Unit 11 Question Bank
Sourcing: items tagged TMU 2021–22 come from the real final paper. Items tagged
Slide come from the TMU lecture. Items tagged Gray's are built from the textbook to cover
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0 / 20 answered
1The superior thyroid artery is a branch of the ( ).
Answer: A
It is the first branch of the external carotid artery, descending to the upper pole. The inferior thyroid artery comes from the thyrocervical trunk of the subclavian.TMU Lecture 13 Slide 15 · Snell's 10e Ch.12
2The inferior thyroid artery arises from the ( ).
Answer: B
From the thyrocervical trunk of the first part of the subclavian artery, ascending to the lower pole from behind.TMU Lecture 13 Slide 9
3Which nerve is at risk when ligating the SUPERIOR thyroid artery?
Answer: C
The external laryngeal nerve, which supplies cricothyroid. Injury weakens the voice and removes its high range. The artery is therefore ligated close to the gland.TMU Lecture 13 Slides 8, 15
4Which nerve is at risk when ligating the INFERIOR thyroid artery?
Answer: D
The recurrent laryngeal nerve, which has a close and variable relation to the artery near the lower pole. It is therefore ligated away from the gland, laterally.TMU Lecture 13 Slides 10, 15
5The recurrent laryngeal nerve supplies ( ).
Answer: A
All intrinsic muscles of the larynx except cricothyroid, which takes the external laryngeal nerve. That single exception is the whole basis of the two-nerve, two-artery pairing.Gray's 4e p.1018
6Bilateral recurrent laryngeal nerve injury causes ( ).
Answer: B
Both cords lie near the midline and the airway is critically narrowed — stridor, and often an emergency tracheostomy. Unilateral injury causes hoarseness alone.Gray's 4e p.1018 (clinical application)
7The inferior thyroid vein drains into the ( ).
Answer: C
Only the inferior thyroid vein descends to the brachiocephalic vein; the superior and middle thyroid veins drain to the internal jugular vein.TMU Lecture 13 Slide 11
8The isthmus of the thyroid gland crosses tracheal rings ( ).
Answer: D
Rings 2–4. This is why a tracheostomy is usually placed below the isthmus, or the isthmus is divided.Gray's 4e p.1017
9Why does a thyroid swelling move upward on swallowing?
Answer: A
The pretracheal fascia encloses the gland and binds it to the larynx and trachea, so the gland rises with the larynx during swallowing. A lymph node or skin lump does not.TMU Lecture 12 Slide 5 · Gray's 4e p.1017
10The parathyroid glands lie ( ).
Answer: B
On the posterior surface of the lateral lobes, within the thyroid's fascial sheath — which is exactly why they are at risk during total thyroidectomy.TMU Lecture 13 Slide 6
11Parathyroid hormone ( ) blood calcium.
Answer: C
PTH raises blood calcium — the opposite of calcitonin from the thyroid's parafollicular cells. Removing the parathyroids causes post-operative hypocalcaemia with tetany.TMU Lecture 13 Slides 5–6
12The left recurrent laryngeal nerve hooks around the ( ).
Answer: D
The left nerve descends into the thorax and hooks under the arch of the aorta; the right hooks under the right subclavian artery. This asymmetry is why left-sided hoarseness may indicate chest disease.Gray's 4e p.1018
13Unexplained hoarseness warrants a chest X-ray because ( ).
Answer: A
Its long intrathoracic course means a bronchial carcinoma at the left hilum, an aortic arch aneurysm or an enlarged left atrium can paralyse it.Gray's 4e p.1018 (clinical application)
14The subclavian artery is divided into three parts by the ( ).
Answer: B
Scalenus anterior — the same principle as pectoralis minor dividing the axillary artery. The third part lies lateral to the muscle, in the scalene fissure.TMU Lecture 13 Slide 12 · Snell's 10e Ch.12
15Which is NOT a branch of the first part of the subclavian artery?
Answer: C
The costocervical trunk arises from the second part. The first part gives the vertebral artery, internal thoracic artery and thyrocervical trunk.Snell's 10e Ch.12
16The cervical pleura rises above the first rib by about ( ).
Answer: D
About 2.5 cm above the medial third of the clavicle — which is why a subclavian central line or a neck stab wound can cause a pneumothorax.Gray's 4e p.1029
17Horner's syndrome consists of ( ).
Answer: A
Damage to the cervical sympathetic trunk gives drooping eyelid (ptosis), constricted pupil (miosis) and loss of facial sweating (anhidrosis) on the same side — classically from an apical lung (Pancoast) tumour.Gray's 4e p.1034
18The thyroidea ima artery, when present, arises from the ( ).
Answer: B
From the brachiocephalic trunk or the aortic arch, ascending to the isthmus in about 10% of people. It is a bleeding hazard during tracheostomy.Gray's 4e p.1018
19Post-thyroidectomy tetany is caused by ( ).
Answer: C
Loss of parathyroid function causes hypocalcaemia — perioral and digital tingling, carpopedal spasm, and positive Trousseau's and Chvostek's signs. Serum calcium is checked routinely after thyroidectomy.Gray's 4e p.1021 (clinical application)
20The main arterial supply to both superior and inferior parathyroid glands is the ( ).
Answer: D
The inferior thyroid artery supplies both pairs — another reason it is handled carefully and ligated away from the gland during thyroid surgery.Gray's 4e p.1018, Fig. 8.180
1 Arteries of the thyroid gland — draw a figure · homework+
Superior thyroid artery — the first branch of the external carotid artery; descends to the upper pole; accompanied by the external laryngeal nerve.
Inferior thyroid artery — a branch of the thyrocervical trunk of the subclavian artery; ascends to the lower pole from behind; closely related to the recurrent laryngeal nerve.
Thyroidea ima — inconstant (~10%), from the brachiocephalic trunk or aortic arch, to the isthmus.TMU Lecture 13 Slide 15
Inferior thyroid artery — a branch of the thyrocervical trunk of the subclavian artery; ascends to the lower pole from behind; closely related to the recurrent laryngeal nerve.
Thyroidea ima — inconstant (~10%), from the brachiocephalic trunk or aortic arch, to the isthmus.TMU Lecture 13 Slide 15
2 Recurrent laryngeal nerve — 3′+
A branch of the vagus nerve [X] supplying all intrinsic muscles of the larynx except cricothyroid, and sensation below the vocal cords.
Right: hooks under the right subclavian artery. Left: descends into the thorax and hooks under the arch of the aorta.
It has a close, variable relation to the inferior thyroid artery at the lower pole of the thyroid.
Injury: unilateral → hoarseness; bilateral → stridor and airway obstruction.TMU Lecture 13 Slide 10 · Gray's 4e p.1018
Right: hooks under the right subclavian artery. Left: descends into the thorax and hooks under the arch of the aorta.
It has a close, variable relation to the inferior thyroid artery at the lower pole of the thyroid.
Injury: unilateral → hoarseness; bilateral → stridor and airway obstruction.TMU Lecture 13 Slide 10 · Gray's 4e p.1018
3 External laryngeal nerve — 2′+
The external branch of the superior laryngeal nerve (from the vagus), descending with the superior thyroid artery to supply the cricothyroid muscle, which tenses the vocal cord.
Injury during ligation of the superior thyroid artery causes a weak, easily tiring voice with loss of the high range — hence the surgical rule to ligate that artery close to the gland.TMU Lecture 13 Slide 8
Injury during ligation of the superior thyroid artery causes a weak, easily tiring voice with loss of the high range — hence the surgical rule to ligate that artery close to the gland.TMU Lecture 13 Slide 8
4 Venous drainage of the thyroid gland — 2′+
Superior thyroid vein → internal jugular vein
Middle thyroid vein → internal jugular vein
Inferior thyroid vein → brachiocephalic vein
The inferior veins form a plexus in front of the trachea and are a bleeding hazard during tracheostomy.TMU Lecture 13 Slide 11
Middle thyroid vein → internal jugular vein
Inferior thyroid vein → brachiocephalic vein
The inferior veins form a plexus in front of the trachea and are a bleeding hazard during tracheostomy.TMU Lecture 13 Slide 11
5 Cupula (dome) of the pleura — 2′+
The upward projection of the cervical parietal pleura and apex of the lung above the first rib into the root of the neck, reaching about 2.5 cm above the medial third of the clavicle.
Clinical: it is punctured in subclavian central line insertion or a stab wound at the root of the neck, causing a pneumothorax.TMU Lecture 13 Slide 13 · Gray's 4e p.1029
Clinical: it is punctured in subclavian central line insertion or a stab wound at the root of the neck, causing a pneumothorax.TMU Lecture 13 Slide 13 · Gray's 4e p.1029
6 Horner's syndrome — 2′+
The triad of ptosis (drooping upper eyelid), miosis (constricted pupil) and anhidrosis (loss of sweating on that side of the face), caused by interruption of the cervical sympathetic trunk.
Classic causes: an apical lung (Pancoast) tumour, neck trauma or surgery, or carotid dissection.Gray's 4e p.1034
Classic causes: an apical lung (Pancoast) tumour, neck trauma or surgery, or carotid dissection.Gray's 4e p.1034
1
Draw and describe the arteries of the thyroid gland and their relations with the nerves.
10′
Set as the drawing homework in TMU Lecture 13.
Arteries
| Artery | Arises from | Reaches | Nerve alongside |
|---|---|---|---|
| Superior thyroid | External carotid artery (1st branch) | Upper pole | External laryngeal nerve |
| Inferior thyroid | Thyrocervical trunk of the subclavian artery | Lower pole, from behind | Recurrent laryngeal nerve |
| Thyroidea ima (~10%) | Brachiocephalic trunk or aortic arch | Isthmus | — |
The nerve relations — and the surgical rules
- The external laryngeal nerve supplies cricothyroid, which tenses the vocal cord. Injury gives a weak voice that tires easily and loses its high notes. Rule: ligate the superior thyroid artery close to the gland, where the nerve has already diverged.
- The recurrent laryngeal nerve supplies all other intrinsic laryngeal muscles. Its relation to the inferior thyroid artery is variable — in front, behind, or between its branches. Rule: ligate the inferior thyroid artery away from the gland, laterally.
Effects of recurrent laryngeal injury
- Unilateral: hoarseness with a paralysed cord
- Bilateral: both cords near the midline → stridor and airway obstruction, possibly requiring emergency tracheostomy
Why the left nerve matters beyond the neck
The left recurrent laryngeal nerve loops under the arch of the aorta, so unexplained hoarseness may indicate bronchial carcinoma, aortic aneurysm or left atrial enlargement — and warrants a chest X-ray.
Marking guide: two arteries with parent vessels 3 · thyroidea ima 0.5 · correct nerve pairing 2 · both surgical rules 2 · unilateral vs bilateral injury 1.5 · left nerve thoracic course 1.
2
Describe the thyroid gland — its position, relations, blood supply and venous drainage.
8′
Position and structure
The largest endocrine gland, lying in the muscular triangle of the neck. Two lateral lobes against the sides of the larynx and trachea, joined by an isthmus crossing tracheal rings 2–4. A pyramidal lobe projects upward from the isthmus in about half of people.
Coverings
Enclosed by the pretracheal fascia, which binds it to the larynx and trachea — hence a thyroid swelling moves up on swallowing.
Relations
- Anteriorly: the infrahyoid strap muscles and sternocleidomastoid
- Posteromedially: the trachea, oesophagus, and the recurrent laryngeal nerve in the groove between them
- Posterolaterally: the carotid sheath
- Posteriorly: the parathyroid glands, within its sheath
Arterial supply
- Superior thyroid artery — from the external carotid — to the upper pole
- Inferior thyroid artery — from the thyrocervical trunk — to the lower pole
- Thyroidea ima — inconstant, from the brachiocephalic trunk or aortic arch
Venous drainage
- Superior and middle thyroid veins → internal jugular vein
- Inferior thyroid vein → brachiocephalic vein
Function
Thyroxine regulates basal metabolic rate and the growth of bone and nervous system; calcitonin lowers blood calcium.
Marking guide: position and parts 1.5 · isthmus level 1 · fascia and swallowing sign 1 · relations 1.5 · arteries 2 · veins 1.
3
Describe the root of the neck and its clinical importance.
7′
Definition
The junctional region between the neck and the thorax, above the first rib and behind the manubrium, through which all structures passing between head and chest are funnelled.
Key structures
- Cupula of the pleura and apex of the lung — rising about 2.5 cm above the medial third of the clavicle
- Subclavian artery — in three parts, divided by scalenus anterior; first part gives the vertebral artery, internal thoracic artery and thyrocervical trunk
- Subclavian vein — in front of scalenus anterior; joins the internal jugular at the venous angle
- Roots and trunks of the brachial plexus — in the scalene fissure with the third part of the artery
- Phrenic nerve — descending on the front of scalenus anterior
- Vagus and recurrent laryngeal nerves
- Cervical sympathetic trunk, with the cervicothoracic (stellate) ganglion
- Thoracic duct on the left, arching to the left venous angle
Clinical importance
- Pneumothorax — the cupula is punctured in subclavian line insertion or a neck stab wound; a chest X-ray is taken after every attempt
- Horner's syndrome — ptosis, miosis and anhidrosis from sympathetic trunk damage, classically by an apical (Pancoast) lung tumour
- Thoracic outlet syndrome — a cervical rib narrowing the scalene fissure compresses the lower trunk or the subclavian artery
- Chylothorax — injury to the thoracic duct during left-sided surgery
Marking guide: definition 1 · pleural cupula 1 · subclavian vessels and plexus 2 · phrenic and sympathetic 1 · two clinical points 2.
4
Describe the subclavian artery and its branches.
6′
Origin
- Right: from the brachiocephalic trunk
- Left: directly from the arch of the aorta
Each arches over the cervical pleura and becomes the axillary artery at the outer border of the first rib.
Parts — divided by scalenus anterior
| Part | Relation | Branches |
|---|---|---|
| First | Medial to the muscle | Vertebral artery · internal thoracic artery · thyrocervical trunk |
| Second | Behind the muscle | Costocervical trunk |
| Third | Lateral to the muscle | Usually none (occasionally the dorsal scapular artery) |
Branches worth knowing further
- Vertebral artery — ascends through the foramina transversaria to supply the brain
- Thyrocervical trunk — gives the inferior thyroid, transverse cervical and suprascapular arteries
- Internal thoracic artery — descends behind the costal cartilages; used as a coronary bypass graft
The third part lies in the scalene fissure with the roots of the brachial plexus, and can be compressed against the first rib to control bleeding in the upper limb.
Marking guide: different origins right and left 1 · termination 1 · division by scalenus anterior 1 · branches by part 2 · one named branch elaborated 1.
5
Explain the anatomical basis of the complications of thyroidectomy.
7′
1 · Voice change — laryngeal nerves
- External laryngeal nerve, running with the superior thyroid artery: supplies cricothyroid. Injury → weak voice, loss of high notes. Prevention: ligate the superior artery close to the gland.
- Recurrent laryngeal nerve, closely related to the inferior thyroid artery: supplies all other intrinsic laryngeal muscles. Unilateral injury → hoarseness; bilateral → stridor and airway obstruction requiring emergency tracheostomy. Prevention: ligate the inferior artery away from the gland.
2 · Hypocalcaemia — parathyroid glands
The four parathyroids lie on the posterior surface of the thyroid lobes within its sheath and are supplied mainly by the inferior thyroid artery. Removal or devascularisation causes hypocalcaemia within 24–48 hours: perioral and digital tingling, carpopedal spasm, and positive Trousseau's and Chvostek's signs. Serum calcium is checked routinely afterwards.
3 · Haemorrhage — the veins
The inferior thyroid veins form a plexus in front of the trachea, and a thyroidea ima artery is present in about 10%. Bleeding into the closed space beneath the strap muscles can compress the trachea and cause airway obstruction — a wound haematoma after thyroidectomy is opened at the bedside.
4 · Pneumothorax
The cupula of the pleura rises into the root of the neck and may be breached in a low dissection.
Marking guide: external laryngeal nerve with rule 1.5 · recurrent laryngeal with unilateral/bilateral 2 · parathyroids and hypocalcaemia 2 · haemorrhage/airway 1 · pneumothorax 0.5.