The Thyroid and Parathyroid Glands

Question 1

What vertebral levels does the thyroid gland sit between?

Answer 1

C5 to T1

Question 2

What cartilaginous structures does the thyroid sit between?

Answer 2

Thyroid cartilage

6th tracheal ring

Question 3

Identify and name the strap muscles that sit over the thyroid gland?

Answer 3

• Omohyoid
• Sternohyoid
• Sternothyroid

Question 4

What two nerves supply the strap muscles?

Answer 4

Recurrent laryngeal nerve

• Supplies everything but cricothyroid
• Runs between trachea and oesophagus

Superior laryngeal nerve

• Supplies cricothyroid
• Runs alongside sup. thyroid artery

Question 5

What is the blood supply to the thyroid gland?

Answer 5

Sup. thyroid artery

Inf. thyroid artery

Question 6

From which artery does the sup thyroid artery arise?

Answer 6

ECA

Question 7

From which artery does the inf thyroid artery arise?

Answer 7

Subclavian

Question 8

What is the drainage of the thyroid artery?

Answer 8

Sup

Middle

Inf

Thyroid veins

Question 9

What do the superior and middle thyroid veins drain into?

Answer 9

IJV

Question 10

What does the inferior thyroid vein drain into?

Answer 10

Left brachiocephalic

Question 11

How are thyroid hormones stored in the gland?

Answer 11

In cavities surrounded by secretory cells

Question 12

What is the cavity combined with the secretory cell collectively known as?

Answer 12

Follicle

Question 13

How arethe thyroid hormones stored within the follicle?

Answer 13

Bound to glycoproteins and is known as colloid

Question 14

Identify

A) Colloid

B) Follicular cells

Answer 14

Question 15

What type of cells line the follicle?

Answer 15

Cuboidal epithelial cells

Question 16

What are the clear cells on histology of the thyroid and what do they produce?

Answer 16

C cells

Secrete calcitonin

Question 17

What hormones are secreted by the thyroid gland?

Answer 17

Thyroxine

• Triiodinothyronine (T3)
• Tetraiodinothyronine (T4)

Calcitonin

Question 18

Where are the superior parathyroid glands?

Answer 18

• Lateral to the thyroid lobes
• Cricoid cartilage level

Question 19

How many thyroid glands does the average person have?

Answer 19

4

Question 20

What is the arterial supply and venous drainage of the parathyroids?

Answer 20

Via the inferior thyroid artery

• Thyroid veins to IJV

Question 21

How are the parathyroid glands seperated from the thyroid?

Answer 21

By a thin fibrous capsule

Question 22

What are the two types of cells in the parathyroid glands?

Answer 22

Chief cells

Oxyphil cells

Question 23

What is parathyroid hormone secreted in response to and what is it’s action?

Answer 23

Low serum calcium

• Stimulates osteoclasts to release Ca²⁺ and phosphate from bone
• Inhibits osteoblasts
• Increases renal calcium reabsorption
• Increases renal phosphate secretion
• Stimulates the kidney to release calcitriol