19. Clinical Anatomy of the Endocrine Glands

Question 1

Describe the position of the pituitary gland.

Answer 1

• Within the sella turcica of the sphenoid bone of the skull
• Just inferior to the hypothalamus

It is labelled as AP and PP on this MRI.

Question 2

What are the two parts of the pituitary gland and what are their functions?

Answer 2

• Anterior pituitary -> Secretion of regulatory hormones (growth hormone, prolactin, FSH, LH, ACTH and TSH)
• Posterior pituitary -> Releases ADH and oxytocin

Question 3

What is the relation of the pituitary gland to these structures:

• Optic chiasm
• Internal carotid artery
• Cavernous sinus

Answer 3

• The optic chiasm is located directly above the pituitary gland.
• The internal carotid arteries and cavernous sinuses lie lateral to the pituitary gland.

Question 4

Describe pituitary tumours.

Answer 4

• Most tumours of the pituitary are benign adenomas, but they may cause problems due to their compressive or secretory effects.
• Compression of the optic chiasm by pituitary masses classically gives bitemporal hemianopia, where the lateral fields of vision are lost.
• Hormonal consequences of secretory adenomas include Cushings Disease (ACTH overproduction), acromegaly (growth hormone overproduction) and galactorrhoea (prolactin overproduction).
• Treatment includes surgical excision, which is usually performed trans-sphenoidally through the nose.

Question 5

Describe the structure of the thyroid gland.

Answer 5

A thin central isthmus connecting the lateral lobes.

Question 6

Describe the position of the thyroid gland.

Answer 6

Anterior to the 2nd-4th tracheal rings

Question 7

What does the thyroid gland secrete?

Answer 7

• T3 and T4 hormones
• Parafollicular C cells within the thyroid parenchyma also produce calcitonin, which antagonises the effect of PTH

Question 8

Describe the position of the parathyroids.

Answer 8

• On the posterior aspect of the thyroid lateral lobes
• There are 4 of them

Question 9

What do the parathyroids secrete?

Answer 9

PTH, responsible for increasing serum calcium levels.

Question 10

Describe the blood supply and drainage of the thyroid and parathyroid glands.

Answer 10

Arterial supply:

• Superior thyroid artery -> From external carotid artery
• Inferior thyroid artery -> From the thyrocervical trunk.

Venous drainage:

• Superior and middle thyroid veins -> Drain to the internal jugular vein
• Inferior thyroid vein -> Drains to the brachiocephalic vein.

Question 11

What structure are the inferior thyroid arteries closely related to?

Answer 11

Recurrent laryngeal nerves

Question 12

Describe goitre.

Answer 12

• Goitre is a swelling due to an enlarged thyroid gland.
• Causes include iodine deficiency, Hashimoto’s thyroiditis (hypothyroidism), Graves’ disease (hyperthyroidism), inflammation and thyroid tumours.
• A mid-line lump in the neck can be identified as of thyroid origin by asking the patient to swallow: thyroid gland swellings and thyroglossal cysts move on swallowing.
• Asking the patient to poke out their tongue will cause a thyroglossal cyst to ascend in the neck, but a thyroid lump will not.

Question 13

What structures does thyroid surgery potentially endanger?

Answer 13

• Recurrent laryngeal nerves
• Parathyroids

Question 14

Are the adrenal glands intraperitoneal or retroperitoneal?

Answer 14

Retroperitoneal

Question 15

What is the function of the adrenal glands?

Answer 15

• Adrenal medulla -> Secretes adrenaline and noradrenaline
• Adrenal cortex:
  
  • Composed of the zona glomerulosa, zona fasciculata and zona reticularis
  • Secretes steroid hormones

Question 16

Describe the blood supply to the adrenal glands.

Answer 16

Superior (branch of inferior phrenic artery), middle (branch of abdominal aorta artery) and inferior (branch of renal artery) adrenal arteries.

Question 17

Innervation of the adrenal medulla is…

Answer 17

Preganglionic sympathetic