W3: Endocrine anatomy Flashcards
Where pituitary
Sella turcica
Sphenoid
Inferior to hypothalamus
Divisions of pituitary
The pituitary gland is divided into an anterior lobe, concerned with the secretion of regulatory hormones (growth hormone, prolactin, FSH, LH, ACTH and TSH) and the posterior lobe, which releases ADH and oxytocin.
Structures surrounding pituitary
The internal carotid arteries and cavernous sinuses lie lateral to the pituitary gland. The optic chiasm is located directly above the pituitary gland
Pituitary Tumours
Most tumours of the pituitary are benign adenomas, but they may cause problems due to their compres- sive 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.
Shape of thyroid
The thyroid, formed of a thin central isthmus connecting the lateral lobes
Where is thyroid
anterior to the 2nd-4th tracheal rings
Parathyroid where
What does it do
The four parathyroid glands are found on the posterior aspect of the thyroid lateral lobes and secrete PTH, responsible for increasing serum calcium levels
What else in in the thyroid
Parafollicular C cells within the thyroid parenchyma produce calcitonin, which antagonises the effect of PTH.
Supply of thyroid and parathyroid
The thyroid and parathyroid glands are supplied superiorly by the superior thyroid artery, a branch of the external carotid artery, and inferiorly by the inferior thyroid artery, a branch of the thyrocervical trunk.
The thyroid gland is drained by the superior and middle thyroid veins, which drain to the internal jugular vein, and the inferior thyroid vein, which drains to the brachiocephalic vein.
Inferior Thyroid Artery and Recurrent Laryngeal Nerve
The inferior thyroid artery passes with the recurrent laryngeal nerve during its ascent to the thyroid gland. This close association means the recurrent laryngeal nerve is vulnerable to damage during surgical ligation of the inferior thyroid artery, which would cause unilateral vocal cord paresis. Thyroid surgery also carries the risk of parathyroid gland damage or destruction.
Thyroid Goitre
There are a number of causes of a goitre (a swelling due to an enlarged thyroid gland). These 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.
Location of kidneys
The adrenal glands are retroperitoneal endocrine glands located bilaterally, superior and medial to the supe- rior poles of the kidneys.
Function of adrenal
The adrenal medulla synthesises and secretes adrenaline and noradrenaline, whilst the adrenal cortex, composed of the zona glomerulosa, zona fasciculata and zona reticularis, secretes steroid hormones.
Supply of adrenal
The adrenal glands are supplied by the superior (branch of inferior phrenic artery), middle (branch of abdominal aorta artery) and inferior (branch of renal artery) adrenal arteries.
Layers of the Adrenal Cortex
The layers of the adrenal cortex, from outermost to innermost, can be remembered using the mnemon- ic GFR (as in glomerular filtration rate) – glomerulosa, fasciculata and reticularis. The zona glomerulosa secretes aldosterone, the zona fasciculata secretes glucocorticoids and the zona reticularis secretes an- drogens.
