MRCS Part A — Neck
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Neck — Revision Notes
Open a topic for focused revision. These teaching points follow the assigned questions.
Neck masses
Multicystic and trans-spatial suggests a lymphatic malformation.
A multiloculated lesion extending across tissue planes favours a lymphatic malformation. The original recall combines a suprahyoid location with nonspecific imaging, so its exact diagnosis cannot be established confidently.
- Lymphatic malformations can occur outside the posterior triangle.
- Thyroglossal cysts may be suprahyoid.
- Ultrasound location, internal contents and tract relationships matter.
Branchial cyst: lateral, anterior SCM border.
A second branchial cleft cyst typically appears near the anterior SCM border around the upper-third/lower-two-thirds junction. Infection can reveal or enlarge a previously unnoticed cyst.
- Most branchial cleft cysts are second-cleft anomalies.
- An adult cystic neck mass requires evaluation for malignancy.
- Avoid automatically labelling every lateral cyst as congenital.
Goitre with an impalpable lower border suggests retrosternal extension.
An enlarged thyroid extending below the thoracic inlet may have an inaccessible lower border and cause tracheal displacement or compression. Cross-sectional imaging defines its mediastinal extent.
- Assess dyspnoea, dysphagia and voice symptoms.
- Pemberton’s sign may suggest thoracic inlet obstruction.
- Not every substernal goitre is hyperthyroid.
Midline hyoid cyst moving with the tongue suggests thyroglossal cyst.
A thyroglossal cyst follows the thyroid descent tract and has a close hyoid relationship. Tongue protrusion is the distinguishing added clinical sign; swallowing alone cannot reliably separate it from thyroid pathology.
- The tract originates at the foramen caecum.
- Confirm a normally located thyroid before excision.
- Sistrunk removes the cyst, central hyoid and tract.
Salivary surgery
Lower-lip asymmetry after submandibular surgery indicates marginal mandibular injury.
The marginal mandibular branch supplies lower-lip depressors. Injury produces lower-lip asymmetry, particularly when the patient smiles or shows the lower teeth.
- The nerve may dip below the mandibular border.
- It is vulnerable during submandibular dissection.
- Facial nerve branches are motor; lingual nerve injury is predominantly sensory.
Anterior tongue general sensation is lingual, not hypoglossal.
The lingual nerve, a V3 branch, supplies general sensation to the anterior two-thirds of the tongue and floor of the mouth. It loops around the submandibular duct, creating an operative hazard.
- Chorda tympani fibres carried with it mediate taste anteriorly.
- Chorda tympani also carries preganglionic salivary fibres.
- Lingual and hypoglossal injury produce different deficits.
Parotidectomy plus numb earlobe suggests great auricular injury.
The great auricular nerve supplies skin over the parotid region and much of the lower auricle, including the lobule. Its superficial SCM course makes it vulnerable during parotid dissection.
- Its roots are C2–C3.
- It emerges from the superficial cervical plexus.
- Lobule numbness does not imply facial motor paralysis.
Tracheostomy
The thyroid isthmus is the classic intervening structure in tracheostomy.
The thyroid isthmus crosses the upper trachea. It can obstruct access and may be divided with haemostasis, although retraction or a different approach may avoid division.
- Position varies, commonly across rings 2–4.
- Inferior thyroid veins can bleed in the operative field.
- Avoid treating isthmus division as mandatory in every technique.
Ascending pharyngeal artery is remote from standard tracheostomy.
The ascending pharyngeal artery ascends deep near the pharynx, away from the usual anterior midline tracheostomy field. The other options have closer relationships to this approach.
- Anterior jugular artery in some recalls is a transcription error.
- A thyroid ima artery can be an unexpected midline vessel.
- Least likely does not mean anatomically impossible under every circumstance.
Laryngeal nerves
Hoarseness from vocal-fold palsy points to vagal laryngeal branches.
The recurrent laryngeal nerve arises from the vagus and supplies most intrinsic laryngeal muscles. Dysphonia is a voice disorder; hypoglossal dysfunction primarily impairs articulation.
- Cricothyroid is supplied by the external superior laryngeal branch.
- Bilateral recurrent nerve palsy can threaten the airway.
- A neck wound can also directly injure the larynx.
Accessory nerve
SCM motor supply is spinal accessory.
Sternocleidomastoid receives its main motor supply from the spinal accessory nerve. Irritation can produce abnormal contraction; destructive palsy produces weakness, so pressure alone does not establish the mechanism.
- Unilateral SCM rotates the face contralaterally.
- Cervical nerves contribute proprioceptive fibres.
- Torticollis has muscular, neurological and inflammatory causes.
Posterior-triangle biopsy endangers CN XI.
The accessory nerve crosses the posterior triangle relatively superficially. Injury denervates trapezius, making lymph-node procedures in this region a recognised hazard.
- Test shoulder shrug against resistance.
- Posterior-triangle injury usually spares SCM.
- Shoulder droop may accompany trapezius wasting.
Weak shrug after neck surgery is accessory palsy.
Trapezius elevates and upwardly rotates the scapula. Accessory palsy therefore weakens shrugging and limits overhead elevation; the problem is scapular mechanics, not isolated glenohumeral abduction.
- Deltoid and supraspinatus initiate glenohumeral abduction.
- Serratus anterior also assists upward scapular rotation.
- Accessory palsy does not itself cause cutaneous shoulder numbness.
The posterior-triangle motor nerve at risk is CN XI.
The accessory nerve has a relatively exposed course across the posterior triangle. The absence of a consistent major accompanying vessel makes direct anatomical identification especially important.
- It supplies trapezius distally.
- It is not unaccompanied by vessels throughout its entire course.
- It has variable relations to the internal jugular vein proximally.
Accessory palsy explains weak shrug, not shoulder skin numbness.
A distal accessory lesion can spare SCM while denervating trapezius. The original key wrongly attributed shoulder sensory loss to this motor nerve, and the supplied alternatives did not provide a defensible single answer.
- CN XI is not a cutaneous sensory nerve.
- Cape-of-shoulder sensation is supraclavicular nerve territory.
- Lateral deltoid-patch sensation is axillary nerve territory.
SCM motor supply is CN XI.
The spinal accessory nerve supplies SCM motor function. Cervical spinal nerves contribute proprioception, which should not be confused with the principal motor innervation.
- Unilateral contraction rotates the face to the opposite side.
- It also tilts the head towards the contracting side.
- Bilateral contraction can flex the neck, depending on fixation.
SCM rotates the face away from its own side.
Left SCM rotates the face towards the right. A lesion proximal to SCM branches can therefore impair rightward head rotation as well as left shoulder shrug.
- Left SCM also produces ipsilateral lateral flexion.
- A distal posterior-triangle lesion may spare head rotation.
- Specify lesion level before assuming both muscles are weak.
head topic
Cheek plus upper anterior teeth suggests proximal infraorbital/V2 injury.
The infraorbital nerve is the terminal continuation of V2. Its superior alveolar branches arise within the canal, so injury sufficiently proximal can affect upper anterior teeth as well as the face.
- It exits through the infraorbital foramen.
- Distal injury alone does not necessarily anaesthetise teeth.
- V3 supplies mandibular teeth through inferior alveolar branches.
Subclavian vessels
A LIMA graft needs adequate proximal left subclavian inflow.
Proximal left subclavian stenosis can reverse or reduce flow through a left internal thoracic coronary graft during arm demand. This is coronary-subclavian steal.
- Compare arm blood pressures and pulses.
- The internal thoracic artery usually arises from the first part.
- Vertebral-subclavian steal causes a different symptom pattern.
Vertebral artery: first part of subclavian, usually enters at C6.
The vertebral artery normally arises medial to anterior scalene, from the first part of the subclavian artery. It usually enters the C6 transverse foramen.
- Anterior scalene divides the artery into three parts.
- Internal thoracic and thyrocervical branches also arise from the first part.
- Anomalous vertebral origins occur.
Classic subclavian steal reverses vertebral flow.
Subclavian stenosis proximal to the vertebral origin lowers distal pressure, drawing blood retrogradely through the ipsilateral vertebral artery. Symptoms may worsen with arm exercise.
- Duplex ultrasound can demonstrate reversal.
- Asymptomatic steal phenomenon differs from symptomatic steal syndrome.
- Coronary steal involves an internal thoracic bypass graft.
Salivary cysts
Ranula usually arises from the sublingual gland.
A ranula usually represents mucus extravasation from the sublingual gland. A plunging ranula extends into the neck through or around mylohyoid.
- A simple ranula remains in the floor of the mouth.
- The lingual nerve and submandibular duct are nearby surgical structures.
- A dermoid is an important floor-of-mouth differential.
Phrenic nerve
Phrenic nerve lies on anterior scalene.
The phrenic nerve descends over anterior scalene beneath prevertebral fascia. Its position is important in lower-neck surgery and regional anaesthesia.
- Its roots are C3–C5, mainly C4.
- Subclavian artery and brachial plexus pass behind anterior scalene.
- Subclavian vein passes anterior to the muscle.
nasal topic
Little’s area connects internal and external carotid arterial systems.
Little’s area is an anterior septal arterial anastomosis. The anterior ethmoidal artery provides an internal carotid contribution through the ophthalmic artery.
- Other conventional contributors include sphenopalatine, greater palatine and superior labial branches.
- Posterior epistaxis is often sphenopalatine territory.
- There is no universally identifiable single most-affected vessel from the original fragment.
Neck trauma
Control catastrophic external bleeding immediately.
Immediate local pressure limits catastrophic external haemorrhage while resuscitation, airway assessment and surgical help proceed. It is a bridge to definitive control, not the whole treatment.
- Avoid circumferential neck compression.
- Activate major-haemorrhage support when indicated.
- Shock or ongoing major bleeding requires urgent definitive intervention.
Accessory nerve landmarks
Accessory nerve emerges behind SCM, not at its anterior border.
The accessory nerve emerges from the posterior SCM border and passes towards the anterior trapezius border. Landmarks are approximate because its course varies.
- Do not confuse this with a cyst at the anterior SCM border.
- Cutaneous cervical plexus branches emerge near the midpoint of the posterior border.
- Direct identification is safer than relying solely on proportions.
Cervical plexus
Shoulder cape sensation is C3–C4 via supraclavicular nerves.
Supraclavicular nerves arise from the superficial cervical plexus and supply the shoulder cape and upper chest. The original pain-only fragment does not distinguish skin innervation from referred pain.
- Phrenic afferents can refer pain to the shoulder.
- The phrenic nerve is C3–C5.
- The lateral deltoid patch is chiefly axillary nerve territory.
Thyroid oncology
Small primary size does not negate clinically positive nodes.
Clinically involved nodes change management despite a small primary tumour. Current ATA guidance supports total thyroidectomy and therapeutic compartment-oriented treatment of documented nodal disease.
- Confirm suspicious nodes appropriately before planning surgery.
- Central and lateral dissections address different compartments.
- Routine dissection of every uninvolved compartment is not implied.
Papillary spreads to nodes; follicular favours blood-borne spread.
Papillary carcinoma commonly spreads through cervical lymphatics and can produce cystic nodal metastases. The original generic fibrosis description is not diagnostic by itself.
- Characteristic nuclei include grooves and intranuclear inclusions.
- Psammoma bodies may occur.
- Evaluate the thyroid in an unexplained cystic cervical node.
Jugular veins
External jugular crosses over SCM towards midclavicle.
The external jugular vein descends from near the mandibular angle, crosses superficial to SCM and pierces deep fascia near the clavicle. It usually drains into the subclavian vein.
- It forms from posterior auricular and posterior retromandibular veins.
- Superficial veins show anatomical variation.
- Internal jugular lies deep to SCM.
Internal jugular is deep and heads towards the sternoclavicular joint.
The IJV descends deep to SCM within the carotid sheath and joins the subclavian vein behind the sternoclavicular joint. A surface line is approximate; ultrasound identifies its actual position.
- It is generally lateral to the carotid artery.
- Relations vary with head rotation and patient anatomy.
- Ultrasound guidance improves venous access safety.
Carotid sheath
Carotid sheath contains artery, IJV and vagus.
The carotid sheath contains the carotid artery, internal jugular vein and vagus. Below the bifurcation the arterial content is common carotid; above it, internal carotid.
- The external carotid leaves the sheath.
- Ansa cervicalis lies on or within its anterior wall.
- The sympathetic trunk lies posterior to the sheath.
Parathyroid anatomy
Inferior thyroid artery usually supplies all four parathyroids.
Both superior and inferior parathyroids usually receive branches from the inferior thyroid artery. Preserving capsular vascular branches reduces postoperative hypoparathyroidism risk.
- Inferior thyroid arises from the thyrocervical trunk.
- Superior parathyroids derive from the fourth pouch.
- Inferior parathyroids descend with thymus from the third pouch.
Laryngeal muscles
High-pitch loss after superior pole surgery suggests cricothyroid weakness.
The external branch of the superior laryngeal nerve supplies cricothyroid and lies close to the superior thyroid vessels. Cricothyroid lengthens and tenses the vocal folds, helping produce high pitch.
- Protect the nerve during superior pole dissection.
- Ligate individual superior thyroid branches close to the gland.
- This differs from recurrent nerve palsy causing more obvious vocal-fold immobility.
Posterior cricoarytenoid is the sole vocal-fold abductor.
Posterior cricoarytenoid rotates the arytenoid cartilages laterally, opening the rima glottidis. Bilateral paralysis can seriously restrict the airway.
- Its main motor supply is recurrent laryngeal.
- Cricothyroid is the standard intrinsic-muscle innervation exception.
- Abduction opens; adduction closes the glottis.
Thyroid surgery
Thyroidectomy risks laryngeal nerves and parathyroids.
The ascending pharyngeal artery is remote from the usual thyroid capsular dissection. Laryngeal nerves and parathyroids are important structures to identify and protect.
- Inferior thyroid branches are closely related to parathyroid perfusion.
- Postoperative neck haematoma can threaten the airway.
- Superior laryngeal motor and sensory branches have different deficits.
A child has a predominantly multicystic, trans-spatial neck lesion on ultrasound. Which diagnosis is most likely?
Answer & teaching notes
Correct Answer: C. Lymphatic malformation (cystic hygroma)
Why this answer is correct
A multiloculated lesion extending across tissue planes favours a lymphatic malformation. The original recall combines a suprahyoid location with nonspecific imaging, so its exact diagnosis cannot be established confidently.
Why the other options are incorrect
High-Yield Facts
- Lymphatic malformations can occur outside the posterior triangle.
- Thyroglossal cysts may be suprahyoid.
- Ultrasound location, internal contents and tract relationships matter.
Exam Pearl: Multicystic and trans-spatial suggests a lymphatic malformation.
Recall clarification: Ambiguous original; imaging description reconstructed. Original answer remains unresolved.
An asymmetric lower-lip smile develops after submandibular gland excision. Which nerve was injured?
Answer & teaching notes
Correct Answer: B. Marginal mandibular branch of the facial nerve
Why this answer is correct
The marginal mandibular branch supplies lower-lip depressors. Injury produces lower-lip asymmetry, particularly when the patient smiles or shows the lower teeth.
Why the other options are incorrect
High-Yield Facts
- The nerve may dip below the mandibular border.
- It is vulnerable during submandibular dissection.
- Facial nerve branches are motor; lingual nerve injury is predominantly sensory.
Exam Pearl: Lower-lip asymmetry after submandibular surgery indicates marginal mandibular injury.
Which structure commonly overlies tracheal rings 2–4 and may require division during tracheostomy?
Answer & teaching notes
Correct Answer: D. Thyroid isthmus
Why this answer is correct
The thyroid isthmus crosses the upper trachea. It can obstruct access and may be divided with haemostasis, although retraction or a different approach may avoid division.
Why the other options are incorrect
High-Yield Facts
- Position varies, commonly across rings 2–4.
- Inferior thyroid veins can bleed in the operative field.
- Avoid treating isthmus division as mandatory in every technique.
Exam Pearl: The thyroid isthmus is the classic intervening structure in tracheostomy.
After neck surgery, vocal-fold paralysis causes hoarseness. The affected laryngeal nerve is a branch of which cranial nerve?
Answer & teaching notes
Correct Answer: A. Vagus nerve
Why this answer is correct
The recurrent laryngeal nerve arises from the vagus and supplies most intrinsic laryngeal muscles. Dysphonia is a voice disorder; hypoglossal dysfunction primarily impairs articulation.
Why the other options are incorrect
High-Yield Facts
- Cricothyroid is supplied by the external superior laryngeal branch.
- Bilateral recurrent nerve palsy can threaten the airway.
- A neck wound can also directly injure the larynx.
Exam Pearl: Hoarseness from vocal-fold palsy points to vagal laryngeal branches.
Recall clarification: Wording standardised; the January 2026 hypoglossal suggestion is corrected, not accepted as a verified original key.
A posterior-triangle mass irritates the motor nerve to sternocleidomastoid, producing torticollis. Which nerve is involved?
Answer & teaching notes
Correct Answer: A. Spinal accessory nerve
Why this answer is correct
Sternocleidomastoid receives its main motor supply from the spinal accessory nerve. Irritation can produce abnormal contraction; destructive palsy produces weakness, so pressure alone does not establish the mechanism.
Why the other options are incorrect
High-Yield Facts
- Unilateral SCM rotates the face contralaterally.
- Cervical nerves contribute proprioceptive fibres.
- Torticollis has muscular, neurological and inflammatory causes.
Exam Pearl: SCM motor supply is spinal accessory.
Recall clarification: Recall mechanism clarified: nerve irritation rather than assuming every compressive lesion causes spasm.
Facial trauma causes cheek and upper-lip numbness with altered sensation in upper anterior teeth. Which nerve is implicated?
Answer & teaching notes
Correct Answer: D. Infraorbital nerve
Why this answer is correct
The infraorbital nerve is the terminal continuation of V2. Its superior alveolar branches arise within the canal, so injury sufficiently proximal can affect upper anterior teeth as well as the face.
Why the other options are incorrect
High-Yield Facts
- It exits through the infraorbital foramen.
- Distal injury alone does not necessarily anaesthetise teeth.
- V3 supplies mandibular teeth through inferior alveolar branches.
Exam Pearl: Cheek plus upper anterior teeth suggests proximal infraorbital/V2 injury.
Which nerve is particularly vulnerable during posterior-triangle lymph-node biopsy?
Answer & teaching notes
Correct Answer: B. Spinal accessory nerve
Why this answer is correct
The accessory nerve crosses the posterior triangle relatively superficially. Injury denervates trapezius, making lymph-node procedures in this region a recognised hazard.
Why the other options are incorrect
High-Yield Facts
- Test shoulder shrug against resistance.
- Posterior-triangle injury usually spares SCM.
- Shoulder droop may accompany trapezius wasting.
Exam Pearl: Posterior-triangle biopsy endangers CN XI.
After posterior-triangle surgery, a patient cannot shrug the shoulder or fully elevate the arm. Which nerve was injured?
Answer & teaching notes
Correct Answer: C. Spinal accessory nerve
Why this answer is correct
Trapezius elevates and upwardly rotates the scapula. Accessory palsy therefore weakens shrugging and limits overhead elevation; the problem is scapular mechanics, not isolated glenohumeral abduction.
Why the other options are incorrect
High-Yield Facts
- Deltoid and supraspinatus initiate glenohumeral abduction.
- Serratus anterior also assists upward scapular rotation.
- Accessory palsy does not itself cause cutaneous shoulder numbness.
Exam Pearl: Weak shrug after neck surgery is accessory palsy.
Recall clarification: Ambiguous generic shoulder weakness options refined to a specific motor deficit.
Arm exercise triggers angina after a left internal thoracic artery coronary bypass. Which lesion best explains this?
Answer & teaching notes
Correct Answer: D. Left subclavian stenosis proximal to the internal thoracic origin
Why this answer is correct
Proximal left subclavian stenosis can reverse or reduce flow through a left internal thoracic coronary graft during arm demand. This is coronary-subclavian steal.
Why the other options are incorrect
High-Yield Facts
- Compare arm blood pressures and pulses.
- The internal thoracic artery usually arises from the first part.
- Vertebral-subclavian steal causes a different symptom pattern.
Exam Pearl: A LIMA graft needs adequate proximal left subclavian inflow.
A blue, fluctuant mucus swelling in the floor of the mouth is a ranula. Which gland is usually responsible?
Answer & teaching notes
Correct Answer: D. Sublingual gland
Why this answer is correct
A ranula usually represents mucus extravasation from the sublingual gland. A plunging ranula extends into the neck through or around mylohyoid.
Why the other options are incorrect
High-Yield Facts
- A simple ranula remains in the floor of the mouth.
- The lingual nerve and submandibular duct are nearby surgical structures.
- A dermoid is an important floor-of-mouth differential.
Exam Pearl: Ranula usually arises from the sublingual gland.
Recall clarification: Original image absent. This is a conditional teaching reconstruction, not verification of the missing image.
The vertebral artery normally arises from which part of the subclavian artery?
Answer & teaching notes
Correct Answer: B. First part
Why this answer is correct
The vertebral artery normally arises medial to anterior scalene, from the first part of the subclavian artery. It usually enters the C6 transverse foramen.
Why the other options are incorrect
High-Yield Facts
- Anterior scalene divides the artery into three parts.
- Internal thoracic and thyrocervical branches also arise from the first part.
- Anomalous vertebral origins occur.
Exam Pearl: Vertebral artery: first part of subclavian, usually enters at C6.
Recall clarification: Missing fourth option reconstructed.
Which nerve descends on the anterior surface of anterior scalene?
Answer & teaching notes
Correct Answer: A. Phrenic nerve
Why this answer is correct
The phrenic nerve descends over anterior scalene beneath prevertebral fascia. Its position is important in lower-neck surgery and regional anaesthesia.
Why the other options are incorrect
High-Yield Facts
- Its roots are C3–C5, mainly C4.
- Subclavian artery and brachial plexus pass behind anterior scalene.
- Subclavian vein passes anterior to the muscle.
Exam Pearl: Phrenic nerve lies on anterior scalene.
Which superficial motor nerve crosses the posterior triangle without a major accompanying vessel?
Answer & teaching notes
Correct Answer: B. Spinal accessory nerve
Why this answer is correct
The accessory nerve has a relatively exposed course across the posterior triangle. The absence of a consistent major accompanying vessel makes direct anatomical identification especially important.
Why the other options are incorrect
High-Yield Facts
- It supplies trapezius distally.
- It is not unaccompanied by vessels throughout its entire course.
- It has variable relations to the internal jugular vein proximally.
Exam Pearl: The posterior-triangle motor nerve at risk is CN XI.
Recall clarification: Fragment expanded; statement confined to the triangle crossing.
Which artery contributes to Little’s area through an ophthalmic artery branch?
Answer & teaching notes
Correct Answer: C. Anterior ethmoidal artery
Why this answer is correct
Little’s area is an anterior septal arterial anastomosis. The anterior ethmoidal artery provides an internal carotid contribution through the ophthalmic artery.
Why the other options are incorrect
High-Yield Facts
- Other conventional contributors include sphenopalatine, greater palatine and superior labial branches.
- Posterior epistaxis is often sphenopalatine territory.
- There is no universally identifiable single most-affected vessel from the original fragment.
Exam Pearl: Little’s area connects internal and external carotid arterial systems.
Recall clarification: Ambiguous most-vessel recall reconstructed as an unambiguous arterial-origin question.
Classic vertebral-subclavian steal produces reversed flow in which artery?
Answer & teaching notes
Correct Answer: C. Ipsilateral vertebral artery
Why this answer is correct
Subclavian stenosis proximal to the vertebral origin lowers distal pressure, drawing blood retrogradely through the ipsilateral vertebral artery. Symptoms may worsen with arm exercise.
Why the other options are incorrect
High-Yield Facts
- Duplex ultrasound can demonstrate reversal.
- Asymptomatic steal phenomenon differs from symptomatic steal syndrome.
- Coronary steal involves an internal thoracic bypass graft.
Exam Pearl: Classic subclavian steal reverses vertebral flow.
Recall clarification: Incomplete options reconstructed.
A conscious patient has severe external bleeding from a neck wound and BP 80/40. Which immediate action controls the bleeding?
Answer & teaching notes
Correct Answer: A. Apply direct local pressure
Why this answer is correct
Immediate local pressure limits catastrophic external haemorrhage while resuscitation, airway assessment and surgical help proceed. It is a bridge to definitive control, not the whole treatment.
Why the other options are incorrect
High-Yield Facts
- Avoid circumferential neck compression.
- Activate major-haemorrhage support when indicated.
- Shock or ongoing major bleeding requires urgent definitive intervention.
Exam Pearl: Control catastrophic external bleeding immediately.
Recall clarification: Missing option reconstructed; transfusion and airway care are concurrent, not omitted.
After posterior-triangle node dissection, trapezius is paralysed but SCM remains functional. Which movement is most directly weakened?
Answer & teaching notes
Correct Answer: D. Ipsilateral shoulder shrug
Why this answer is correct
A distal accessory lesion can spare SCM while denervating trapezius. The original key wrongly attributed shoulder sensory loss to this motor nerve, and the supplied alternatives did not provide a defensible single answer.
Why the other options are incorrect
High-Yield Facts
- CN XI is not a cutaneous sensory nerve.
- Cape-of-shoulder sensation is supraclavicular nerve territory.
- Lateral deltoid-patch sensation is axillary nerve territory.
Exam Pearl: Accessory palsy explains weak shrug, not shoulder skin numbness.
Recall clarification: Original key rejected; stem and options reconstructed. Original MCQ has no secure answer as written.
The accessory nerve typically emerges from which SCM border before crossing the posterior triangle?
Answer & teaching notes
Correct Answer: C. Posterior border near the upper-third/lower-two-thirds junction
Why this answer is correct
The accessory nerve emerges from the posterior SCM border and passes towards the anterior trapezius border. Landmarks are approximate because its course varies.
Why the other options are incorrect
High-Yield Facts
- Do not confuse this with a cyst at the anterior SCM border.
- Cutaneous cervical plexus branches emerge near the midpoint of the posterior border.
- Direct identification is safer than relying solely on proportions.
Exam Pearl: Accessory nerve emerges behind SCM, not at its anterior border.
Recall clarification: Fragment with uncertain anterior-border wording reconstructed; exact original question remains unresolved.
Which root pair supplies the supraclavicular nerves to the skin over the shoulder and clavicle?
Answer & teaching notes
Correct Answer: A. C3–C4
Why this answer is correct
Supraclavicular nerves arise from the superficial cervical plexus and supply the shoulder cape and upper chest. The original pain-only fragment does not distinguish skin innervation from referred pain.
Why the other options are incorrect
High-Yield Facts
- Phrenic afferents can refer pain to the shoulder.
- The phrenic nerve is C3–C5.
- The lateral deltoid patch is chiefly axillary nerve territory.
Exam Pearl: Shoulder cape sensation is C3–C4 via supraclavicular nerves.
Recall clarification: Pain-only fragment reconstructed as a root-supply question; original scenario remains unknown.
Loss of general sensation from the anterior tongue and floor of the mouth follows submandibular surgery. Which nerve was injured?
Answer & teaching notes
Correct Answer: D. Lingual nerve
Why this answer is correct
The lingual nerve, a V3 branch, supplies general sensation to the anterior two-thirds of the tongue and floor of the mouth. It loops around the submandibular duct, creating an operative hazard.
Why the other options are incorrect
High-Yield Facts
- Chorda tympani fibres carried with it mediate taste anteriorly.
- Chorda tympani also carries preganglionic salivary fibres.
- Lingual and hypoglossal injury produce different deficits.
Exam Pearl: Anterior tongue general sensation is lingual, not hypoglossal.
Recall clarification: Missing fourth option reconstructed.
A 1-cm papillary thyroid carcinoma has confirmed clinical cervical nodal metastases. Which operative strategy is most appropriate?
Answer & teaching notes
Correct Answer: A. Total thyroidectomy with therapeutic dissection of involved nodal compartments
Why this answer is correct
Clinically involved nodes change management despite a small primary tumour. Current ATA guidance supports total thyroidectomy and therapeutic compartment-oriented treatment of documented nodal disease.
Why the other options are incorrect
High-Yield Facts
- Confirm suspicious nodes appropriately before planning surgery.
- Central and lateral dissections address different compartments.
- Routine dissection of every uninvolved compartment is not implied.
Exam Pearl: Small primary size does not negate clinically positive nodes.
Recall clarification: Fragment reconstructed; confirmed nodal disease explicitly added because enlargement alone is insufficient.
A young adult has a cystic cervical nodal metastasis from a thyroid primary. Which histology is most likely?
Answer & teaching notes
Correct Answer: D. Papillary thyroid carcinoma
Why this answer is correct
Papillary carcinoma commonly spreads through cervical lymphatics and can produce cystic nodal metastases. The original generic fibrosis description is not diagnostic by itself.
Why the other options are incorrect
High-Yield Facts
- Characteristic nuclei include grooves and intranuclear inclusions.
- Psammoma bodies may occur.
- Evaluate the thyroid in an unexplained cystic cervical node.
Exam Pearl: Papillary spreads to nodes; follicular favours blood-borne spread.
Recall clarification: Stem refined; original nonspecific histology alone cannot conclusively subtype the tumour.
Which line best approximates the surface course of the external jugular vein?
Answer & teaching notes
Correct Answer: C. Angle of mandible to the middle of the clavicle
Why this answer is correct
The external jugular vein descends from near the mandibular angle, crosses superficial to SCM and pierces deep fascia near the clavicle. It usually drains into the subclavian vein.
Why the other options are incorrect
High-Yield Facts
- It forms from posterior auricular and posterior retromandibular veins.
- Superficial veins show anatomical variation.
- Internal jugular lies deep to SCM.
Exam Pearl: External jugular crosses over SCM towards midclavicle.
What is the principal motor nerve supply of sternocleidomastoid?
Answer & teaching notes
Correct Answer: C. Spinal accessory nerve
Why this answer is correct
The spinal accessory nerve supplies SCM motor function. Cervical spinal nerves contribute proprioception, which should not be confused with the principal motor innervation.
Why the other options are incorrect
High-Yield Facts
- Unilateral contraction rotates the face to the opposite side.
- It also tilts the head towards the contracting side.
- Bilateral contraction can flex the neck, depending on fixation.
Exam Pearl: SCM motor supply is CN XI.
Which line conventionally approximates the internal jugular vein’s surface course?
Answer & teaching notes
Correct Answer: B. Mastoid region to the sternoclavicular joint
Why this answer is correct
The IJV descends deep to SCM within the carotid sheath and joins the subclavian vein behind the sternoclavicular joint. A surface line is approximate; ultrasound identifies its actual position.
Why the other options are incorrect
High-Yield Facts
- It is generally lateral to the carotid artery.
- Relations vary with head rotation and patient anatomy.
- Ultrasound guidance improves venous access safety.
Exam Pearl: Internal jugular is deep and heads towards the sternoclavicular joint.
A young adult develops a soft lateral cyst at the anterior SCM border after a respiratory infection. Which diagnosis is most likely?
Answer & teaching notes
Correct Answer: D. Second branchial cleft cyst
Why this answer is correct
A second branchial cleft cyst typically appears near the anterior SCM border around the upper-third/lower-two-thirds junction. Infection can reveal or enlarge a previously unnoticed cyst.
Why the other options are incorrect
High-Yield Facts
- Most branchial cleft cysts are second-cleft anomalies.
- An adult cystic neck mass requires evaluation for malignancy.
- Avoid automatically labelling every lateral cyst as congenital.
Exam Pearl: Branchial cyst: lateral, anterior SCM border.
Recall clarification: January 2023 fragment expanded; infection does not prove congenital origin.
Which nerve is a principal content of the carotid sheath?
Answer & teaching notes
Correct Answer: B. Vagus nerve
Why this answer is correct
The carotid sheath contains the carotid artery, internal jugular vein and vagus. Below the bifurcation the arterial content is common carotid; above it, internal carotid.
Why the other options are incorrect
High-Yield Facts
- The external carotid leaves the sheath.
- Ansa cervicalis lies on or within its anterior wall.
- The sympathetic trunk lies posterior to the sheath.
Exam Pearl: Carotid sheath contains artery, IJV and vagus.
A proximal left accessory nerve lesion paralyses both SCM and trapezius. Which head movement is weakened?
Answer & teaching notes
Correct Answer: C. Rotation of the face to the right
Why this answer is correct
Left SCM rotates the face towards the right. A lesion proximal to SCM branches can therefore impair rightward head rotation as well as left shoulder shrug.
Why the other options are incorrect
High-Yield Facts
- Left SCM also produces ipsilateral lateral flexion.
- A distal posterior-triangle lesion may spare head rotation.
- Specify lesion level before assuming both muscles are weak.
Exam Pearl: SCM rotates the face away from its own side.
Recall clarification: Proximal lesion explicitly specified to avoid confusing it with distal trapezius-only palsy.
After thyroidectomy, hypocalcaemia follows parathyroid devascularisation. Which artery provides their principal supply?
Answer & teaching notes
Correct Answer: C. Inferior thyroid artery
Why this answer is correct
Both superior and inferior parathyroids usually receive branches from the inferior thyroid artery. Preserving capsular vascular branches reduces postoperative hypoparathyroidism risk.
Why the other options are incorrect
High-Yield Facts
- Inferior thyroid arises from the thyrocervical trunk.
- Superior parathyroids derive from the fourth pouch.
- Inferior parathyroids descend with thymus from the third pouch.
Exam Pearl: Inferior thyroid artery usually supplies all four parathyroids.
Recall clarification: Missing fourth option reconstructed.
Earlobe numbness after parotidectomy suggests injury to which nerve?
Answer & teaching notes
Correct Answer: B. Great auricular nerve
Why this answer is correct
The great auricular nerve supplies skin over the parotid region and much of the lower auricle, including the lobule. Its superficial SCM course makes it vulnerable during parotid dissection.
Why the other options are incorrect
High-Yield Facts
- Its roots are C2–C3.
- It emerges from the superficial cervical plexus.
- Lobule numbness does not imply facial motor paralysis.
Exam Pearl: Parotidectomy plus numb earlobe suggests great auricular injury.
Recall clarification: Missing fourth option reconstructed.
Which structure is least likely to be injured during a standard midline cervical tracheostomy?
Answer & teaching notes
Correct Answer: A. Ascending pharyngeal artery
Why this answer is correct
The ascending pharyngeal artery ascends deep near the pharynx, away from the usual anterior midline tracheostomy field. The other options have closer relationships to this approach.
Why the other options are incorrect
High-Yield Facts
- Anterior jugular artery in some recalls is a transcription error.
- A thyroid ima artery can be an unexpected midline vessel.
- Least likely does not mean anatomically impossible under every circumstance.
Exam Pearl: Ascending pharyngeal artery is remote from standard tracheostomy.
Recall clarification: Anterior jugular artery corrected to vein; absolute not-injured wording replaced with least likely.
A neck swelling displaces the trachea and its lower border cannot be palpated. Which diagnosis is most likely?
Answer & teaching notes
Correct Answer: C. Retrosternal goitre
Why this answer is correct
An enlarged thyroid extending below the thoracic inlet may have an inaccessible lower border and cause tracheal displacement or compression. Cross-sectional imaging defines its mediastinal extent.
Why the other options are incorrect
High-Yield Facts
- Assess dyspnoea, dysphagia and voice symptoms.
- Pemberton’s sign may suggest thoracic inlet obstruction.
- Not every substernal goitre is hyperthyroid.
Exam Pearl: Goitre with an impalpable lower border suggests retrosternal extension.
A midline neck cyst near the hyoid moves with swallowing and tongue protrusion. Which diagnosis is most likely?
Answer & teaching notes
Correct Answer: B. Thyroglossal duct cyst
Why this answer is correct
A thyroglossal cyst follows the thyroid descent tract and has a close hyoid relationship. Tongue protrusion is the distinguishing added clinical sign; swallowing alone cannot reliably separate it from thyroid pathology.
Why the other options are incorrect
High-Yield Facts
- The tract originates at the foramen caecum.
- Confirm a normally located thyroid before excision.
- Sistrunk removes the cyst, central hyoid and tract.
Exam Pearl: Midline hyoid cyst moving with the tongue suggests thyroglossal cyst.
Recall clarification: Original C3/swallowing-only recall ambiguous; midline and tongue movement reconstructed. Original diagnosis is not securely resolved.
Loss of high-pitched voice after superior thyroid pedicle ligation indicates paralysis of which muscle?
Answer & teaching notes
Correct Answer: D. Cricothyroid
Why this answer is correct
The external branch of the superior laryngeal nerve supplies cricothyroid and lies close to the superior thyroid vessels. Cricothyroid lengthens and tenses the vocal folds, helping produce high pitch.
Why the other options are incorrect
High-Yield Facts
- Protect the nerve during superior pole dissection.
- Ligate individual superior thyroid branches close to the gland.
- This differs from recurrent nerve palsy causing more obvious vocal-fold immobility.
Exam Pearl: High-pitch loss after superior pole surgery suggests cricothyroid weakness.
Recall clarification: Options reconstructed from a short-answer recall.
Which is the only muscle that abducts the true vocal folds?
Answer & teaching notes
Correct Answer: D. Posterior cricoarytenoid
Why this answer is correct
Posterior cricoarytenoid rotates the arytenoid cartilages laterally, opening the rima glottidis. Bilateral paralysis can seriously restrict the airway.
Why the other options are incorrect
High-Yield Facts
- Its main motor supply is recurrent laryngeal.
- Cricothyroid is the standard intrinsic-muscle innervation exception.
- Abduction opens; adduction closes the glottis.
Exam Pearl: Posterior cricoarytenoid is the sole vocal-fold abductor.
Recall clarification: Missing fourth option reconstructed.
Which structure is least typically at risk during routine thyroidectomy?
Answer & teaching notes
Correct Answer: B. Ascending pharyngeal artery
Why this answer is correct
The ascending pharyngeal artery is remote from the usual thyroid capsular dissection. Laryngeal nerves and parathyroids are important structures to identify and protect.
Why the other options are incorrect
High-Yield Facts
- Inferior thyroid branches are closely related to parathyroid perfusion.
- Postoperative neck haematoma can threaten the airway.
- Superior laryngeal motor and sensory branches have different deficits.
Exam Pearl: Thyroidectomy risks laryngeal nerves and parathyroids.
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