The musculoskeletal system, as the name implies, is actually a combination of the muscular system and the skeletal system. These two systems work together so closely, they are often considered as a unit.
The Muscles
The primary functions of the muscles — holding us upright and helping us move — are generally well-recognized. What might be less obvious is that the muscles also help keep us warm. (Think shivering.) Muscles should normally enable us to maintain healthy posture, hold the internal organs in their proper places, and move flexibly with a reasonable degree of effort. (That is, it is to be expected that lifting furniture requires exertion. Lifting a paperback book should be quite a bit easier. In other words, the effort required should be reasonable relative to the task.)
The Skeleton
The skeleton also, of course, helps hold us upright. The bones provide places for the muscles to attach, and in this way they aid in movement. A variety of joints contribute to movement, as well, and should normally do so without creaking, cracking, stiffness, or pain. Bones provide protection for the body’s organs, enable some minerals to be stored until they need to be drawn upon, and are the base from which blood cell production takes place.
Healthy Muscles, Bones, & Joints
The musculoskeletal system is not a system that tends to be an obvious indicator of health the way some other systems are. However, there are a few things you can watch for.
We all recognize that it is normal for muscles to be achy after heavy use, but if recovery time seems to be unexpectedly long, or if the muscles are in pain with no known cause, that may be a red flag. Muscles that cramp up (again, without a clear immediate cause) may indicate nutrient deficiencies (particularly of potassium and/or magnesium), and/or misalignment of the spine. (When the spine is unbalanced, it puts an uneven burden on the various muscles.)
Muscles should be kept toned and flexible through regular exercise in order to avoid injury.
Strong bones are not an easy thing to gauge through casual observation, but an unusual tendency to breakage should be checked out. Joints should allow for free and easy movement. Keeping the surrounding muscles strong helps avoid putting unnecessary strain on joints, ligaments, and tendons.