Learnin On The Job

Question 1

2 arteries supplying the thyroid (and what they supply)

Answer 1

Inferior thyroid artery supplies the 4 parathyroid glands

Superior thyroid artery

Question 2

Where are the 2 thyroid arteries from?

Answer 2

Inferior thyroid artery comes from thyrocervical trunk off the subclavian artery (continuation of the brachiocephalic trunk)

Superior thyroid artery from the external carotid artery (from common carotid)

Question 3

Nerves of concern during thyroidectomy

Answer 3

Superior laryngeal nerve and recurrrent branch of the laryngeal nerve

-and the vagus if it’s a total thyroidectomy and you’re getting pretty lateral

Question 4

What does the superior laryngeal nerve innervate?

Answer 4

All intrinsic thyroid muscles EXCEPT for cricothyroid muscles are innervated by recurrent laryngeal nerve

The cricothyroid muscles are innervated by the superior laryngeal nerve

Question 5

Contrast the courses of the r. vs. l. recurrent laryngeal nerve

Answer 5

Right recurrent laryngeal passes under and around the subclavian artery

Left recurrent laryngeal nerve passes under and around the arch of the aorta

Question 6

What connects the two lobes of the thyroid?

(a) Location in relation to the tracheal rings

Answer 6

Isthmus connects the two lobes

(a) Isthmus located around the 2nd ring of the trachea

Question 7

2 remnants of the thyroid migration caudally from the pharynx

Answer 7

Embryologically the thyroid starts w/ the pharynx then migrates caudally

2 possible remnants

• pyramidal lobe of the thyroid
• thyroglossal cyst

Question 8

Describe the venous drainage of the thyroid artery

Answer 8

Superior, middle, and inferior veins drain the thyroid

-don’t get confused b/c there is no middle thyroid artery (only a middle thyroid vein)

Question 9

Arterial supply of the parathyroid glands

Answer 9

All 4 are supplied by the inferior thyroid artery

Question 10

3 muscles involved in a thyroidectomy

Answer 10

Sternohyoid- most anterior, connects sternum up to hyoid

Then thyrohyoid and sternothyroid muscles

Question 11

How to decide how big of margins to take on a melanoma?

Answer 11

Brrewlow criteria: depth of the melanoma determines excision margin

• melanoma in situ gets 5 mm margin
• under 1mm: 1 cm margin
• 1.01-2mm depth (tumor thickness): 1-2 cm margin
• 2 or more mm: 2 cm margin

Question 12

Relationship of vitamin D deficiency to parathyroid hormone levels

Answer 12

Vitamin D deficiency can cause secondary hyperparathyroidism
-need vit D to absorb Ca2+ => low vit D = low absorbed Ca so glands just keep pumping out parathyroid hormone in response to low serum Ca

Question 13

Tumor marker for medullary thyroid cancer

Answer 13

Calcitonin

-medullary thyroid cancer is the only one that arises from the C-cells = parafollicular cells (they make calcitonin

Question 14

Most common etiology of primary hyperparathyroidism

Answer 14

• 80-85% parathyroid adenoma

- 10% multiple gland hyperplasia

Question 15

Indications for surgery in a pt w/ asymptomatic hyperparathyroidism

Answer 15

1. Serum Ca2+ > 11 (but a little wiggle room here maybe even 10.5)
2. GFR under 60
   - indicating level 3 renal insufficiency
3. Osteoporosis, h/o nephrolithiasis
4. Age under 50

Question 16

Name and differentiate the two types of bariatric surgery

Answer 16

Restrictive = sense of satiety w/ less food
-gastric bypass, sleeve gastectomy, lap band

Malabsorptive = shorten amount of SI available for food absoprtion
-massive multiple foul-smelling BMs a day (ew)

Question 17

Compare prognosis of omphalocele vs. gastrochesis

Answer 17

Abdominal wall defects

-omphalocele is covered by membrane, but worse prognosis b/c 50% have associated cardiac defects => get echo

Question 18

Tx of umbilical vs. inguinal hernia in the newborn

Answer 18

Fix inguinal hernia in newborn before it leaves the hospital- b/c baby’s cry which increases their intraabdominal pressure

Watch and wait for up to 4-5 years for umbilical hernia to spontaneously resolve (which it normally does)