The external and extreme capsules are two thin sheets of white matter in each hemisphere, either side of the claustrum: the external capsule lies between the putamen and the claustrum, and the extreme capsule between the claustrum and the insular cortex. Going outward from the putamen: external capsule, claustrum, extreme capsule, insula. [1][2]
The putamen and insula are lit together; the external and extreme capsules are not drawn on their own. The front (coronal) slice button cuts through them. Drag to turn, pinch or scroll to zoom, tap any part to name it; .
Not a separate shape in this atlas; lit: the part that holds it. Lit: the whole putamen and insula, on both sides. The external and extreme capsules lie between these two lit parts, the putamen on the inner side and the insula on the outer side, with the claustrum between the two capsules. The BodyParts3D model has no shape for either capsule or for the claustrum, so the pair either side of all three is lit and nothing is drawn at a guessed point. [1][2][3]
Lit here: the putamen and the insula, the parts the external and extreme capsules lie between — see each on its own page.
The external capsule lies between the putamen, the outer part of the lentiform nucleus, and the claustrum. [1]
The extreme capsule lies between the claustrum and the insular cortex; it is the outermost of the three capsules, the internal capsule being the innermost. [2]
The putamen separates the external capsule from the internal capsule on its inner side, and the claustrum separates it from the extreme capsule on its outer side; around the lentiform nucleus the external capsule eventually joins the internal capsule. [1]
All of them lie to the side of the corpus striatum; the extreme capsule is easiest to see in a horizontal section, just outside the claustrum. [2]
What it does
The external capsule holds corticocortical association fibres, which connect one area of the cerebral cortex with another. [1]
It is also a route for cholinergic fibres from the basal forebrain to the cerebral cortex. [1]
The extreme capsule is also made of association fibres; it is thought to be part of the ventral stream of language and of the limbic system, and its role in picture naming suggests it helps retrieve the meaning of words from memory. [2]
Connections
The claustrum, the thin sheet of grey matter between the two capsules, is connected with almost the whole cortex. [3]
Inside it
Each is described as a thin white sheet of white-matter fibre tracts, not a nucleus. [1][2]
Other names
Capsula extrema (Latin) for the extreme capsule. [2]
Size
The model has no shape for the external and extreme capsules itself, so it is not measured here. The left putamen that holds it measures about 43 mm front to back, 26 mm top to bottom and 18 mm side to side on this model (the box it fits in, not its volume). [4]
The model has no shape for the external and extreme capsules itself, so it is not measured here. The left insula that holds it measures about 52 mm front to back, 35 mm top to bottom and 19 mm side to side on this model (the box it fits in, not its volume). [4]
Facts describe anatomy and normal function only. The 3D model is the adult male BodyParts3D brain (credits and licence); real brains vary in size and shape, so its measurements describe one model, not anyone’s brain.
