Brain Tour : Our Brain : Looking at the Cerebrum :

Certain parts of the cerebral hemispheres and diencephalon constitute the limbic system. It is a bone-shaped groups of structures that encircles the brain and assumes a primary function in emotions such as pain, pleasure, anger, rage, fear, sorrow, sexual feelings, docility and affection. It is therefore sometimes called the "visceral" or "emotional" brain.

Although behaviour is a function of the entire nervous system, the limbic system controls most involuntary aspects, the aspects related to survival, and some experiments suggest that it has a major role in controlling the overall pattern in behaviour. Together with portions of the cerebrum, the limbic system also functions in memory; memory impairment results from damage to the limbic system.

The limbic system also links the forebrain and the midbrain and controls certain aspects of muscle tone, such as the positioning of an arm so that the fingers are in the best position to type or play the piano.