Medulla oblongata

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What it is
The lowest part of the brainstem, tapering from the pons down to the foramen magnum where it becomes the spinal cord. Its front shows the two pyramids either side of the anterior median fissure and the oval olives lateral to them.
Function
Vital centres for breathing, heart rate and blood pressure; reflexes of swallowing, coughing and vomiting; nuclei of cranial nerves IX-XII; and the crossing of the motor pyramids.
Size
About 3 cm long; 1 cm wide below, 2 cm wide at the pons
Clinical note
Most motor fibres cross here (decussation of the pyramids), so each side of the brain moves the opposite side of the body; tonsillar herniation compresses the medulla and stops breathing.

Nearby nervous structures Abducens nerve root (CN VI), Accessory nerve root (CN XI), C1 spinal nerve, Facial nerve root (CN VII), Fourth ventricle, Glossopharyngeal nerve root (CN IX), Hypoglossal nerve root (CN XII), Pons, Vagus nerve root (CN X), Vestibulocochlear nerve root (CN VIII)