|Brain: Internal capsule|
|Horizontal section of right cerebral hemisphere. (Capsula interna labeled at upper left.)|
|The motor tract.|
|Gray's||subject #189 836|
The internal capsule is V-shaped when cut both coronally (on the same plane as the face) and horizontally/transversely (the same plane as the brim of a top hat).
When cut horizontally:
- the bend in the V is called the "genu".
- the part in front of the genu is the "anterior limb". or crus anterius.
- the part behind the genu is called the "posterior limb" or crus posterius.
There is also a retrolenticular and a sublenticular part to the internal capsule.
- The posterior limb of the internal capsule contains corticospinal fibers and sensory fibers from the body.
- The anterior limb of the internal capsule contains:
- The retrolenticular part contains fibers from the optic system, coming from the lateral geniculate nucleus of the thalamus. More posteriorly, this becomes the optic radiation. Some fibers from the medial geniculate nucleus (which carry auditory information) also pass in the retrolenticular internal capsule, but most are in the sublenticular part.
They can affect sensory and motor systems on the opposite side of the body, and possibly eyesight (to the contralateral visual field).
Hearing should not be affected in a single capsule lesion, as this information crosses over to both sides of the brain while in the brainstem.
- BrainMaps at UCDavis internal capsule
- NeuroNames hier-180
- Roche Lexicon - illustrated navigator, at Elsevier 13048.000-2