“The foot’s bone connected to the ankle bone, the ankle bones connected to the leg bone, the leg’s bone’s connected to the…”
That is actually how it works – so here we go…
Every muscle in the body moves something…that’s what muscle does, as it contracts, it pulls. There are three types of muscle tissue: Smooth muscle, which is involved in movement inside the body, like in the intestines, the bladder, the uterus,etc.; Cardiac muscle which is involved in the pumping of blood into and out of the heart and so affects our blood pressure and pulse; and skeletal muscle which is the way we pull bones together to produce external movement.
Both smooth muscle and cardiac muscle are “involuntary”. That simply means we don’t have to think about moving the food we eat long our digestive tract, nor do we have to remember to tell our heart to keep the blood moving.
Otherwise, external movement takes at least an initial conscious thought…”I think I’ll go get something to eat.” So you get up out of your chair and either walk to the fridge and grab a piece of fruit or stuff to make a sandwich – or – to jump in your car and drive to the nearest fast food place. Hopefully you do the first, but either way you made a conscious decision to move your body.
Now luckily for us, we don’t have to think about the mechanics of putting one foot in front of the other or opening the refrigerator door, we learned that in toddler 101. But the sequence of movements were orchestrated by a series of nerve signals sent from the brain, through the spinal cord nerves to the muscles involved in the motor activity.
Okay, back to the muscles. Basically what skeletal muscles do is to pull bones together or apart. It is the result of muscles in the front of the upper arm that bend the elbow (pulling the bone in the lower arm closer to the bone in the upper arm), and the muscles at the back that straighten the elbow. Picture this: The bicep muscle group brings your sandwich to your face; the tricep muscles take it away. Not too complicated.
During movement, muscles perform one of three tasks. The muscle that actually produces the movement is called an “agonist” or prime mover. The opposing muscle is called the “antagonist”, because it’s job is to control the speed and force of
the prime mover. The third task is helping with the movement. These muscles are called “synergists”.
Obviously, eating a sandwich takes the cooperation and coordination of many, many muscles; the hand, wrist, upper and lower arm (both front and back) along with muscles in the face head and neck. It also involves muscles in the chest, side of the ribcage and the back. (Don’t forget cooperation of your good judgement and will-power also!). Think how enormous AND miraculous that is…and we never even think about it as we devour that fat, juicy sandwich. The sad fact is, we take the miracle of our bodies completly for granted!
Muscles continuously change their tasks – back and forth, depending on the movement being done. Think of some guys lifting something by a big rope from one place to another, say cargo from the dock to the ship.
One big guy is the head rope- puller, and he has a bunch of helpers behind him on the rope. On the dock another guy is slowing the pull down, and he has a bunch of helpers. It is the timing coordination, cooperation and precision that pulls that off without a mishap. If one guy on the pulling end doesn’t do his job, the carge is likely to swing the wrong direction. If a guy on the dock doesn’t do his best, the cargo will move to fast…and watch out!
That is the way our body moves effortlessly and efficiently in everyday activities, like taking a shower, getting dressed, eating breakfast, picking up the dishes, etc.
On the other hand, skeletal muscle takes some thought…unless it is an involuntary action caused by a relex in response to a given stimulus, i.e., when something flies near your face, you don’t stomp your foot, you wave your hand by your face to shoo the object away.