Head Practice Questions

Q: Which of the following muscles is NOT an elevator of the mandible?

Digastric. The muscles of mastication are responsible for the movements of the mandible at the temporomandibular joint (TMJ). These movements include elevation (closing the mouth), depression (opening the mouth), protrusion, retraction, and side-to-side movements. ### **Explanation of the Correct Answer** **D. Digastric:** This is the correct answer because the digastric muscle (specifically the anterior belly) acts as a **depressor** of the mandible. When the hyoid bone is fixed by the infrahyoid muscles, the contraction of the digastric pulls the symphysis menti downward, helping to open the mouth. It is not an elevator. ### **Analysis of Incorrect Options (Elevators)** The "elevators" of the mandible are the primary muscles of mastication that close the jaw: * **A. Temporalis:** A fan-shaped muscle that elevates the mandible. Its posterior fibers also act as the primary retractor of the jaw. * **B. Medial Pterygoid:** Often called the "internal masseter," it forms a sling with the masseter to powerfully elevate the mandible. * **C. Masseter:** The most powerful muscle of mastication; its primary action is elevation. ### **High-Yield Clinical Pearls for NEET-PG** * **Innervation Rule:** All four primary muscles of mastication (Masseter, Temporalis, Medial, and Lateral Pterygoids) are supplied by the **Mandibular nerve (V3)**. * **The "Opener":** The **Lateral Pterygoid** is the only primary muscle of mastication that helps depress (open) the mandible. Remember: "Lateral Lowers." * **Digastric Nerve Supply:** This is a common exam favorite. The **Anterior belly** is supplied by the Nerve to Mylohyoid (V3), while the **Posterior belly** is supplied by the Facial Nerve (VII). * **Gravity:** While muscles like the digastric and lateral pterygoid assist, gravity is the primary force for jaw depression in a standing position.

Q: An 8-year-old boy had an extensive mastoidectomy due to an infection that did not respond to antibiotics. Postoperatively, he developed Bell's palsy (facial paralysis). A feature of this paralysis was the accumulation of saliva in the oral vestibule, leading to dribbling from the corner of his mouth. Which of the following muscles was paralyzed, causing this specific symptom?

Buccinator. ### Explanation **Correct Option: C. Buccinator** The clinical presentation describes **Bell’s palsy** (lower motor neuron facial nerve palsy) following mastoid surgery. The facial nerve (CN VII) is at risk during mastoidectomy as it traverses the facial canal in the petrous temporal bone. The **buccinator** muscle, supplied by the buccal branch of the facial nerve, forms the muscular substance of the cheek. Its primary functional role during mastication is to flatten the cheek against the teeth and gums. This action prevents food and saliva from accumulating in the **oral vestibule** (the space between the teeth/gums and the cheeks/lips) and directs it back toward the occlusal surfaces of the teeth. Paralysis of the buccinator leads to a loss of cheek tone, causing saliva and food boluses to pool in the vestibule, resulting in the characteristic dribbling seen in this patient. **Analysis of Incorrect Options:** * **A. Zygomaticus major:** This muscle draws the angle of the mouth upward and backward (smiling). While paralyzed in Bell’s palsy, it does not control the accumulation of fluids in the vestibule. * **B. Orbicularis oculi:** This muscle is responsible for closing the eyelids. Paralysis leads to *lagophthalmos* (inability to close the eye), not oral symptoms. * **D. Levator palpebrae superioris:** This muscle elevates the upper eyelid and is supplied by the **Oculomotor nerve (CN III)**. It is not affected in facial nerve palsy. **High-Yield Clinical Pearls for NEET-PG:** * **Hyperacusis:** Occurs in facial nerve palsy if the nerve to the **stapedius** is involved (loss of dampening of sound). * **Chorda Tympani involvement:** Leads to loss of taste (ageusia) on the anterior 2/3rd of the tongue and reduced salivation (submandibular/sublingual glands). * **Mastoid Surgery Risk:** The facial nerve is most commonly injured in its **tympanic (horizontal)** or **mastoid (vertical)** segments during middle ear surgeries.

Q: Injury to which of the following nerves leads to paralysis of the posterior belly of the digastric muscle?

Facial nerve. The digastric muscle is unique because its two bellies arise from different embryological sources, each retaining the nerve supply of its respective branchial arch. **1. Why the Facial Nerve (CN VII) is correct:** The **posterior belly of the digastric** develops from the **second branchial arch**. Therefore, it is innervated by the digastric branch of the **facial nerve**, which arises just after the nerve exits the stylomastoid foramen. Injury to the facial nerve results in paralysis of this belly along with the muscles of facial expression and the stylohyoid muscle. **2. Why the other options are incorrect:** * **Trigeminal nerve (CN V):** The mandibular division ($V_3$) supplies the **anterior belly of the digastric** because it is derived from the **first branchial arch**. * **Accessory nerve (CN XI):** This nerve supplies the sternocleidomastoid and trapezius muscles. It does not innervate the suprahyoid muscles. * **Ansa cervicalis:** This loop of the cervical plexus ($C1-C3$) supplies the **infrahyoid muscles** (omohyoid, sternohyoid, and sternothyroid), except for the thyrohyoid (supplied by $C1$ via the hypoglossal nerve). **High-Yield NEET-PG Pearls:** * **Dual Nerve Supply:** The digastric muscle is a classic example of a muscle with two different nerve supplies ($V_3$ for anterior; $VII$ for posterior). * **Stylohyoid Connection:** Both the posterior belly of the digastric and the stylohyoid are 2nd arch muscles supplied by the facial nerve. * **Action:** The digastric muscle acts to depress the mandible (opening the mouth) or elevate the hyoid bone during swallowing.

Q: The anterior ethmoidal nerve is a branch of the nasociliary nerve. Which of the following areas is NOT supplied by the anterior ethmoidal nerve?

Maxillary sinus. **Explanation:** The **anterior ethmoidal nerve** is a terminal branch of the **nasociliary nerve** (a branch of the Ophthalmic division of the Trigeminal nerve, CN V1). Understanding its course is key to identifying its distribution: it leaves the orbit through the anterior ethmoidal canal, enters the anterior cranial fossa, and then descends into the nasal cavity. **Why Maxillary Sinus is the Correct Answer:** The **Maxillary sinus** is primarily supplied by the **Superior Alveolar nerves** (Anterior, Middle, and Posterior) and the **Infraorbital nerve**, all of which are branches of the **Maxillary division (CN V2)**. The anterior ethmoidal nerve (CN V1) does not contribute to its innervation. **Analysis of Incorrect Options:** * **Interior of the nasal cavity:** After passing through the cribriform plate, the nerve divides into internal nasal branches that supply the anterior part of the nasal septum and the lateral nasal wall. * **Dural sheath of the anterior cranial fossa:** As the nerve passes over the cribriform plate, it gives off meningeal branches to the dura mater of the anterior cranial fossa. * **Ethmoidal air cells:** The nerve provides sensory innervation to the **anterior and middle ethmoidal air cells** during its course through the ethmoidal canal. **High-Yield Clinical Pearls for NEET-PG:** * **External Nasal Nerve:** The anterior ethmoidal nerve terminates as the external nasal nerve, supplying the skin of the **tip and bridge of the nose**. * **Hilton’s Law Application:** The nerve supplies the ethmoidal sinuses it traverses. * **Sneeze Reflex:** The anterior ethmoidal nerve is a major afferent pathway for the sneeze reflex triggered by nasal irritants. * **Little’s Area:** While the nerve supplies the anterior septum, remember that the blood supply to this area (Kiesselbach's plexus) involves both ICA and ECA branches.

Q: A 55-year-old woman has undergone facial surgery for the excision of a malignant parotid tumor. A week postoperatively, marked weakness is seen in the musculature of the patient's lower lip. Which of the following nerves was most likely injured during the parotidectomy?

Marginal mandibular branch of facial. **Explanation:** The **facial nerve (CN VII)** provides motor innervation to the muscles of facial expression. After exiting the stylomastoid foramen, it enters the parotid gland and divides into five terminal branches: Temporal, Zygomatic, Buccal, Marginal Mandibular, and Cervical. 1. **Why Option A is correct:** The **Marginal Mandibular branch** supplies the muscles of the lower lip, specifically the *depressor anguli oris*, *depressor labii inferioris*, and *mentalis*. Injury to this nerve during parotid surgery is a known complication that results in drooping of the corner of the mouth and weakness in depressing the lower lip, leading to an asymmetrical smile. 2. **Why other options are incorrect:** * **Zygomatic branch:** Supplies the orbicularis oculi; injury would cause inability to close the eye tightly. * **Mandibular division of Trigeminal (V3):** Provides sensory innervation to the lower face and motor innervation to the muscles of mastication (e.g., masseter), not the muscles of facial expression. * **Buccal branch:** Supplies the buccinator and muscles of the upper lip; injury would affect cheek tension and the ability to whistle or pucker. **High-Yield NEET-PG Pearls:** * **Pes Anserinus:** The "goose's foot" pattern formed by the branching of the facial nerve within the parotid gland. * **Safe Plane:** During parotidectomy, the facial nerve is the critical landmark that divides the gland into superficial and deep lobes. * **Most common nerve injured:** The marginal mandibular nerve is particularly vulnerable because it often dips below the lower border of the mandible before ascending to the lip.

Q: Ear ossicles articulate with each other through which type of joints?

Synovial. The ear ossicles (Malleus, Incus, and Stapes) are connected to one another by **synovial joints**, which allow for the precise movement and transmission of sound vibrations from the tympanic membrane to the oval window [1]. ### **Why Synovial is Correct:** There are two primary articulations between the ossicles: 1. **Incudomalleolar Joint:** A **saddle-type** synovial joint between the head of the malleus and the body of the incus [1]. 2. **Incudostapedial Joint:** A **ball-and-socket** synovial joint between the lentiform process of the incus and the head of the stapes [1]. These joints are lined with hyaline cartilage and contained within a fibrous capsule, facilitating the mechanical amplification of sound. ### **Why Other Options are Incorrect:** * **Synostosis (A):** This refers to the bony fusion of two bones (e.g., skull sutures in adults). If ossicles fused, it would lead to conductive hearing loss. * **Synchondrosis (C):** A primary cartilaginous joint (e.g., growth plates). Ossicular joints are mobile, not rigid cartilaginous connections. * **Syndesmosis (D):** A fibrous joint connected by ligaments (e.g., distal tibiofibular joint). While the **stapes base** is attached to the oval window by a fibrous "tympanostapedial syndesmosis," the articulations *between* the ossicles themselves are synovial [1]. ### **High-Yield Clinical Pearls for NEET-PG:** * **Otosclerosis:** Often involves the fixation of the stapes footplate (syndesmosis), leading to conductive deafness. * **Muscle Protection:** The **Tensor Tympani** (supplied by CN V3) and **Stapedius** (supplied by CN VII) dampen excessive ossicular movement to protect the inner ear from loud noises (Acoustic Reflex) [1]. * **Development:** Malleus and Incus are derived from the **1st Pharyngeal Arch** (Meckel’s cartilage), while the Stapes is derived from the **2nd Pharyngeal Arch** (Reichert’s cartilage).

Q: After extraction of the 3rd molar, paraesthesia occurs over the chin. This is due to the involvement of which nerve?

Inferior alveolar nerve.. The extraction of a mandibular third molar (wisdom tooth) is a common surgical procedure that carries a risk of nerve injury due to the close anatomical proximity of specific branches of the mandibular nerve ($V_3$). ### Why Option A is Correct The **Inferior Alveolar Nerve (IAN)** runs within the mandibular canal, which is located immediately inferior to the roots of the third molar. During extraction, the nerve can be compressed or damaged. The IAN eventually exits the **mental foramen** (near the premolars) as the **mental nerve**. The mental nerve provides sensory innervation to the **skin of the chin**, the lower lip, and the labial gingiva. Therefore, damage to the IAN results in paresthesia (numbness or tingling) over the chin. ### Why Other Options are Incorrect * **B. Lingual Nerve:** This nerve lies on the lingual (tongue) side of the third molar. Injury to this nerve would cause loss of sensation and taste to the **anterior 2/3 of the tongue** and the floor of the mouth, but not the skin of the chin. * **C. Buccal Nerve:** This nerve provides sensory innervation to the **cheek** (buccal mucosa). It does not supply the chin. * **D. All of the above:** Incorrect because the sensory distribution of the lingual and buccal nerves does not include the mental region. ### High-Yield Clinical Pearls for NEET-PG * **Mental Nerve:** It is the terminal branch of the IAN. Remember: **IAN $\rightarrow$ Mental Nerve $\rightarrow$ Chin/Lower Lip.** * **Radiographic Sign:** On an OPG (Orthopantomogram), if the mandibular canal is diverted or the roots of the 3rd molar appear darkened/nicked, there is a high risk of IAN injury. * **Nerve most commonly injured:** While IAN injury is common, the **Lingual nerve** is also frequently at risk during the surgical flap reflection for 3rd molar surgery. Always distinguish between "numbness of the tongue" (Lingual) vs. "numbness of the chin" (IAN).

Q: What is the distance of the promontory from the tympanic membrane?

2 mm. The **middle ear (tympanic cavity)** is a narrow, air-filled space shaped like a biconcave disc [1]. Its narrowest dimension is the distance between the lateral wall (tympanic membrane) and the medial wall (labyrinthine wall). 1. **Why 2 mm is correct:** The medial wall of the middle ear features a rounded projection called the **promontory**, which is formed by the basal turn of the cochlea. Because the tympanic membrane is "tented" inwards (at the umbo), the distance between the umbo and the promontory is the narrowest part of the cavity, measuring approximately **2 mm**. 2. **Why other options are wrong:** * **5 mm:** This is the approximate distance at the floor (hypotympanum) of the middle ear. * **6 mm:** This represents the vertical and anteroposterior diameters of the tympanic cavity, but not the width. * **7 mm:** This is the approximate distance at the roof (epitympanum) of the middle ear. **High-Yield NEET-PG Pearls:** * **Dimensions of the Middle Ear:** Remember the "2-4-6" rule for the width of the cavity: 2 mm at the center (level of the promontory), 4 mm at the floor, and 6 mm at the roof. * **Promontory:** It is covered by the **tympanic plexus** (formed by the tympanic branch of the Glossopharyngeal nerve, CN IX). * **Clinical Significance:** In cases of **Glomus Jugulare** or **Glomus Tympanicum**, a "red flush" may be seen behind the tympanic membrane over the promontory (Rising Sun sign). * **Anatomy:** The promontory lies between the **fenestra vestibuli** (oval window) above and the **fenestra cochleae** (round window) below and behind.

Q: Ceruminous glands are modified which of the following glands?

Apocrine glands. The **ceruminous glands** are specialized sudoriferous (sweat) glands located in the subcutaneous layer of the external auditory canal. They are histologically classified as **modified apocrine glands**. 1. **Why Apocrine is Correct:** These glands produce a secretion that mixes with the oily sebum from sebaceous glands to form **cerumen (earwax)**. Like other apocrine glands (found in the axilla and groin), they secrete by budding off a portion of the apical cytoplasm. Their primary role is to lubricate the canal and provide a protective barrier against foreign bodies, insects, and microbes. 2. **Analysis of Incorrect Options:** * **Eccrine glands:** These are the common sweat glands found all over the body (especially palms and soles) involved in thermoregulation. They secrete via exocytosis without loss of cell cytoplasm. * **Sebaceous glands:** These are holocrine glands that secrete sebum into hair follicles. While they contribute to earwax, the ceruminous glands themselves are not modified sebaceous glands. * **Holocrine glands:** This refers to a mode of secretion where the entire cell disintegrates (e.g., sebaceous glands). Ceruminous glands do not function this way. **High-Yield Clinical Pearls for NEET-PG:** * **Location:** Ceruminous glands are found only in the **outer cartilaginous 1/3rd** of the external auditory canal. The inner 2/3rd (bony part) lacks these glands. * **Function of Cerumen:** It has an acidic pH (approx. 6.1) which inhibits bacterial and fungal growth (otomycosis). * **Other Modified Apocrine Glands:** **Moll’s glands** (eyelids) and **Mammary glands** are also important examples of modified apocrine glands frequently tested in exams.

Question 1

Which of the following muscles is NOT an elevator of the mandible?

Accepted Answer

Digastric

Answer

Temporalis

Answer

Medial pterygoid

Answer

Masseter

Question 2

Enophthalmos is due to palsy of which muscle?

Accepted Answer

Orbital muscle

Answer

Levator palpebrae superioris

Answer

Superior tarsal muscle

Answer

Inferior tarsal muscle

Question 3

An 8-year-old boy had an extensive mastoidectomy due to an infection that did not respond to antibiotics. Postoperatively, he developed Bell's palsy (facial paralysis). A feature of this paralysis was the accumulation of saliva in the oral vestibule, leading to dribbling from the corner of his mouth. Which of the following muscles was paralyzed, causing this specific symptom?

Accepted Answer

Buccinator

Answer

Zygomaticus major

Answer

Orbicularis oculi

Answer

Levator palpebrae superioris

Question 4

Injury to which of the following nerves leads to paralysis of the posterior belly of the digastric muscle?

Accepted Answer

Facial nerve

Answer

Accessory nerve

Answer

Trigeminal nerve

Answer

Ansa cervicalis

Question 5

The anterior ethmoidal nerve is a branch of the nasociliary nerve. Which of the following areas is NOT supplied by the anterior ethmoidal nerve?

Accepted Answer

Maxillary sinus

Answer

Interior of the nasal cavity

Answer

Dural sheath of the anterior cranial fossa

Answer

Ethmoidal air cells

Question 6

A 55-year-old woman has undergone facial surgery for the excision of a malignant parotid tumor. A week postoperatively, marked weakness is seen in the musculature of the patient's lower lip. Which of the following nerves was most likely injured during the parotidectomy?

Accepted Answer

Marginal mandibular branch of facial

Answer

Zygomatic branch of facial

Answer

Mandibular division of the trigeminal nerve

Answer

Buccal branch of facial

Question 7

Ear ossicles articulate with each other through which type of joints?

Accepted Answer

Synovial

Answer

Synostosis

Answer

Synchondrosis

Answer

Syndesmosis

Question 8

After extraction of the 3rd molar, paraesthesia occurs over the chin. This is due to the involvement of which nerve?

Accepted Answer

Inferior alveolar nerve.

Answer

Lingual nerve.

Answer

Buccal nerve.

Answer

All of the above.

Question 9

What is the distance of the promontory from the tympanic membrane?

Accepted Answer

2 mm

Answer

5 mm

Answer

6 mm

Answer

7 mm

Question 10

Ceruminous glands are modified which of the following glands?

Accepted Answer

Apocrine glands

Answer

Eccrine glands

Answer

Sebaceous glands

Answer

Holocrine glands

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