Chapter: Nervous System; Topic: Cranial Nerves; Subtopic: Parasympathetic Pathways to Lacrimal Gland
Keyword Definitions:
Lacrimal gland: Exocrine gland that secretes tears to lubricate and protect the eye.
Parasympathetic supply: Autonomic fibers responsible for secretory stimulation of glands.
Greater petrosal nerve: A branch of the facial nerve that carries parasympathetic fibers to the lacrimal gland.
Pterygopalatine ganglion: A parasympathetic ganglion where preganglionic fibers from the facial nerve synapse before reaching the lacrimal gland.
Lead Question - 2014
Parasympathetic supply to lacrimal glands are passed through?
a) Lesser petrosal nerve
b) Chorda tympani
c) Greater petrosal nerve
d) Lingual nerve
Explanation:
The parasympathetic fibers to the lacrimal gland originate from the superior salivatory nucleus of the facial nerve. They travel via the greater petrosal nerve, synapse in the pterygopalatine ganglion, and then reach the lacrimal gland through the zygomatic and lacrimal nerves. This pathway controls tear secretion. Hence, the correct answer is c) Greater petrosal nerve.
1) Which ganglion is involved in the parasympathetic pathway to the lacrimal gland?
a) Ciliary ganglion
b) Otic ganglion
c) Pterygopalatine ganglion
d) Submandibular ganglion
The pterygopalatine ganglion (also called sphenopalatine) is where the preganglionic parasympathetic fibers from the greater petrosal nerve synapse. Postganglionic fibers then reach the lacrimal gland via the zygomatic branch of the maxillary nerve. Hence, the correct answer is c) Pterygopalatine ganglion.
2) The greater petrosal nerve is a branch of which cranial nerve?
a) Trigeminal
b) Facial
c) Glossopharyngeal
d) Vagus
The greater petrosal nerve arises from the facial nerve (cranial nerve VII) at the geniculate ganglion. It carries preganglionic parasympathetic fibers to the pterygopalatine ganglion, which later innervate the lacrimal and nasal glands. Hence, the correct answer is b) Facial nerve.
3) Which nerve carries postganglionic fibers to the lacrimal gland?
a) Zygomatic nerve
b) Auriculotemporal nerve
c) Lingual nerve
d) Nasociliary nerve
After synapsing in the pterygopalatine ganglion, postganglionic fibers travel via the zygomatic nerve (branch of V2) and join the lacrimal nerve (branch of V1) to reach the lacrimal gland. Hence, the correct answer is a) Zygomatic nerve.
4) Which cranial nucleus gives origin to fibers supplying the lacrimal gland?
a) Inferior salivatory nucleus
b) Superior salivatory nucleus
c) Edinger-Westphal nucleus
d) Dorsal motor nucleus of vagus
The superior salivatory nucleus of the pons provides preganglionic parasympathetic fibers that travel through the facial nerve and greater petrosal nerve to reach the lacrimal gland, promoting tear secretion. Hence, the correct answer is b) Superior salivatory nucleus.
5) (Clinical) Damage to the greater petrosal nerve results in?
a) Loss of taste
b) Dryness of eyes
c) Hyperlacrimation
d) Facial palsy
Injury to the greater petrosal nerve disrupts parasympathetic innervation to the lacrimal gland, leading to dryness of the eye due to reduced tear secretion. This may occur in facial nerve lesions proximal to the geniculate ganglion. Hence, the correct answer is b) Dryness of eyes.
6) (Clinical) A lesion at the geniculate ganglion affects which functions?
a) Lacrimation and taste
b) Hearing only
c) Facial sensation
d) Eye movements
A lesion at the geniculate ganglion affects both lacrimation (greater petrosal nerve) and taste (chorda tympani). Patients may present with dry eyes and loss of taste on the anterior two-thirds of the tongue. Hence, the correct answer is a) Lacrimation and taste.
7) (Clinical) Which symptom indicates greater petrosal nerve damage in facial palsy?
a) Loss of corneal reflex
b) Decreased lacrimation
c) Hyperacusis
d) Vertigo
In facial palsy affecting the segment proximal to the greater petrosal nerve, decreased lacrimation occurs due to interruption of parasympathetic fibers to the lacrimal gland. Hence, the correct answer is b) Decreased lacrimation.
8) (Clinical) A patient with Bell’s palsy complains of dry eyes. Which structure is likely involved?
a) Chorda tympani
b) Greater petrosal nerve
c) Stapedius branch
d) Temporal branch of facial nerve
Dry eyes in Bell’s palsy suggest involvement of the greater petrosal nerve due to interruption of parasympathetic supply to the lacrimal gland. This differentiates proximal from distal facial nerve lesions. Hence, the correct answer is b) Greater petrosal nerve.
9) (Clinical) Which condition may cause excessive tearing (epiphora) despite normal nerve function?
a) Blocked nasolacrimal duct
b) Facial nerve palsy
c) Damage to pterygopalatine ganglion
d) Geniculate ganglion lesion
Excessive tearing, or epiphora, usually results from a blocked nasolacrimal duct, preventing proper tear drainage into the nasal cavity. The parasympathetic pathway remains intact. Hence, the correct answer is a) Blocked nasolacrimal duct.
10) (Clinical) Which condition is characterized by dry eyes and mouth due to autoimmune destruction of lacrimal and salivary glands?
a) Myasthenia gravis
b) Sjögren’s syndrome
c) Bell’s palsy
d) Sarcoidosis
Sjögren’s syndrome causes autoimmune destruction of lacrimal and salivary glands, leading to dry eyes (xerophthalmia) and dry mouth (xerostomia). Parasympathetic pathways remain intact, but glandular tissue is damaged. Hence, the correct answer is b) Sjögren’s syndrome.
Chapter: Anatomy of Eye; Topic: Glands of Eyelid; Subtopic: Sweat and Sebaceous Glands near Eyelid Margin
Keyword Definitions:
Moll’s gland: Modified apocrine sweat glands located near eyelash follicles at the eyelid margin.
Zeis gland: Sebaceous glands associated with eyelash follicles.
Meibomian gland: Large sebaceous glands in the tarsal plate secreting oily film to prevent tear evaporation.
Krause gland: Accessory lacrimal gland contributing to tear secretion.
Lead Question (2014):
Sweat gland near the lid margins
a) Moll
b) Zeis
c) Meibomian
d) Krause
Explanation:
The sweat glands near the eyelid margin are Moll’s glands, which are modified apocrine sweat glands associated with the eyelashes. They help lubricate the eyelid margin and maintain ocular hygiene. Infections of these glands cause stye-like conditions. Answer: Moll’s gland. Understanding their anatomy aids in diagnosing eyelid pathologies such as hordeolum and blepharitis.
1) Blockage of Moll’s gland leads to which condition?
a) Chalazion
b) External hordeolum
c) Internal hordeolum
d) Dacryocystitis
Explanation:
Blockage or infection of Moll’s gland results in external hordeolum (stye), presenting as a painful, red swelling at the eyelid margin. It differs from chalazion, which involves Meibomian glands. Proper eyelid hygiene and warm compresses are preventive. Answer: External hordeolum. It reflects inflammation of apocrine glands near lashes.
2) Which gland is responsible for the lipid layer of tear film?
a) Krause
b) Moll
c) Meibomian
d) Zeis
Explanation:
The Meibomian glands secrete an oily (lipid) layer that prevents evaporation of tears. Dysfunction of these glands causes dry eye syndrome and ocular irritation. Their ducts open at the eyelid margin posterior to the lashes. Answer: Meibomian gland. Proper function maintains ocular surface stability and comfort during blinking.
3) Sebaceous glands associated with eyelash follicles are called:
a) Moll
b) Zeis
c) Krause
d) Wolfring
Explanation:
The Zeis glands are sebaceous glands connected to eyelash follicles, producing oily secretions that lubricate lashes. Infection leads to external hordeolum as well. They differ from Meibomian glands, which are embedded in the tarsal plate. Answer: Zeis gland. Their role is vital for lash protection and smooth movement of eyelids.
4) Accessory lacrimal glands of Krause are located in:
a) Conjunctival fornix
b) Eyelid margin
c) Tarsal plate
d) Caruncle
Explanation:
The glands of Krause are small accessory lacrimal glands found in the conjunctival fornix. They supplement tear secretion along with glands of Wolfring. Their secretions maintain ocular surface moisture and corneal transparency. Answer: Conjunctival fornix. Damage can lead to dry eye due to reduced tear volume.
5) A 35-year-old woman presents with a painful, red swelling at the eyelid margin near an eyelash follicle. Most likely involved gland is:
a) Meibomian
b) Krause
c) Moll
d) Wolfring
Explanation:
A Moll’s gland infection causes external hordeolum, presenting as a painful, red nodule near the eyelash base. It is bacterial, commonly due to Staphylococcus aureus. Warm compresses help drain infection. Answer: Moll’s gland. Clinically, location and tenderness distinguish it from internal hordeolum or chalazion.
6) Blockage of Meibomian gland results in:
a) Chalazion
b) Stye
c) Blepharitis
d) Dacryoadenitis
Explanation:
Obstruction of a Meibomian gland leads to a chalazion, a chronic, non-infective, granulomatous swelling within the tarsal plate. It appears firm and painless, unlike stye, which is acute and tender. Answer: Chalazion. Surgical drainage or steroid injection may be required if persistent, though small lesions may resolve spontaneously.
7) Glands of Wolfring are situated near:
a) Tarsal border
b) Conjunctival fornix
c) Caruncle
d) Limbus
Explanation:
The glands of Wolfring are accessory lacrimal glands located near the tarsal border. They provide continuous tear secretion to keep the cornea moist. Along with Krause glands, they supplement the main lacrimal gland. Answer: Tarsal border. Their dysfunction contributes to chronic dryness or irritation in ocular surface diseases.
8) A patient with chronic blepharitis develops recurrent chalazia. Which gland dysfunction is most likely?
a) Zeis
b) Meibomian
c) Krause
d) Moll
Explanation:
Chronic blepharitis causing recurrent chalazia is linked to Meibomian gland dysfunction. Blocked ducts lead to stagnation and lipogranulomatous inflammation. Long-standing inflammation alters tear composition. Answer: Meibomian gland. Regular lid hygiene and warm compresses are key to management. Antibiotics may be needed if secondary infection occurs.
9) Which gland opens near the base of eyelashes and secretes oily material?
a) Moll
b) Krause
c) Zeis
d) Meibomian
Explanation:
The Zeis glands open at the base of eyelashes and secrete oily material to lubricate lash follicles. Their blockage can cause external hordeolum. Answer: Zeis gland. Proper lubrication from these glands prevents eyelash brittleness and maintains smooth eyelid motion during blinking and protection from dust.
10) A 50-year-old diabetic presents with a firm, painless swelling in the tarsal plate lasting weeks. Diagnosis?
a) Internal hordeolum
b) Chalazion
c) External hordeolum
d) Dacryoadenitis
Explanation:
A chronic, firm, painless swelling in the tarsal plate indicates chalazion, due to Meibomian gland blockage. It is non-suppurative and commonly seen in diabetics and patients with seborrheic dermatitis. Answer: Chalazion. Histologically, it represents lipogranulomatous inflammation. Excision or intralesional corticosteroids may be needed for persistent cases.
Topic: Visual System
Subtopic: Retina and Photoreceptors
Keywords:
• Retina: Light-sensitive layer at the back of the eye.
• Cones: Photoreceptor cells responsible for color vision and visual acuity.
• Photoreceptor: Specialized cell that responds to light.
• Visual System: Structures and pathways involved in vision.
Lead Question - 2013 (September 2008)
Number of cones in Retina?
a) 3-5 millions
b) 10-20 millions
c) 25-50 millions
d) 50-100 millions
Answer and Explanation:
Correct answer is a) 3-5 millions. The human retina contains approximately 3 to 5 million cone photoreceptors concentrated in the central region called the fovea. These cones enable high-resolution color vision under bright light (photopic) conditions and are essential for tasks requiring fine visual detail. (50 words)
1. Rod cells are responsible for:
a) Color vision
b) Low-light vision
c) High-resolution vision
d) Motion detection
Explanation:
Rod cells are specialized for low-light (scotopic) vision, providing black and white images in dim conditions, with high sensitivity but low spatial resolution. (Answer: b)
2. Fovea centralis contains predominantly:
a) Rods
b) Cones
c) Bipolar cells
d) Ganglion cells
Explanation:
The fovea centralis contains the highest concentration of cone cells, essential for sharp central vision and color discrimination in bright light. (Answer: b)
3. Cone cells are most sensitive to which type of light?
a) Dim light
b) Bright light
c) Infrared light
d) Ultraviolet light
Explanation:
Cone cells function optimally in bright light conditions, enabling high acuity and color perception. (Answer: b)
4. Total number of rod cells in human retina is approximately:
a) 120 million
b) 6 million
c) 3 million
d) 1 million
Explanation:
The human retina contains around 120 million rod cells, which mediate vision in low-light conditions and are more numerous than cone cells. (Answer: a)
5. The three types of cones are sensitive to:
a) Red, Green, Blue wavelengths
b) Ultraviolet, Infrared, Visible
c) Alpha, Beta, Gamma
d) Rod, Cone, Bipolar
Explanation:
Cone cells are categorized into three types based on spectral sensitivity to red (long), green (medium), and blue (short) wavelengths, enabling color vision. (Answer: a)
6. Clinical condition related to cone dysfunction is called:
a) Night blindness
b) Color blindness
c) Glaucoma
d) Cataract
Explanation:
Color blindness is caused by defective or absent cone cells, impairing color discrimination, typically inherited and most commonly affecting red-green perception. (Answer: b)
7. Which layer of retina contains photoreceptors?
a) Ganglion cell layer
b) Inner nuclear layer
c) Outer nuclear layer
d) Plexiform layer
Explanation:
The photoreceptors, including rods and cones, are located in the outer nuclear layer of the retina, where they transduce light into neural signals. (Answer: c)
8. Cone density is maximum at:
a) Optic disc
b) Peripheral retina
c) Fovea centralis
d) Macula lutea
Explanation:
Cone density peaks in the fovea centralis, the central region of the retina, responsible for sharp and detailed central vision. (Answer: c)
9. Cone cells mediate which type of vision?
a) Scotopic
b) Photopic
c) Mesopic
d) None
Explanation:
Cone cells mediate photopic vision, functioning under bright light conditions, essential for color perception and high visual acuity. (Answer: b)
10. Cone dysfunction may lead to which of the following disorders?
a) Glaucoma
b) Achromatopsia
c) Retinitis pigmentosa
d) Optic neuritis
Explanation:
Achromatopsia is a congenital condition caused by cone dysfunction, resulting in color blindness, poor visual acuity, and photophobia. (Answer: b)
Topic: Eye Anatomy
Subtopic: Lacrimal Apparatus
Keywords:
Lacrimal Punctum: Small openings on the medial aspect of the eyelids that drain tears into the lacrimal canaliculi.
Upper Eyelid: The superior movable fold covering the eye, containing the upper lacrimal punctum near the medial canthus.
Lower Eyelid: The inferior movable fold, containing the lower lacrimal punctum near the medial canthus.
Lacrimal Canaliculi: Small channels that transport tears from the puncta to the lacrimal sac.
Lead Question - 2013:
Lacrimal punctum of upper and lower eyelids are?
a) They are opposed
b) No relation
c) Upper punctum is medial
d) Upper punctum is lateral
Answer & Explanation:
Correct answer: a) They are opposed.
Explanation: The lacrimal puncta of the upper and lower eyelids are located at the medial ends of the eyelid margins and face each other directly. They collect tears from the ocular surface and drain them into the canaliculi. Proper anatomical alignment ensures effective tear drainage and prevents epiphora.
MCQ 1:
Function of the lacrimal puncta is to:
a) Produce tears
b) Drain tears into canaliculi
c) Secrete mucus
d) Block tear drainage
Answer & Explanation:
Correct answer: b) Drain tears into canaliculi.
Explanation: The lacrimal puncta serve as entry points for tears to drain from the eye's surface into the lacrimal canaliculi, proceeding to the lacrimal sac and nasolacrimal duct. Proper function prevents tear overflow (epiphora) and maintains ocular surface health by facilitating tear clearance.
MCQ 2:
The lacrimal puncta are located at the:
a) Lateral canthus
b) Medial canthus
c) Center of eyelid margin
d) Superior orbital rim
Answer & Explanation:
Correct answer: b) Medial canthus.
Explanation: Both upper and lower lacrimal puncta are situated at the medial canthus of the eyelids, where they collect tears and drain them into the canaliculi. Their correct position ensures effective tear drainage, and abnormalities can lead to tearing disorders or infections like dacryocystitis.
MCQ 3:
The lacrimal canaliculi drain into the:
a) Lacrimal sac
b) Nasolacrimal duct
c) Conjunctival sac
d) Orbit
Answer & Explanation:
Correct answer: a) Lacrimal sac.
Explanation: The upper and lower lacrimal canaliculi drain tears from the puncta into the lacrimal sac, which then drains into the nasolacrimal duct. This anatomical route is essential for proper tear drainage and maintaining a healthy ocular surface, preventing tear stagnation and infection.
MCQ 4 (Clinical):
A patient with epiphora may have obstruction at which structure?
a) Lacrimal puncta
b) Lacrimal gland
c) Retina
d) Cornea
Answer & Explanation:
Correct answer: a) Lacrimal puncta.
Explanation: Epiphora, or excessive tearing, often results from blockage of the lacrimal puncta or canaliculi, preventing proper tear drainage. Clinical examination of the puncta for patency is vital to diagnose causes of tearing and guide appropriate management, such as dilation or surgery.
MCQ 5:
Which part of the lacrimal apparatus produces tears?
a) Lacrimal sac
b) Lacrimal gland
c) Lacrimal puncta
d) Canaliculi
Answer & Explanation:
Correct answer: b) Lacrimal gland.
Explanation: The lacrimal gland, located in the superolateral orbit, produces the aqueous component of tears. Tears are distributed across the ocular surface and drained by the lacrimal puncta and canaliculi. Understanding this system aids in diagnosing dry eye and tear drainage disorders.
MCQ 6 (Clinical):
A patient with infection around the medial canthus may have involvement of which structure?
a) Lacrimal puncta
b) Eyelid margin
c) Nasolacrimal duct
d) Retina
Answer & Explanation:
Correct answer: a) Lacrimal puncta.
Explanation: Infections such as canaliculitis or dacryocystitis often involve the lacrimal puncta, leading to swelling, redness, and tenderness near the medial canthus. Timely recognition and treatment prevent spread of infection and maintain tear drainage function, highlighting the importance of punctal assessment in clinical exams.
MCQ 7:
The direction of lacrimal flow is from:
a) Canaliculi → Puncta → Lacrimal sac
b) Eye surface → Puncta → Canaliculi → Lacrimal sac
c) Lacrimal sac → Puncta → Eye surface
d) Lacrimal gland → Lacrimal sac → Canaliculi
Answer & Explanation:
Correct answer: b) Eye surface → Puncta → Canaliculi → Lacrimal sac.
Explanation: Tears produced by the lacrimal gland flow over the ocular surface, enter the upper and lower lacrimal puncta, pass into the canaliculi, and drain into the lacrimal sac. This unidirectional flow is crucial to tear clearance and ocular surface health.
MCQ 8 (Clinical):
Which symptom suggests lacrimal punctal stenosis?
a) Sudden vision loss
b) Persistent watery eyes
c) Eye pain
d) Eyelid drooping
Answer & Explanation:
Correct answer: b) Persistent watery eyes.
Explanation: Lacrimal punctal stenosis refers to narrowing of the punctal openings, causing impaired tear drainage and chronic tearing (epiphora). Diagnosis involves slit-lamp examination and punctal dilation tests. Recognizing this prevents complications like conjunctivitis and helps in planning corrective procedures.
MCQ 9:
The upper and lower lacrimal puncta are located:
a) On the lateral aspect of the eyelids
b) At the medial eyelid margin
c) Centrally on the eyelid
d) On the superior orbital rim
Answer & Explanation:
Correct answer: b) At the medial eyelid margin.
Explanation: The upper and lower lacrimal puncta are small openings situated at the medial ends of the eyelid margins. They collect tears from the ocular surface and direct them into the canaliculi, crucial for tear drainage and ocular surface health maintenance.
MCQ 10 (Clinical):
A blocked lacrimal punctum leads to:
a) Dry eyes
b) Epiphora
c) Visual loss
d) Glaucoma
Answer & Explanation:
Correct answer: b) Epiphora.
Explanation: Blockage of the lacrimal punctum impairs tear drainage, resulting in overflow of tears onto the cheeks, known as epiphora. Identifying this condition is critical in clinical practice to prevent chronic tearing and secondary infections, often treated by punctal dilation or surgery.
Chapter: Head & Neck Anatomy
Topic: Arterial Supply
Subtopic: Ophthalmic Artery
Keywords:
Ophthalmic artery: First branch of the internal carotid artery after it enters the cranial cavity.
Internal carotid artery (ICA): Major artery supplying the brain and orbit.
Cavernous part of ICA: Segment traversing the cavernous sinus.
Cerebral part of ICA: Also called supraclinoid part, gives rise to ophthalmic artery.
Middle cerebral artery (MCA): Largest branch of ICA, supplies lateral cerebral hemisphere.
Facial artery: Branch of external carotid artery, supplies face.
1) Lead Question - 2012
Ophthalmic artery is a branch of?
a) Cavernous part of ICA
b) Cerebral part of ICA
c) MCA
d) Facial artery
Explanation: The ophthalmic artery arises from the cerebral (supraclinoid) part of the internal carotid artery just after it emerges from the cavernous sinus. It enters the orbit through the optic canal along with the optic nerve. Hence, the correct answer is cerebral part of ICA.
2) A patient presents with sudden monocular blindness. The most likely artery involved is?
a) Ophthalmic artery
b) Middle cerebral artery
c) Posterior communicating artery
d) Basilar artery
Explanation: Monocular blindness is commonly due to embolism or occlusion of the ophthalmic artery, a branch of the internal carotid artery. Retinal artery occlusion can cause sudden painless loss of vision. Correct answer is ophthalmic artery.
3) The central artery of retina is a branch of?
a) Middle cerebral artery
b) Ophthalmic artery
c) Basilar artery
d) External carotid artery
Explanation: The central artery of retina is a crucial end artery supplying the inner retina. It arises from the ophthalmic artery. Occlusion results in irreversible blindness. Correct answer is ophthalmic artery.
4) In cavernous sinus thrombosis, which artery is most closely related?
a) Maxillary artery
b) Ophthalmic artery
c) Internal carotid artery
d) Vertebral artery
Explanation: The cavernous sinus contains the cavernous part of ICA along with cranial nerves. Infection may spread to ICA leading to complications. Correct answer is internal carotid artery.
5) Which artery supplies the extraocular muscles?
a) Lacrimal artery
b) Muscular branches of ophthalmic artery
c) Posterior cerebral artery
d) Anterior cerebral artery
Explanation: Extraocular muscles receive blood supply from muscular branches of the ophthalmic artery. These branches ensure adequate perfusion of recti and oblique muscles. Correct answer is muscular branches of ophthalmic artery.
6) Which artery passes through the optic canal along with optic nerve?
a) Central retinal artery
b) Ophthalmic artery
c) Middle meningeal artery
d) Anterior cerebral artery
Explanation: The ophthalmic artery travels with the optic nerve through the optic canal to enter the orbit. This close relation explains visual loss in ICA occlusion. Correct answer is ophthalmic artery.
7) The lacrimal gland is mainly supplied by?
a) Facial artery
b) Lacrimal branch of ophthalmic artery
c) Posterior auricular artery
d) Maxillary artery
Explanation: The lacrimal gland receives its primary supply from the lacrimal artery, a branch of ophthalmic artery. It also anastomoses with infraorbital and middle meningeal arteries. Correct answer is lacrimal branch of ophthalmic artery.
8) Which artery forms an anastomosis with branches of external carotid artery on the face?
a) Central retinal artery
b) Supraorbital and supratrochlear branches of ophthalmic artery
c) Middle meningeal artery
d) Basilar artery
Explanation: The supraorbital and supratrochlear arteries, branches of ophthalmic artery, anastomose with superficial temporal and facial arteries, forming important ICA–ECA collateral channels. Correct answer is supraorbital and supratrochlear branches of ophthalmic artery.
9) Which part of ICA gives rise to posterior communicating artery?
a) Petrous part
b) Cavernous part
c) Cerebral (supraclinoid) part
d) Cervical part
Explanation: The posterior communicating artery arises from the cerebral (supraclinoid) part of ICA, connecting anterior circulation with posterior circulation. Correct answer is cerebral part.
10) Aneurysm of which artery commonly causes third nerve palsy?
a) Posterior communicating artery
b) Ophthalmic artery
c) Basilar artery
d) Anterior communicating artery
Explanation: Posterior communicating artery aneurysm compresses the oculomotor nerve leading to ptosis, diplopia, and pupillary dilation. Correct answer is posterior communicating artery.
11) A patient with severe facial trauma has massive epistaxis. Which artery is most likely responsible?
a) Ophthalmic artery
b) Sphenopalatine artery
c) Basilar artery
d) Internal carotid artery
Explanation: The sphenopalatine artery (terminal branch of maxillary artery, ECA system) is the main arterial source of severe posterior epistaxis. Correct answer is sphenopalatine artery.