The internal capsule is a band of white matter deep in each cerebral hemisphere: it passes between the caudate nucleus and thalamus on the inner side and the putamen and globus pallidus on the outer side, and carries fibres up to and down from the cerebral cortex. [1]
The 3D brain needs JavaScript. The text below still says where the internal capsule is and what it does.
Slice
Opens cut by a top (axial) slice through the internal capsule. Drag to turn, pinch or scroll to zoom, tap any part to name it; .
Takes part in: movement — see every part of each lit together.
Where it is
A paired white-matter structure in the lower inner part of each cerebral hemisphere. [1]
It separates the caudate nucleus and thalamus (inside) from the putamen and globus pallidus (outside), and also runs between the caudate nucleus and putamen. [1]
Cut horizontally it is V-shaped: an anterior limb and a posterior limb, with the bend between them called the genu. [1]
Above the basal ganglia its fibres fan out as the corona radiata; below, they gather into the crus of the cerebral peduncle in the midbrain. [1]
What it does
It is a two-way tract: ascending and descending fibres pass through it on their way to and from the cerebral cortex. [1]
The corticospinal tract makes up a large part of it, carrying motor commands from the primary motor cortex down to the motor neurons of the spinal cord. [1][2]
Touch and body-position signals pass up through it from the thalamus to the postcentral gyrus, and visual signals pass through its back part on their way to the occipital lobe. [1]
Connections
Anterior limb: fibres between the thalamus and the frontal lobe, from the frontal lobe to the pons, and from the cortex to the striatum. [1]
Genu: corticobulbar fibres from the motor cortex to the cranial-nerve nuclei that move the head and face. [1]
Posterior limb: corticospinal fibres in its front half, sensory fibres from the thalamus to the postcentral gyrus further back, and the start of the optic radiation from the lateral geniculate nucleus to the visual cortex. [1][3]
Inside it
It has five named parts: the anterior limb, genu and posterior limb, plus a retrolenticular part behind the lentiform nucleus (visual fibres) and a sublenticular part beneath it (auditory fibres to the temporal lobe). [1]
Its blood comes mainly from the lenticulostriate branches of the middle cerebral artery, with the recurrent artery of Heubner and the anterior choroidal artery supplying the lower parts. [1]
Other names
Capsula interna (Latin); the anterior limb is also called the crus anterius. [1]
Size
On this model the left internal capsule measures about 54 mm front to back, 33 mm top to bottom and 23 mm side to side (the box it fits in, not its volume); the right one is its mirror image. [4]
Centre of the left internal capsule compared with the centre of the left thalamus: 13 mm further forward, 7 mm higher, 8 mm further from the midline; 17 mm apart in a straight line. [4]
Centre of the left internal capsule compared with the centre of the left putamen: 6 mm further back, 3 mm higher, 7 mm closer to the midline; 10 mm apart in a straight line. [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.