Thyroid Gland (199-213)

Question 1

What is the arterial supply to the thyroid gland?;

Answer 1

Superior thyroid artery (1st branch of external carotid). Inferior thyroid artery (branch of thyrocervical trunck [branch of subclavian gland]). In around 10% population there is additionally the thyroid ima artery (arises from brachiocephalic trunk)

Question 2

What is the venous drainage of the thyroid gland?;

Answer 2

Superior, middle and inferior thyroid veins, which form a venous plexus.
Superior & middle drain into internal jugular.
Inferior drains into brachiocephalic vein.

Question 3

What is the lymphatic drainage of the thyroid gland?;

Answer 3

Paratracheal and deep cervical lymph nodes.

Question 4

Name three complications following thyroid surgery;

Answer 4

Hypercalcaemia, reccurent laryngeal nerve injury, bleeding/haematoma

Question 5

What is embryological origin of the parathyroid glands?;

Answer 5

Superior parathyroid - 4th pharyngeal pouch (endoderm). Inferior parathyroid - 3rd pharyngeal pouch (endoderm)

Question 6

What is the blood supply to the parathyroid glands?;

Answer 6

Similar to thyroid gland. Arterial supply mostly via inferior thyroid artery. Collateral arterial supply from superior thyroid artery (plus thyroid ima artery in 10% population). Venous drainage into superior, middle and inferior thyroid veins)

Question 7

Name the cartilages of the larynx;

Answer 7

Unpaired (3) - epiglottis, thyroid, cricoid cartilages.
Paired (3) - arytenoid, corniculate, cuneiform.

Question 8

Name the muscles of the larynx;

Answer 8

• Cricothyroid,
• Thyroarytenoid,
• Posterior cricoarytenoid,
• Lateral cricoarytenoid,
• Transerve and oblique arytenoids.

Question 9

Which muscle abducts the vocal cord?;

Answer 9

Posterior cricoarytenoid (sole abductor of vocal folds)

Question 10

What is the motor nerve supply to the intrinsic laryngeal muscles?;

Answer 10

All by inferior laryngeal nerve (branch of recurrent laryngeal [branch of vagus CN X]) expect cricothyroid which is innverated by superior laryngeal nerve (branch of vagus CN X)

Question 11

What is the sensory nerve supply of the larynx?;

Answer 11

Recurrent laryngeal- sensory to infraglottis (plusmotor innervation of all internal muscles of larynx (except criothyroid)).
Superior laryngeal nerve - sensory to supraglottis (motor innveration to cricothyroid muscle)

Question 12

What is the lymphatic drainage of the larynx?;

Answer 12

Drain into deep cervical lymphatics

Question 13

Name some benign vocal cord diseases;

Answer 13

Singers nodule, polps, papilloma, cysts

Question 14

Briefly describe the management principles of treating laryngeal cancers;

Answer 14

• Radiotherapy (T1-2, N0)
• Surgery (endoscopic resection, partial laryngectomy, total laryngectomy), chemotherapy, immunotherapy

Question 15

What layers would you go through when performing a tracheostomy?;

Answer 15

1. Skin,
2. sucutaneous fat,
3. Platysma
4. Superifical or investing layer of deep cervical fascia
5. Strap muscles (sternohyoid & sternothyroid)
6. Pretracheal fascia,
7. Thryoid istmhmus
8. Trachea