All brains are wrinkly. Wrinkles in your brain are a good thing. Wrinkles are biology’s way of maximizing surface area while conserving space.
The plateaus of the brain are called gyri (or a gyrus).
The smaller, sunken in wrinkles are called sulci (or a sulcus). Sunken in sulci – that’s how I remember it.
The larger canyons of the brain are called fissures. These are the groves that separate the hemispheres and the lobes of the brain.