However, the brain is surrounded by cerebral-spinal fluid inside the skull and thus when the skull accelerates the brain tends to continue its original motion, (Newton's First Law of Motion). Aside fr...However, the brain is surrounded by cerebral-spinal fluid inside the skull and thus when the skull accelerates the brain tends to continue its original motion, (Newton's First Law of Motion). Aside from some slowing due to drag within the fluid, the brain will then strike the hard inside surface of the skull at nearly full speed and come to rest, or even bounce and change direction, over a very small time interval.
