Chapter: Anatomy
Topic: Nervous System
Subtopic: Nerve Anastomosis
Keywords:
Galen's Anastomosis: A nerve connection between the internal and external laryngeal nerves.
Recurrent Laryngeal Nerve: Branch of the vagus nerve supplying motor function to intrinsic laryngeal muscles.
Internal Laryngeal Nerve: Provides sensation to the laryngeal mucosa above the vocal cords.
External Laryngeal Nerve: Supplies the cricothyroid muscle responsible for pitch modulation.
Lead Question - 2013:
Galen's anastomosis is between ?
a) Recurrent laryngeal nerve and external laryngeal nerve
b) Recurrent laryngeal nerve and internal laryngeal nerve
c) Internal laryngeal nerve and external laryngeal nerve
d) None of the above
Answer & Explanation:
Correct answer: c) Internal laryngeal nerve and external laryngeal nerve.
Explanation: Galen's anastomosis refers to the communication between the internal and external laryngeal nerves. This connection is significant for overlapping sensory and motor innervation in the larynx, ensuring coordinated function. Understanding this anastomosis is important in surgeries to avoid vocal complications.
MCQ 1
Which nerve provides sensation above the vocal cords?
a) Recurrent laryngeal nerve
b) Internal laryngeal nerve
c) External laryngeal nerve
d) Hypoglossal nerve
Answer & Explanation:
Correct answer: b) Internal laryngeal nerve.
Explanation: The internal laryngeal nerve supplies sensory innervation to the laryngeal mucosa above the vocal cords. This nerve plays a crucial role in the cough reflex, preventing aspiration. Damage can lead to loss of sensation and predispose to aspiration pneumonia in clinical practice.
MCQ 2
The cricothyroid muscle is innervated by which nerve?
a) Recurrent laryngeal nerve
b) Internal laryngeal nerve
c) External laryngeal nerve
d) Accessory nerve
Answer & Explanation:
Correct answer: c) External laryngeal nerve.
Explanation: The external laryngeal nerve innervates the cricothyroid muscle, which adjusts vocal cord tension and modulates pitch. Clinically, damage may result in hoarseness. Understanding this is vital during thyroid surgeries to prevent vocal changes.
MCQ 3
Which statement about the recurrent laryngeal nerve is true?
a) It supplies the cricothyroid muscle.
b) It provides sensation above the vocal cords.
c) It supplies all intrinsic laryngeal muscles except the cricothyroid.
d) It is a branch of the external carotid artery.
Answer & Explanation:
Correct answer: c) It supplies all intrinsic laryngeal muscles except the cricothyroid.
Explanation: The recurrent laryngeal nerve provides motor supply to all intrinsic laryngeal muscles except the cricothyroid. This anatomical detail is crucial during neck surgeries, as injury can cause vocal cord paralysis and hoarseness.
MCQ 4 (Clinical):
A patient presents with hoarseness post-thyroidectomy. Which nerve is most likely injured?
a) Internal laryngeal nerve
b) External laryngeal nerve
c) Recurrent laryngeal nerve
d) Hypoglossal nerve
Answer & Explanation:
Correct answer: c) Recurrent laryngeal nerve.
Explanation: The recurrent laryngeal nerve is prone to injury during thyroidectomy due to its anatomical proximity. Injury leads to hoarseness or loss of voice, as it innervates the intrinsic laryngeal muscles except cricothyroid. Early recognition is essential to manage vocal dysfunction.
MCQ 5
What is the function of the external laryngeal nerve?
a) Sensory innervation above vocal cords
b) Motor supply to cricothyroid muscle
c) Motor supply to all intrinsic laryngeal muscles
d) Sensory innervation below vocal cords
Answer & Explanation:
Correct answer: b) Motor supply to cricothyroid muscle.
Explanation: The external laryngeal nerve provides motor innervation to the cricothyroid muscle, essential for modulating voice pitch. Injury affects high-pitched voice production. Knowledge of this nerve’s function aids clinicians in assessing voice disorders after surgery.
MCQ 6 - (Clinical)
Which anastomosis ensures backup sensory innervation if one laryngeal nerve is damaged?
a) Galen's anastomosis
b) Beclard's anastomosis
c) Thyrohyoid anastomosis
d) Ansell’s anastomosis
Answer & Explanation:
Correct answer: a) Galen's anastomosis.
Explanation: Galen's anastomosis connects the internal and external laryngeal nerves, providing backup sensory innervation. This redundancy ensures partial preservation of laryngeal sensation if one nerve is injured, reducing clinical deficits like aspiration.
MCQ 7
Which nerve loops around the aortic arch on the left side?
a) External laryngeal nerve
b) Internal laryngeal nerve
c) Left recurrent laryngeal nerve
d) Right recurrent laryngeal nerve
Answer & Explanation:
Correct answer: c) Left recurrent laryngeal nerve.
Explanation: The left recurrent laryngeal nerve loops around the aortic arch, while the right loops around the subclavian artery. This anatomical variation is important for surgeons to avoid inadvertent injury during mediastinal procedures.
MCQ 8 - (Clinical):
A patient has loss of high-pitched voice but normal cough reflex. Which nerve is likely damaged?
a) Recurrent laryngeal nerve
b) Internal laryngeal nerve
c) External laryngeal nerve
d) Hypoglossal nerve
Answer & Explanation:
Correct answer: c) External laryngeal nerve.
Explanation: The external laryngeal nerve controls the cricothyroid muscle, affecting pitch modulation. Its damage leads to loss of high-pitched voice without affecting the cough reflex, which depends on the internal laryngeal nerve.
MCQ 9
Which nerve is primarily responsible for cough reflex initiation?
a) External laryngeal nerve
b) Internal laryngeal nerve
c) Recurrent laryngeal nerve
d) Glossopharyngeal nerve
Answer & Explanation:
Correct answer: b) Internal laryngeal nerve.
Explanation: The internal laryngeal nerve provides sensory input to the larynx above vocal cords and is critical for initiating the cough reflex. Damage to this nerve impairs protective reflexes, leading to aspiration risk in patients.
MCQ 10 - (Clinical):
During surgery, accidental cutting of which nerve affects voice pitch but not vocal cord movement?
a) Internal laryngeal nerve
b) External laryngeal nerve
c) Recurrent laryngeal nerve
d) Vagus nerve
Answer & Explanation:
Correct answer: b) External laryngeal nerve.
Explanation: The external laryngeal nerve innervates the cricothyroid muscle, controlling voice pitch. Injury does not paralyze vocal cords but impairs pitch modulation, leading to monotonous speech. Surgeons must carefully preserve this nerve during thyroid and neck surgeries.
Topic: Skull Foramina
Subtopic: Jugular Foramen Contents
Keywords:
Jugular Foramen: An opening in the base of the skull transmitting several important structures.
Emissary Vein: Veins that connect intracranial venous sinuses with veins outside the skull, allowing blood drainage.
Vagus Nerve (CN X): A cranial nerve controlling autonomic functions and motor control of the larynx, heart, and viscera.
Mandibular Nerve (V3): The third branch of the trigeminal nerve, providing sensory and motor innervation to the lower face.
Internal Jugular Vein: Drains blood from the brain, face, and neck, exiting the skull through the jugular foramen.
Lead Question - 2013:
All pass through jugular foramen except:
a) Emissary vein
b) Vagus nerve
c) Mandibular nerve
d) Internal jugular vein
Answer & Explanation:
Correct answer: c) Mandibular nerve.
Explanation: The jugular foramen transmits the glossopharyngeal, vagus, accessory nerves, internal jugular vein, and emissary veins. The mandibular nerve (V3), part of the trigeminal nerve, passes through the foramen ovale, not the jugular foramen. This distinction is crucial in understanding cranial nerve pathways and related pathologies.
MCQ 1 :
Which cranial nerve exits through the jugular foramen?
a) Optic nerve
b) Facial nerve
c) Vagus nerve
d) Olfactory nerve
Answer & Explanation:
Correct answer: c) Vagus nerve.
Explanation: The vagus nerve (CN X) exits the skull through the jugular foramen, playing a pivotal role in autonomic control of thoracic and abdominal viscera. Clinically, injury at this site can cause voice changes and autonomic dysfunction, making its identification critical in surgery.
MCQ 2:
The emissary vein connects which two venous systems?
a) Systemic veins and arterial system
b) Intracranial venous sinuses and extracranial veins
c) Jugular vein and carotid artery
d) Cerebral veins and heart chambers
Answer & Explanation:
Correct answer: b) Intracranial venous sinuses and extracranial veins.
Explanation: Emissary veins connect the intracranial venous sinuses with veins outside the skull, providing alternate venous drainage routes. They are clinically significant as they may facilitate the spread of infections from superficial to intracranial structures, potentially leading to conditions like meningitis.
MCQ 3 :
Which nerve is not associated with the jugular foramen?
a) Glossopharyngeal nerve
b) Accessory nerve
c) Hypoglossal nerve
d) Vagus nerve
Answer & Explanation:
Correct answer: c) Hypoglossal nerve.
Explanation: The hypoglossal nerve exits the skull through the hypoglossal canal, not the jugular foramen. In contrast, the glossopharyngeal, vagus, and accessory nerves all pass through the jugular foramen. Recognizing this anatomical detail is important for surgical planning and diagnosing cranial nerve injuries.
MCQ 4 (Clinical):
A patient shows dysphagia and hoarseness after skull base fracture. Which nerve is likely injured?
a) Optic nerve
b) Mandibular nerve
c) Vagus nerve
d) Facial nerve
Answer & Explanation:
Correct answer: c) Vagus nerve.
Explanation: Dysphagia and hoarseness are typical symptoms of vagus nerve injury, which exits via the jugular foramen. Damage during skull base fractures can affect laryngeal muscle control, impairing voice and swallowing functions. Early diagnosis is essential for rehabilitation and preventing aspiration pneumonia.
MCQ 5:
Which structure is NOT transmitted by the jugular foramen?
a) Internal jugular vein
b) Glossopharyngeal nerve
c) Facial nerve
d) Accessory nerve
Answer & Explanation:
Correct answer: c) Facial nerve.
Explanation: The facial nerve exits through the stylomastoid foramen, not the jugular foramen. The jugular foramen primarily transmits the internal jugular vein, glossopharyngeal, vagus, and accessory nerves. Knowledge of these pathways helps prevent nerve injury during otologic and skull base surgeries.
MCQ 6(Clinical):
A patient has jugular foramen syndrome. Which of the following is least likely?
a) Hoarseness
b) Shoulder weakness
c) Loss of taste in anterior two-thirds of tongue
d) Dysphagia
Answer & Explanation:
Correct answer: c) Loss of taste in anterior two-thirds of tongue.
Explanation: Loss of taste in the anterior two-thirds of the tongue is mediated by the facial nerve (chorda tympani), not involved in the jugular foramen. Jugular foramen syndrome affects the glossopharyngeal, vagus, and accessory nerves, leading to hoarseness, dysphagia, and shoulder weakness.
MCQ 7:
The mandibular nerve exits the skull through which foramen?
a) Jugular foramen
b) Foramen ovale
c) Hypoglossal canal
d) Foramen magnum
Answer & Explanation:
Correct answer: b) Foramen ovale.
Explanation: The mandibular nerve (V3) exits the skull through the foramen ovale. This nerve carries both sensory and motor fibers, supplying the lower face. Distinguishing its exit point from the jugular foramen is important for diagnosing nerve entrapments and surgical interventions.
MCQ 8 (Clinical):
Following trauma, a patient shows unilateral vocal cord paralysis. Which nerve is likely affected?
a) Hypoglossal nerve
b) Vagus nerve
c) Mandibular nerve
d) Accessory nerve
Answer & Explanation:
Correct answer: b) Vagus nerve.
Explanation: The vagus nerve innervates the intrinsic laryngeal muscles. Trauma affecting the jugular foramen may impair this nerve, causing unilateral vocal cord paralysis. This leads to hoarseness and aspiration risk. Proper assessment of vocal function helps in identifying vagus nerve injuries post trauma.
MCQ 9:
Which is a function of the glossopharyngeal nerve passing through the jugular foramen?
a) Motor supply to cricothyroid
b) Sensory to external ear and oropharynx
c) Motor to tongue muscles
d) Vision processing
Answer & Explanation:
Correct answer: b) Sensory to external ear and oropharynx.
Explanation: The glossopharyngeal nerve (CN IX) carries sensory information from the external ear and oropharynx and provides taste from the posterior third of the tongue. Its passage through the jugular foramen is clinically significant, as injury may cause impaired gag reflex and taste sensation.
MCQ 10 (Clinical):
A patient has absent gag reflex but intact shoulder movement. Which structure is likely involved?
a) Accessory nerve
b) Hypoglossal nerve
c) Glossopharyngeal nerve
d) Mandibular nerve
Answer & Explanation:
Correct answer: c) Glossopharyngeal nerve.
Explanation: The glossopharyngeal nerve mediates the afferent limb of the gag reflex. Damage leads to its absence, while the accessory nerve (responsible for shoulder movement) remains intact. Understanding this helps localize cranial nerve injuries during neurological examinations.
Chapter: Anatomy
Topic: Neck Anatomy
Subtopic: Occipital Triangle Contents
Keywords:
Occipital Triangle: A subdivision of the posterior triangle of the neck containing nerves and vessels.
Great Auricular Nerve: A sensory nerve from the cervical plexus that supplies the skin over the parotid gland and auricle.
Suprascapular Nerve: A nerve from the upper trunk of the brachial plexus providing motor function to the supraspinatus and infraspinatus muscles.
Lesser Occipital Nerve: A sensory nerve providing sensation to the skin of the scalp posterior and superior to the ear.
Occipital Artery: A branch of the external carotid artery supplying the posterior scalp.
Lead Question - 2013:
All are contents of occipital triangle except:
a) Great auricular nerve
b) Suprascapular nerve
c) Lesser occipital nerve
d) Occipital artery
Answer & Explanation:
Correct answer: a) Great auricular nerve.
Explanation: The occipital triangle typically contains the accessory nerve, suprascapular nerve, lesser occipital nerve, and occipital artery. The great auricular nerve is found in the submandibular region. Recognizing anatomical contents is critical for surgical approaches and avoiding nerve injuries during neck surgeries.
MCQ 1:
Which nerve passes through the occipital triangle?
a) Hypoglossal nerve
b) Accessory nerve
c) Vagus nerve
d) Mandibular nerve
Answer & Explanation:
Correct answer: b) Accessory nerve.
Explanation: The accessory nerve (CN XI) traverses the occipital triangle, providing motor innervation to the sternocleidomastoid and trapezius muscles. This anatomical feature is clinically important during procedures in the neck region to prevent iatrogenic nerve injury and consequent shoulder dysfunction.
MCQ 2:
The suprascapular nerve arises from which part of the brachial plexus?
a) Lateral cord
b) Posterior cord
c) Upper trunk
d) Medial cord
Answer & Explanation:
Correct answer: c) Upper trunk.
Explanation: The suprascapular nerve originates from the upper trunk of the brachial plexus. It passes through the occipital triangle to innervate the supraspinatus and infraspinatus muscles. Injury to this nerve may result in weakness of shoulder abduction and external rotation, affecting daily activities.
MCQ 3:
The occipital artery is a branch of which artery?
a) Internal carotid artery
b) Subclavian artery
c) External carotid artery
d) Vertebral artery
Answer & Explanation:
Correct answer: c) External carotid artery.
Explanation: The occipital artery branches from the external carotid artery, supplying blood to the posterior scalp. In the occipital triangle, its anatomical course is relevant during surgical procedures to prevent inadvertent bleeding and ensure adequate blood supply post-intervention.
MCQ 4 (Clinical):
A patient presents with drooping shoulder after lymph node biopsy in the neck. Which nerve is most likely injured?
a) Suprascapular nerve
b) Accessory nerve
c) Lesser occipital nerve
d) Great auricular nerve
Answer & Explanation:
Correct answer: b) Accessory nerve.
Explanation: The accessory nerve supplies the sternocleidomastoid and trapezius muscles. Injury during lymph node biopsy in the posterior triangle can lead to shoulder drooping and limited arm abduction. Knowledge of its course in the occipital triangle is vital to prevent surgical complications and ensure functional preservation.
MCQ 5:
The lesser occipital nerve provides sensory innervation to:
a) Anterior neck skin
b) Posterior scalp above the ear
c) Lower face
d) Suprascapular region
Answer & Explanation:
Correct answer: b) Posterior scalp above the ear.
Explanation: The lesser occipital nerve arises from the cervical plexus and supplies the skin posterior and superior to the ear. Damage can result in sensory loss or neuralgia. Clinicians should understand this anatomy for accurate diagnosis of cervical neuralgia and during neck dissections.
MCQ 6 (Clinical):
Following neck trauma, a patient has loss of sensation behind the ear. Which nerve is likely affected?
a) Great auricular nerve
b) Lesser occipital nerve
c) Accessory nerve
d) Hypoglossal nerve
Answer & Explanation:
Correct answer: b) Lesser occipital nerve.
Explanation: The lesser occipital nerve provides sensation to the scalp posterior and superior to the ear. Trauma in the occipital triangle may damage this nerve, leading to localized sensory deficits. Early identification helps guide management and prevents chronic neuralgia complications.
MCQ 7:
Which structure is NOT a content of the occipital triangle?
a) Accessory nerve
b) Suprascapular artery
c) Brachial plexus trunks
d) Vagus nerve
Answer & Explanation:
Correct answer: d) Vagus nerve.
Explanation: The vagus nerve does not pass through the occipital triangle; it exits the skull through the jugular foramen. The accessory nerve, suprascapular artery, and brachial plexus trunks are present in the occipital triangle, knowledge crucial for surgical and diagnostic procedures in the cervical region.
MCQ 8 (Clinical):
During radical neck dissection, which nerve must be preserved to maintain shoulder function?
a) Accessory nerve
b) Vagus nerve
c) Hypoglossal nerve
d) Suprascapular nerve
Answer & Explanation:
Correct answer: a) Accessory nerve.
Explanation: The accessory nerve innervates the trapezius and sternocleidomastoid muscles, critical for shoulder elevation and head rotation. Preserving it during radical neck dissection prevents postoperative shoulder dysfunction. This highlights the importance of detailed anatomical knowledge to reduce surgical morbidity.
MCQ 9:
The great auricular nerve primarily supplies sensation to:
a) Scalp
b) Parotid region and area over the mastoid
c) Anterior neck
d) Upper limb
Answer & Explanation:
Correct answer: b) Parotid region and area over the mastoid.
Explanation: The great auricular nerve, from the cervical plexus, provides sensory innervation to the skin over the parotid gland, mastoid process, and ear. It does not pass through the occipital triangle but is relevant in surgical landmarks for neck procedures.
MCQ 10 (Clinical):
A patient reports a burning sensation over the scalp behind the ear. Which nerve is implicated?
a) Great auricular nerve
b) Accessory nerve
c) Lesser occipital nerve
d) Suprascapular nerve
Answer & Explanation:
Correct answer: c) Lesser occipital nerve.
Explanation: A burning scalp sensation behind the ear is characteristic of lesser occipital neuralgia. The nerve’s anatomical path in the occipital triangle makes it susceptible to compression or trauma. Recognizing this helps clinicians in managing neuralgic pain effectively.
Chapter: Anatomy
Topic: Skull and Nasal Cavity
Subtopic: Olfactory Region
Keywords:
Olfactory Region: The superior part of the nasal cavity responsible for smell perception.
Nasal Bone: Paired bones forming the bridge of the nose.
Cribriform Plate of Ethmoid: Horizontal plate of the ethmoid bone containing foramina for olfactory nerve fibers.
Sphenoid Bone: Bone located at the base of the skull, behind the ethmoid bone.
Temporal Bone: Bone forming part of the side and base of the skull.
Lead Question - 2013:
The roof of the olfactory region is formed by?
a) Nasal bone
b) Cribriform plate of ethmoid
c) Sphenoid
d) Temporal bone
Answer & Explanation:
Correct answer: b) Cribriform plate of ethmoid.
Explanation: The cribriform plate of the ethmoid bone forms the roof of the olfactory region. It has multiple small foramina that allow passage of olfactory nerve fibers into the nasal cavity. Its fragile nature makes it a potential site for cerebrospinal fluid leakage in trauma cases.
MCQ 1:
Which structure transmits olfactory nerve fibers into the nasal cavity?
a) Foramen magnum
b) Cribriform plate of ethmoid
c) Jugular foramen
d) Optic canal
Answer & Explanation:
Correct answer: b) Cribriform plate of ethmoid.
Explanation: The cribriform plate of the ethmoid bone contains tiny foramina allowing passage of olfactory nerve fibers from the nasal cavity to the olfactory bulb. This anatomical pathway is crucial for the sense of smell and is clinically important as it can be disrupted in skull base fractures.
MCQ 2:
Which nerve is responsible for the sense of smell?
a) Trigeminal nerve
b) Olfactory nerve
c) Facial nerve
d) Glossopharyngeal nerve
Answer & Explanation:
Correct answer: b) Olfactory nerve.
Explanation: The olfactory nerve (CN I) is responsible for transmitting smell sensations from the nasal mucosa to the olfactory bulb. Its fibers pass through the cribriform plate. Damage to this nerve leads to anosmia, which is the loss of the sense of smell, often following head trauma.
MCQ 3:
The cribriform plate is part of which bone?
a) Frontal bone
b) Sphenoid bone
c) Ethmoid bone
d) Occipital bone
Answer & Explanation:
Correct answer: c) Ethmoid bone.
Explanation: The cribriform plate is a horizontal part of the ethmoid bone. It forms the roof of the nasal cavity and supports the olfactory bulb. The small perforations allow the olfactory nerve fibers to pass, and any injury here can lead to cerebrospinal fluid leaks.
MCQ 4 (Clinical):
A patient presents with anosmia following head trauma. Which structure is most likely injured?
a) Cribriform plate
b) Nasal septum
c) Sphenoid sinus
d) Frontal sinus
Answer & Explanation:
Correct answer: a) Cribriform plate.
Explanation: Trauma to the cribriform plate of the ethmoid bone may damage the olfactory nerve fibers passing through its foramina, leading to anosmia. Early identification of this injury is crucial for managing CSF leaks and preventing complications such as meningitis.
MCQ 5:
Which bone does NOT contribute to the nasal cavity structure?
a) Nasal bone
b) Maxilla
c) Temporal bone
d) Ethmoid bone
Answer & Explanation:
Correct answer: c) Temporal bone.
Explanation: The temporal bone does not contribute to the structure of the nasal cavity. Instead, it forms part of the lateral skull base. The nasal bone, maxilla, and ethmoid bone collectively form the framework of the nasal cavity, supporting nasal structures and passage of nerves and vessels.
MCQ 6 (Clinical):
CSF rhinorrhea following head injury suggests a breach in which anatomical structure?
a) Nasal bone
b) Cribriform plate
c) Sphenoid bone
d) Maxillary sinus
Answer & Explanation:
Correct answer: b) Cribriform plate.
Explanation: A fracture of the cribriform plate of the ethmoid bone can lead to cerebrospinal fluid leakage into the nasal cavity, manifesting as CSF rhinorrhea. This condition increases the risk of meningitis and requires surgical repair for the breach to prevent complications.
MCQ 7:
Which of the following is a clinical test for olfactory nerve function?
a) Finger-nose test
b) Smell identification test
c) Pupillary light reflex
d) Gag reflex
Answer & Explanation:
Correct answer: b) Smell identification test.
Explanation: The smell identification test assesses olfactory nerve function by having patients identify familiar odors. This helps diagnose anosmia or hyposmia, which may be caused by trauma to the cribriform plate, neurodegenerative diseases, or infections.
MCQ 8 (Clinical):
A patient with a tumor at the cribriform plate may present with which symptom?
a) Hearing loss
b) Loss of smell
c) Double vision
d) Facial muscle weakness
Answer & Explanation:
Correct answer: b) Loss of smell.
Explanation: A tumor at the cribriform plate can compress the olfactory nerve, leading to anosmia. Such lesions are clinically significant as they may go unnoticed until advanced stages. Early detection is vital to prevent further neurological deficits and enable appropriate surgical management.
MCQ 9:
Which nerve fiber type passes through the cribriform plate?
a) Motor fibers
b) Sensory fibers
c) Mixed fibers
d) Autonomic fibers
Answer & Explanation:
Correct answer: b) Sensory fibers.
Explanation: The olfactory nerve consists of sensory fibers that transmit smell information from the nasal mucosa to the olfactory bulb through the cribriform plate. This pathway is critical for olfaction, and damage results in loss of smell perception, a common issue after head trauma.
MCQ 10 (Clinical):
A patient with anosmia and clear nasal discharge likely has which condition?
a) Chronic sinusitis
b) Allergic rhinitis
c) CSF rhinorrhea
d) Deviated nasal septum
Answer & Explanation:
Correct answer: c) CSF rhinorrhea.
Explanation: Anosmia accompanied by clear, watery nasal discharge suggests CSF rhinorrhea due to cribriform plate injury. This condition poses infection risks like meningitis. Identifying the origin of the leak using beta-2 transferrin testing is essential for proper surgical management and preventing complications.
Chapter: Anatomy
Topic: Ear Anatomy
Subtopic: Chorda Tympani
Keywords:
Chorda Tympani: A branch of the facial nerve that carries taste sensations and parasympathetic fibers.
Middle Ear: Air-filled cavity in the temporal bone containing auditory ossicles.
Inner Ear: Contains cochlea and vestibular apparatus, responsible for hearing and balance.
External Auditory Canal: Tube running from the outer ear to the tympanic membrane (eardrum).
Lead Question - 2013:
Chorda tympani is a part of?
a) Middle ear
b) Inner ear
c) External auditory canal
d) None of the above
Answer & Explanation:
Correct answer: a) Middle ear.
Explanation: The chorda tympani is a branch of the facial nerve (CN VII) that traverses the middle ear cavity. It carries taste fibers from the anterior two-thirds of the tongue and parasympathetic fibers to salivary glands. Its anatomical course makes it vulnerable during middle ear surgeries, potentially causing taste disturbances.
MCQ 1:
The chorda tympani carries which type of fibers?
a) Motor fibers only
b) Sensory fibers only
c) Taste and parasympathetic fibers
d) Somatic sensory fibers
Answer & Explanation:
Correct answer: c) Taste and parasympathetic fibers.
Explanation: The chorda tympani carries taste fibers from the anterior two-thirds of the tongue and parasympathetic fibers to the submandibular and sublingual salivary glands. Understanding its anatomy is essential during middle ear surgeries to prevent postoperative taste disorders or xerostomia.
MCQ 2:
Chorda tympani is a branch of which cranial nerve?
a) Trigeminal nerve (CN V)
b) Facial nerve (CN VII)
c) Glossopharyngeal nerve (CN IX)
d) Vagus nerve (CN X)
Answer & Explanation:
Correct answer: b) Facial nerve (CN VII).
Explanation: The chorda tympani branches from the facial nerve and carries taste sensations and parasympathetic fibers. Damage during middle ear surgery can cause loss of taste in the anterior tongue and reduced salivation, emphasizing the need for careful surgical technique in otologic procedures.
MCQ 3:
Which structure does the chorda tympani pass through?
a) Internal auditory canal
b) Middle ear cavity
c) External auditory canal
d) Cochlear duct
Answer & Explanation:
Correct answer: b) Middle ear cavity.
Explanation: The chorda tympani runs through the middle ear cavity between the malleus and incus. It is susceptible to injury during middle ear surgeries, such as tympanoplasty or mastoidectomy, which may result in taste disturbances or dry mouth due to loss of parasympathetic innervation.
MCQ 4 (Clinical):
A patient complains of loss of taste in the anterior two-thirds of the tongue after ear surgery. Which nerve is likely injured?
a) Glossopharyngeal nerve
b) Hypoglossal nerve
c) Chorda tympani
d) Vagus nerve
Answer & Explanation:
Correct answer: c) Chorda tympani.
Explanation: The chorda tympani carries taste sensation from the anterior two-thirds of the tongue. Injury during middle ear procedures leads to loss of taste in that region. Recognizing this risk allows surgeons to plan safer approaches, preserving nerve integrity and reducing postoperative complications.
MCQ 5:
The parasympathetic fibers of the chorda tympani innervate which glands?
a) Parotid gland
b) Submandibular and sublingual glands
c) Lacrimal gland
d) Thyroid gland
Answer & Explanation:
Correct answer: b) Submandibular and sublingual glands.
Explanation: The chorda tympani carries parasympathetic fibers to the submandibular and sublingual salivary glands, facilitating saliva production. Disruption of these fibers during ear surgeries can cause xerostomia, impacting oral health and digestion, making anatomical knowledge vital for clinicians.
MCQ 6 (Clinical):
A patient presents with dry mouth and loss of taste in the anterior tongue post ear infection. Which nerve is affected?
a) Hypoglossal nerve
b) Chorda tympani
c) Glossopharyngeal nerve
d) Mandibular nerve
Answer & Explanation:
Correct answer: b) Chorda tympani.
Explanation: An ear infection involving the middle ear can inflame or damage the chorda tympani, leading to loss of taste in the anterior two-thirds of the tongue and decreased salivation from submandibular and sublingual glands. Recognizing this aids in targeted treatment to restore function.
MCQ 7:
Which other cranial nerve contributes to taste sensation besides the chorda tympani?
a) Trigeminal nerve
b) Glossopharyngeal nerve
c) Vagus nerve
d) Hypoglossal nerve
Answer & Explanation:
Correct answer: b) Glossopharyngeal nerve.
Explanation: The glossopharyngeal nerve (CN IX) supplies taste sensation to the posterior one-third of the tongue, while the chorda tympani supplies the anterior two-thirds. Damage to either can result in ageusia, so differentiating these pathways is essential in clinical diagnosis of taste disturbances.
MCQ 8 (Clinical):
During middle ear surgery, which structure is at risk if not carefully identified?
a) Eustachian tube
b) Chorda tympani
c) Tympanic membrane
d) Semicircular canals
Answer & Explanation:
Correct answer: b) Chorda tympani.
Explanation: The chorda tympani runs through the middle ear cavity and is at risk during surgeries like tympanoplasty. Accidental injury can cause loss of taste in the anterior tongue and reduced salivary flow, necessitating meticulous surgical technique to preserve nerve integrity and prevent postoperative complications.
MCQ 9:
The chorda tympani merges with which nerve to reach the tongue?
a) Lingual nerve
b) Hypoglossal nerve
c) Glossopharyngeal nerve
d) Facial nerve trunk
Answer & Explanation:
Correct answer: a) Lingual nerve.
Explanation: The chorda tympani joins the lingual nerve, a branch of the mandibular nerve (V3), to carry taste sensations and parasympathetic fibers to the anterior two-thirds of the tongue. Understanding this anatomical relationship helps in avoiding nerve injury during oral or otologic surgeries.
MCQ 10 (Clinical):
A patient reports altered taste and dry mouth after facial nerve palsy. Which branch is most likely affected?
a) Temporal branch
b) Zygomatic branch
c) Chorda tympani
d) Buccal branch
Answer & Explanation:
Correct answer: c) Chorda tympani.
Explanation: In facial nerve palsy, the chorda tympani may be affected, causing loss of taste in the anterior two-thirds of the tongue and decreased salivation from submandibular and sublingual glands. This emphasizes the importance of preserving nerve branches during facial surgeries to maintain function.
Topic: Ear Anatomy
Subtopic: Stapedius Nerve
Keywords:
Stapedius Nerve: A small branch of the facial nerve that innervates the stapedius muscle in the middle ear.
Trigeminal Nerve (CN V): Supplies motor function to muscles of mastication and sensory to face.
Facial Nerve (CN VII): Provides motor innervation to facial muscles and carries taste and parasympathetic fibers.
Vagus Nerve (CN X): Supplies parasympathetic fibers to thoracic and abdominal organs and sensory/motor fibers to larynx and pharynx.
Lead Question - 2013:
Stapedius nerve is a branch of?
a) Trigeminal nerve
b) Facial nerve
c) Vagus nerve
d) None
Answer & Explanation:
Correct answer: b) Facial nerve.
Explanation: The stapedius nerve is a branch of the facial nerve (CN VII). It innervates the stapedius muscle in the middle ear, which stabilizes the stapes bone to dampen loud sounds. Dysfunction can lead to hyperacusis, highlighting the nerve's clinical importance in auditory protection and sound modulation.
MCQ 1:
The stapedius muscle helps to:
a) Amplify sound
b) Stabilize the stapes
c) Transmit sound to the cochlea
d) Open the Eustachian tube
Answer & Explanation:
Correct answer: b) Stabilize the stapes.
Explanation: The stapedius muscle dampens excessive vibrations of the stapes bone to protect the inner ear from loud sounds. Innervated by the stapedius nerve (branch of facial nerve), its dysfunction causes hyperacusis. Understanding this helps in diagnosing auditory sensitivity disorders after middle ear pathology or surgery.
MCQ 2:
Damage to the facial nerve can cause which auditory symptom?
a) Sensorineural hearing loss
b) Conductive hearing loss
c) Hyperacusis
d) Tinnitus
Answer & Explanation:
Correct answer: c) Hyperacusis.
Explanation: Damage to the stapedius nerve branch of the facial nerve results in paralysis of the stapedius muscle. This reduces damping of sound vibrations, leading to hyperacusis—an increased sensitivity to normal sounds. Recognizing this is essential in facial nerve palsy evaluations to assess auditory system involvement.
MCQ 3:
The stapedius nerve emerges from which part of the facial nerve?
a) Intracranial segment
b) Geniculate ganglion
c) Tympanic segment
d) Mastoid segment
Answer & Explanation:
Correct answer: c) Tympanic segment.
Explanation: The stapedius nerve branches from the tympanic segment of the facial nerve. It passes through the middle ear to innervate the stapedius muscle. Knowledge of this anatomy is critical during middle ear surgery to avoid damaging the nerve, which would cause hyperacusis and affect sound modulation.
MCQ 4 (Clinical):
A patient with Bell's palsy reports sensitivity to loud sounds. Which nerve is likely involved?
a) Auriculotemporal nerve
b) Vestibulocochlear nerve
c) Stapedius nerve
d) Glossopharyngeal nerve
Answer & Explanation:
Correct answer: c) Stapedius nerve.
Explanation: In Bell's palsy, the facial nerve is inflamed or compressed, potentially affecting the stapedius nerve. This leads to hyperacusis due to lack of stapes stabilization. Identifying this clinical sign aids in diagnosis and indicates the extent of facial nerve involvement.
MCQ 5:
The primary function of the stapedius muscle is to:
a) Transmit sound to the cochlea
b) Amplify high-frequency sounds
c) Stabilize the stapes during loud noise
d) Regulate middle ear pressure
Answer & Explanation:
Correct answer: c) Stabilize the stapes during loud noise.
Explanation: The stapedius muscle contracts in response to loud sounds, stabilizing the stapes to dampen excessive vibration and protect the inner ear. This reflex, known as the acoustic reflex, is essential for auditory system protection and is mediated via the facial nerve pathway.
MCQ 6 (Clinical):
Which condition may result from stapedius muscle paralysis?
a) Otosclerosis
b) Hyperacusis
c) Conductive hearing loss
d) Vertigo
Answer & Explanation:
Correct answer: b) Hyperacusis.
Explanation: Paralysis of the stapedius muscle due to stapedius nerve damage removes its dampening effect on stapes movement. This leads to hyperacusis, where normal environmental sounds are perceived as excessively loud and uncomfortable. Understanding this helps differentiate auditory hypersensitivity disorders from other hearing impairments.
MCQ 7:
The stapedius muscle attaches to which auditory ossicle?
a) Malleus
b) Incus
c) Stapes
d) Tympanic membrane
Answer & Explanation:
Correct answer: c) Stapes.
Explanation: The stapedius muscle attaches to the neck of the stapes, the smallest bone in the human body. Its contraction stabilizes the stapes to modulate sound transmission. Injury to the stapedius nerve affects this function, emphasizing the importance of precise anatomical knowledge during middle ear surgeries.
MCQ 8 (Clinical):
During middle ear surgery, which nerve is at risk of damage affecting auditory sensitivity?
a) Facial nerve
b) Auditory nerve
c) Chorda tympani
d) Stapedius nerve
Answer & Explanation:
Correct answer: d) Stapedius nerve.
Explanation: The stapedius nerve traverses the middle ear cavity, making it vulnerable during procedures like stapedectomy. Damage results in stapedius muscle paralysis and hyperacusis. Surgeons must carefully navigate the middle ear anatomy to preserve this nerve and prevent postoperative auditory sensitivity disorders.
MCQ 9:
The stapedius reflex is primarily a protective mechanism against:
a) Low-frequency sounds
b) High-intensity sounds
c) Continuous ambient noise
d) Vestibular imbalance
Answer & Explanation:
Correct answer: b) High-intensity sounds.
Explanation: The stapedius reflex, mediated by the stapedius nerve, contracts the stapedius muscle in response to high-intensity sounds. This reduces the transmission of sound energy to the inner ear, protecting cochlear hair cells. Clinical tests of this reflex assess middle ear and facial nerve integrity.
MCQ 10 (Clinical):
A patient with congenital absence of the stapedius muscle experiences:
a) Complete deafness
b) Hyperacusis
c) Vertigo
d) Tinnitus
Answer & Explanation:
Correct answer: b) Hyperacusis.
Explanation: Congenital absence of the stapedius muscle prevents normal damping of stapes vibrations, leading to hyperacusis. Patients perceive everyday sounds as painfully loud. This emphasizes the stapedius muscle’s protective role and the importance of assessing auditory reflexes in patients with unexplained sound sensitivity.
Topic: Neck Anatomy
Subtopic: Muscular Layers of Neck
Keywords:
Platysma: A superficial muscle in the anterior neck involved in facial expression.
Trapezius: A large muscle extending over the back of the neck and shoulders, moving scapula and supporting arm.
Sternocleidomastoid: A prominent muscle in the neck responsible for head rotation and flexion.
Longus Colli: A deep neck muscle located along the anterior vertebral column, stabilizing the cervical spine.
Lead Question - 2013:
Deep injury of neck always involves?
a) Platysma
b) Trapezius
c) Sternocleidomastoid
d) Longus colli
Answer & Explanation:
Correct answer: a) Platysma.
Explanation: The platysma is the most superficial muscle of the anterior neck. Any deep penetrating neck injury must traverse this thin muscle layer first. Its involvement is a critical marker during trauma assessment, as it helps determine the depth of injury and the need for further surgical exploration or imaging.
MCQ 1:
Platysma is supplied by which nerve?
a) Facial nerve (CN VII)
b) Accessory nerve (CN XI)
c) Hypoglossal nerve (CN XII)
d) Vagus nerve (CN X)
Answer & Explanation:
Correct answer: a) Facial nerve (CN VII).
Explanation: The platysma muscle is innervated by the cervical branch of the facial nerve (CN VII). It plays a role in facial expression by tensing the skin of the neck. Knowledge of this innervation is important during neck surgeries to avoid iatrogenic nerve damage.
MCQ 2:
Which muscle is primarily responsible for head rotation?
a) Platysma
b) Sternocleidomastoid
c) Longus colli
d) Trapezius
Answer & Explanation:
Correct answer: b) Sternocleidomastoid.
Explanation: The sternocleidomastoid muscle, innervated by the accessory nerve (CN XI), is responsible for head rotation and flexion. Injury to this muscle can limit neck movement and should be evaluated in neck trauma or surgical cases for functional assessment and appropriate management.
MCQ 3:
Which layer is first encountered in a penetrating neck injury?
a) Longus colli
b) Platysma
c) Sternocleidomastoid
d) Prevertebral fascia
Answer & Explanation:
Correct answer: b) Platysma.
Explanation: The platysma is the most superficial muscle layer in the neck, lying just beneath the skin. Any penetrating injury that reaches deep structures must pass through the platysma. This layer's involvement helps clinicians assess the severity and depth of neck trauma during evaluation.
MCQ 4 (Clinical):
A deep stab wound in the neck penetrates the platysma. What is the next critical assessment?
a) Check for vascular injury
b) Assess skin laceration only
c) Examine for hairline fracture
d) Evaluate external auditory canal
Answer & Explanation:
Correct answer: a) Check for vascular injury.
Explanation: Once the platysma is breached in neck trauma, there is a high risk of injury to vital structures such as the carotid artery and jugular vein. Immediate assessment for vascular injury is essential to prevent exsanguination or air embolism, requiring rapid imaging or surgical exploration.
MCQ 5:
The longus colli muscle lies in relation to which structure?
a) Anterior to vertebral bodies
b) Posterior to sternocleidomastoid
c) Lateral to carotid sheath
d) Superficial to platysma
Answer & Explanation:
Correct answer: a) Anterior to vertebral bodies.
Explanation: The longus colli is a deep muscle situated along the anterior surface of cervical vertebrae, stabilizing and flexing the neck. Injury to this muscle is rare due to its deep position, but its anatomical relation to vertebrae is important in cervical spine trauma or surgery.
MCQ 6 (Clinical):
A patient presents with loss of neck flexion strength after trauma. Which muscle is likely injured?
a) Trapezius
b) Longus colli
c) Platysma
d) Sternocleidomastoid
Answer & Explanation:
Correct answer: b) Longus colli.
Explanation: The longus colli muscle plays a key role in cervical spine flexion and stabilization. Trauma to this deep neck structure may result in weakness during neck flexion and cervical instability. Diagnosis requires imaging studies, and management involves conservative or surgical treatment depending on severity.
MCQ 7:
The sternocleidomastoid inserts into which bony structure?
a) Clavicle and sternum
b) Temporal bone
c) Mandible
d) Hyoid bone
Answer & Explanation:
Correct answer: a) Clavicle and sternum.
Explanation: The sternocleidomastoid muscle originates from the manubrium of the sternum and the clavicle and inserts onto the mastoid process of the temporal bone. Its contraction results in head rotation and flexion, and injury may impair these movements, impacting neck function assessment.
MCQ 8 (Clinical):
In penetrating neck trauma, platysma penetration indicates?
a) Superficial wound
b) Deep injury potentially involving vital structures
c) Skin laceration only
d) Mandibular fracture
Answer & Explanation:
Correct answer: b) Deep injury potentially involving vital structures.
Explanation: Penetration of the platysma in neck trauma signifies a deep wound. Vital structures such as major blood vessels and the trachea may be involved, requiring immediate medical attention with imaging or surgical exploration to prevent life-threatening complications.
MCQ 9:
Which nerve innervates the sternocleidomastoid muscle?
a) Accessory nerve (CN XI)
b) Hypoglossal nerve (CN XII)
c) Vagus nerve (CN X)
d) Facial nerve (CN VII)
Answer & Explanation:
Correct answer: a) Accessory nerve (CN XI).
Explanation: The accessory nerve (CN XI) supplies motor innervation to the sternocleidomastoid and trapezius muscles. Injury to CN XI during surgical procedures in the neck can cause shoulder droop and impaired head rotation, making its anatomical course critical to avoid damage.
MCQ 10 (Clinical):
A patient has difficulty turning head to the opposite side after neck trauma. Which muscle is most likely affected?
a) Platysma
b) Sternocleidomastoid
c) Trapezius
d) Longus colli
Answer & Explanation:
Correct answer: b) Sternocleidomastoid.
Explanation: The sternocleidomastoid muscle contracts to rotate the head to the opposite side. Injury to this muscle or its nerve (accessory nerve) following trauma can cause reduced head rotation strength, highlighting the need for careful evaluation during physical and neurological examination of neck injuries.
Topic: Eye Anatomy
Subtopic: Lacrimal Apparatus
Keywords:
Lacrimal Punctum: Small openings on the medial aspect of the eyelids that drain tears into the lacrimal canaliculi.
Upper Eyelid: The superior movable fold covering the eye, containing the upper lacrimal punctum near the medial canthus.
Lower Eyelid: The inferior movable fold, containing the lower lacrimal punctum near the medial canthus.
Lacrimal Canaliculi: Small channels that transport tears from the puncta to the lacrimal sac.
Lead Question - 2013:
Lacrimal punctum of upper and lower eyelids are?
a) They are opposed
b) No relation
c) Upper punctum is medial
d) Upper punctum is lateral
Answer & Explanation:
Correct answer: a) They are opposed.
Explanation: The lacrimal puncta of the upper and lower eyelids are located at the medial ends of the eyelid margins and face each other directly. They collect tears from the ocular surface and drain them into the canaliculi. Proper anatomical alignment ensures effective tear drainage and prevents epiphora.
MCQ 1:
Function of the lacrimal puncta is to:
a) Produce tears
b) Drain tears into canaliculi
c) Secrete mucus
d) Block tear drainage
Answer & Explanation:
Correct answer: b) Drain tears into canaliculi.
Explanation: The lacrimal puncta serve as entry points for tears to drain from the eye's surface into the lacrimal canaliculi, proceeding to the lacrimal sac and nasolacrimal duct. Proper function prevents tear overflow (epiphora) and maintains ocular surface health by facilitating tear clearance.
MCQ 2:
The lacrimal puncta are located at the:
a) Lateral canthus
b) Medial canthus
c) Center of eyelid margin
d) Superior orbital rim
Answer & Explanation:
Correct answer: b) Medial canthus.
Explanation: Both upper and lower lacrimal puncta are situated at the medial canthus of the eyelids, where they collect tears and drain them into the canaliculi. Their correct position ensures effective tear drainage, and abnormalities can lead to tearing disorders or infections like dacryocystitis.
MCQ 3:
The lacrimal canaliculi drain into the:
a) Lacrimal sac
b) Nasolacrimal duct
c) Conjunctival sac
d) Orbit
Answer & Explanation:
Correct answer: a) Lacrimal sac.
Explanation: The upper and lower lacrimal canaliculi drain tears from the puncta into the lacrimal sac, which then drains into the nasolacrimal duct. This anatomical route is essential for proper tear drainage and maintaining a healthy ocular surface, preventing tear stagnation and infection.
MCQ 4 (Clinical):
A patient with epiphora may have obstruction at which structure?
a) Lacrimal puncta
b) Lacrimal gland
c) Retina
d) Cornea
Answer & Explanation:
Correct answer: a) Lacrimal puncta.
Explanation: Epiphora, or excessive tearing, often results from blockage of the lacrimal puncta or canaliculi, preventing proper tear drainage. Clinical examination of the puncta for patency is vital to diagnose causes of tearing and guide appropriate management, such as dilation or surgery.
MCQ 5:
Which part of the lacrimal apparatus produces tears?
a) Lacrimal sac
b) Lacrimal gland
c) Lacrimal puncta
d) Canaliculi
Answer & Explanation:
Correct answer: b) Lacrimal gland.
Explanation: The lacrimal gland, located in the superolateral orbit, produces the aqueous component of tears. Tears are distributed across the ocular surface and drained by the lacrimal puncta and canaliculi. Understanding this system aids in diagnosing dry eye and tear drainage disorders.
MCQ 6 (Clinical):
A patient with infection around the medial canthus may have involvement of which structure?
a) Lacrimal puncta
b) Eyelid margin
c) Nasolacrimal duct
d) Retina
Answer & Explanation:
Correct answer: a) Lacrimal puncta.
Explanation: Infections such as canaliculitis or dacryocystitis often involve the lacrimal puncta, leading to swelling, redness, and tenderness near the medial canthus. Timely recognition and treatment prevent spread of infection and maintain tear drainage function, highlighting the importance of punctal assessment in clinical exams.
MCQ 7:
The direction of lacrimal flow is from:
a) Canaliculi → Puncta → Lacrimal sac
b) Eye surface → Puncta → Canaliculi → Lacrimal sac
c) Lacrimal sac → Puncta → Eye surface
d) Lacrimal gland → Lacrimal sac → Canaliculi
Answer & Explanation:
Correct answer: b) Eye surface → Puncta → Canaliculi → Lacrimal sac.
Explanation: Tears produced by the lacrimal gland flow over the ocular surface, enter the upper and lower lacrimal puncta, pass into the canaliculi, and drain into the lacrimal sac. This unidirectional flow is crucial to tear clearance and ocular surface health.
MCQ 8 (Clinical):
Which symptom suggests lacrimal punctal stenosis?
a) Sudden vision loss
b) Persistent watery eyes
c) Eye pain
d) Eyelid drooping
Answer & Explanation:
Correct answer: b) Persistent watery eyes.
Explanation: Lacrimal punctal stenosis refers to narrowing of the punctal openings, causing impaired tear drainage and chronic tearing (epiphora). Diagnosis involves slit-lamp examination and punctal dilation tests. Recognizing this prevents complications like conjunctivitis and helps in planning corrective procedures.
MCQ 9:
The upper and lower lacrimal puncta are located:
a) On the lateral aspect of the eyelids
b) At the medial eyelid margin
c) Centrally on the eyelid
d) On the superior orbital rim
Answer & Explanation:
Correct answer: b) At the medial eyelid margin.
Explanation: The upper and lower lacrimal puncta are small openings situated at the medial ends of the eyelid margins. They collect tears from the ocular surface and direct them into the canaliculi, crucial for tear drainage and ocular surface health maintenance.
MCQ 10 (Clinical):
A blocked lacrimal punctum leads to:
a) Dry eyes
b) Epiphora
c) Visual loss
d) Glaucoma
Answer & Explanation:
Correct answer: b) Epiphora.
Explanation: Blockage of the lacrimal punctum impairs tear drainage, resulting in overflow of tears onto the cheeks, known as epiphora. Identifying this condition is critical in clinical practice to prevent chronic tearing and secondary infections, often treated by punctal dilation or surgery.
Chapter: Anatomy
Topic: Tongue Anatomy
Subtopic: Muscles of the Tongue
Keywords:
Styloglossus: Muscle that retracts and elevates the tongue; innervated by hypoglossal nerve (CN XII).
Hyoglossus: Muscle that depresses the tongue; innervated by hypoglossal nerve (CN XII).
Palatoglossus: Muscle that elevates posterior tongue and closes oropharyngeal isthmus; innervated by vagus nerve (CN X).
Genioglossus: Muscle responsible for tongue protrusion; innervated by hypoglossal nerve (CN XII).
Lead Question - 2013:
Protrusion of tongue not possible in damage of?
a) Styloglossus
b) Hyoglossus
c) Palatoglossus
d) Genioglossus
Answer & Explanation:
Correct answer: d) Genioglossus.
Explanation: The genioglossus muscle is the primary muscle responsible for tongue protrusion. It is innervated by the hypoglossal nerve (CN XII). Damage to this muscle or its nerve results in inability to protrude the tongue and deviation toward the side of the lesion, critical in neurological exams.
MCQ 1:
Which nerve innervates the genioglossus muscle?
a) Vagus nerve (CN X)
b) Hypoglossal nerve (CN XII)
c) Glossopharyngeal nerve (CN IX)
d) Trigeminal nerve (CN V)
Answer & Explanation:
Correct answer: b) Hypoglossal nerve (CN XII).
Explanation: The genioglossus muscle receives motor innervation from the hypoglossal nerve (CN XII). It is responsible for protruding the tongue. Damage to the hypoglossal nerve leads to tongue deviation and atrophy, which are key clinical signs in neurological assessments.
MCQ 2:
The palatoglossus muscle is innervated by which nerve?
a) Hypoglossal nerve (CN XII)
b) Vagus nerve (CN X)
c) Facial nerve (CN VII)
d) Accessory nerve (CN XI)
Answer & Explanation:
Correct answer: b) Vagus nerve (CN X).
Explanation: Unlike other tongue muscles, the palatoglossus is innervated by the vagus nerve (CN X) via the pharyngeal plexus. It elevates the posterior tongue and plays a role in closing the oropharyngeal isthmus, important in swallowing. Damage may cause swallowing difficulties.
MCQ 3:
Which muscle retracts and elevates the tongue?
a) Styloglossus
b) Genioglossus
c) Hyoglossus
d) Palatoglossus
Answer & Explanation:
Correct answer: a) Styloglossus.
Explanation: The styloglossus muscle, innervated by the hypoglossal nerve (CN XII), retracts and elevates the tongue. It aids in swallowing and speech. Dysfunction may affect tongue retraction, causing speech and swallowing impairments, requiring clinical assessment during neurological or ENT examinations.
MCQ 4 (Clinical):
Which muscle is paralyzed if tongue deviates toward one side on protrusion?
a) Hyoglossus
b) Genioglossus
c) Palatoglossus
d) Styloglossus
Answer & Explanation:
Correct answer: b) Genioglossus.
Explanation: Paralysis of the genioglossus muscle leads to tongue deviation toward the affected side upon protrusion, as the unopposed contralateral muscle pushes the tongue sideways. This is a key clinical sign of hypoglossal nerve damage, aiding in early neurological diagnosis.
MCQ 5:
Function of the hyoglossus muscle is to:
a) Protrude tongue
b) Retract tongue
c) Depress the tongue
d) Elevate tongue
Answer & Explanation:
Correct answer: c) Depress the tongue.
Explanation: The hyoglossus muscle, innervated by the hypoglossal nerve (CN XII), depresses the sides of the tongue. It plays a critical role in tongue movement for articulation and swallowing. Damage leads to weakness in tongue depression, contributing to speech and swallowing difficulties.
MCQ 6 (Clinical):
After hypoglossal nerve injury, which symptom is expected?
a) Difficulty in tongue protrusion
b) Inability to blink
c) Loss of palatal elevation
d) Deviation of uvula
Answer & Explanation:
Correct answer: a) Difficulty in tongue protrusion.
Explanation: Hypoglossal nerve (CN XII) injury results in paralysis of tongue muscles (except palatoglossus), leading to tongue deviation towards the affected side and difficulty protruding the tongue. These signs are essential in clinical evaluation of cranial nerve lesions and in differential diagnosis of bulbar palsies.
MCQ 7:
Which muscle elevates the posterior tongue?
a) Styloglossus
b) Palatoglossus
c) Hyoglossus
d) Genioglossus
Answer & Explanation:
Correct answer: b) Palatoglossus.
Explanation: The palatoglossus muscle elevates the posterior tongue and closes the oropharyngeal isthmus during swallowing. It is innervated by the vagus nerve (CN X). Dysfunction may present as difficulty in swallowing and speech impairment, making it a clinically important muscle in cranial nerve assessment.
MCQ 8 (Clinical):
Which nerve damage leads to inability to retract the tongue?
a) Hypoglossal nerve
b) Vagus nerve
c) Trigeminal nerve
d) Facial nerve
Answer & Explanation:
Correct answer: a) Hypoglossal nerve.
Explanation: The hypoglossal nerve (CN XII) supplies the styloglossus and hyoglossus muscles that retract the tongue. Damage to this nerve leads to weakness in tongue retraction and deviation toward the affected side, providing crucial diagnostic information in neurology.
MCQ 9:
The muscle primarily responsible for tongue protrusion is:
a) Palatoglossus
b) Styloglossus
c) Hyoglossus
d) Genioglossus
Answer & Explanation:
Correct answer: d) Genioglossus.
Explanation: The genioglossus muscle is the prime mover for tongue protrusion. Innervated by the hypoglossal nerve (CN XII), it pulls the tongue forward. Damage leads to inability to protrude the tongue and deviation to the affected side, important in clinical examinations for cranial nerve dysfunction.
MCQ 10 (Clinical):
Which clinical test assesses the function of the hypoglossal nerve?
a) Asking the patient to smile
b) Asking the patient to protrude the tongue
c) Testing the gag reflex
d) Checking pupil size
Answer & Explanation:
Correct answer: b) Asking the patient to protrude the tongue.
Explanation: Testing the hypoglossal nerve (CN XII) involves asking the patient to protrude the tongue. Any deviation or weakness indicates nerve dysfunction. This simple clinical test helps localize neurological lesions and is essential during cranial nerve examination in patients with suspected neurological disorders.
Topic: Cerebral Circulation
Subtopic: Internal Carotid Artery Branches
Keywords:
Internal Carotid Artery: Major artery supplying blood to the brain, entering the skull via the carotid canal.
Anterior Cerebral Artery: Terminal branch of the internal carotid artery supplying medial brain surfaces.
Middle Cerebral Artery: Largest terminal branch of internal carotid, supplying lateral brain regions.
Posterior Communicating Artery: Connects internal carotid artery to posterior cerebral artery, part of circle of Willis.
Cavernous Artery: Small branches supplying structures within the cavernous sinus, not a terminal branch.
Lead Question - 2013:
Terminal branches of internal carotid artery are all except?
a) Anterior cerebral artery
b) Middle cerebral artery
c) Posterior communicating artery
d) Cavernous artery
Answer & Explanation:
Correct answer: d) Cavernous artery.
Explanation: The terminal branches of the internal carotid artery are the anterior cerebral artery and middle cerebral artery. The posterior communicating artery is a branch but not terminal. The cavernous artery supplies structures within the cavernous sinus and is not considered a terminal branch. Accurate knowledge is crucial in vascular neurology.
MCQ 1:
Which artery is part of the circle of Willis?
a) Anterior cerebral artery
b) Middle cerebral artery
c) External carotid artery
d) Cavernous artery
Answer & Explanation:
Correct answer: a) Anterior cerebral artery.
Explanation: The anterior cerebral artery is a critical component of the circle of Willis, supplying medial brain surfaces and connecting via the anterior communicating artery. This anastomotic system provides collateral blood flow to the brain, important in cerebral circulation stability and stroke prevention.
MCQ 2:
The middle cerebral artery supplies which part of the brain?
a) Occipital lobe
b) Medial frontal lobe
c) Lateral cerebral hemisphere
d) Brainstem
Answer & Explanation:
Correct answer: c) Lateral cerebral hemisphere.
Explanation: The middle cerebral artery (MCA) is the largest terminal branch of the internal carotid artery and supplies the lateral cerebral hemispheres, including frontal, parietal, and temporal lobes. It is commonly involved in ischemic strokes, causing contralateral motor and sensory deficits.
MCQ 3:
Which artery connects the internal carotid artery to the posterior cerebral artery?
a) Anterior communicating artery
b) Posterior communicating artery
c) Middle cerebral artery
d) External carotid artery
Answer & Explanation:
Correct answer: b) Posterior communicating artery.
Explanation: The posterior communicating artery links the internal carotid artery to the posterior cerebral artery as part of the circle of Willis. It provides collateral circulation in cases of carotid or vertebral artery stenosis, essential for maintaining cerebral perfusion under pathological conditions.
MCQ 4 (Clinical):
Occlusion of which artery causes contralateral motor and sensory deficits?
a) Anterior cerebral artery
b) Middle cerebral artery
c) Posterior communicating artery
d) Cavernous artery
Answer & Explanation:
Correct answer: b) Middle cerebral artery.
Explanation: Middle cerebral artery (MCA) occlusion leads to contralateral motor and sensory deficits, especially in the face and upper limb, along with aphasia if dominant hemisphere is involved. Rapid identification is crucial in stroke management to prevent permanent neurological damage.
MCQ 5:
The anterior cerebral artery primarily supplies which region?
a) Lateral temporal lobe
b) Medial frontal and parietal lobes
c) Occipital lobe
d) Brainstem
Answer & Explanation:
Correct answer: b) Medial frontal and parietal lobes.
Explanation: The anterior cerebral artery (ACA) supplies the medial surfaces of the frontal and parietal lobes. ACA stroke may cause weakness in the contralateral lower limb and urinary incontinence, making its clinical identification important in cerebrovascular diagnosis.
MCQ 6 (Clinical):
A patient has reduced blood flow in the circle of Willis. Which artery provides collateral flow?
a) Posterior communicating artery
b) External carotid artery
c) Superior thyroid artery
d) Cavernous artery
Answer & Explanation:
Correct answer: a) Posterior communicating artery.
Explanation: The posterior communicating artery forms a critical part of the circle of Willis, allowing collateral circulation between the anterior and posterior circulations. In cases of internal carotid or vertebrobasilar artery stenosis, it ensures adequate cerebral perfusion, preventing ischemic damage.
MCQ 7:
Which of the following is not a branch of the internal carotid artery?
a) Ophthalmic artery
b) Anterior choroidal artery
c) Middle cerebral artery
d) Facial artery
Answer & Explanation:
Correct answer: d) Facial artery.
Explanation: The facial artery arises from the external carotid artery and supplies superficial facial structures. The internal carotid artery primarily supplies intracranial structures, giving branches like the ophthalmic, anterior choroidal, and middle cerebral arteries. Understanding these origins is important in vascular and surgical anatomy.
MCQ 8 (Clinical):
Posterior communicating artery aneurysm typically affects which nerve?
a) Optic nerve (CN II)
b) Oculomotor nerve (CN III)
c) Trigeminal nerve (CN V)
d) Hypoglossal nerve (CN XII)
Answer & Explanation:
Correct answer: b) Oculomotor nerve (CN III).
Explanation: Aneurysm of the posterior communicating artery often compresses the oculomotor nerve, causing ptosis, diplopia, and pupil dilation (blown pupil). Recognizing these clinical signs is crucial in diagnosing intracranial aneurysms, facilitating timely neurosurgical intervention.
MCQ 9:
The ophthalmic artery is a branch of which artery?
a) External carotid artery
b) Internal carotid artery
c) Vertebral artery
d) Subclavian artery
Answer & Explanation:
Correct answer: b) Internal carotid artery.
Explanation: The ophthalmic artery is the first major branch of the internal carotid artery after it enters the cranial cavity. It supplies the eye and orbit, and its compromise may cause visual loss, making it essential in ophthalmologic and neurologic assessments.
MCQ 10 (Clinical):
In carotid artery dissection, which artery is primarily involved?
a) Internal carotid artery
b) External carotid artery
c) Subclavian artery
d) Vertebral artery
Answer & Explanation:
Correct answer: a) Internal carotid artery.
Explanation: Carotid artery dissection often involves the internal carotid artery, leading to stenosis or pseudoaneurysm formation. It can present with ipsilateral headache, Horner’s syndrome, and ischemic stroke. Early diagnosis via imaging and anticoagulation or surgery is vital to prevent complications.