The Command Element is composed of the Commander and his staff. It provides the command and control system for effective planning and execution of the operation.
The Ground Combat Element conducts grouund combat operations. The size varies from a platoon to one or more divisions (MARDIV). It has its own combat support units and organic service support capability.
The Air Combat Element conducts air operations and provides aviation support to the GCE and the CSSE. It varies in size from a reinforced squadron to one or more wings (MAW).
The Combat Service Support element provides the range of combat service support functins and capabilities necessary to support the MAGTF mission. It varies in size from a task organized detachment to one or more Force Service Support Groups (FSSG). They provide the "beans, bullets and the bandaids". The medical battalion is found here.
Links to other sites on the Web
Medical Officer of the USMC Homepage