Internal capsule

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Telencephalon-Horiconatal.jpg

== Internal Capsule ==

The internal capsule is a white matter structure situated in the brain. It is a crucial pathway that contains both ascending and descending axons, which transmit information between the cerebral cortex and the brainstem or spinal cord. The internal capsule is divided into several parts: the anterior limb, the genu, and the posterior limb.

Anatomy

The internal capsule is bordered by the caudate nucleus medially and the lentiform nucleus laterally. It is divided into three main parts:

• Anterior limb: Located between the head of the caudate nucleus and the lentiform nucleus. It contains fibers that connect the thalamus to the frontal lobe.
• Genu: The bend between the anterior and posterior limbs. It contains corticobulbar fibers, which are involved in motor control of the face.
• Posterior limb: Located between the thalamus and the lentiform nucleus. It contains corticospinal fibers, which are involved in motor control of the body, and sensory fibers from the thalamus to the sensory cortex.

Function

The internal capsule plays a vital role in the transmission of motor and sensory information. It contains:

• Corticospinal tract: Transmits motor signals from the cerebral cortex to the spinal cord.
• Corticobulbar tract: Transmits motor signals from the cerebral cortex to the brainstem.
• Thalamocortical fibers: Transmit sensory information from the thalamus to the cerebral cortex.
• Corticothalamic fibers: Transmit information from the cerebral cortex to the thalamus.

Clinical Significance

Lesions in the internal capsule can lead to significant neurological deficits. Common conditions associated with damage to the internal capsule include:

• Stroke: Can cause motor and sensory deficits depending on the location of the lesion.
• Multiple sclerosis: Demyelination can affect the fibers within the internal capsule, leading to various neurological symptoms.
• Traumatic brain injury: Can result in damage to the internal capsule, affecting motor and sensory pathways.

Imaging

The internal capsule can be visualized using various neuroimaging techniques such as MRI and CT scan. These imaging modalities help in diagnosing conditions affecting the internal capsule and planning appropriate treatment strategies.

See Also

• Cerebral cortex
• Thalamus
• Caudate nucleus
• Lentiform nucleus
• Corticospinal tract
• Corticobulbar tract