pituita

The pituitary gland sits at the base of the brain, below the hypothalamus, about the size of a pea. Galen in the 2nd century examined it and concluded it was a conduit for pituita—Latin for phlegm, mucus, or excess bodily fluid. He believed the brain produced mucus that dripped down through this gland into the throat and nasal cavity.

This made perfect sense to Galen. Everyone produced mucus. Everyone's nose ran. Everyone felt congested sometimes. The pituitary must be a mucus management system. For thirteen centuries, this was the accepted theory. Medical texts repeated it without question. The gland drains snot from the brain.

In the 16th century, Vesalius noticed the pituitary wasn't actually connected to the nasal cavity in the way Galen described. But he kept the name. In the 19th century, endocrinologists discovered the pituitary produces hormones—growth hormone, oxytocin, prolactin, and others—controlling growth, reproduction, metabolism, blood pressure, and stress response. It is one of the most important glands in the body. It had nothing to do with draining mucus.

Every biology student still learns the pituitary gland without learning that its name is medieval garbage dressed up as anatomy. We still call it the pituitary—'the mucus gland'—even though it controls whether you grow tall or stay short, whether your bones harden properly, whether your body can reproduce. Galen's error became immortal.