Chapter: Neuroanatomy; Topic: Cranial Nerves; Subtopic: Oculomotor Nerve (III Cranial Nerve)
Key Definitions:
• Oculomotor nerve: The third cranial nerve responsible for most extraocular movements, eyelid elevation, and pupillary constriction.
• Extraocular muscles: Muscles that control eye movement; include superior, inferior, medial recti, lateral rectus, superior oblique, and inferior oblique.
• Abducent nerve: The sixth cranial nerve that supplies the lateral rectus muscle, responsible for abduction of the eye.
Lead Question (NEET PG 2015):
1. Oculomotor nerve supplies all extraocular muscles except:
A) Superior rectus
B) Inferior rectus
C) Lateral rectus
D) Medial rectus
Answer: C) Lateral rectus
Explanation: The oculomotor nerve (cranial nerve III) supplies the superior rectus, inferior rectus, medial rectus, and inferior oblique muscles, along with levator palpebrae superioris. The lateral rectus is supplied by the abducent nerve (cranial nerve VI), and the superior oblique is supplied by the trochlear nerve (cranial nerve IV). Thus, among the given options, the muscle not innervated by the oculomotor nerve is the lateral rectus.
Related (Guessed) Questions with Explanations:
2. Which nerve supplies the superior oblique muscle?
A) Oculomotor nerve
B) Trochlear nerve
C) Abducent nerve
D) Optic nerve
Answer: B) Trochlear nerve
Explanation: The superior oblique muscle is supplied by the trochlear nerve (cranial nerve IV), the only cranial nerve emerging dorsally from the brainstem.
3. A patient with right oculomotor nerve palsy will show which of the following signs?
A) Medial deviation of eyeball
B) Lateral deviation of eyeball
C) Downward and inward gaze
D) Upward deviation of eyeball
Answer: B) Lateral deviation of eyeball
Explanation: Oculomotor nerve palsy causes paralysis of most extraocular muscles, leaving the lateral rectus (abducent) and superior oblique (trochlear) unopposed, producing a “down and out” eye position.
4. Which of the following muscles is responsible for abduction of the eyeball?
A) Medial rectus
B) Lateral rectus
C) Superior rectus
D) Inferior oblique
Answer: B) Lateral rectus
Explanation: The lateral rectus, innervated by the abducent nerve, abducts the eyeball away from the midline.
5. The levator palpebrae superioris is innervated by:
A) Trochlear nerve
B) Oculomotor nerve
C) Abducent nerve
D) Facial nerve
Answer: B) Oculomotor nerve
Explanation: The superior division of the oculomotor nerve supplies the levator palpebrae superioris, responsible for eyelid elevation.
6. Which cranial nerve emerges from the dorsal aspect of the brainstem?
A) Oculomotor nerve
B) Trochlear nerve
C) Abducent nerve
D) Trigeminal nerve
Answer: B) Trochlear nerve
Explanation: The trochlear nerve is the only cranial nerve to emerge dorsally from the midbrain and decussates before innervating the contralateral superior oblique.
7. Damage to the oculomotor nerve results in which of the following?
A) Ptosis and mydriasis
B) Miosis and proptosis
C) Ptosis and miosis
D) Proptosis and diplopia only
Answer: A) Ptosis and mydriasis
Explanation: Oculomotor nerve palsy causes ptosis due to levator palpebrae paralysis and mydriasis from sphincter pupillae involvement.
8. Which of the following nerves carries parasympathetic fibers to the sphincter pupillae?
A) Abducent nerve
B) Trochlear nerve
C) Oculomotor nerve
D) Optic nerve
Answer: C) Oculomotor nerve
Explanation: The parasympathetic fibers from the Edinger–Westphal nucleus travel via the oculomotor nerve to the ciliary ganglion, innervating the sphincter pupillae.
9. The nucleus of the oculomotor nerve is located in which part of the brainstem?
A) Pons
B) Midbrain
C) Medulla oblongata
D) Thalamus
Answer: B) Midbrain
Explanation: The oculomotor nucleus is located in the midbrain at the level of the superior colliculus, near the midline.
10. A lesion in the right abducent nerve will result in inability to:
A) Elevate the eye
B) Depress the eye
C) Adduct the eye
D) Abduct the eye
Answer: D) Abduct the eye
Explanation: The abducent nerve supplies the lateral rectus muscle, which abducts the eye; its palsy causes inability to move the eye laterally.
11. Which of the following statements about the oculomotor nerve is true?
A) It carries only motor fibers
B) It carries motor and sensory fibers
C) It carries motor and parasympathetic fibers
D) It carries sensory and sympathetic fibers
Answer: C) It carries motor and parasympathetic fibers
Explanation: The oculomotor nerve contains somatic motor fibers to extraocular muscles and parasympathetic fibers to the sphincter pupillae and ciliary muscle.
Chapter: Neuroanatomy; Topic: Autonomic Nervous System; Subtopic: Sympathetic System – Central Control
Key Definitions:
• Sympathetic system: The division of the autonomic nervous system responsible for “fight or flight” responses such as increased heart rate, pupil dilation, and vasoconstriction.
• Hypothalamus: The central regulatory area of the brain that integrates autonomic and endocrine functions.
• Edinger–Westphal nucleus: Parasympathetic nucleus associated with the oculomotor nerve controlling pupil constriction and lens accommodation.
Lead Question (NEET PG 2015):
1. Major central nucleus of sympathetic system is:
A) Nucleus ambiguus
B) Nucleus tractus solitarius
C) Edinger–Westphal nucleus
D) Hypothalamus
Answer: D) Hypothalamus
Explanation: The hypothalamus acts as the major central control nucleus for the sympathetic division of the autonomic nervous system. It integrates inputs from higher cortical centers and regulates autonomic outflow via descending hypothalamospinal tracts to the brainstem and spinal cord. The posterior and lateral regions of the hypothalamus primarily influence sympathetic activity, while the anterior region governs parasympathetic control.
Related (Guessed) Questions with Explanations:
2. The Edinger–Westphal nucleus is related to which function?
A) Accommodation reflex
B) Lacrimation
C) Salivation
D) Swallowing
Answer: A) Accommodation reflex
Explanation: The Edinger–Westphal nucleus provides parasympathetic fibers through the oculomotor nerve to the ciliary muscle and sphincter pupillae, mediating accommodation and pupillary constriction.
3. Which of the following nuclei is parasympathetic in nature?
A) Nucleus ambiguus
B) Edinger–Westphal nucleus
C) Nucleus tractus solitarius
D) Hypothalamic nucleus
Answer: B) Edinger–Westphal nucleus
Explanation: The Edinger–Westphal nucleus belongs to the cranial parasympathetic nuclei, controlling ocular parasympathetic functions.
4. The sympathetic preganglionic neurons are located in which region of the spinal cord?
A) Cervical
B) Thoracolumbar
C) Lumbosacral
D) Sacral
Answer: B) Thoracolumbar
Explanation: Sympathetic preganglionic neurons arise from the intermediolateral cell column of spinal segments T1 to L2, giving the system its thoracolumbar origin.
5. Which structure integrates autonomic and endocrine responses?
A) Cerebellum
B) Thalamus
C) Hypothalamus
D) Pons
Answer: C) Hypothalamus
Explanation: The hypothalamus connects the nervous and endocrine systems via the pituitary gland, coordinating homeostatic autonomic and hormonal responses.
6. The nucleus tractus solitarius primarily receives which type of fibers?
A) Somatic motor
B) Visceral sensory
C) Somatic sensory
D) Visceral motor
Answer: B) Visceral sensory
Explanation: The nucleus tractus solitarius receives afferent visceral sensory input, including baroreceptor and chemoreceptor signals from cranial nerves VII, IX, and X.
7. The lateral horn of the spinal cord (T1–L2) contains:
A) Parasympathetic preganglionic neurons
B) Sympathetic preganglionic neurons
C) Somatic motor neurons
D) Sensory interneurons
Answer: B) Sympathetic preganglionic neurons
Explanation: The intermediolateral cell column located in the lateral horn of T1–L2 spinal cord segments houses sympathetic preganglionic neurons.
8. The hypothalamus exerts its autonomic influence mainly via:
A) Corticospinal tract
B) Reticulospinal tract
C) Hypothalamospinal tract
D) Rubrospinal tract
Answer: C) Hypothalamospinal tract
Explanation: The hypothalamus sends descending fibers through the hypothalamospinal tract to regulate autonomic centers in the brainstem and spinal cord.
9. The “fight or flight” response is mediated primarily by which neurotransmitter?
A) Acetylcholine
B) Dopamine
C) Noradrenaline
D) Serotonin
Answer: C) Noradrenaline
Explanation: Noradrenaline (norepinephrine) is the principal neurotransmitter released by postganglionic sympathetic neurons to produce the fight-or-flight response.
10. The parasympathetic control of the pupil arises from:
A) Edinger–Westphal nucleus
B) Nucleus tractus solitarius
C) Nucleus ambiguus
D) Hypoglossal nucleus
Answer: A) Edinger–Westphal nucleus
Explanation: The Edinger–Westphal nucleus sends preganglionic fibers through the oculomotor nerve to constrict the pupil via the ciliary ganglion.
11. The posterior hypothalamus primarily regulates:
A) Parasympathetic activity
B) Sympathetic activity
C) Endocrine secretion only
D) Circadian rhythm
Answer: B) Sympathetic activity
Explanation: The posterior and lateral parts of the hypothalamus are concerned with sympathetic outflow, while the anterior part controls parasympathetic tone.
Chapter: Head and Neck Anatomy
Topic: Scalp
Subtopic: Layers and Clinical Anatomy of the Scalp
Key Definitions:
• Scalp: The soft tissue covering the calvaria, extending from the supraorbital margins to the superior nuchal lines.
• Aponeurosis (Galea aponeurotica): A tough tendinous sheet connecting the frontalis and occipitalis muscles.
• Subaponeurotic tissue: The loose areolar connective tissue layer beneath the aponeurosis, allowing movement of the scalp over the skull.
• Pericranium: The periosteum covering the outer surface of the skull bones.
Lead Question (NEET PG 2015):
1. Dangerous area of scalp is:
A) Superficial fascia
B) Aponeurosis
C) Subaponeurotic tissue
D) Pericranium
Answer: C) Subaponeurotic tissue
Explanation: The subaponeurotic (loose areolar) tissue is called the “dangerous area of the scalp” because it contains emissary veins that connect the superficial veins of the scalp with intracranial venous sinuses. Infections from this layer can spread through these veins to the intracranial venous sinuses, leading to complications like meningitis or cavernous sinus thrombosis.
Related (Guessed) Questions with Explanations:
2. Which layer of the scalp contains emissary veins?
A) Skin
B) Superficial fascia
C) Subaponeurotic tissue
D) Pericranium
Answer: C) Subaponeurotic tissue
Explanation: Emissary veins traverse the loose areolar (subaponeurotic) layer, linking extracranial veins with intracranial venous sinuses.
3. The scalp consists of how many layers?
A) 3
B) 4
C) 5
D) 6
Answer: C) 5
Explanation: The five layers of scalp are remembered by the mnemonic “SCALP” — Skin, Connective tissue, Aponeurosis, Loose areolar tissue, and Pericranium.
4. The mnemonic “SCALP” represents the layers of scalp. The letter ‘A’ stands for:
A) Aponeurosis
B) Areolar tissue
C) Arteries
D) Adipose tissue
Answer: A) Aponeurosis
Explanation: ‘A’ in SCALP refers to the aponeurosis (galea aponeurotica) which connects frontalis and occipitalis muscles.
5. Infection from the dangerous area of the scalp can spread to:
A) Cervical lymph nodes
B) Intracranial venous sinuses
C) Submandibular gland
D) Middle ear
Answer: B) Intracranial venous sinuses
Explanation: Through emissary veins, infection from the subaponeurotic layer may reach intracranial venous sinuses like the superior sagittal or cavernous sinus.
6. The layer of scalp most difficult to separate in dissection is:
A) Skin
B) Superficial fascia
C) Aponeurosis
D) Subaponeurotic tissue
Answer: B) Superficial fascia
Explanation: The superficial fascia is dense and fibrofatty, tightly bound to the skin and aponeurosis, making surgical separation difficult.
7. Which structure connects scalp veins to dural venous sinuses?
A) Superficial temporal veins
B) Emissary veins
C) Diploic veins
D) Meningeal veins
Answer: B) Emissary veins
Explanation: Emissary veins pass through skull foramina and connect extracranial veins with intracranial dural venous sinuses.
8. Which artery mainly supplies the posterior scalp?
A) Superficial temporal artery
B) Occipital artery
C) Facial artery
D) Maxillary artery
Answer: B) Occipital artery
Explanation: The occipital artery, a branch of the external carotid artery, supplies the posterior part of the scalp.
9. The pericranium corresponds anatomically to:
A) Endosteum of skull
B) Periosteum of skull
C) Dura mater
D) Pia mater
Answer: B) Periosteum of skull
Explanation: The pericranium is the periosteal layer covering the outer surface of skull bones and continues with sutural ligaments.
10. Which muscle forms part of the epicranius?
A) Frontalis and occipitalis
B) Temporalis and masseter
C) Orbicularis oculi and zygomaticus
D) Sternocleidomastoid and trapezius
Answer: A) Frontalis and occipitalis
Explanation: The epicranius (occipitofrontalis) consists of the frontalis and occipitalis muscles connected by the galea aponeurotica.
11. The scalp is freely movable because of which layer?
A) Skin
B) Connective tissue
C) Aponeurosis
D) Subaponeurotic tissue
Answer: D) Subaponeurotic tissue
Explanation: The loose areolar tissue beneath the aponeurosis allows the scalp to move over the skull during expression or injury.
Chapter: Head and Neck Anatomy; Topic: Scalp; Subtopic: Layers and Clinical Anatomy of the Scalp
Key Definitions:
• Scalp: The soft tissue covering the skull extending from the supraorbital margins anteriorly to the superior nuchal lines posteriorly.
• Subaponeurotic tissue: The loose areolar connective tissue layer beneath the aponeurosis that allows free movement of the scalp.
• Emissary veins: Veins that connect the extracranial veins of the scalp with the intracranial dural venous sinuses.
• Pericranium: The periosteal layer covering the external surface of the skull bones.
Lead Question (NEET PG 2015):
1. Dangerous area of scalp is:
A) Superficial fascia
B) Aponeurosis
C) Subaponeurotic tissue
D) Pericranium
Answer: C) Subaponeurotic tissue
Explanation: The subaponeurotic (loose areolar) tissue is known as the dangerous area of the scalp because it contains emissary veins that communicate with intracranial venous sinuses. Infections in this layer can spread through these veins to cause intracranial complications such as meningitis or cavernous sinus thrombosis. Thus, this layer provides a potential route for the spread of infection from extracranial to intracranial structures.
Related (Guessed) Questions with Explanations:
2. Which layer of the scalp contains emissary veins?
A) Skin
B) Superficial fascia
C) Subaponeurotic tissue
D) Pericranium
Answer: C) Subaponeurotic tissue
Explanation: The loose areolar tissue beneath the aponeurosis contains emissary veins that connect superficial veins of the scalp with intracranial dural venous sinuses.
3. The scalp consists of how many layers?
A) 3
B) 4
C) 5
D) 6
Answer: C) 5
Explanation: The five layers of the scalp are remembered by the mnemonic “SCALP” — Skin, Connective tissue, Aponeurosis, Loose areolar tissue, and Pericranium.
4. In the mnemonic SCALP, ‘A’ stands for:
A) Aponeurosis
B) Areolar tissue
C) Arteries
D) Adipose tissue
Answer: A) Aponeurosis
Explanation: ‘A’ represents the galea aponeurotica, a strong fibrous layer connecting frontalis and occipitalis muscles of the epicranius.
5. Infection from the dangerous area of the scalp can spread to:
A) Cervical lymph nodes
B) Intracranial venous sinuses
C) Submandibular gland
D) Middle ear
Answer: B) Intracranial venous sinuses
Explanation: Through emissary veins, infection in the subaponeurotic layer can spread to intracranial venous sinuses like the cavernous or superior sagittal sinus.
6. The layer of scalp most difficult to separate in dissection is:
A) Skin
B) Superficial fascia
C) Aponeurosis
D) Subaponeurotic tissue
Answer: B) Superficial fascia
Explanation: The dense connective tissue of the superficial fascia tightly binds the skin to the aponeurosis, making surgical separation difficult.
7. Which structure connects scalp veins to dural venous sinuses?
A) Superficial temporal veins
B) Emissary veins
C) Diploic veins
D) Meningeal veins
Answer: B) Emissary veins
Explanation: Emissary veins pass through foramina in the skull and connect extracranial veins of the scalp with intracranial dural venous sinuses.
8. Which artery mainly supplies the posterior scalp?
A) Superficial temporal artery
B) Occipital artery
C) Facial artery
D) Maxillary artery
Answer: B) Occipital artery
Explanation: The occipital artery, a branch of the external carotid artery, provides the main arterial supply to the posterior scalp.
9. The pericranium corresponds anatomically to:
A) Endosteum of skull
B) Periosteum of skull
C) Dura mater
D) Pia mater
Answer: B) Periosteum of skull
Explanation: The pericranium acts as the periosteum of the outer surface of skull bones and is continuous with sutural ligaments.
10. Which muscle forms part of the epicranius?
A) Frontalis and occipitalis
B) Temporalis and masseter
C) Orbicularis oculi and zygomaticus
D) Sternocleidomastoid and trapezius
Answer: A) Frontalis and occipitalis
Explanation: The epicranius or occipitofrontalis consists of the frontalis and occipitalis muscles connected by the galea aponeurotica.
11. The scalp is freely movable because of which layer?
A) Skin
B) Connective tissue
C) Aponeurosis
D) Subaponeurotic tissue
Answer: D) Subaponeurotic tissue
Explanation: The loose areolar tissue beneath the aponeurosis allows the scalp to glide over the skull, facilitating its mobility.
Chapter: Head and Neck Anatomy; Topic: Parotid Gland; Subtopic: Nerve Relations and Surgical Anatomy
Key Definitions:
• Parotid gland: The largest salivary gland located anteroinferior to the external acoustic meatus.
• Facial nerve (VII): The motor nerve of facial expression that passes through the parotid gland but does not supply it.
• Parotid duct (Stensen’s duct): The duct that opens opposite the upper second molar tooth in the oral cavity.
• Superficial and deep lobes: Two anatomical parts of the parotid gland separated by the facial nerve.
Lead Question (NEET PG 2015):
1. Which nerve is preserved in dissecting the superficial and deep lobes of parotid gland?
a) Glossopharyngeal
b) Hypoglossal
c) Lingual
d) Facial
Answer: d) Facial
Explanation: The facial nerve (cranial nerve VII) passes through the parotid gland and divides it into superficial and deep lobes. It emerges from the stylomastoid foramen, enters the parotid gland, and divides into its five terminal branches — temporal, zygomatic, buccal, marginal mandibular, and cervical — forming the parotid plexus. During parotid surgery, this nerve must be carefully preserved to prevent facial paralysis. The nerve is thus the key landmark and structure preserved during dissection of the parotid gland.
Guessed Questions (Related to Parotid Gland and Facial Nerve):
2. Which nerve supplies secretomotor fibers to the parotid gland?
a) Facial nerve
b) Glossopharyngeal nerve
c) Hypoglossal nerve
d) Vagus nerve
Answer: b) Glossopharyngeal nerve
Explanation: The glossopharyngeal nerve (cranial nerve IX) via its tympanic and lesser petrosal branches provides parasympathetic secretomotor fibers to the parotid gland through the otic ganglion. Stimulation increases salivation, while damage reduces secretion.
3. Injury to the marginal mandibular branch of the facial nerve causes:
a) Drooping of upper eyelid
b) Drooping of mouth angle
c) Loss of forehead wrinkling
d) Loss of lacrimation
Answer: b) Drooping of mouth angle
Explanation: The marginal mandibular branch of the facial nerve supplies muscles of the lower lip. Injury to this branch during submandibular or parotid surgery results in asymmetry and drooping of the mouth corner when smiling or talking.
4. The facial nerve exits the skull through which foramen?
a) Jugular foramen
b) Stylomastoid foramen
c) Foramen ovale
d) Internal acoustic meatus
Answer: b) Stylomastoid foramen
Explanation: After passing through the facial canal in the temporal bone, the facial nerve exits via the stylomastoid foramen to supply the muscles of facial expression, then enters the parotid gland where it forms its plexus.
5. Frey’s syndrome after parotidectomy is due to:
a) Regeneration of sympathetic fibers
b) Regeneration of parasympathetic fibers to sweat glands
c) Infection of parotid duct
d) Obstruction of facial vein
Answer: b) Regeneration of parasympathetic fibers to sweat glands
Explanation: Frey’s syndrome (gustatory sweating) occurs when postganglionic parasympathetic fibers, damaged during surgery, reinnervate sweat glands of the skin. It results in sweating and redness of the cheek during eating.
6. The duct of the parotid gland opens into the oral cavity opposite:
a) Upper first molar
b) Upper second molar
c) Lower first molar
d) Lower second molar
Answer: b) Upper second molar
Explanation: The parotid (Stensen’s) duct crosses the masseter, pierces the buccinator, and opens opposite the upper second molar tooth in the vestibule of the mouth.
7. During surgery, which structure is used as a landmark to locate the facial nerve in the parotid gland?
a) Posterior belly of digastric
b) Sternocleidomastoid
c) Parotid duct
d) Masseter muscle
Answer: a) Posterior belly of digastric
Explanation: The posterior belly of the digastric and the tragal pointer serve as reliable landmarks for identifying the main trunk of the facial nerve during parotid surgery.
8. Involvement of the facial nerve within the parotid gland produces which condition?
a) Bell’s palsy
b) Ramsay Hunt syndrome
c) Hemifacial paralysis
d) Both a and c
Answer: d) Both a and c
Explanation: Damage to the facial nerve within the parotid gland causes ipsilateral facial paralysis, similar to Bell’s palsy, leading to inability to close the eye, drooling, and loss of facial symmetry.
9. Which of the following structures does not pass through the parotid gland?
a) Facial nerve
b) External carotid artery
c) Retromandibular vein
d) Hypoglossal nerve
Answer: d) Hypoglossal nerve
Explanation: The hypoglossal nerve (XII) does not pass through the parotid gland; it lies deep to the posterior belly of the digastric muscle and supplies tongue muscles. The other three structures traverse the gland.
10. A 50-year-old man with a parotid tumor develops inability to close his right eye and drooping of the mouth. Which structure is likely involved?
a) Hypoglossal nerve
b) Facial nerve
c) Trigeminal nerve
d) Glossopharyngeal nerve
Answer: b) Facial nerve
Explanation: The tumor compresses or invades the facial nerve within the parotid gland, resulting in ipsilateral facial paralysis characterized by inability to close the eyelid and drooping of the mouth corner.
11. Parasympathetic fibers to the parotid gland relay in which ganglion?
a) Pterygopalatine ganglion
b) Otic ganglion
c) Submandibular ganglion
d) Ciliary ganglion
Answer: b) Otic ganglion
Explanation: The glossopharyngeal nerve provides preganglionic fibers via the lesser petrosal nerve to the otic ganglion, from where postganglionic fibers reach the parotid gland through the auriculotemporal nerve to stimulate secretion.
Chapter: Neuroanatomy; Topic: Cranial Nerves; Subtopic: Parasympathetic Supply of the Eye
Key Definitions:
• Intrinsic ocular muscles: Muscles within the eyeball that control pupil size and lens shape — sphincter pupillae and ciliary muscle.
• Parasympathetic fibers: Autonomic fibers responsible for constriction of the pupil and accommodation of the lens.
• Edinger–Westphal nucleus: Midbrain nucleus providing parasympathetic fibers via the oculomotor nerve to the eye.
• Ciliary ganglion: Parasympathetic ganglion located behind the eyeball, relaying fibers to the sphincter pupillae and ciliary muscle.
Lead Question (NEET PG 2015):
1. Which intrinsic ocular muscle is supplied by parasympathetic innervation?
a) Superior rectus
b) Superior oblique
c) Constrictor pupillae
d) Dilator pupillae
Answer: c) Constrictor pupillae
Explanation: The constrictor (sphincter) pupillae is supplied by parasympathetic fibers originating from the Edinger–Westphal nucleus. These fibers travel via the oculomotor nerve to the ciliary ganglion, and from there through short ciliary nerves to reach the sphincter pupillae. Activation of these fibers causes pupillary constriction (miosis). In contrast, the dilator pupillae is supplied by sympathetic fibers from the superior cervical ganglion. Thus, constrictor pupillae represents the parasympathetic innervation of the eye.
Guessed Questions (Related to Ocular Nerves and Muscles):
2. Parasympathetic fibers to the ciliary muscle are carried by which nerve?
a) Trochlear nerve
b) Abducent nerve
c) Oculomotor nerve
d) Optic nerve
Answer: c) Oculomotor nerve
Explanation: The oculomotor nerve (III) carries preganglionic parasympathetic fibers from the Edinger–Westphal nucleus to the ciliary ganglion, which then supply the ciliary muscle for lens accommodation.
3. The dilator pupillae muscle is supplied by which type of fibers?
a) Parasympathetic
b) Sympathetic
c) Somatic motor
d) Sensory
Answer: b) Sympathetic
Explanation: The dilator pupillae receives sympathetic postganglionic fibers from the superior cervical ganglion via the long ciliary nerves, leading to pupillary dilation (mydriasis).
4. Which ganglion is associated with the oculomotor nerve?
a) Ciliary ganglion
b) Otic ganglion
c) Pterygopalatine ganglion
d) Submandibular ganglion
Answer: a) Ciliary ganglion
Explanation: The ciliary ganglion is the parasympathetic ganglion linked to the oculomotor nerve. It relays fibers that control the sphincter pupillae and ciliary muscle functions.
5. Which muscle of the eye causes accommodation for near vision?
a) Superior rectus
b) Inferior oblique
c) Ciliary muscle
d) Superior oblique
Answer: c) Ciliary muscle
Explanation: The ciliary muscle, controlled by parasympathetic fibers from the oculomotor nerve, contracts to reduce tension on the suspensory ligaments, thickening the lens for near focus.
6. A lesion of the Edinger–Westphal nucleus results in:
a) Miosis
b) Mydriasis
c) Ptosis
d) Diplopia
Answer: b) Mydriasis
Explanation: Destruction of the Edinger–Westphal nucleus interrupts parasympathetic supply to the sphincter pupillae, leading to unopposed sympathetic activity and dilated pupil (mydriasis).
7. Which of the following muscles is not an intrinsic muscle of the eye?
a) Ciliary muscle
b) Sphincter pupillae
c) Superior rectus
d) Dilator pupillae
Answer: c) Superior rectus
Explanation: The superior rectus is an extrinsic ocular muscle that moves the eyeball upward. Intrinsic muscles include the ciliary, sphincter pupillae, and dilator pupillae, which control lens and pupil function.
8. The light reflex (pupillary constriction in response to light) is mediated through which nucleus?
a) Red nucleus
b) Edinger–Westphal nucleus
c) Solitary nucleus
d) Trochlear nucleus
Answer: b) Edinger–Westphal nucleus
Explanation: The afferent limb of the light reflex is via the optic nerve, and the efferent limb is mediated by parasympathetic fibers from the Edinger–Westphal nucleus via the oculomotor nerve to the sphincter pupillae.
9. Damage to the short ciliary nerves results in loss of:
a) Accommodation and light reflex
b) Corneal reflex
c) Lacrimation
d) Eye movement
Answer: a) Accommodation and light reflex
Explanation: Short ciliary nerves carry postganglionic parasympathetic fibers to the ciliary muscle and sphincter pupillae. Their damage leads to paralysis of accommodation and loss of pupillary light reflex.
10. Which of the following best describes the effect of sympathetic stimulation on the eye?
a) Pupillary constriction
b) Lens accommodation
c) Pupillary dilation
d) Convergence of eyeballs
Answer: c) Pupillary dilation
Explanation: Sympathetic stimulation activates the dilator pupillae via fibers from the superior cervical ganglion, resulting in dilation of the pupil (mydriasis) as part of the fight-or-flight response.
11. A patient has a dilated, non-reactive pupil after head trauma. Which structure is likely damaged?
a) Ciliary ganglion
b) Superior cervical ganglion
c) Abducent nucleus
d) Trochlear nerve
Answer: a) Ciliary ganglion
Explanation: Injury to the ciliary ganglion disrupts parasympathetic postganglionic fibers to the sphincter pupillae, causing a fixed, dilated pupil unresponsive to light, a classic sign of parasympathetic failure.
Chapter: Head and Neck Anatomy; Topic: Lymphatic Drainage of Head and Neck; Subtopic: Lymphatic Drainage of Lips
Key Definitions:
• Lymph nodes: Small, bean-shaped structures that filter lymph and help the body fight infection.
• Submandibular nodes: Nodes located beneath the jaw, receiving lymph from upper lip and lateral lower lip.
• Submental nodes: Nodes situated below the chin, draining the central lower lip and chin.
• Preauricular (parotid) nodes: Nodes located in front of the ear, receiving lymph from the eyelids and lateral face, not the lips.
Lead Question (NEET PG 2015):
1. Lips does not drain into which group of lymph nodes?
a) Submandibular nodes
b) Sublingual nodes
c) Preauricular parotid
d) None of the above
Answer: c) Preauricular parotid
Explanation: The lymphatic drainage of the lips is divided as follows: the upper lip and lateral parts of the lower lip drain into the submandibular nodes, while the central part of the lower lip and chin drain into the submental nodes. The preauricular (parotid) nodes receive lymph from the lateral eyelids, forehead, and scalp, not from the lips. Therefore, the lips do not drain into the preauricular group of lymph nodes. This knowledge is clinically important in oral cancer metastasis and infections of the oral region.
Guessed Questions (Related to Lymphatic Drainage of Head and Neck):
2. The central part of the lower lip drains into which lymph nodes?
a) Submandibular nodes
b) Submental nodes
c) Deep cervical nodes
d) Preauricular nodes
Answer: b) Submental nodes
Explanation: The submental lymph nodes receive lymph from the central lower lip, chin, and anterior floor of the mouth. These nodes lie in the submental triangle between the anterior bellies of digastric muscles.
3. The upper lip drains mainly into which lymph nodes?
a) Parotid nodes
b) Submandibular nodes
c) Submental nodes
d) Retropharyngeal nodes
Answer: b) Submandibular nodes
Explanation: The submandibular nodes receive lymph from the upper lip, lateral lower lip, and upper oral cavity. These nodes lie superficial to the submandibular gland and drain into deep cervical nodes.
4. A carcinoma at the midline of the lower lip will first spread to which nodes?
a) Submandibular
b) Submental
c) Parotid
d) Deep cervical
Answer: b) Submental
Explanation: The central lower lip and chin region drain to submental nodes; hence, metastasis from a carcinoma in this region will first involve submental nodes before spreading further.
5. Which of the following lymph node groups receives lymph from the scalp and forehead?
a) Submental nodes
b) Parotid (preauricular) nodes
c) Submandibular nodes
d) Deep cervical nodes
Answer: b) Parotid (preauricular) nodes
Explanation: The preauricular nodes drain the lateral scalp, forehead, and eyelids. They do not receive lymph from the lips or oral cavity, distinguishing them from submandibular nodes.
6. The deep cervical lymph nodes receive direct drainage from all of the following except:
a) Palatine tonsil
b) Tongue
c) Lips
d) Scalp
Answer: c) Lips
Explanation: The lips first drain into submental and submandibular nodes before reaching the deep cervical group. Other structures like the tonsil and tongue can have direct drainage to the deep cervical chain.
7. A 40-year-old patient presents with swelling under the chin after a dental infection of the central incisor. Which lymph node is enlarged?
a) Submandibular
b) Submental
c) Jugulodigastric
d) Parotid
Answer: b) Submental
Explanation: Infections from the central lower incisor region drain into the submental nodes due to their anatomic connection with the central lower lip and chin area.
8. Which lymph node group is referred to as the "tonsillar node"?
a) Submental node
b) Jugulodigastric node
c) Jugulo-omohyoid node
d) Parotid node
Answer: b) Jugulodigastric node
Explanation: The jugulodigastric node, a deep cervical node located near the posterior belly of digastric, is known as the tonsillar node as it drains the palatine tonsil and pharyngeal regions.
9. Lymph from the tip of the tongue drains first into:
a) Submandibular nodes
b) Submental nodes
c) Deep cervical nodes
d) Parotid nodes
Answer: b) Submental nodes
Explanation: The tip of the tongue and anterior floor of the mouth drain into submental nodes, while lateral borders of the anterior tongue drain into submandibular nodes.
10. In carcinoma of the lateral border of the tongue, the first group of lymph nodes involved are:
a) Submental nodes
b) Submandibular nodes
c) Jugulodigastric nodes
d) Parotid nodes
Answer: b) Submandibular nodes
Explanation: The anterior two-thirds of the tongue, especially its lateral borders, primarily drain into the submandibular lymph nodes before reaching the deep cervical nodes.
11. Infections of the upper lip and cheek are most likely to cause swelling in which lymph nodes?
a) Submandibular
b) Submental
c) Parotid
d) Buccal
Answer: a) Submandibular
Explanation: The submandibular lymph nodes drain the upper lip, lateral lower lip, and cheek area. Infection or inflammation in these regions commonly leads to enlargement of these nodes.
Chapter: Head and Neck Anatomy; Topic: Parotid Gland; Subtopic: Parasympathetic Innervation of the Parotid Gland
Key Definitions:
• Parotid gland: The largest salivary gland located anteroinferior to the external acoustic meatus, secreting serous saliva to aid digestion.
• Glossopharyngeal nerve (CN IX): Cranial nerve providing preganglionic parasympathetic fibers to the parotid gland through the lesser petrosal nerve.
• Auriculotemporal nerve: A branch of the mandibular nerve (V3) carrying postganglionic parasympathetic fibers from the otic ganglion to the parotid gland.
• Otic ganglion: A small parasympathetic ganglion situated below the foramen ovale that relays fibers to the parotid gland.
Lead Question (NEET PG 2015):
1. Postganglionic fibres to parotid gland is supplied by?
a) Glossopharyngeal nerve
b) Auriculotemporal nerve
c) Both of the above
d) None of the above
Answer: b) Auriculotemporal nerve
Explanation: The parasympathetic secretomotor pathway to the parotid gland begins in the inferior salivatory nucleus. Preganglionic fibers travel via the glossopharyngeal nerve (CN IX) and its branch, the lesser petrosal nerve, to the otic ganglion, where they synapse. Postganglionic fibers then travel through the auriculotemporal nerve, a branch of the mandibular nerve (V3), to reach the parotid gland. This pathway stimulates salivary secretion. Thus, the auriculotemporal nerve provides postganglionic fibers, while the glossopharyngeal nerve provides preganglionic fibers.
Guessed Questions (Related to Parotid Gland Innervation):
2. Preganglionic parasympathetic fibers to the parotid gland are carried by:
a) Facial nerve
b) Glossopharyngeal nerve
c) Vagus nerve
d) Trigeminal nerve
Answer: b) Glossopharyngeal nerve
Explanation: The glossopharyngeal nerve provides preganglionic parasympathetic fibers via its tympanic branch and the lesser petrosal nerve to the otic ganglion, which relay to the parotid gland for salivation.
3. The otic ganglion is functionally related to which cranial nerve?
a) Trigeminal nerve
b) Glossopharyngeal nerve
c) Facial nerve
d) Vagus nerve
Answer: b) Glossopharyngeal nerve
Explanation: Though anatomically associated with the mandibular division of the trigeminal nerve, the otic ganglion is functionally connected to the glossopharyngeal nerve, which supplies its preganglionic fibers.
4. Frey’s syndrome (gustatory sweating) occurs due to injury to:
a) Auriculotemporal nerve
b) Lingual nerve
c) Facial nerve
d) Glossopharyngeal nerve
Answer: a) Auriculotemporal nerve
Explanation: In Frey’s syndrome, injury to the auriculotemporal nerve during parotid surgery causes parasympathetic fibers to regrow abnormally to sweat glands, leading to sweating and flushing during eating.
5. A lesion in the otic ganglion would lead to decreased secretion from which gland?
a) Submandibular gland
b) Sublingual gland
c) Parotid gland
d) Lacrimal gland
Answer: c) Parotid gland
Explanation: The otic ganglion relays parasympathetic fibers from the glossopharyngeal nerve to the parotid gland; damage to it impairs salivary secretion from this gland.
6. Parasympathetic stimulation of the parotid gland causes:
a) Vasoconstriction and thick secretion
b) Vasodilation and watery secretion
c) Decreased blood flow
d) None of the above
Answer: b) Vasodilation and watery secretion
Explanation: Parasympathetic stimulation increases blood flow to the parotid gland and promotes secretion of watery, enzyme-rich saliva for digestion.
7. Which nerve is preserved during parotid gland surgery to avoid facial paralysis?
a) Glossopharyngeal nerve
b) Facial nerve
c) Auriculotemporal nerve
d) Lingual nerve
Answer: b) Facial nerve
Explanation: The facial nerve divides the parotid gland into superficial and deep lobes; careful preservation of this nerve during surgery prevents facial muscle paralysis.
8. Postganglionic sympathetic fibers to the parotid gland arise from:
a) Superior cervical ganglion
b) Otic ganglion
c) Submandibular ganglion
d) Pterygopalatine ganglion
Answer: a) Superior cervical ganglion
Explanation: Sympathetic fibers arise from the superior cervical ganglion, travel via the external carotid plexus, and reach the parotid gland to cause vasoconstriction and reduce salivary flow.
9. The auriculotemporal nerve is a branch of which cranial nerve division?
a) Maxillary nerve
b) Mandibular nerve
c) Ophthalmic nerve
d) Facial nerve
Answer: b) Mandibular nerve
Explanation: The auriculotemporal nerve originates from the posterior division of the mandibular nerve (V3) and carries postganglionic parasympathetic fibers to the parotid gland along with sensory fibers to the temporal region.
10. Inflammation of the parotid gland (mumps) causes pain due to stretching of its capsule, which is innervated by:
a) Auriculotemporal nerve
b) Facial nerve
c) Glossopharyngeal nerve
d) Lingual nerve
Answer: a) Auriculotemporal nerve
Explanation: The parotid fascia and capsule are supplied by the auriculotemporal nerve. In mumps, the gland swells within its tight capsule, causing pain referred to the ear region.
11. A patient with injury to the glossopharyngeal nerve will have decreased secretion from which gland?
a) Submandibular gland
b) Sublingual gland
c) Parotid gland
d) Lacrimal gland
Answer: c) Parotid gland
Explanation: The glossopharyngeal nerve provides preganglionic parasympathetic fibers to the parotid gland. Damage leads to loss of salivary secretion from the parotid, though other glands remain unaffected.
Chapter: Head and Neck Anatomy; Topic: Parotid Gland; Subtopic: Parasympathetic (Secretomotor) Innervation of the Parotid Gland
Key Definitions:
• Parotid gland: The largest salivary gland situated in front of the ear, secreting serous saliva that aids digestion.
• Secretomotor fibers: Parasympathetic fibers that stimulate secretion from glands such as salivary and lacrimal glands.
• Tympanic plexus: A network of nerves in the middle ear formed by the tympanic branch of the glossopharyngeal nerve, giving rise to the lesser petrosal nerve.
• Otic ganglion: A parasympathetic ganglion related to the mandibular nerve (V3) that relays secretomotor fibers to the parotid gland via the auriculotemporal nerve.
Lead Question (NEET PG 2015):
1. Secretomotor fibers to parotid glands are through -
a) Tympanic plexus
b) Geniculate ganglion
c) Greater petrosal nerve
d) None
Answer: a) Tympanic plexus
Explanation: The secretomotor (parasympathetic) pathway to the parotid gland originates in the inferior salivatory nucleus of the medulla. Preganglionic fibers pass through the glossopharyngeal nerve (CN IX) and its tympanic branch, which forms the tympanic plexus in the middle ear. From this plexus arises the lesser petrosal nerve, which carries fibers to the otic ganglion. After synapsing there, postganglionic fibers reach the parotid gland via the auriculotemporal nerve (a branch of the mandibular nerve, V3). Thus, the tympanic plexus is the route for secretomotor fibers to the parotid gland.
Guessed Questions (Related to Parotid Gland and its Nerve Supply):
2. Which nerve carries preganglionic parasympathetic fibers to the parotid gland?
a) Facial nerve
b) Glossopharyngeal nerve
c) Vagus nerve
d) Trigeminal nerve
Answer: b) Glossopharyngeal nerve
Explanation: The glossopharyngeal nerve carries preganglionic fibers from the inferior salivatory nucleus to the parotid gland through the tympanic branch and lesser petrosal nerve, making it the main secretomotor nerve of the gland.
3. The otic ganglion is functionally associated with which cranial nerve?
a) Trigeminal nerve
b) Glossopharyngeal nerve
c) Facial nerve
d) Vagus nerve
Answer: b) Glossopharyngeal nerve
Explanation: Although anatomically attached to the mandibular division of the trigeminal nerve (V3), the otic ganglion receives its preganglionic fibers from the glossopharyngeal nerve and is thus functionally linked to CN IX.
4. Postganglionic fibers from the otic ganglion reach the parotid gland through:
a) Auriculotemporal nerve
b) Lingual nerve
c) Inferior alveolar nerve
d) Buccal nerve
Answer: a) Auriculotemporal nerve
Explanation: The auriculotemporal nerve, a branch of the mandibular nerve, carries postganglionic parasympathetic fibers from the otic ganglion to the parotid gland, completing the secretomotor pathway.
5. The lesser petrosal nerve arises from which structure?
a) Tympanic plexus
b) Geniculate ganglion
c) Superior cervical ganglion
d) Pterygopalatine ganglion
Answer: a) Tympanic plexus
Explanation: The lesser petrosal nerve originates from the tympanic plexus, carrying preganglionic parasympathetic fibers from the glossopharyngeal nerve to the otic ganglion before reaching the parotid gland.
6. A lesion at the otic ganglion will cause:
a) Dryness of mouth due to decreased parotid secretion
b) Facial paralysis
c) Loss of taste on anterior tongue
d) Decreased lacrimation
Answer: a) Dryness of mouth due to decreased parotid secretion
Explanation: The otic ganglion mediates parasympathetic transmission to the parotid gland. Damage interrupts this pathway, resulting in reduced salivation and a dry mouth.
7. Frey’s syndrome following parotidectomy results from regeneration of fibers of:
a) Auriculotemporal nerve
b) Glossopharyngeal nerve
c) Facial nerve
d) Lingual nerve
Answer: a) Auriculotemporal nerve
Explanation: During healing after parotidectomy, parasympathetic fibers from the auriculotemporal nerve aberrantly regenerate to sweat glands, causing gustatory sweating (Frey’s syndrome) when eating.
8. The parotid duct opens opposite which tooth in the oral cavity?
a) Upper first molar
b) Upper second molar
c) Lower first molar
d) Upper canine
Answer: b) Upper second molar
Explanation: The Stensen’s (parotid) duct passes horizontally across the masseter muscle, pierces the buccinator, and opens into the vestibule of the mouth opposite the upper second molar tooth.
9. Inflammation of the parotid gland (mumps) is painful due to involvement of which nerve?
a) Auriculotemporal nerve
b) Facial nerve
c) Glossopharyngeal nerve
d) Mandibular nerve
Answer: a) Auriculotemporal nerve
Explanation: The parotid capsule, derived from deep cervical fascia, is supplied by the auriculotemporal nerve. Swelling of the gland stretches this capsule, causing severe pain radiating to the ear.
10. Which cranial nerve nucleus gives rise to the preganglionic fibers for the parotid gland?
a) Superior salivatory nucleus
b) Inferior salivatory nucleus
c) Dorsal motor nucleus of vagus
d) Nucleus ambiguus
Answer: b) Inferior salivatory nucleus
Explanation: The inferior salivatory nucleus in the medulla oblongata gives rise to preganglionic parasympathetic fibers that travel via the glossopharyngeal nerve to supply the parotid gland.
11. Which ganglion mediates the secretomotor fibers for the parotid gland?
a) Pterygopalatine ganglion
b) Otic ganglion
c) Submandibular ganglion
d) Ciliary ganglion
Answer: b) Otic ganglion
Explanation: The otic ganglion is the parasympathetic relay center for the parotid gland. It receives fibers from the lesser petrosal nerve and sends postganglionic fibers to the gland through the auriculotemporal nerve.
Chapter: Neuroanatomy; Topic: Cranial Nerves; Subtopic: Facial Nerve and Its Lesions
Key Definitions:
• Facial nerve (VII): A mixed cranial nerve with motor, sensory, and parasympathetic fibers supplying muscles of facial expression, taste to anterior tongue, and secretomotor fibers to salivary and lacrimal glands.
• Chorda tympani: A branch of the facial nerve carrying taste fibers from the anterior two-thirds of the tongue and secretomotor fibers to submandibular and sublingual glands.
• Greater petrosal nerve: Parasympathetic branch of the facial nerve supplying the lacrimal gland.
• Facial palsy: Paralysis of facial muscles due to lesion of the facial nerve, leading to asymmetry of the face and loss of expression.
Lead Question (NEET PG 2015):
1. Features of facial nerve palsy are all except -
a) Loss of salivation
b) Loss of lacrimation
c) Facial muscle paralysis
d) Loss of taste sensation from posterior tongue
Answer: d) Loss of taste sensation from posterior tongue
Explanation: The facial nerve supplies taste fibers to the anterior two-thirds of the tongue via the chorda tympani. Taste from the posterior one-third of the tongue is supplied by the glossopharyngeal nerve (IX). Therefore, facial nerve palsy leads to loss of taste from the anterior tongue, not the posterior. Other features include paralysis of muscles of facial expression, loss of salivation from submandibular and sublingual glands, and loss of lacrimation due to greater petrosal nerve involvement. Hence, the correct answer is “Loss of taste sensation from posterior tongue.”
Guessed Questions (Related to Facial Nerve and Its Lesions):
2. The facial nerve exits the skull through which foramen?
a) Foramen ovale
b) Stylomastoid foramen
c) Jugular foramen
d) Internal acoustic meatus
Answer: b) Stylomastoid foramen
Explanation: After passing through the facial canal in the temporal bone, the facial nerve exits the skull via the stylomastoid foramen and enters the parotid gland, where it divides into its five terminal branches supplying facial muscles.
3. Which branch of the facial nerve carries taste sensation?
a) Greater petrosal nerve
b) Chorda tympani
c) Auriculotemporal nerve
d) Lingual nerve
Answer: b) Chorda tympani
Explanation: The chorda tympani branch carries taste sensation from the anterior two-thirds of the tongue and parasympathetic fibers to submandibular and sublingual glands via the lingual nerve.
4. A patient presents with inability to close his eye and drooping of the mouth on one side. Which nerve is affected?
a) Trigeminal nerve
b) Facial nerve
c) Glossopharyngeal nerve
d) Accessory nerve
Answer: b) Facial nerve
Explanation: Damage to the facial nerve causes paralysis of orbicularis oculi and orbicularis oris muscles, leading to inability to close the eye and drooping of the mouth corner — classic features of facial nerve palsy.
5. Bell’s palsy involves a lesion of which structure?
a) Upper motor neuron
b) Lower motor neuron of facial nerve
c) Glossopharyngeal nerve
d) Trigeminal nerve
Answer: b) Lower motor neuron of facial nerve
Explanation: Bell’s palsy is a lower motor neuron lesion of the facial nerve, resulting in flaccid paralysis of all muscles of facial expression on the affected side, including the forehead.
6. Which of the following structures is not supplied by the facial nerve?
a) Lacrimal gland
b) Submandibular gland
c) Parotid gland
d) Sublingual gland
Answer: c) Parotid gland
Explanation: The parotid gland is supplied by parasympathetic fibers from the glossopharyngeal nerve, not the facial nerve. The facial nerve passes through but does not innervate it.
7. A lesion of the facial nerve proximal to the geniculate ganglion will result in:
a) Only facial paralysis
b) Loss of lacrimation, salivation, and taste
c) Loss of corneal reflex only
d) Loss of hearing
Answer: b) Loss of lacrimation, salivation, and taste
Explanation: Lesion proximal to the geniculate ganglion affects all branches — greater petrosal (lacrimation), chorda tympani (taste and salivation), and motor fibers, leading to multiple deficits.
8. The greater petrosal nerve carries parasympathetic fibers to:
a) Parotid gland
b) Lacrimal gland
c) Submandibular gland
d) Sublingual gland
Answer: b) Lacrimal gland
Explanation: The greater petrosal nerve, a branch of the facial nerve, carries preganglionic parasympathetic fibers to the pterygopalatine ganglion, from where postganglionic fibers supply the lacrimal gland to stimulate tear secretion.
9. Which muscle of the middle ear is supplied by the facial nerve?
a) Tensor tympani
b) Stapedius
c) Tensor veli palatini
d) Levator veli palatini
Answer: b) Stapedius
Explanation: The stapedius muscle, supplied by the facial nerve, dampens the vibrations of the stapes to protect the inner ear from loud sounds. Paralysis causes hyperacusis (increased sound sensitivity).
10. In upper motor neuron facial palsy, which part of the face is spared?
a) Forehead
b) Lower face
c) Both sides
d) Eye muscles
Answer: a) Forehead
Explanation: In UMN facial palsy, the upper face (forehead) is spared due to bilateral cortical representation, while the contralateral lower facial muscles are affected.
11. After a temporal bone fracture, a patient presents with facial paralysis, loss of taste, and hyperacusis. The lesion is likely at which site?
a) At the stylomastoid foramen
b) At the facial canal proximal to chorda tympani
c) At the geniculate ganglion
d) At the internal acoustic meatus
Answer: b) At the facial canal proximal to chorda tympani
Explanation: A lesion at this site affects motor fibers (facial paralysis), chorda tympani (loss of taste), and stapedius (hyperacusis). The location explains the combination of these clinical findings.