Pituitary gland

Function

The pituitary — a pea-sized general commanding the endocrine orchestra — hangs from the hypothalamus by the infundibulum in the bony sella turcica. Its posterior lobe is brain tissue: it stores and releases hypothalamic oxytocin and ADH. Its anterior lobe, guided by hypothalamic releasing hormones in the portal blood, secretes six hormones: growth hormone, prolactin, ACTH, TSH, FSH and LH.

This dual structure makes it the junction of neural and hormonal control — the body's finest integration of rhythm, stress, growth and reproduction. Above it the optic chiasm crosses; swelling of the gland presses that crossing first.

Blood supply

Superior and inferior hypophyseal arteries from the internal carotid; the portal system delivers hypothalamic command.

Nerve supply

Hypothalamic-hypophyseal tract (posterior); no direct nerve control of the anterior lobe.

Clinical relevance

Pituitary adenoma

Benign tumours press the optic chiasm (bitemporal hemianopia) or secrete — prolactinomas galactorrhoea, acromegaly from GH, Cushing from ACTH.

Sheehan syndrome

Postpartum pituitary infarction after haemorrhagic shock — the failure to lactate is the first clue.

Diabetes insipidus

ADH deficiency floods the kidneys — polyuria and polydipsia with dilute urine.

Related conditions

• Cushing's syndrome
• Pituitary adenoma