Chiari malformations, or hindbrain hernias, consist of an internal, anatomical abnormality where the lower-most part of the brain becomes squeezed through the large opening at the base of the skull (known as the foramen magnumThe large, ovoid opening at the base of the skull, measuring about 3 x 3.5cm, through which the spinal cord passes, to c…), into the top of the spinal canalThe individual bones that comprise the spinal column are made up of a weight-bearing “body” and other components whi…. There are two main forms of Chiari malformationAn anatomical abnormality affecting the lowermost part of brain, where it joins the spinal cord, at the top of the neck…., type 1 and type 2. Type 1 presents mainly but not exclusively in adult life. Type 2 is seen mostly in children and is associated with the conditions of spina bifidaDuring development, at each level of the spine two plates of bone migrate towards one another and fuse, in the midline, … and hydrocephalusMeaning “water on (or in) the brain”, this word refers to an anatomical state in which there is an abnormally large …. In both forms of Chiari there is, essentially, a mis-match between the volume of the lower-most part of the cranial cavity (known as the posterior fossa) and the volume of that part of the brain which lies within this cavity. This part of the brain is referred to as the cerebellum – meaning the “little brain”. More specifically, it is a part of the cerebellumThis word means the “little brain” and refers to a large part of the brain that sits in lowermost part of the skull,… known as the tonsils that protrude through the foramen magnumThe large, ovoid opening at the base of the skull, measuring about 3 x 3.5cm, through which the spinal cord passes, to c…, into the spinal canalThe individual bones that comprise the spinal column are made up of a weight-bearing “body” and other components whi…. The cerebellar tonsilsThe lower-most part of the cerebellum is made up of a pair of structures, one on each side of the midline, known as the … have nothing to do with the tissueIn everyday speech a piece of tissue is a thin sheet of paper, used to wrap a present or, in a slightly different form, … at the back of the mouth, which becomes inflamed when someone has a sore throat. It is simply the case that early anatomists, when they were dissecting the human body to see how we are all put together, happened to give the same name to two very different structures, in different parts of the body. Tonsilla is a Latin word referring to a post used for tying up a ship and perhaps the stump-like appearance of the cerebellar tonsilsThe lower-most part of the cerebellum is made up of a pair of structures, one on each side of the midline, known as the … was likened to a ship’s mooring post. It is important to stress that Chiari malformations are essentially benign – always provided that other conditions, which may mimic Chiari, have been excluded.