for the Cricothyroid (External Laryngeal Nerve). 2. **Clinical Correlation:** Bilateral RLN injury leads to paralysis of the PCA muscles, causing the vocal cords to remain adducted (closed), which results in acute respiratory distress and requires an emergency tracheostomy. 3. **Mnemonic:** **P**osterior **C**ricoarytenoid = **P**ulls **C**ords **A**part.

Question 620: The external maxillary artery is a branch of which of the following arteries?

A. Internal carotid artery
B. External carotid artery (Correct Answer)
C. Second part of trigeminal artery
D. Facial artery

Explanation: **Explanation:** The **External Maxillary Artery** is the historical and clinical synonym for the **Facial Artery**. It is one of the eight branches of the **External Carotid Artery (ECA)**, specifically arising from its anterior aspect in the carotid triangle, just above the lingual artery. It follows a tortuous course to accommodate the movements of the pharynx and the mandible during mastication and speech. **Analysis of Options:** * **Option B (Correct):** The facial artery (external maxillary) is the third anterior branch of the ECA. It provides the primary arterial supply to the muscles of facial expression and the skin of the face. * **Option A:** The **Internal Carotid Artery** has no branches in the neck; it enters the skull to supply the brain and the eyes (via the ophthalmic artery). * **Option C:** The **Trigeminal Artery** is a fetal communication between the carotid and basilar systems; it is not a source of the maxillary or facial arteries. * **Option D:** This is a distractor. While the facial artery *is* the external maxillary artery, the question asks which artery it is a **branch of**. Therefore, the parent vessel (ECA) is the correct answer. **High-Yield NEET-PG Pearls:** * **Branches of ECA (Mnemonic: "S**ome **A**nyone **L**ike **F**or **M**aking **P**izza **O**ut **S**oon"): **S**uperior thyroid, **A**scending pharyngeal, **L**ingual, **F**acial (External Maxillary), **M**axillary (Internal Maxillary), **P**osterior auricular, **O**ccipital, **S**uperficial temporal. * The **Internal Maxillary Artery** is simply referred to as the **Maxillary Artery** (a terminal branch of the ECA). * The facial artery can be palpated at the **lower border of the mandible** at the anterior edge of the masseter muscle (the "facial pulse").

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