Head — MCQs

Head Indian Medical PG Practice Questions and MCQs

Question 1181: Protrusion of mandible is due to which of the following muscles?

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

Explanation: ***Lateral pterygoid*** - The **lateral pterygoid muscle** is the primary muscle responsible for **protrusion of the mandible**. - Its bilateral contraction pulls the condyle of the mandible and the articular disc anteriorly, causing the lower jaw to move forward. *Medial pterygoid* - The **medial pterygoid muscle** primarily functions in **elevation** and **side-to-side movements** of the mandible. - While it assists in some mandibular movements, its main role is not protrusion. *Masseter* - The **masseter muscle** is a strong muscle involved in **elevating the mandible** and is crucial for **closing the jaw** (biting and chewing). - It does not contribute significantly to the forward movement or protrusion of the mandible. *Temporalis* - The **temporalis muscle** is a major muscle of mastication, responsible for **elevating the mandible** and **retracting** it. - Its fibers, particularly the posterior ones, pull the mandible backward, directly opposing protrusion.

Question 1182: Which branch of facial nerve supplies muscles of lower lip

A. Marginal mandibular (Correct Answer)
B. Buccal
C. Cervical
D. Temporal

Explanation: ***Marginal mandibular*** - The **marginal mandibular branch** of the facial nerve innervates muscles of the lower lip and chin, including the **depressor labii inferioris**, **depressor anguli oris**, and **mentalis**. - Damage to this nerve causes an inability to depress the lower lip, leading to an **asymmetric smile**. *Buccal* - The **buccal branch** primarily innervates the **buccinator muscle** and the muscles of the upper lip. - It is crucial for **cheek compression** (e.g., blowing or sucking) and expression around the mouth. *Cervical* - The **cervical branch** supplies the **platysma muscle**, a broad sheet of muscle in the neck that helps depress the mandible and draw down the corners of the mouth. - It does not directly innervate the muscles of the lower lip. *Temporal* - The **temporal branch** provides motor innervation to the muscles of the forehead and around the eye, including the **frontalis** and **orbicularis oculi**. - It is responsible for actions like raising the eyebrows and closing the eyelids.

Question 1183: Trismus is due to spasm of which of the following muscles

A. Mentalis
B. Lateral pterygoid
C. Buccinator
D. Medial pterygoid (Correct Answer)

Explanation: ***Medial pterygoid*** - **Trismus** is characterized by persistent spasm of the **muscles of mastication**, leading to difficulty opening the mouth. - The **medial pterygoid** is a strong jaw **closer** muscle, and its spasm contributes significantly to trismus along with other masticatory muscles (masseter and temporalis). - Among the given options, medial pterygoid is the muscle of mastication that causes trismus when in spasm. *Mentalis* - The **mentalis muscle** is primarily involved in **pouting** and elevating the lower lip. - While it affects the lower face, it does not directly control jaw opening or closing to cause trismus. - It is **not a muscle of mastication**. *Lateral pterygoid* - The **lateral pterygoid muscle** is primarily responsible for **depressing** (opening) the jaw and is also involved in protrusion and side-to-side movements. - While it is a muscle of mastication, in the context of trismus (jaw closure spasm), the **medial pterygoid** (jaw closer) is more directly implicated than the lateral pterygoid. *Buccinator* - The **buccinator muscle** forms the muscular wall of the cheek and is involved in **chewing**, whistling, and keeping food between the teeth. - It does not directly control jaw opening or closing, and its spasm would not be the primary cause of trismus. - It is **not a muscle of mastication**.

Question 1184: Orbital blow-out fracture involves:

A. Lateral wall and roof of orbit
B. Medial wall and floor of orbit (Correct Answer)
C. Medial wall and roof of orbit
D. Lateral wall and floor of orbit

Explanation: Medial wall and floor of orbit - An orbital blow-out fracture typically involves the **medial wall** (lamina papyracea of the ethmoid bone) and the **floor** (maxillary bone) of the orbit because these are the weakest bony structures. - The force of impact on the globe is transmitted to the orbital walls, causing them to fracture outwards into the adjacent sinuses. *Lateral wall and roof of orbit* - The **lateral wall** (zygomatic bone) and **roof** (frontal bone) of the orbit are structurally strong and less commonly involved in isolated blow-out fractures. - Fractures in these areas typically result from high-impact trauma and are often associated with other facial bone injuries. *Medial wall and roof of orbit* - While the **medial wall** is frequently involved, the **roof** of the orbit is a thick, sturdy bone and is less susceptible to blow-out forces. - Fractures of the orbital roof usually occur due to direct impact or high-energy trauma to the forehead. *Lateral wall and floor of orbit* - Although the **floor** is commonly fractured, the **lateral wall** is a robust structure and is not typically involved in isolated blow-out fractures. - Combined fractures of the lateral wall and floor would indicate a more extensive orbital impact, often with other mid-facial trauma.

Question 1185: Middle meningeal artery is a branch of which artery?

A. Maxillary artery (Correct Answer)
B. Superficial temporal artery
C. Facial artery
D. Ophthalmic artery

Explanation: ***Maxillary artery*** - The **middle meningeal artery** is a major branch of the **maxillary artery**, which itself is a terminal branch of the **external carotid artery**. - It supplies blood to the **dura mater** and cranial bones and is notably vulnerable to injury in temporal bone fractures. *Superficial temporal artery* - The **superficial temporal artery** is the other terminal branch of the **external carotid artery** (alongside the maxillary artery). - It supplies the scalp and superficial temporal region but does not give rise to the middle meningeal artery. *Facial artery* - The **facial artery** is a branch of the **external carotid artery** but primarily supplies structures of the face, such as muscles of facial expression and superficial facial tissues. - It does not give rise to the middle meningeal artery, which has an intracranial course. *Ophthalmic artery* - The **ophthalmic artery** is a branch of the **internal carotid artery** and supplies structures within the orbit, including the eye. - It does not contribute to the blood supply of the dura mater in the area supplied by the middle meningeal artery.

Question 1186: CSF Otorrhea is due to trauma of:

A. Tympanic membrane
B. Cribriform plate
C. Parietal bone
D. Petrous temporal bone (Correct Answer)

Explanation: ***Petrous temporal bone*** - **CSF otorrhea** (leakage of cerebrospinal fluid from the ear) most commonly results from a fracture of the **petrous portion of the temporal bone**. - This bone forms part of the skull base and houses structures of the inner and middle ear, a fracture here can create a direct communication between the **subarachnoid space** and the external ear canal. *Tympanic membrane* - A rupture of the **tympanic membrane** alone would lead to **otorrhea** (ear discharge), but it would primarily involve blood or middle ear fluid, not CSF. - While a ruptured tympanic membrane is necessary for CSF to exit the ear canal, the source of the CSF leak itself is proximal to the middle ear. *Cribriform plate* - A fracture of the **cribriform plate** typically results in **CSF rhinorrhea** (CSF leakage from the nose), as it is located structurally above the nasal cavity. - It is not directly involved in CSF leakage from the ear. *Parietal bone* - Fractures of the **parietal bone** are typically associated with epidural or subdural hematomas or brain injury, depending on the extent of the trauma. - They are not a usual cause of CSF leakage from the ear since this bone does not contain CSF pathways that directly communicate with the ear.

Question 1187: Which artery lies deep to the pterion?

A. Temporal artery
B. Frontal artery
C. Parietal artery
D. Middle meningeal artery (Correct Answer)

Explanation: ***Middle meningeal artery*** - The **pterion** is a weak area of the skull where four bones meet: the frontal, parietal, temporal, and sphenoid bones. The **middle meningeal artery** runs deep to this point. - A blow to the pterion can cause a rupture of the middle meningeal artery, leading to an **epidural hematoma**. *Temporal artery* - The **superficial temporal artery** is located more superficially, anterior to the ear, and is not deep to the pterion. - It is a branch of the **external carotid artery** and supplies the scalp. *Frontal artery* - The **frontal branch of the superficial temporal artery** supplies the forehead, but it does not run deep to the pterion. - The main frontal artery (part of the ophthalmic artery) is located within the orbit. *Parietal artery* - This term is non-specific; there isn't a single major artery referred to solely as the "parietal artery" in this context. - The **parietal branch of the superficial temporal artery** supplies the parietal region of the scalp but is superficial rather than deep to the pterion.

Question 1188: Muscle in the lid attached to posterior tarsal margin is:

A. Muller's muscle (Correct Answer)
B. Superior rectus
C. Superior oblique
D. Levator palpebrae superioris

Explanation: Muller's muscle - Also known as the **superior tarsal muscle**, it is a **smooth muscle** that originates from the underside of the levator palpebrae superioris and inserts directly onto the **superior tarsal plate (posterior tarsal margin)**. - Its sympathetic innervation helps maintain the **upper eyelid position** and contributes to eyelid elevation, with damage leading to **ptosis (Horner's syndrome)**. *Superior rectus* - This is an **extrinsic ocular muscle** responsible for **elevating the eyeball** and also contributes to adduction and intorsion [1]. - It does not insert on the tarsal margin but rather on the **sclera** of the eyeball. *Superior oblique* - This is another **extrinsic ocular muscle** primarily responsible for **intorsion** (medial rotation) of the eyeball and also contributes to depression and abduction [1]. - Its tendon passes through the **trochlea** and inserts on the **posterolateral superior aspect of the sclera**, not the eyelid. *Levator palpebrae superioris* - This **striated skeletal muscle** is the **primary elevator of the upper eyelid**, innervated by the oculomotor nerve (CN III). - While it is the main elevator, its fibrous aponeurosis inserts onto the anterior surface of the tarsal plate and the skin, and **Muller's muscle** arises from its undersurface and inserts directly into the posterior tarsal margin.

Question 1189: The volume of the orbit is about:

A. 40 cc
B. 30 cc (Correct Answer)
C. 60 cc
D. 50 cc

Explanation: ***30 cc*** - The average **volume of the orbit** in adults is approximately **30 cubic centimeters (cc)** or 30 mL. - This volume accommodates the **eyeball** (approximately 7 cc), extraocular muscles, orbital fat, nerves (optic nerve), blood vessels, and lacrimal gland. - This is a standard anatomical measurement taught in medical education and used clinically for orbital imaging assessment. *40 cc* - This value **exceeds** the normal orbital volume by approximately 33%. - The actual orbital volume is closer to **30 cc**, not 40 cc. - This measurement does not represent the standard anatomical dimension. *50 cc* - This volume is significantly **larger** than the average orbital capacity. - It represents nearly **67% more** than the actual orbital volume. - This is not consistent with normal orbital anatomy. *60 cc* - This is **double** the actual average orbital volume. - Such a measurement far exceeds the normal anatomical dimensions of the human orbit. - The correct value is 30 cc, making this option clearly incorrect.

Question 1190: Frankfort horizontal is a reference plane constructed by joining which of the following landmarks?

A. Porion and Nasion
B. Porion and Sella
C. Nasion and Sella
D. Porion and Orbitale (Correct Answer)

Explanation: Frankfort horizontal is a reference plane constructed by joining which of the following landmarks? ***Porion and Orbitale*** - The **Frankfort horizontal plane** is a standard anatomical reference plane used in craniometry and orthodontics. - It is constructed by connecting the **uppermost point of the external auditory meatus (porion)** with the **lowest point on the inferior margin of the bony orbit (orbitale)**. *Porion and Nasion* - The **nasion** is the point where the frontal and nasal bones meet, and its connection to the porion does not define the Frankfort horizontal plane. - This line would represent a different cranial orientation, not the internationally recognized Frankfort plane. *Porion and Sella* - The **sella** (sella turcica) is a saddle-shaped depression in the sphenoid bone housing the pituitary gland, which is an internal landmark. - Connecting the porion to the sella would create an internal reference line, not a surface-based horizontal plane typically used for facial analysis. *Nasion and Sella* - The line connecting the **nasion** and **sella** is known as the **Sella-Nasion line**, a common reference line in cephalometric analysis. - This line represents the anterior cranial base and is used to assess jaw relationships and growth patterns, separate from the Frankfort horizontal plane.

Practice by Chapter

Skull and Facial Bones

Practice Questions

Scalp and Facial Muscles

Practice Questions

Dural Venous Sinuses

Practice Questions

Cranial Cavity

Practice Questions

Orbit and Contents

Practice Questions

Temporal and Infratemporal Regions

Practice Questions

Pterygopalatine Fossa

Practice Questions

Oral Cavity

Practice Questions

Paranasal Sinuses

Practice Questions

Applied Anatomy and Clinical Correlations

Practice Questions

Want unlimited practice?

Get full access to all questions, explanations, and performance tracking.

Start For Free

Head — MCQs

Head — MCQs

On this page

Practice by Chapter

Want unlimited practice?