19. Clinical Anatomy of the Endocrine Glands Flashcards
Describe the position of the pituitary gland.
- 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.
What are the two parts of the pituitary gland and what are their functions?
- Anterior pituitary -> Secretion of regulatory hormones (growth hormone, prolactin, FSH, LH, ACTH and TSH)
- Posterior pituitary -> Releases ADH and oxytocin
What is the relation of the pituitary gland to these structures:
- Optic chiasm
- Internal carotid artery
- Cavernous sinus
- The optic chiasm is located directly above the pituitary gland.
- The internal carotid arteries and cavernous sinuses lie lateral to the pituitary gland.
Describe pituitary tumours.
- 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.
Describe the structure of the thyroid gland.
A thin central isthmus connecting the lateral lobes.
Describe the position of the thyroid gland.
Anterior to the 2nd-4th tracheal rings
What does the thyroid gland secrete?
- T3 and T4 hormones
- Parafollicular C cells within the thyroid parenchyma also produce calcitonin, which antagonises the effect of PTH
Describe the position of the parathyroids.
- On the posterior aspect of the thyroid lateral lobes
- There are 4 of them
What do the parathyroids secrete?
PTH, responsible for increasing serum calcium levels.
Describe the blood supply and drainage of the thyroid and parathyroid glands.
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.
What structure are the inferior thyroid arteries closely related to?
Recurrent laryngeal nerves
Describe goitre.
- 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.
What structures does thyroid surgery potentially endanger?
- Recurrent laryngeal nerves
- Parathyroids
Are the adrenal glands intraperitoneal or retroperitoneal?
Retroperitoneal
What is the function of the adrenal glands?
- Adrenal medulla -> Secretes adrenaline and noradrenaline
- Adrenal cortex:
- Composed of the zona glomerulosa, zona fasciculata and zona reticularis
- Secretes steroid hormones
Describe the blood supply to the adrenal glands.
Superior (branch of inferior phrenic artery), middle (branch of abdominal aorta artery) and inferior (branch of renal artery) adrenal arteries.
Innervation of the adrenal medulla is…
Preganglionic sympathetic
