The midbrain
Midbrain · mesencephalon
The top part of the brainstem, which helps control eye movements, reflexes and alertness.
What it does
The midbrain is the short upper section of the brainstem, between the thalamus and the pons. It contains centres for eye movements and pupil size, relays for hearing and vision reflexes, and the dopamine-making cells that feed the basal ganglia.
Surprising fact
It is the midbrain that makes your head and eyes swing automatically towards a sudden flash or bang, before you have consciously noticed it.
Why it matters
Doctors shine a light in your eyes to check your pupils because the reflex runs through the midbrain, giving a quick check on brainstem function.
Nearby
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Sources
Drafted with AI help; awaiting a human fact-check against these sources.
Open in the 3D atlas · Suggest a correction · Not medical advice.
3D models: Z-Anatomy & BodyParts3D (CC BY-SA 4.0 / 2.1 JP). Card text CC BY 4.0.