A medical question for you !

TheSpirits: Usually, an accident where you hit your head hard causes hematoma. A hematoma is a blood mass that forms under your skull when a blood vessel ruptures. The source of hematoma is usually the middle meningeal artery or vein.
So the question is : Why do doctors always check the pupils, especially on the damaged side when paramedics bring the victim to the hospital ? Do pupils tell them something about the victim's condition ?

EraseThisFace: Pupils are often fixed (do not react to light) and dilated when a severe head trauma occurs.

TheSpirits: Do you know what exactly make the pupils dilate ?

HardcoreHerbivore: LSD.

StuckInTheSixties:

(laughs hysterically)

TheSpirits: @HardcoreHerbivore: Thank you , but I don't think LSD. is the right answer

HardcoreHerbivore: Sorry.I couldn`t resist.

TheSpirits: LOL

EraseThisFace: I'm not sure. It may indicate damage to the cerebral cortex.

jes51: they look at the pupils for dialation concusion and trauma

Comrade_: sexual arousal causes pupil dilation.

http://www.nlm.nih.gov/medlineplus/ency/article/000028.htm
as a symptom for head trauma: "Changes in, or unequal size of pupils"

..I didn't find the answer for "why".

duncan124: I think they look for balance as well. Are you moving your head and eyes together to look for something or are they moving apart? The head swings to the left while the eyes are going round to the right? Which is what happens when what caused the build up of blood is still going on and the hematoma is not the first thing to worry about.
Did you have a good reason to ask us this?

duncan124: Pupils are dilated when blood is not reaching them. That is , pupils are not dilated because muscles are active so when the muscles are stoped they become dilated.

Geoff: If the pupils are different sizes it often indicates a head injury more serious than concussion (or more correctly a mild traumatic brain injury - MTBI).