The adrenal medulla is the reddish-brown core of each adrenal gland. It is developmentally part of the sympathetic nervous system: its chromaffin cells act like modified postganglionic neurons and, when stimulated by preganglionic sympathetic fibres, pour adrenaline and noradrenaline straight into the blood.
| Location | Central core of each adrenal gland, surrounded by the adrenal cortex |
|---|---|
| Secretes |
|
| Nerve Supply | Preganglionic sympathetic fibres from the greater, lesser and least splanchnic nerves |
| Blood Supply | Medullary arterioles from the capsular plexus; Cortical sinusoids passing through the cortex |
| Venous drainage |
|
Releases catecholamines during stress or exercise to raise heart rate, blood pressure and blood glucose, dilate airways and redirect blood flow to muscles.
A phaeochromocytoma is a catecholamine-secreting tumour of the medulla that causes episodes of headache, sweating, palpitations and severe hypertension; it is diagnosed with plasma or urine metanephrines. Surgery requires alpha-blockade first to prevent a hypertensive crisis. Neuroblastoma, a childhood cancer, often arises from the medulla.
A chromaffin cell tumour releasing adrenaline and noradrenaline, causing paroxysmal hypertension, sweating, headache and palpitations.
A malignant tumour of neural crest cells in young children, often starting in the adrenal medulla and presenting as an abdominal mass.
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