The major components of the brain include the gray and white matter and the ventricles of the brain. The gray matter consists mainly of the cytosol of nerve cells, and the white matter consists of the dendrites or axons of nerve cells. The gray matter consists mainly of the nuclei of the cerebral cortex and the deeper part of the brain, mainly the nucleus accumbens, the red nucleus, the substantia nigra, and the nucleus accumbens, the nucleus accumbens, and the caudate nucleus. The white matter of the brain is mainly the intracerebral nerve fibers, including the corticospinal tract, the corticomedullary tract, the spinal thalamus tract, and so on. The internal capsule is where the brain fibers are concentrated. If there is a lesion in the internal capsule, even if it is a small infarct, the patient may develop clinically severe symptoms and signs, which may manifest as hemiparesis, hemianopia, hemianesthesia, and also speech dysfunction.