Endocrine system · Head and neck
Pituitary gland !
The pituitary is a pea-sized gland hanging below the brain; as the master gland it controls the thyroid, adrenals, growth, milk and the sex glands.
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What it is
A pea-sized gland hanging from the brain in the sella turcica.
What it does
The master gland: controls the thyroid, adrenals, growth, milk and the sex glands.
Key facts
- Where
- Sella turcica, under the optic chiasm, between the cavernous sinuses
- Blood supply
- Superior and inferior hypophyseal arteries (internal carotid); portal system
- Nerve
- Hypothalamus: releasing hormones (anterior), nerve tract (posterior)
- Function
- Anterior: GH, PRL, TSH, ACTH, FSH, LH; posterior: ADH, oxytocin
Relations
- Above
- Diaphragma sellae, pierced by the stalk; above it the optic chiasm and the hypothalamus
- Below
- Floor of the sella turcica and, below it, the sphenoid sinus, the route used in transsphenoidal surgery
- Lateral
- Cavernous sinus on each side, containing the internal carotid artery and the oculomotor, trochlear, abducens, ophthalmic and maxillary nerves
- In front
- Tuberculum sellae and the anterior clinoid processes of the sphenoid bone
- Behind
- Dorsum sellae and, behind it, the basilar artery in front of the pons
How to find it
Not palpable. It sits in the hypophyseal fossa of the sella turcica, directly above the sphenoid sinus; in endoscopic transsphenoidal surgery the sellar floor is the bulge in the upper back wall of the sinus, between the carotid bulges on each side and the optic nerve bulges above them.
Examination
- Confrontation visual fields, followed by formal perimetry: loss in both temporal fields points to compression of the optic chiasm by a sellar mass
On imaging
Contrast MRI in thin coronal and sagittal slices. Adenomas under 10 mm are microadenomas and larger ones macroadenomas; a microadenoma usually enhances less than the normal gland. On T1 images the posterior lobe is normally bright (stored ADH); the bright spot is lost in central diabetes insipidus. The gland normally swells in puberty and pregnancy.
Common problems
- Pituitary adenoma: a benign tumour that can make too much of a hormone or press on the optic chiasm (losing side vision in both eyes).
How it is diagnosed
Hormone blood tests, visual field test and MRI.
Treatment
- Medicines for some hormone-making tumours.
- Surgery through the nose and sphenoid sinus (transsphenoidal).
- Hormone replacement when the gland is underactive.
Clinical notes
- Transsphenoidal surgery reaches the sella through the nose and sphenoid sinus; risks include CSF leak, diabetes insipidus (often temporary) and injury to the internal carotid artery
- Sheehan syndrome: after severe postpartum haemorrhage, the gland, enlarged by pregnancy, infarcts; failure to breastfeed and absent periods are early clues of hypopituitarism
- An adenoma growing sideways invades the cavernous sinus and can palsy the oculomotor nerve (drooping lid, eye turned down and out)
- Excess growth hormone causes acromegaly (gigantism before the growth plates close); excess ACTH from an adenoma is Cushing disease
Anatomical variants
- Empty sella: the sella is mostly filled with CSF and the gland is flattened against its floor; often an incidental MRI finding with normal pituitary function
- The gland is normally larger in adolescence and in pregnancy, which should not be mistaken for a tumour on MRI
Development
Rathke's pouch grows up from the roof of the primitive mouth to meet the infundibulum growing down from the diencephalon; leftover cells along this path can give rise to craniopharyngioma.
Memory aid
Anterior lobe hormones: FLAT PiG (FSH, LH, ACTH, TSH, Prolactin, GH).
Related conditions
- Hyponatraemia
- Syndrome of inappropriate antidiuretic hormone secretion (SIADH)
- Hypothyroidism
- Pituitary adenoma
- Diabetes insipidus (central and nephrogenic)
- Prolactinoma (hyperprolactinaemia)
- Acromegaly and gigantism
- Hypopituitarism (incl. Sheehan syndrome and pituitary apoplexy)
- Multiple endocrine neoplasia (MEN 1, 2A, 2B)
- Male hypogonadism
- Childhood brain tumours (medulloblastoma, pilocytic astrocytoma, craniopharyngioma)
- Functional hypothalamic amenorrhoea
- Anorexia nervosa
- Perinatal depression and postpartum psychosis
- Premenstrual dysphoric disorder (PMDD)
- Gender dysphoria
Test yourself
Think of the answer, then tap the question to see it.
What visual field defect does a pituitary tumour growing upward classically cause?
Bitemporal hemianopia, from pressure on the crossing nasal fibres of the optic chiasm, often starting in the upper outer quadrants.
How do the anterior and posterior lobes of the pituitary gland differ in origin?
The anterior lobe comes from Rathke's pouch (mouth ectoderm); the posterior lobe is brain tissue made of hypothalamic axons.
Which is the most common hormone-secreting pituitary adenoma and how does it present?
Prolactinoma: absent periods and milk discharge in women, low libido and erectile problems in men; usually treated with medicine first.
What is Sheehan syndrome?
Infarction of the pituitary gland, enlarged by pregnancy, after severe postpartum haemorrhage; failure to breastfeed and absent periods are early clues.
Which structures lie in the cavernous sinus beside the pituitary gland?
The internal carotid artery and the oculomotor, trochlear, abducens, ophthalmic and maxillary nerves; a sideways adenoma can palsy the oculomotor nerve.
Educational information, not medical advice. For any symptom, see a health professional.
Its names
- Official Latin (TA2)
- glandula pituitaria TA2 3854
- Official Spanish (DeCS)
- Hipófisis
- English (TA2)
- Pituitary gland
- Also called
- hypophysis
Related
Sources: Terminologia Anatomica (TA2); Anatomy, Head and Neck, Pituitary Gland; 7.2 The Skull (OpenStax (Rice University), 2022) · adapted, CC BY 4.0.
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Representative model, for educational purposes only.
