The thalamus is a pair of cerebral ganglia. They are oval masses of white and gray matter. They lie upon each side of the third ventricle, between the tails of the caudate nuclei. They rest upon the crura cerebri. Each thalamus forms a large portion of the floor of the body of the lateral ventricle. Its posterior end projects into the descending cornu of that ventricle The peduncles of the pineal gland run along the upper border of each thalamus. It sends a flow of information from a variety of receptors to the cerebral cortex.