The Thyroid Gland

Question 1

What is the thyroid gland and where is it located

Answer 1

located in the anterior neck, spanning between the C5 and T1 vertebrae. It is an endocrine gland, divided into two lobes which are connected by an isthmus. It is said to have a butterfly shape.

Question 2

Which levels does the thyroid gland span between

Answer 2

C5 and T1 vertebrae

Question 3

It lies behind which muscles?

Answer 3

the sternohyoid and sternothyroid

Question 4

The thyroid gland wraps around which cartilage

Answer 4

cricoid cartilage and superior tracheal rings

Question 5

it is inferior to the thyroid cartilage of the

Answer 5

larynx.

Question 6

The gland is in the WHAT of the neck, along with the trachea, oesophagus and pharynx.

Answer 6

visceral compartment

Question 7

The compartment is bound by

Answer 7

pretracheal fascia

Question 8

During development, the thyroid gland initially forms in the

Answer 8

floor of the primitive pharynx, near the base of the tongue

It descends down the neck to lie in its adult anatomical position

Question 9

The thyroid gland secretes hormones directly into the blood. Therefore it needs to be highly vascularised

What does this mean?

Answer 9

to supply (an organ or tissue) with blood vessels.

Question 10

Blood supply to the thyroid gland is achieved by two main arteries;

Answer 10

the superior and inferior thyroid arteries.

These are paired arteries arising on both the left and right.

Question 11

The superior thyroid artery is the first branch of the external carotid artery. After arising, the artery descends toward the thyroid gland. As a generalisation, it supplies the

Answer 11

superior and anterior portions of the gland.

Question 12

The superior thyroid artery is the first branch of the

Answer 12

external carotid artery

Question 13

The inferior thyroid artery arises from the

Answer 13

thyrocervical trunk (which in turn is a branch of the subclavian artery).

Question 14

Where does The inferior thyroid artery run and supply

Answer 14

The artery travels superomedially to reach the inferior pole of the thyroid. It tends to supply the postero-inferior aspect.

Question 15

In a small proportion of people (around 10%), there is an additional artery present;

Answer 15

the thyroid ima artery

Question 16

Where does the the thyroid ima artery come from and what does it supply

Answer 16

It comes from the brachiocephalic trunk of the arch of aorta, supplying the anterior surface and isthmus.

Question 17

Venous drainage is carried out by the

Answer 17

superior, middle and inferior thyroid veins, which form a venous plexus

Question 18

he superior and middle veins drain into the

Answer 18

internal jugular veins,

Question 19

whereas the inferior drains into

Answer 19

the brachiocephalic vein.

Question 20

The thyroid gland is innervated by branches derived from the sympathetic trunk. However, these nerves do not control endocrine secretion – release of hormones is regulated by

Answer 20

pituitary gland.

Question 21

The are two recurrent laryngeal nerves; one left and one right. They arise from their respective

Answer 21

vagus nerves, and descend into the chest.

Question 22

In the chest, they hook around the subclavian artery (right RL nerve), or the arch of aorta (left RL nerve). The nerves then ascend back up the neck, running between the trachea and oesophagus. They pass underneath the thyroid gland to innervate the larynx.

What nerves do this

Answer 22

The two recurrent laryngeal nerves

Question 23

What is the function of the extrinsic laryngeal muscles (sternothyroid, thyrohyoid etc.)?

Answer 23

They move the larynx up and down the neck and support its central positon, this is particularly important for swallowing.

Question 24

Where may you create an emergency airway?

Answer 24

Between the thyroid and cricoid cartilage, through the cricothyroid membrane.

Question 25

Why does the thyroid gland have such a good blood supply?

Answer 25

Iodine is present in very low concentration in the blood so the gland needs a
high blood flow to ensure adequate delivery of iodine.

Question 26

Which structure may be compressed by an enlarged thyroid gland?

Answer 26

The trachea

Question 27

What is the location of the parathyroid glands and how many are there?

Answer 27

They are positioned on the posterior surface of the thyroid gland, there are
four.

Question 28

What is the only complete cartilage ring around the airway?

Answer 28

The cricoid cartilage.

Question 29

A patient may develop hypocalcaemia after thyroid surgery, why?

Answer 29

The parathyroid glands may be (accidentally or deliberately) removed during
thyroid surgery which will cause acute (sudden) hypoparathyroidism.