Chapter: Head and Neck Anatomy; Topic: Muscles of the Neck; Subtopic: Scalenus Anterior Muscle
Keyword Definitions:
• Scalenus Anterior: A deep muscle of the neck that lies between the subclavian artery and vein, arising from cervical vertebrae and inserted on the scalene tubercle of the first rib.
• Phrenic Nerve: A motor nerve to the diaphragm that descends on the anterior surface of the scalenus anterior.
• Subclavian Artery: The main artery of the upper limb passing posterior to scalenus anterior.
• Subclavian Vein: Major vein draining the upper limb, lying anterior to scalenus anterior.
Lead Question – 2014
The key to the root of the neck is the scalenus anterior muscle. Which among the following is TRUE about scalenus anterior?
a) Not Pierced by phrenic nerve
b) Attached to scalene tubercle on 2nd rib
c) Separates subclavian artery from subclavian vein
d) Pierced by phrenic nerve
Explanation:
The scalenus anterior muscle originates from transverse processes of C3–C6 and inserts into the scalene tubercle on the first rib. The phrenic nerve passes on its anterior surface but does not pierce it. It separates the subclavian vein (anterior) from the subclavian artery (posterior). Therefore, option (c) is correct.
1) Which structure passes anterior to the scalenus anterior muscle?
a) Subclavian vein
b) Subclavian artery
c) Brachial plexus
d) Sympathetic trunk
Explanation:
The subclavian vein lies anterior to the scalenus anterior, while the subclavian artery and brachial plexus pass posteriorly. This anatomical relationship is key for central venous access and surgical reference in neck dissections. Thus, (a) is correct.
2) Which structure lies directly posterior to scalenus anterior?
a) Subclavian vein
b) Subclavian artery
c) External jugular vein
d) Internal jugular vein
Explanation:
The subclavian artery lies posterior to the scalenus anterior, forming a vital landmark at the root of the neck. The brachial plexus also emerges from behind this muscle. Hence, (b) is correct.
3) The scalenus anterior muscle arises from:
a) Transverse processes of C1–C4
b) Transverse processes of C3–C6
c) Spinous processes of C2–C5
d) Costal processes of C4–C7
Explanation:
Scalenus anterior originates from anterior tubercles of transverse processes of C3–C6 vertebrae and inserts onto the scalene tubercle on the first rib. This origin helps flex and laterally bend the neck. Hence, (b) is correct.
4) Which nerve lies on the anterior surface of the scalenus anterior?
a) Long thoracic nerve
b) Phrenic nerve
c) Dorsal scapular nerve
d) Suprascapular nerve
Explanation:
The phrenic nerve descends obliquely downward on the anterior surface of the scalenus anterior, deep to the prevertebral fascia. It is a key landmark during central venous catheterization. Hence, (b) is correct.
5) The scalene tubercle is found on which rib?
a) First rib
b) Second rib
c) Third rib
d) Fourth rib
Explanation:
The scalene tubercle is a small ridge on the upper surface of the first rib, serving as the insertion point for scalenus anterior. It separates the grooves for the subclavian vein and artery. Thus, (a) is correct.
6) Clinical Case: During subclavian venous catheterization, which muscle landmark is used to avoid arterial puncture?
a) Sternocleidomastoid
b) Scalenus anterior
c) Omohyoid
d) Platysma
Explanation:
The scalenus anterior separates the subclavian vein (anterior) from the artery (posterior). Knowledge of this landmark helps avoid accidental subclavian artery puncture during catheterization. Hence, (b) is correct.
7) Clinical Case: A patient has diaphragmatic paralysis due to injury of a nerve descending over the scalenus anterior. Which nerve is affected?
a) Vagus nerve
b) Phrenic nerve
c) Recurrent laryngeal nerve
d) Hypoglossal nerve
Explanation:
The phrenic nerve descends obliquely on the scalenus anterior and supplies the diaphragm. Injury causes diaphragmatic paralysis, especially during neck surgery or trauma. Thus, (b) is correct.
8) Clinical Case: A tumor compressing the structures between scalenus anterior and medius causes which condition?
a) Thoracic outlet syndrome
b) Horner’s syndrome
c) Bell’s palsy
d) Torticollis
Explanation:
Compression of the subclavian artery and lower trunk of brachial plexus between scalenus anterior and medius results in thoracic outlet syndrome, presenting with pain, paresthesia, and vascular compromise in the upper limb. Hence, (a) is correct.
9) Clinical Case: In a neck dissection, which structure is used as a landmark to identify the phrenic nerve?
a) Scalenus medius
b) Scalenus anterior
c) Omohyoid
d) Trapezius
Explanation:
The phrenic nerve runs vertically down the anterior surface of the scalenus anterior. Surgeons use this muscle as a landmark to protect the phrenic nerve during neck dissection. Thus, (b) is correct.
10) Clinical Case: A man with penetrating trauma near the root of the neck presents with bleeding from behind the scalenus anterior. The likely vessel injured is:
a) Subclavian vein
b) Subclavian artery
c) Internal jugular vein
d) External jugular vein
Explanation:
The subclavian artery lies posterior to the scalenus anterior. Injury in this location leads to pulsatile bleeding deep to the muscle. Hence, (b) is correct.
Chapter: Head and Neck Anatomy; Topic: Muscles of the Tongue; Subtopic: Embryological Origin of Tongue Muscles
Keyword Definitions:
• Occipital Myotomes: Embryonic muscle segments that give rise to intrinsic and most extrinsic muscles of the tongue.
• Palatoglossus: Muscle of the tongue derived from the 4th pharyngeal arch and supplied by the vagus nerve (cranial part of accessory nerve).
• Hypoglossal Nerve: Motor nerve that supplies all tongue muscles except palatoglossus.
• Pharyngeal Arch: Embryonic structures that form muscles and nerves of the face and neck.
Lead Question – 2014
Tongue muscle which is not developed from occipital myotome?
a) Styloglossus
b) Hyoglossus
c) Genioglossus
d) Palatoglossus
Explanation:
All muscles of the tongue, except the palatoglossus, develop from occipital myotomes and are supplied by the hypoglossal nerve. Palatoglossus arises from the fourth pharyngeal arch and is innervated by the pharyngeal branch of the vagus nerve. Hence, palatoglossus is the only tongue muscle not derived from occipital myotome. Correct answer: (d).
1) Which nerve supplies all intrinsic and extrinsic muscles of the tongue except one?
a) Glossopharyngeal nerve
b) Hypoglossal nerve
c) Vagus nerve
d) Trigeminal nerve
Explanation:
The hypoglossal nerve (cranial nerve XII) supplies all intrinsic and extrinsic tongue muscles except the palatoglossus, which is supplied by the vagus nerve via the pharyngeal plexus. This distinction is important in neurological testing of tongue deviation. Hence, (b) is correct.
2) Which tongue muscle is supplied by the vagus nerve?
a) Genioglossus
b) Styloglossus
c) Hyoglossus
d) Palatoglossus
Explanation:
The palatoglossus muscle is the only tongue muscle supplied by the vagus nerve through the pharyngeal plexus. It functions to elevate the posterior part of the tongue during swallowing. All other tongue muscles receive innervation from the hypoglossal nerve. Thus, (d) is correct.
3) The hypoglossal nerve is derived from which embryonic structure?
a) First pharyngeal arch
b) Occipital myotomes
c) Neural crest cells
d) Mandibular prominence
Explanation:
The hypoglossal nerve develops from occipital myotomes, which migrate anteriorly to form the intrinsic and extrinsic muscles of the tongue. This embryological link explains its motor supply to the tongue. Therefore, (b) is correct.
4) Which muscle forms the bulk of the tongue and is responsible for protrusion?
a) Genioglossus
b) Hyoglossus
c) Styloglossus
d) Palatoglossus
Explanation:
The genioglossus is the largest and most powerful tongue muscle, responsible for protrusion and depression of the tongue. It arises from the superior mental spine of the mandible. Injury to its nerve supply causes tongue deviation. Hence, (a) is correct.
5) Clinical Case: A patient with tongue deviation to the right has a lesion of which nerve?
a) Left hypoglossal nerve
b) Right hypoglossal nerve
c) Glossopharyngeal nerve
d) Vagus nerve
Explanation:
Unilateral hypoglossal nerve paralysis causes deviation of the tongue toward the affected side upon protrusion due to unopposed action of the opposite genioglossus. Hence, deviation to the right indicates right hypoglossal nerve damage. Answer: (b).
6) Clinical Case: During swallowing, the posterior part of the tongue is elevated by which muscle?
a) Genioglossus
b) Palatoglossus
c) Hyoglossus
d) Styloglossus
Explanation:
Palatoglossus elevates the posterior tongue to aid swallowing, closing the oropharyngeal isthmus. It’s supplied by the vagus nerve via the pharyngeal plexus. This function distinguishes it from other extrinsic muscles. Thus, (b) is correct.
7) Clinical Case: In a patient with lesion of the vagus nerve, which tongue function is most affected?
a) Protrusion
b) Retraction
c) Elevation of posterior tongue
d) Depression
Explanation:
The vagus nerve supplies the palatoglossus muscle, which elevates the posterior tongue during swallowing. Vagus nerve damage leads to dysphagia and poor closure of the oropharyngeal isthmus. Therefore, (c) is correct.
8) The styloglossus muscle acts to:
a) Protrude tongue
b) Retract and elevate tongue
c) Depress tongue
d) Flatten tongue
Explanation:
The styloglossus retracts and elevates the tongue. It originates from the styloid process and inserts into the lateral tongue. This muscle assists in swallowing and repositioning the tongue after protrusion. Hence, (b) is correct.
9) The hyoglossus muscle arises from:
a) Hyoid bone
b) Styloid process
c) Mandible
d) Palatine aponeurosis
Explanation:
The hyoglossus originates from the greater horn and body of the hyoid bone. It depresses the sides of the tongue and assists in retracting it. It is innervated by the hypoglossal nerve. Hence, (a) is correct.
10) Clinical Case: During thyroid surgery, accidental damage to the hypoglossal nerve would affect which function?
a) Vocal cord movement
b) Tongue movement
c) Swallowing reflex only
d) Soft palate elevation
Explanation:
The hypoglossal nerve controls intrinsic and extrinsic tongue muscles (except palatoglossus). Damage leads to deviation, atrophy, and difficulty in speech and swallowing. Vocal cord movements remain unaffected as they depend on recurrent laryngeal nerve. Hence, (b) is correct.
Chapter: Ear Anatomy; Topic: Temporal Bone and Mastoid Air Cells; Subtopic: Korner’s Septum
Keyword Definitions:
Korner’s Septum: A bony plate separating the petrosal and squamous portions of the mastoid air cells, a remnant of the petrosquamous suture.
Petrosquamous Suture: The junction between the petrous and squamous parts of the temporal bone.
Mastoid Air Cells: Air-filled spaces within the mastoid part of the temporal bone communicating with the middle ear cavity.
Temporal Bone: Bone of the skull containing structures of the ear and part of the cranial base.
Lead Question – 2014
Korner's septum is seen in?
a) Petrosquamous suture
b) Temporosquamous suture
c) Petromastoid suture
d) Frontozygomatic suture
Explanation: Korner’s septum is a remnant of the petrosquamous suture that separates the petrous and squamous parts of the temporal bone. It may cause surgical difficulty during mastoidectomy by obscuring mastoid air cell communication. It marks the boundary between anatomic compartments of mastoid cells. Hence, the correct answer is Petrosquamous suture.
1) The mastoid antrum communicates with which part of the middle ear?
a) Epitympanum
b) Mesotympanum
c) Hypotympanum
d) Eustachian tube
Explanation: The mastoid antrum is a large air-filled cavity within the mastoid process that communicates directly with the epitympanum (attic) through the aditus ad antrum. This allows ventilation and drainage of the mastoid air cell system. Infection can spread from the middle ear to mastoid through this pathway. Answer: Epitympanum.
2) Which muscle separates the parotid gland from the mastoid process?
a) Sternocleidomastoid
b) Digastric
c) Trapezius
d) Splenius capitis
Explanation: The sternocleidomastoid muscle arises from the mastoid process and acts as a landmark for various neck structures. The parotid gland lies anteromedial to this muscle, which separates it from the mastoid process and posterior auricular structures. This anatomical relation is clinically relevant in parotid surgery. Answer: Sternocleidomastoid.
3) Tegmen tympani forms the roof of which cavity?
a) Tympanic cavity
b) Mastoid antrum
c) External auditory canal
d) Eustachian tube
Explanation: The tegmen tympani is a thin plate of bone forming the roof of the tympanic cavity and mastoid antrum. It separates the middle ear from the middle cranial fossa. Infection of the middle ear can erode this thin bone, leading to intracranial complications like meningitis. Answer: Tympanic cavity.
4) Which nerve is at risk during mastoidectomy due to its relation to Korner’s septum?
a) Facial nerve
b) Vestibulocochlear nerve
c) Glossopharyngeal nerve
d) Vagus nerve
Explanation: The facial nerve runs in the fallopian canal along the medial wall of the mastoid cavity and may be at risk during mastoidectomy if Korner’s septum is not identified. The septum can obscure landmarks and mislead the surgeon. Hence, careful anatomical identification prevents nerve injury. Answer: Facial nerve.
5) Which sinus is most closely related to the mastoid antrum posteriorly?
a) Sigmoid sinus
b) Cavernous sinus
c) Superior sagittal sinus
d) Transverse sinus
Explanation: The sigmoid sinus lies posterior to the mastoid antrum within the mastoid part of the temporal bone. In mastoiditis, infection may spread to this venous sinus, causing sigmoid sinus thrombosis—a serious intracranial complication. Hence, the posterior relation is the sigmoid sinus. Answer: Sigmoid sinus.
6) (Clinical) A 35-year-old male with chronic otitis media undergoes mastoidectomy. The surgeon encounters a bony septum dividing mastoid cells. This structure is most likely?
a) Korner’s septum
b) Tegmen tympani
c) Facial canal
d) Sinodural plate
Explanation: During mastoidectomy, a bony partition dividing mastoid air cells indicates the presence of Korner’s septum—a remnant of the petrosquamous suture. It must be removed for complete clearance. Unawareness may lead to incomplete surgery or residual infection. Answer: Korner’s septum.
7) (Clinical) In mastoiditis, infection can spread to the posterior cranial fossa through erosion of?
a) Sigmoid sinus plate
b) Tegmen tympani
c) Tympanic membrane
d) Round window
Explanation: The sigmoid sinus plate forms a thin bony barrier between mastoid air cells and the posterior cranial fossa. Infection of mastoid cells may erode this plate and spread to the sigmoid sinus or meninges. This can lead to sigmoid sinus thrombosis. Answer: Sigmoid sinus plate.
8) (Clinical) A patient with chronic ear discharge has erosion of the roof of the middle ear cavity. Which intracranial complication is most likely?
a) Temporal lobe abscess
b) Cerebellar abscess
c) Sigmoid sinus thrombosis
d) Petrositis
Explanation: Erosion of the tegmen tympani (roof of the middle ear) allows infection to spread into the temporal lobe of the brain. This may lead to a temporal lobe abscess, presenting with seizures or altered mental status. Answer: Temporal lobe abscess.
9) (Clinical) Facial nerve palsy following chronic otitis media results from erosion of?
a) Fallopian canal
b) Tegmen tympani
c) Sinodural plate
d) Lateral semicircular canal
Explanation: The facial nerve traverses the fallopian canal, which lies close to the middle ear. Chronic infection may erode this canal, leading to facial nerve paralysis. This complication indicates advanced disease requiring urgent surgical intervention. Answer: Fallopian canal.
10) (Clinical) A child with mastoiditis develops neck swelling and fever due to extension into the digastric groove. This condition is called?
a) Bezold’s abscess
b) Luc’s abscess
c) Zygomatic abscess
d) Citelli’s abscess
Explanation: Bezold’s abscess results from mastoiditis extending through the tip of the mastoid process into the digastric groove, forming a deep neck abscess. It presents with neck swelling below the ear and restricted neck movements. Answer: Bezold’s abscess.
Chapter: Cranial Nerves; Topic: Facial Nerve (VII Cranial Nerve); Subtopic: Chorda Tympani Nerve
Keyword Definitions:
Chorda Tympani: A branch of the facial nerve that carries taste fibers from the anterior two-thirds of the tongue and preganglionic parasympathetic fibers to the submandibular and sublingual glands.
Preganglionic Parasympathetic Fibers: Nerve fibers that originate from the central nervous system and synapse in peripheral ganglia before reaching the target organ.
Facial Nerve: The seventh cranial nerve that supplies muscles of facial expression and carries special sensory and parasympathetic fibers.
Submandibular Ganglion: A parasympathetic ganglion associated with the chorda tympani and lingual nerve, supplying salivary glands.
Lead Question – 2014
What is true about chorda tympani?
a) Postganglionic sympathetic
b) Preganglionic sympathetic
c) Preganglionic parasympathetic
d) Postganglionic parasympathetic
Explanation: The chorda tympani carries preganglionic parasympathetic fibers originating from the superior salivatory nucleus of the facial nerve. These fibers join the lingual nerve and synapse in the submandibular ganglion, providing secretomotor fibers to the submandibular and sublingual glands. It also conveys taste fibers from the anterior two-thirds of the tongue. Answer: Preganglionic parasympathetic.
1) The chorda tympani nerve joins which branch of the trigeminal nerve?
a) Lingual nerve
b) Inferior alveolar nerve
c) Auriculotemporal nerve
d) Buccal nerve
Explanation: The chorda tympani joins the lingual nerve, a branch of the mandibular division of the trigeminal nerve. Through this connection, it carries taste fibers from the anterior two-thirds of the tongue and parasympathetic fibers to the submandibular and sublingual glands. This anatomical association is crucial for salivation and taste perception. Answer: Lingual nerve.
2) The chorda tympani nerve passes through which cavity of the ear?
a) Tympanic cavity
b) External auditory canal
c) Mastoid antrum
d) Eustachian tube
Explanation: The chorda tympani traverses the tympanic cavity, passing between the handle of the malleus and the long process of the incus. It then exits through the petrotympanic fissure to join the lingual nerve. Its proximity to middle ear structures explains taste disturbances after middle ear infections or surgeries. Answer: Tympanic cavity.
3) Which ganglion is associated with the chorda tympani nerve?
a) Submandibular ganglion
b) Otic ganglion
c) Pterygopalatine ganglion
d) Geniculate ganglion
Explanation: The chorda tympani carries preganglionic parasympathetic fibers to the submandibular ganglion. Postganglionic fibers from this ganglion innervate the submandibular and sublingual salivary glands. This connection plays a key role in salivary secretion under parasympathetic control. Answer: Submandibular ganglion.
4) Taste sensation from the anterior two-thirds of the tongue is carried by?
a) Chorda tympani
b) Glossopharyngeal nerve
c) Vagus nerve
d) Lingual nerve only
Explanation: The chorda tympani, a branch of the facial nerve, carries taste fibers from the anterior two-thirds of the tongue via the lingual nerve. The glossopharyngeal nerve serves the posterior third, and the vagus nerve supplies the epiglottis region. Hence, the major taste pathway anteriorly is through the chorda tympani. Answer: Chorda tympani.
5) Loss of taste in the anterior two-thirds of the tongue and decreased salivation may indicate a lesion of?
a) Chorda tympani
b) Greater petrosal nerve
c) Glossopharyngeal nerve
d) Auriculotemporal nerve
Explanation: Damage to the chorda tympani results in loss of taste sensation from the anterior two-thirds of the tongue and reduced secretion from submandibular and sublingual glands. This occurs in facial nerve injury distal to the geniculate ganglion but proximal to its junction with the lingual nerve. Answer: Chorda tympani.
6) (Clinical) A 25-year-old patient reports taste loss on the left anterior tongue after otitis media. Which nerve is affected?
a) Chorda tympani
b) Glossopharyngeal
c) Lingual
d) Hypoglossal
Explanation: The chorda tympani passes through the middle ear cavity and can be damaged during infection or surgery. Loss of taste on the anterior two-thirds of the tongue on the same side and decreased salivation confirm chorda tympani involvement. Answer: Chorda tympani.
7) (Clinical) A lesion at the stylomastoid foramen will cause which deficit?
a) Facial paralysis only
b) Loss of taste and salivation
c) Loss of lacrimation
d) Loss of smell
Explanation: The chorda tympani branches off the facial nerve proximal to the stylomastoid foramen. Therefore, a lesion at the stylomastoid foramen affects only motor fibers causing facial paralysis, without loss of taste or salivation. Answer: Facial paralysis only.
8) (Clinical) During parotid surgery, which nerve function remains unaffected by facial nerve injury?
a) Taste from anterior tongue
b) Motor supply to buccinator
c) Secretion from parotid gland
d) Movement of orbicularis oculi
Explanation: The parotid gland receives parasympathetic innervation from the glossopharyngeal nerve via the otic ganglion, not the facial nerve. Thus, parotid secretion remains intact even if the facial nerve (and chorda tympani) are injured. Answer: Secretion from parotid gland.
9) (Clinical) A patient presents with reduced salivation but normal tear secretion. The lesion is most likely proximal to which branch?
a) Chorda tympani
b) Greater petrosal nerve
c) Nerve to stapedius
d) Posterior auricular nerve
Explanation: The chorda tympani carries parasympathetic fibers to salivary glands. A lesion proximal to its origin but distal to the greater petrosal nerve causes loss of salivation without affecting lacrimation. Answer: Chorda tympani.
10) (Clinical) A tumor compressing the facial nerve at the internal acoustic meatus will result in all except?
a) Facial paralysis
b) Loss of lacrimation
c) Loss of taste
d) Loss of hearing
Explanation: The internal acoustic meatus contains both facial and vestibulocochlear nerves. Compression here leads to facial paralysis, loss of taste from chorda tympani, and decreased lacrimation. Hearing loss, however, occurs if the vestibulocochlear nerve is involved. If spared, hearing remains normal. Answer: Loss of hearing (if vestibulocochlear intact).
Chapter: Cranial Nerves; Topic: Facial Nerve (VII Cranial Nerve); Subtopic: Vidian Nerve (Nerve of the Pterygoid Canal)
Keyword Definitions:
Vidian Nerve: Also known as the nerve of the pterygoid canal, it carries both parasympathetic and sympathetic fibers to the pterygopalatine ganglion.
Greater Petrosal Nerve: A branch of the facial nerve carrying preganglionic parasympathetic fibers from the superior salivatory nucleus.
Deep Petrosal Nerve: A sympathetic nerve derived from the internal carotid plexus.
Pterygopalatine Ganglion: A parasympathetic ganglion in the pterygopalatine fossa associated with facial nerve fibers for lacrimation and nasal secretions.
Lead Question – 2014
Vidian nerve is formed by union of?
a) Superficial petrosal nerve and deep petrosal nerve
b) Greater petrosal nerve and superficial petrosal nerve
c) Greater petrosal nerve and deep petrosal nerve
d) Greater petrosal nerve and external petrosal nerve
Explanation: The Vidian nerve (nerve of the pterygoid canal) is formed by the union of the greater petrosal nerve (carrying preganglionic parasympathetic fibers) and the deep petrosal nerve (carrying postganglionic sympathetic fibers). It passes through the pterygoid canal to reach the pterygopalatine ganglion, where parasympathetic fibers synapse and sympathetic fibers pass without synapse. Answer: Greater petrosal nerve and deep petrosal nerve.
1) The Vidian nerve passes through which bony canal?
a) Carotid canal
b) Pterygoid canal
c) Optic canal
d) Foramen rotundum
Explanation: The Vidian nerve traverses the pterygoid canal, which lies within the sphenoid bone. It connects the foramen lacerum region to the pterygopalatine fossa. The canal transmits the nerve along with accompanying vessels. Its course is important during surgical approaches to the skull base. Answer: Pterygoid canal.
2) The parasympathetic fibers of the Vidian nerve synapse in which ganglion?
a) Otic ganglion
b) Submandibular ganglion
c) Pterygopalatine ganglion
d) Ciliary ganglion
Explanation: The parasympathetic fibers from the greater petrosal component of the Vidian nerve synapse in the pterygopalatine ganglion. From there, postganglionic fibers supply the lacrimal gland, nasal mucosa, and palate glands, controlling secretion. The sympathetic fibers, however, pass through without synapsing. Answer: Pterygopalatine ganglion.
3) The sympathetic fibers in the Vidian nerve originate from?
a) Superior cervical ganglion
b) Middle cervical ganglion
c) Inferior cervical ganglion
d) Celiac ganglion
Explanation: The sympathetic fibers in the Vidian nerve arise from the superior cervical ganglion. They travel along the internal carotid plexus as the deep petrosal nerve, which later joins the greater petrosal nerve to form the Vidian nerve. These fibers are responsible for vasoconstriction in nasal mucosa. Answer: Superior cervical ganglion.
4) Which type of fibers are present in the Vidian nerve?
a) Only sympathetic
b) Only parasympathetic
c) Both sympathetic and parasympathetic
d) Only sensory
Explanation: The Vidian nerve carries a combination of sympathetic and parasympathetic fibers. Parasympathetic fibers arise from the facial nerve via the greater petrosal nerve, and sympathetic fibers originate from the internal carotid plexus via the deep petrosal nerve. Together, they regulate lacrimal and nasal secretions. Answer: Both sympathetic and parasympathetic.
5) The greater petrosal nerve arises from which part of the facial nerve?
a) Geniculate ganglion
b) Stylomastoid foramen
c) Chorda tympani
d) Internal acoustic meatus
Explanation: The greater petrosal nerve arises from the geniculate ganglion of the facial nerve. It carries preganglionic parasympathetic fibers destined for the lacrimal and nasal glands through the pterygopalatine ganglion. Its lesion leads to dry eyes and nasal dryness. Answer: Geniculate ganglion.
6) (Clinical) Injury to the Vidian nerve during endoscopic sinus surgery results in?
a) Loss of lacrimation and nasal dryness
b) Loss of taste sensation
c) Facial paralysis
d) Loss of hearing
Explanation: The Vidian nerve carries secretomotor fibers to lacrimal and nasal glands. Surgical injury leads to loss of lacrimation and nasal mucosal dryness. It does not affect facial motor function or taste, as those are carried by other facial branches. Answer: Loss of lacrimation and nasal dryness.
7) (Clinical) In a case of deep petrosal nerve damage, which function is lost?
a) Vasoconstriction of nasal mucosa
b) Salivation
c) Lacrimation
d) Taste sensation
Explanation: The deep petrosal nerve carries sympathetic fibers responsible for vasoconstriction in nasal mucosa. Injury leads to vasodilation, nasal congestion, and increased secretion. Other autonomic functions like lacrimation and salivation remain unaffected. Answer: Vasoconstriction of nasal mucosa.
8) (Clinical) Which symptom best indicates a lesion at the pterygopalatine ganglion?
a) Loss of lacrimation and nasal secretion
b) Loss of taste
c) Facial paralysis
d) Tinnitus
Explanation: The pterygopalatine ganglion receives parasympathetic fibers from the Vidian nerve. Lesions here lead to reduced lacrimation and nasal dryness but no facial weakness. This condition may follow trauma or skull base surgery. Answer: Loss of lacrimation and nasal secretion.
9) (Clinical) Which surgical nerve block relieves sphenopalatine neuralgia?
a) Vidian nerve block
b) Auriculotemporal nerve block
c) Lingual nerve block
d) Glossopharyngeal nerve block
Explanation: The Vidian nerve block can relieve sphenopalatine neuralgia by interrupting parasympathetic and sympathetic fibers that mediate pain and nasal secretions. It is used in refractory cases of cluster headache or chronic rhinitis. Answer: Vidian nerve block.
10) (Clinical) A lesion in the greater petrosal nerve proximal to its junction with deep petrosal nerve leads to?
a) Dry eyes and nasal mucosa
b) Excessive salivation
c) Loss of hearing
d) Facial muscle paralysis
Explanation: The greater petrosal nerve carries preganglionic parasympathetic fibers to the lacrimal and nasal glands. A lesion before its junction with the deep petrosal nerve results in dryness of eyes and nasal mucosa due to loss of secretomotor fibers. Answer: Dry eyes and nasal mucosa.
Chapter: ENT (Ear, Nose, and Throat); Topic: Nasal Cavity & Nasal Septum; Subtopic: Epistaxis and Vascular Areas of Nasal Septum
Keyword Definitions:
Woodruff’s Area: A vascular area in the posteroinferior part of the lateral nasal wall rich in venous plexus, common site for posterior epistaxis.
Epistaxis: Medical term for nosebleed, caused by rupture of nasal blood vessels.
Kiesselbach’s Plexus: Anterior nasal septal vascular network responsible for anterior epistaxis.
Posterior Epistaxis: Bleeding from deeper nasal vessels, more severe and common in elderly hypertensive patients.
Lead Question - 2014
Woodruff's area is located at ?
a) Antero-inferior part of nasal septum
b) Posteroinferior part of nasal septum
c) Superior part of nasal septum
d) Posteroinferior part of lateral nasal wall
Explanation: Woodruff’s area is found in the posteroinferior part of the lateral nasal wall, behind the inferior turbinate. It contains the Woodruff’s venous plexus, which is a common source of posterior epistaxis. This area is distinct from Kiesselbach’s plexus, which lies anteriorly. Answer: (d) Posteroinferior part of lateral nasal wall.
1) The main arterial supply of Woodruff’s area is from?
a) Sphenopalatine artery
b) Anterior ethmoidal artery
c) Facial artery
d) Greater palatine artery
The sphenopalatine artery, a terminal branch of the maxillary artery, supplies the posterior nasal cavity including Woodruff’s area. It contributes to posterior epistaxis. Bleeding here is often more severe than anterior nosebleeds. Answer: (a) Sphenopalatine artery.
2) Kiesselbach’s plexus is also known as?
a) Little’s area
b) Woodruff’s area
c) Jacobson’s plexus
d) Meckel’s area
Kiesselbach’s plexus is called Little’s area. It is situated on the anteroinferior part of the nasal septum and is the common site for anterior nosebleeds, especially in children. It receives branches from both internal and external carotid arteries. Answer: (a) Little’s area.
3) Which vessel is primarily involved in posterior epistaxis?
a) Anterior ethmoidal artery
b) Posterior ethmoidal artery
c) Sphenopalatine artery
d) Facial artery
Posterior epistaxis usually involves rupture of the sphenopalatine artery, which is a terminal branch of the maxillary artery. It causes deep bleeding, often in elderly hypertensive patients, and may require nasal packing or arterial ligation. Answer: (c) Sphenopalatine artery.
4) A 65-year-old hypertensive man presents with severe nasal bleeding not visible anteriorly. The most likely source is?
a) Kiesselbach’s plexus
b) Woodruff’s area
c) Septal branch of facial artery
d) Internal carotid artery
Severe posterior nasal bleeding in an elderly hypertensive patient is most commonly from Woodruff’s area, supplied by the sphenopalatine artery. Such posterior epistaxis often requires posterior nasal packing or cauterization. Answer: (b) Woodruff’s area.
5) Which nerve runs near Woodruff’s area and is related to nasal sensation?
a) Infraorbital nerve
b) Nasopalatine nerve
c) Greater palatine nerve
d) Olfactory nerve
The greater palatine nerve passes near Woodruff’s area, providing sensory innervation to the posterior part of the nasal cavity. It is a branch of the pterygopalatine ganglion. Answer: (c) Greater palatine nerve.
6) In posterior nasal bleeding, the best treatment option is?
a) Cauterization of Little’s area
b) Anterior nasal packing
c) Posterior nasal packing
d) Cold saline irrigation
Posterior epistaxis requires posterior nasal packing to compress Woodruff’s plexus. If unsuccessful, surgical ligation of the sphenopalatine artery or internal maxillary artery may be needed. Answer: (c) Posterior nasal packing.
7) Which structure lies superior to Woodruff’s area?
a) Middle turbinate
b) Inferior turbinate
c) Sphenoethmoidal recess
d) Nasolacrimal duct
Woodruff’s area lies below the inferior turbinate. Above it, the middle turbinate and sphenoethmoidal recess are found. Thus, the superior structure relative to Woodruff’s area is the middle turbinate. Answer: (a) Middle turbinate.
8) A patient develops nasal bleeding after trauma to the posterior lateral wall. Which venous plexus is likely involved?
a) Pterygoid plexus
b) Kiesselbach’s plexus
c) Woodruff’s plexus
d) Cavernous sinus
Trauma to the posterior lateral wall of the nasal cavity affects Woodruff’s venous plexus. This venous network causes posterior epistaxis and may be difficult to control without posterior packing. Answer: (c) Woodruff’s plexus.
9) Which part of the nasal cavity receives venous drainage from Woodruff’s area?
a) Facial vein
b) Pterygoid venous plexus
c) Cavernous sinus
d) Ophthalmic vein
Woodruff’s area drains into the pterygoid venous plexus through posterior nasal veins. This connection explains the potential spread of infection to deep facial spaces. Answer: (b) Pterygoid venous plexus.
10) During posterior epistaxis, ligation of which artery controls bleeding most effectively?
a) Facial artery
b) Internal carotid artery
c) Sphenopalatine artery
d) Lingual artery
The sphenopalatine artery supplies Woodruff’s area and is responsible for posterior epistaxis. Surgical ligation of this artery through an endoscopic approach effectively controls persistent bleeding. Answer: (c) Sphenopalatine artery.
Chapter: ENT (Ear, Nose & Throat); Topic: Middle Ear Anatomy; Subtopic: Walls and Boundaries of Middle Ear Cavity
Keyword Definitions:
Scutum: A small bony plate on the lateral wall of the middle ear near the epitympanic recess, separating the external auditory canal from the middle ear.
Epitympanic Recess: The upper part of the tympanic cavity containing the head of the malleus and body of the incus.
Middle Ear: Air-filled space within the temporal bone that transmits sound vibrations from the eardrum to the inner ear via ossicles.
Cholesteatoma: Abnormal growth of keratinizing squamous epithelium that often erodes the scutum.
Lead Question - 2014
Scutum is present in middle ear ?
a) Roof
b) Lateral wall
c) Medial wall
d) Floor
Explanation: The scutum is a thin bony ridge forming part of the lateral wall of the epitympanic recess in the middle ear. It separates the external auditory canal from the epitympanum. Erosion of the scutum is a classic sign of attic cholesteatoma. Answer: (b) Lateral wall.
1) The scutum forms a boundary between?
a) Tympanic cavity and internal ear
b) Epitympanic recess and external auditory canal
c) Mastoid antrum and tympanic cavity
d) Cochlea and vestibule
The scutum separates the epitympanic recess (upper middle ear) from the external auditory canal. It is a small but significant landmark in otologic surgery, often eroded by attic cholesteatoma. Answer: (b) Epitympanic recess and external auditory canal.
2) Scutum erosion is commonly seen in?
a) Otitis externa
b) Serous otitis media
c) Attic cholesteatoma
d) Otosclerosis
Erosion of the scutum is characteristic of attic cholesteatoma, a keratinizing lesion that damages ossicles and bone. It appears as blunting or absence of the scutum on CT scan. Answer: (c) Attic cholesteatoma.
3) The scutum lies near which ossicle in the middle ear?
a) Malleus head
b) Incus long process
c) Stapes footplate
d) Tensor tympani
The scutum is located adjacent to the head of the malleus in the epitympanic recess. The malleus and incus articulate here, forming part of the ossicular chain. Answer: (a) Malleus head.
4) A 35-year-old male with foul-smelling ear discharge and attic perforation likely has erosion of which structure?
a) Tegmen tympani
b) Scutum
c) Promontory
d) Round window
In chronic suppurative otitis media with attic perforation, cholesteatoma formation often erodes the scutum, indicating lateral attic wall destruction. It is visible in HRCT as a missing bony edge. Answer: (b) Scutum.
5) Which imaging modality best detects scutum erosion?
a) MRI
b) CT temporal bone
c) Ultrasound
d) X-ray skull
High-resolution CT scan of the temporal bone is the best imaging tool to visualize scutum erosion, ossicular status, and cholesteatoma extension. Answer: (b) CT temporal bone.
6) In which wall of the tympanic cavity is the epitympanic recess located?
a) Lateral wall
b) Roof
c) Floor
d) Medial wall
The epitympanic recess lies in the upper lateral portion of the tympanic cavity, above the level of the tympanic membrane. It houses the head of the malleus and body of the incus. Answer: (a) Lateral wall.
7) Which structure is superior to the scutum?
a) Tegmen tympani
b) Round window
c) Promontory
d) Facial canal
The tegmen tympani, forming the roof of the middle ear cavity, lies above the scutum. It separates the middle ear from the middle cranial fossa. Answer: (a) Tegmen tympani.
8) A cholesteatoma eroding the scutum will likely cause which symptom?
a) Conductive hearing loss
b) Sensorineural hearing loss
c) Vertigo only
d) Facial paralysis only
Erosion of the scutum by cholesteatoma causes conductive hearing loss due to ossicular chain disruption. The lesion may extend to mastoid or facial canal if untreated. Answer: (a) Conductive hearing loss.
9) The scutum is a part of which bone?
a) Temporal bone
b) Sphenoid bone
c) Ethmoid bone
d) Occipital bone
The scutum is a part of the squamous temporal bone. It forms part of the superior wall of the external auditory canal near the attic region. Answer: (a) Temporal bone.
10) The scutum is clinically significant because?
a) It protects the cochlea
b) It separates middle ear from inner ear
c) It is the site of early bone erosion in cholesteatoma
d) It forms the base of the mastoid antrum
The scutum is the site of early bone erosion in attic cholesteatoma. Detection of its erosion is an important radiological sign of cholesteatoma progression requiring surgical management. Answer: (c) It is the site of early bone erosion in cholesteatoma.
Chapter: ENT (Ear, Nose & Throat); Topic: Internal Ear Anatomy; Subtopic: Bony and Membranous Labyrinth
Keyword Definitions:
Bony labyrinth: A series of cavities within the petrous part of the temporal bone consisting of the cochlea, vestibule, and semicircular canals, filled with perilymph.
Membranous labyrinth: A system of sacs and ducts suspended within the bony labyrinth, filled with endolymph and includes utricle, saccule, cochlear duct, and semicircular ducts.
Utricle: A membranous sac within the vestibule responsible for sensing linear acceleration and head position.
Perilymph & Endolymph: Fluids within the labyrinths that play key roles in hearing and balance.
Lead Question - 2014
Not a part of bony labyrinth?
a) Cochlea
b) Vestibule
c) Utricle
d) Semicircular canal
Explanation: The utricle is part of the membranous labyrinth, not the bony labyrinth. The bony labyrinth includes the cochlea, vestibule, and semicircular canals, which house the membranous structures filled with endolymph. Perilymph lies between the bony and membranous labyrinths. Answer: (c) Utricle.
1) Which of the following forms part of the membranous labyrinth?
a) Cochlea
b) Saccule
c) Vestibule
d) Semicircular canal
The saccule is part of the membranous labyrinth. It lies within the vestibule and helps detect vertical linear acceleration. The cochlea, vestibule, and semicircular canals are bony structures housing membranous ducts. Answer: (b) Saccule.
2) The perilymph of the inner ear is continuous with which space?
a) Subdural space
b) Subarachnoid space
c) Epidural space
d) Middle ear cavity
Perilymph communicates with the subarachnoid space through the cochlear aqueduct. It is similar in composition to cerebrospinal fluid and surrounds the membranous labyrinth inside the bony labyrinth. Answer: (b) Subarachnoid space.
3) Which structure lies in the vestibule of the inner ear?
a) Organ of Corti
b) Utricle and saccule
c) Cochlear duct
d) Semicircular ducts
The vestibule houses the utricle and saccule of the membranous labyrinth. They contain maculae that detect head position and linear acceleration. Answer: (b) Utricle and saccule.
4) A patient with vertigo due to damage of semicircular canals will primarily lose?
a) Hearing
b) Sense of rotation
c) Vision
d) Smell
Semicircular canals detect angular (rotational) acceleration. Damage to them causes vertigo, imbalance, and nystagmus due to disturbed vestibular input. Answer: (b) Sense of rotation.
5) Which fluid fills the membranous labyrinth?
a) Perilymph
b) Endolymph
c) CSF
d) Plasma
The membranous labyrinth is filled with endolymph, a potassium-rich fluid crucial for transduction of sound and balance signals. Answer: (b) Endolymph.
6) The bony labyrinth is part of which bone?
a) Occipital
b) Temporal
c) Parietal
d) Sphenoid
The bony labyrinth lies within the dense petrous part of the temporal bone, providing protection for delicate auditory and vestibular structures. Answer: (b) Temporal.
7) Which part of the labyrinth is involved in hearing?
a) Cochlea
b) Semicircular canals
c) Utricle
d) Saccule
The cochlea converts sound waves into nerve impulses through the organ of Corti. The semicircular canals, utricle, and saccule handle balance functions. Answer: (a) Cochlea.
8) The macula in the utricle detects?
a) Angular acceleration
b) Linear acceleration and head tilt
c) Sound frequency
d) Air vibrations
The maculae in the utricle and saccule are sensory areas that detect linear acceleration and head position relative to gravity, maintaining static equilibrium. Answer: (b) Linear acceleration and head tilt.
9) A patient with Meniere’s disease has excess?
a) Endolymph
b) Perilymph
c) CSF
d) Mucus
Meniere’s disease involves endolymphatic hydrops — excessive accumulation of endolymph within the membranous labyrinth, causing vertigo, tinnitus, and fluctuating hearing loss. Answer: (a) Endolymph.
10) The vestibulocochlear nerve arises from which structures?
a) Cochlea and vestibular apparatus
b) Utricle and saccule only
c) Cochlear duct only
d) Tympanic cavity
The vestibulocochlear nerve (CN VIII) has two divisions: cochlear (from cochlea) for hearing, and vestibular (from utricle, saccule, semicircular ducts) for balance. Answer: (a) Cochlea and vestibular apparatus.
Chapter: Anatomy; Topic: Head and Neck; Subtopic: Lymphatic Drainage of Thyroid Gland
Keyword Definitions:
Thyroid gland: A butterfly-shaped endocrine gland located in the lower anterior neck, responsible for producing thyroid hormones (T3 and T4).
Lymphatic drainage: The process by which lymph from tissues drains into nearby lymph nodes for immune filtration.
Deep cervical nodes: A group of lymph nodes located along the internal jugular vein, receiving lymph from deep structures of the head and neck.
Prelaryngeal and pretracheal nodes: Small lymph nodes anterior to the larynx and trachea that also receive thyroid drainage.
Lead Question - 2014
Lymphatic drainage of thyroid gland is mainly?
a) Sublingual nodes
b) Submandibular nodes
c) Deep cervical nodes
d) Submental nodes
Explanation: The thyroid gland drains mainly into the deep cervical lymph nodes via the prelaryngeal, pretracheal, and paratracheal lymph nodes. These channels then reach the superior and inferior deep cervical groups along the internal jugular vein. Knowledge of this drainage is vital in thyroid cancer surgery. Answer: (c) Deep cervical nodes.
1) The prelaryngeal lymph node is also known as?
a) Virchow’s node
b) Delphian node
c) Sentinel node
d) Submandibular node
The prelaryngeal lymph node is called the Delphian node. It lies above the isthmus of the thyroid gland and drains the upper part of the thyroid. Its enlargement can indicate thyroid carcinoma or laryngeal cancer. Answer: (b) Delphian node.
2) Which of the following lymph nodes receive lymph from the lower pole of the thyroid gland?
a) Submandibular nodes
b) Pretracheal and paratracheal nodes
c) Deep posterior cervical nodes
d) Occipital nodes
The lower pole of the thyroid gland drains into pretracheal and paratracheal nodes before reaching the inferior deep cervical nodes. This pathway is important in the spread of papillary and follicular thyroid cancers. Answer: (b) Pretracheal and paratracheal nodes.
3) A patient with papillary carcinoma thyroid is found to have an enlarged node along the internal jugular vein. Which group is most likely involved?
a) Submental
b) Deep cervical
c) Submandibular
d) Parotid
Papillary thyroid carcinoma commonly spreads via lymphatics to the deep cervical lymph nodes along the internal jugular vein. These nodes are part of the jugulodigastric and jugulo-omohyoid groups. Answer: (b) Deep cervical.
4) The lymph from the upper pole of the thyroid primarily drains into?
a) Superior deep cervical nodes
b) Inferior deep cervical nodes
c) Submental nodes
d) Parotid nodes
Lymph from the upper pole of the thyroid drains first into the prelaryngeal (Delphian) node and then into the superior deep cervical nodes located near the internal jugular vein. Answer: (a) Superior deep cervical nodes.
5) The lymph from the isthmus of the thyroid drains mainly into?
a) Paratracheal nodes
b) Pretracheal nodes
c) Submandibular nodes
d) Preauricular nodes
The thyroid isthmus drains mainly into pretracheal nodes, which then drain into the inferior deep cervical group. The isthmus is often involved in central neck dissection in thyroid malignancy surgery. Answer: (b) Pretracheal nodes.
6) Metastasis to the left supraclavicular lymph node from thyroid carcinoma occurs through?
a) Thoracic duct
b) Subclavian vein
c) Pretracheal lymphatics
d) Vertebral vein
The left supraclavicular node (Virchow’s node) receives lymph via the thoracic duct. Thyroid cancers can rarely spread through this channel to reach it, signaling advanced disease. Answer: (a) Thoracic duct.
7) Which of the following cancers most commonly shows cervical lymph node metastasis?
a) Papillary thyroid carcinoma
b) Follicular thyroid carcinoma
c) Medullary thyroid carcinoma
d) Anaplastic carcinoma
Papillary carcinoma of the thyroid is the most common thyroid cancer and has a high tendency to spread via lymphatics to cervical nodes, especially the deep cervical and paratracheal groups. Answer: (a) Papillary thyroid carcinoma.
8) A surgeon performing total thyroidectomy must preserve which structure to prevent hoarseness?
a) External laryngeal nerve
b) Internal laryngeal nerve
c) Recurrent laryngeal nerve
d) Glossopharyngeal nerve
The recurrent laryngeal nerve runs close to the inferior thyroid artery and supplies all intrinsic laryngeal muscles except cricothyroid. Injury causes hoarseness and vocal cord paralysis. Answer: (c) Recurrent laryngeal nerve.
9) Which of the following nodes first receives lymph from thyroid malignancy?
a) Paratracheal
b) Submandibular
c) Preauricular
d) Buccal
Thyroid malignancy initially spreads to the central compartment nodes — pretracheal, paratracheal, and prelaryngeal — before involving deep cervical lymph nodes. Answer: (a) Paratracheal.
10) A patient with thyroid swelling develops dysphagia and dyspnea due to nodal enlargement in which area?
a) Superior deep cervical
b) Paratracheal
c) Submandibular
d) Buccal
Massive enlargement of paratracheal lymph nodes can compress the trachea and esophagus, causing dyspnea and dysphagia in thyroid malignancy. These nodes drain the lower thyroid and are important in staging cancer. Answer: (b) Paratracheal.
Chapter: Anatomy; Topic: Ear; Subtopic: Cochlea and Organ of Corti
Keyword Definitions:
Organ of Corti: The sensory structure located on the basilar membrane of the cochlea that contains hair cells responsible for converting sound vibrations into nerve impulses.
Basilar membrane: A flexible membrane within the cochlea on which the organ of Corti rests; it helps in sound frequency discrimination.
Cochlea: A spiral-shaped structure in the inner ear responsible for hearing.
Hair cells: Specialized auditory receptor cells in the organ of Corti that transduce mechanical sound vibrations into electrical signals.
Lead Question - 2014
Organ of Corti is situated in?
a) Basilar membrane
b) Utricle
c) Saccule
d) None of the above
Explanation: The organ of Corti is located on the basilar membrane inside the cochlear duct (scala media) of the inner ear. It consists of inner and outer hair cells, supporting cells, and the tectorial membrane. It converts mechanical sound waves into electrical impulses transmitted to the brain via the cochlear nerve. Answer: (a) Basilar membrane.
1) The tectorial membrane in the cochlea is related to?
a) Scala vestibuli
b) Scala tympani
c) Organ of Corti
d) Helicotrema
The tectorial membrane is a gelatinous structure that overlies the organ of Corti within the cochlear duct. It plays a crucial role in stimulating hair cells during sound vibration. Its shearing motion against the stereocilia triggers electrical signals. Answer: (c) Organ of Corti.
2) Which of the following fluids surrounds the organ of Corti?
a) Perilymph
b) Endolymph
c) Cerebrospinal fluid
d) Blood plasma
The organ of Corti lies in the cochlear duct, which is filled with endolymph. Endolymph is rich in potassium ions, essential for depolarizing the hair cells during sound transmission. Perilymph surrounds the duct but does not directly bathe the hair cells. Answer: (b) Endolymph.
3) Inner hair cells in the organ of Corti function primarily to?
a) Detect head position
b) Transmit sound impulses
c) Regulate perilymph pressure
d) Support outer hair cells
Inner hair cells are the primary auditory receptors that convert mechanical vibrations into nerve impulses. They synapse with afferent fibers of the cochlear nerve, transmitting auditory signals to the brain. Damage to these cells causes sensorineural hearing loss. Answer: (b) Transmit sound impulses.
4) Which structure separates scala media from scala tympani?
a) Basilar membrane
b) Reissner’s membrane
c) Vestibular membrane
d) Tectorial membrane
The basilar membrane separates the scala media (cochlear duct) from the scala tympani. It supports the organ of Corti and vibrates in response to sound, enabling frequency discrimination. Answer: (a) Basilar membrane.
5) Damage to the organ of Corti results in?
a) Conductive hearing loss
b) Sensorineural hearing loss
c) Central hearing loss
d) None of these
Destruction of the organ of Corti or its hair cells causes irreversible sensorineural hearing loss because these cells cannot regenerate. It affects perception of sound intensity and frequency discrimination. Answer: (b) Sensorineural hearing loss.
6) A 45-year-old man develops hearing loss after prolonged exposure to loud machinery. The most likely site of damage is?
a) Tympanic membrane
b) Organ of Corti
c) Eustachian tube
d) Auditory ossicles
Chronic noise exposure damages the outer hair cells of the organ of Corti, leading to noise-induced sensorineural hearing loss. The basal turn of the cochlea is affected first, causing high-frequency hearing loss. Answer: (b) Organ of Corti.
7) The nerve supply to the organ of Corti is via?
a) Vestibular nerve
b) Cochlear nerve
c) Facial nerve
d) Glossopharyngeal nerve
The organ of Corti is innervated by the cochlear division of the vestibulocochlear nerve (cranial nerve VIII). The afferent fibers synapse with inner hair cells to transmit sound to the auditory cortex. Answer: (b) Cochlear nerve.
8) Which type of hair cells are more numerous in the organ of Corti?
a) Inner hair cells
b) Outer hair cells
c) Both equal
d) Absent
The outer hair cells are more numerous, arranged in three rows, whereas inner hair cells form a single row. Outer cells amplify sound vibrations and enhance auditory sensitivity, while inner hair cells send primary auditory signals. Answer: (b) Outer hair cells.
9) The structure directly overlying the hair cells in organ of Corti is?
a) Basilar membrane
b) Tectorial membrane
c) Reissner’s membrane
d) Vestibular membrane
The tectorial membrane lies above the hair cells of the organ of Corti. Sound vibrations cause the basilar membrane to move against the tectorial membrane, bending the stereocilia and initiating auditory transduction. Answer: (b) Tectorial membrane.
10) A patient with loss of high-frequency hearing likely has damage at which part of the cochlea?
a) Apex
b) Middle turn
c) Base
d) Entire cochlea
High-frequency sounds are detected at the basal turn of the cochlea where the basilar membrane is narrow and stiff. Damage here, often from loud noises, results in high-frequency hearing loss. Answer: (c) Base.