The parathryoid gland- teachmeanatomy

Question 1

The parathyroid glands

Answer 1

are endocrine glands located in the anterior neck.

Question 2

They are responsible for the production of

Answer 2

parathyroid hormone (PTH)

Question 3

parathyroid hormone (PTH),

Answer 3

acts to increase the level of serum calcium.

Question 4

where is the parathryoud gland usually located

Answer 4

on the posterior aspect of the thyroid gland. They are flattened and oval in shape – situated external to the thyroid gland itself but within the pretracheal fascia.

Question 5

Most individuals have …….. parathyroid glands, although variation in number (from two to six) is common

Answer 5

four

Question 6

PTH glands can be divided into

Answer 6

Superior parathyroid glands (x2)

Inferior parathyroid glands (x2)

Question 7

Superior parathyroid glands (x2) are derived from the

Answer 7

derived from the fourth pharyngeal pouch.

Question 8

location of the superior PTh glands (x2)

Answer 8

They are located at the middle of the posterior border of each thyroid lobe, approximately 1cm superior to the entry of the inferior thyroid artery into the thyroid gland.

Question 9

Inferior parathyroid glands (x2) are derived from the

Answer 9

third pharyngeal pouch.

Question 10

location fo the inferior PTH gland x2

Answer 10

Although inconsistent in location between individuals, the inferior parathyroid glands are usually found near the inferior poles of the thyroid gland.

Question 11

In a small number of people, the inferior parathyroid glands can be found as far inferiorly as the

Answer 11

superior mediastinum.

Question 12

vascualr supply is similar to the

Answer 12

thyroid gland

Question 13

arterial supply chiefly via the

Answer 13

inferior thyroid artery (as this artery supplies the posterior aspect of the thyroid gland – where the parathyroids are located).

Question 14

Collateral arterial supply is from the

Answer 14

superior thyroid artery and thyroid ima artery.

Question 15

Venous drainage is into the

Answer 15

superior, middle, and inferior thyroid veins.

Question 16

Lymphatics

Answer 16

The lymphatic drainage from the parathyroid glands is to the paratracheal and deep cervical nodes.

Question 18

Nerves

Answer 18

The parathyroid glands have an extensive supply of sympathetic nerves derived from thyroid branches of the cervical ganglia.

Note: these nerves are vasomotor, not secretomotor – endocrine secretion of parathyroid hormone is under hormonal control.

Question 19

Clinical Relevance: Parathyroid Glands and Hypocalcaemia

Answer 19

Due to their location on the posterior aspect of thyroid gland, the parathyroid glands are at a high risk of being damaged or removed inadvertently during thyroid surgery.

This can result in an acute drop in serum calcium – hypocalcaemia. Clinical features include tetany, muscle cramps and paraesthesia of the fingers, toes, and mouth.

Because of this risk, it is usually standard post-operative practice to check the parathyroid hormone and serum calcium in all patients following thyroid surgery.

Question 20

A surgeon is performing a minimally invasive parathyroidectomy for primary hypercalcaemia. Which surface of the thryoid are the parathyroid glands located?

Answer 20

posteriorly

Question 21

Which embryological structure gives rise to the superior parathyroid glands?

Answer 21

fourth pharngeal pouch

Question 22

The third pouch gives rise to the

Answer 22

The third pouch gives rise to the inferior parathyroid glands.