The thalamus (3rd ventricle) is a dense nucleus that bulges into the third ventricle from each side. The thalamus serves as a central relay station for sensory impulses ascending from other parts of the nervous system to the cerebral cortex. It receives all sensory impulses (except those associated with the sense of smell) and channels them to appropriate regions of the cortex for interpretation. In addition, all regions of the cerebral cortex communicate with the thalamus by means of descending fibers. The thalamus seems to produce a general awareness of certain sensations such as pain, touch, and temperature.