| Parasthesia | abnormal sensation in the extremity. |
| Pericranium | a muscle layer between the skull and scalp. |
| Periosteum | a muscle layer between the skull and scalp. (Called pericranium when on the skull). |
| Posterior Fossa | A general term for the back area of the brain. This is where the brainstem, cerebellum and cerebellar tonsils lie. |