The thyroid and parathyroid glands

Question 1

Where is the thyroid gland?

Answer 1

Anterior to the trachea and inferior to the larynx

Question 2

What vertebral level and anatomical locations help find the thyroid gland?

Answer 2

It is located between the vertebral level of C 5- T 1 and between the cricoid cartilage

cartilage and the 6^th tracheal ring.

Question 3

What does the isthmus lie opposite?

Answer 3

1st to 2nd tracheal rings

Question 4

Answer 4

Question 5

What strap muscles overlie the thyroid gland?

Answer 5

Sternohyoid muscle

Sternothyroid muscle

Question 6

Name the two nerves that supply the muscles of the vocal cords and describe their location in relation to the thyroid gland:

Answer 6

1. Recurrent laryngeal nerve**. – runs between trachea and oesophagus
2. Superior laryngeal nerve- Branch of vagus nerve at the level of C2 vertebra and descends medially towards the thyrohyoid membrane, the membrane between the thyroid cartilage and hyoid bone

Question 7

From which major artery in the neck does the superior thyroid artery arise?

Answer 7

External carotid artery

Question 8

From which artery does the inferior thyroid artery arise?

Answer 8

Thyrocervical trunk which is a branch of the subclavian artery

Question 9

Into which vein does the superior thyroid vein drain?

Answer 9

IJV

Question 10

Into which vein does the middle thyroid vein drain?

Answer 10

IJV

Question 11

Into which vein does the inferior thyroid vein drain?

Answer 11

Brachiocephalic vein

Question 12

Where are the hormones of the thyroid gland stored?

Answer 12

in cavities, surrounded by secretory cells. These make up a follicle. Within the cavity of the follicle, the hormone is bound to a glycoprotein and is called as colloid

Question 13

What happens during secretion to the thyroid hormone?

Answer 13

During secretion the hormone is re-absorbed from the cavity, and then released into the surrounding interstitial spaces.

Question 14

How can you recognise thyroid glands?

Answer 14

easy histology as pinkish circles looking like this. Every single colloid follicle is lined by a simple non-stratified relatively simple type of epithelium. Can see plexus of blood vessels between the little follicle circles.

Question 15

What do follicular cells look like?

Answer 15

are almost columnar in appearance in some regions, whilst elsewhere they have a low cuboidal appearance

Question 16

What does thryoid hormone make?

Answer 16

a hormone called calcitonin and these are found in spaces between the cells.

Question 17

What do parafollicular cells look like?

Answer 17

Have a red cytoplasm

Question 18

Answer 18

Question 19

Answer 19

1 = Colloid follicle

2 = Interfollicular connective tissue (Toby thinks follicular cells so gonna be brought up tomorrow

3 = Parafillicularcells

Question 20

What type of cell do you see lining the follicle?

Answer 20

Squamous follicular cells

Question 21

What colour does the colloid stain?

Answer 21

Yellow

Question 22

What do the C cells secrete?

Answer 22

Calcitonin

Question 23

What hormones does the thyroid gland secrete?

Answer 23

Thyroxine

Triiodothyronine

Question 24

Where does the parathyroid glands lie?

Answer 24

Lateral half of the posterior surface of each thyroid lobe external to the thyroid fibrous capsule

Question 25

How many parathyroid gland most people have?

Answer 25

4

They are seperated from the thyroid gland by a thin fibrous capsule

Question 26

The superior parathyroids are situated at?

Answer 26

the level of the inferior border of the cricoid cartilage

Question 27

. The inferior parathyroids are usually located where?

Answer 27

near the inferior poles of the thyroid, though their position is variable.

Question 28

Arterial supply to both superior and inferior parathyroids is predominantly from what?

Answer 28

the inferior thyroid arteries

Question 29

What is venous drainage done by?

Answer 29

via the veins draining the thyroid to the internal jugular veins.

Question 30

What is this?

Answer 30

Parathyroid gland

Question 31

Answer 31

The parathyroid – chief cells (1) and oxyphil cells (2). Chief cells are more numerous and have a darker staining cytoplasm. Lighter cells are oxyphil cells. The white parts are fat.

Question 32

What hormone is secreted by the parathyroid gland and what is the action of this hormone?

Answer 32

Parathyroid hormone- Maintains appropriate balance of calcium in blood stream and tissues

Question 33

What cells does this hormone act upon and what is their subsequent action?

Answer 33

Stimulates the conversion of immature osteoclasts to mature type- Subsequently increasing bone degradation