AN35.1-10 | Deep structures in the neck — Gate Quiz

Correct. The pretracheal visceral fascia tethers the thyroid gland to the larynx and trachea via its attachment to the thyroid cartilage and hyoid bone. When the larynx and trachea rise during swallowing, the thyroid gland moves with them.

The pretracheal (visceral) fascia attaches superiorly to the laryngeal structures. Swallowing elevates the larynx → the tethered thyroid moves upward. Tongue protrusion movement is characteristic of a thyroglossal cyst (tethered to the foramen caecum via the thyroglossal duct remnant).

Correct. The deep cervical artery is a branch of the costocervical trunk (Part 2 of the subclavian artery), not the thyrocervical trunk (Part 1). The thyrocervical trunk gives off inferior thyroid, suprascapular, and superficial cervical arteries.

The thyrocervical trunk (Part 1 of subclavian) gives: inferior thyroid artery, suprascapular artery, and superficial cervical artery. The costocervical trunk (Part 2) gives: supreme intercostal artery and deep cervical artery.

Correct. The accessory nerve (CN XI) traverses the posterior triangle — it crosses superficially, just deep to the investing fascia — and is vulnerable to injury during posterior triangle surgery (lymph node biopsy, neck dissection). Injury paralyses the trapezius → dropped shoulder, inability to shrug, limited arm abduction above 90°.

CN XI (accessory nerve) runs through the posterior triangle from the SCM to the trapezius. It is the nerve most at risk in posterior triangle lymph node biopsy. Long thoracic nerve injury causes medial winging of the scapula (serratus anterior paralysis), not the drooped shoulder pattern.

Correct. Transient unilateral RLN neuropraxia (from stretch, traction, or temporary clipping) causes hoarseness that resolves over weeks to months as the nerve recovers. Permanent transection would not recover. External SLN injury causes pitch and singing problems (cricothyroid paralysis) but not frank hoarseness.

Unilateral RLN injury = hoarseness (paralysis of all intrinsic laryngeal muscles except cricothyroid). Transient neuropraxia (nerve intact but stunned) recovers over weeks to months. Bilateral injury would cause respiratory distress requiring tracheostomy.

Correct. The dilator pupillae muscle is innervated by sympathetic fibres via the cervical chain. When the sympathetic supply is disrupted (Horner), the dilator is paralysed. The sphincter pupillae (CN III, parasympathetic) then acts unopposed → constriction (miosis).

In Horner syndrome, loss of sympathetic tone means the dilator pupillae is non-functional. The parasympathetic sphincter pupillae (CN III Edinger-Westphal nucleus) acts unopposed → miosis. CN III palsy causes mydriasis (opposite pattern).

Correct. The left brachiocephalic vein has a long horizontal course across the midline anterior to the great vessels and aortic arch. A retrosternal or substernal goitre extending into the superior mediastinum commonly compresses the left brachiocephalic vein, causing bilateral upper limb and facial venous congestion.

The left brachiocephalic vein crosses the midline and is compressed by retrosternal goitre. The inferior thyroid veins drain directly into the left brachiocephalic vein — a large goitre in the thoracic inlet compresses this structure. SVC compression would produce a more dramatic superior vena cava syndrome.

Correct. The left RLN loops under the arch of the aorta at the level of the ligamentum arteriosum (remnant of the ductus arteriosus) before ascending in the left tracheo-oesophageal groove. This is why left-sided mediastinal pathology (aortic aneurysm, left-sided lung/mediastinal masses) can cause left-sided hoarseness.

The left RLN hooks under the aortic arch (at the ligamentum arteriosum). The right RLN hooks under the right subclavian artery (shorter course). Remember: the nerves hook under the sixth pharyngeal arch artery derivatives — on the right the sixth arch artery involutes, leaving only the subclavian.

Correct. The clinical picture (young woman, wasting of intrinsic hand muscles, medial forearm numbness, supraclavicular bony prominence) strongly suggests neurological thoracic outlet syndrome from a cervical rib. A plain X-ray of the cervicothoracic junction is the first-line investigation to visualise the cervical rib.

Cervical rib is the first diagnosis to consider in a young woman with lower trunk brachial plexus features and a supraclavicular mass. Plain X-ray cervicothoracic junction is the initial investigation — simple, cheap, and confirmatory. Nerve conduction studies and vascular Doppler are useful for further characterisation.

Correct. The thoracic duct collects lymph from the abdomen (including lymphatics draining the stomach) and empties into the left venous angle (left IJV + left subclavian junction). Tumour cells can travel this route and seed the left supraclavicular nodes (Virchow's node = Troisier's sign).

The thoracic duct is the key conduit: abdominal lymph (including from gastric and other abdominal tumours) → cisterna chyli → thoracic duct → left venous angle → left supraclavicular nodes. Virchow's node involvement (Troisier's sign) signals intraabdominal malignancy.

Correct. Widening of the prevertebral soft tissue on lateral X-ray indicates a retropharyngeal collection. The retropharyngeal space communicates inferiorly with the "danger space" (between alar and prevertebral fasciae) which extends directly into the posterior mediastinum — hence the risk of descending necrotising mediastinitis, a life-threatening complication.

The retropharyngeal space is posterior to the pharynx and anterior to the alar fascia. It communicates via the danger space (between alar and prevertebral fasciae) with the posterior mediastinum. This is why retropharyngeal abscess can cause descending necrotising mediastinitis — the most feared complication.