Internal Capsule

  1. The internal capsule is a large band of fibres, situated in the inferomedial part of each cerebral hemisphere.

 2. In horizontal section of the brain, it appears V-shaped with ita concavity directed laterally. The concavity is occupied by the lentiform nucleus.

 

3. (The internal capsule contains fibres going to and coming from the cerebral cortex. It can be compared to a narrow gate where the fibres are densely crowded. )

 4. When traced upwards, the fibres of the capsule diverge and are continuous with the corona radiata

 5. When traced downwards, its fibres converge and many of them are continuous with the crus cerebri of the midbrain.

 6. The internal capsule is divided into the following parts.

 • The anterior limb lies between the head of the caudate nucleus and the lentiform nucleus

 • The genu is the lies between the anterior and posterior limbs.

 • The posterior limb lies behveen the thalamus and the lentiform nucleus.

 • The sublentiform part lies below the lentiform nucleus. It can be seen in a coronal section.

The retrolentiform part lies behind the lentiform nucleus.

Relations:-

Medially: Head of caudate nucleus and thalamus

Laterally:-Lentiform nucleus

Fibres of Internal Capsule :-

 1. Motor fibres

 2. Pyramidal fibres

 3. Extrapyramidal fibres

 4. sensory fibrrs

5.Constituent fibres

Written by: RB Sah, MBBS 

Reference: ANATOMY book BD Chaurasiya and other books