Internal Capsule
- It is a collection of white mater fibers.
- has 2 limbs called anterior and posterior ,2 limbs joined each other by genu
- Anterior limb is related medialy to the head of the caudate nuclues, laterally to the lentiform nuclues(anterior)
- Posterior limb is related medially to the thalamus ,laterally to the lentiform nucleus (posterior)
- Anterior limb contains-frontopontine fibers
- Genu contains-cortico nuclear fibers( efferent fibers for cranial nerve nuclei)
- Posterior limb contains- cortico spinal fibers( Ant 2/3),thalamo cortical fibers
Blood supply of the internal capsule
- From striate arteries derived from anterior choroidal arteries ,anterior cerebral,middle cerebral arteries.
Lesions- Because internal capsule contain cortico spinal tracts in the poterior limb anterior 2/3 if there is a any lesion in that region cause to have contralateral motor weakness in the body except face.
- Likewise if the lesion is in the genu area contralateral lower half of the face will have a muscle weakness (since upper half of the face is supplied by the both cortical ares there is no motor weakness on the upper facial muscles)
Causes for the lesions- Hemorrhage of a striate artery(cerebro vascular accident)
- Thrombosis of a striate artery
- Effect of the lesion to the body varies according to the site of the lesion of internal capsule.
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