By Elizabeth A. Murray, Mount St. Joseph University
It is well known that various types of cells link together to make up the many types of tissues of the body, and different tissues combine to form organs. When it comes to muscle tissue, there are basically three types: cardiac muscle, smooth muscle, and skeletal muscle.
Differentiating Between the Muscle Tissues
The three muscle tissues are basically differentiated by their microscopic structure—which is not exactly relevant to gross anatomy, since gross in this sense means “able to be seen with the naked eye”.
But the three types of muscle are also differentiated by whether we can voluntarily control them or not. And this corresponds to their relationship with the nervous system. In fact, we have distinct divisions of the nervous system related to the control of voluntary muscle versus the subconscious control of involuntary muscle.
Cardiac Muscles as Involuntary Muscles
The cardiac muscle is only found in the heart. It makes up the walls of the heart chambers and is one of the two types of involuntary muscle, which means that we cannot control its action directly.
Although we can increase our physical activity level, and that will cause the heart to beat faster and with more force, but that’s indirect control. When an unfortunate person is suffering from atrial fibrillation, or maybe a heart attack, he or she cannot will their heart back into rhythm, or make it start beating again.
This article comes directly from content in the video series How We Move: The Gross Anatomy of Motion. Watch it now, on Wondrium.
Smooth Muscles: Another Involuntary Muscle
The name smooth muscle is due to the internal appearance of the cells in this type of muscle, but it is also involuntary muscle that we cannot consciously control. Smooth muscle is typically found in the walls of hollow organs, like the stomach, the bladder, the uterus, and the walls of blood vessels—but it’s also found in other locations, like the tiny muscles in the skin that give us goosebumps, or in the iris of the eye to cause the pupil to dilate or constrict.
As with cardiac muscle, we can do things that affect smooth muscle, like eat food that will cause the stomach to churn, but we can’t voluntarily make smooth muscle operate or stop contracting. For example, one cannot control the growling of an empty stomach, no matter how much they want their stomach to stop making all kinds of crazy noises in the public.
Skeletal Muscles: The Voluntary Muscles
The third kind of muscle tissue, and really the only type that’s directly relevant to gross anatomical structure, is known as skeletal muscle. It is given that name because of its general ability to move the bones of the skeleton through its attachments.
The skeletal muscle is our voluntary muscle tissue, subject to our conscious control. With that said, we can develop what become more or less subconscious patterns of muscle action—sometimes called muscle memory—like knowing how to swing a tennis racket, throw a ball, drive a car, or perform a particular dance routine, without really thinking about it.
The same goes for our postural muscles, like those in our back since we don’t have to constantly tell them to keep our spine straight. However, if someone told you to stand up straight, you certainly could voluntarily fix that posture.
Involuntary Reflexes in Skeletal Muscles
There are many reflexes, that is involuntary movements, that are sometimes included within our skeletal muscles. These encompass a few innate reflexes and plenty of learned reflexes. An example of an innate reflex is the grasping reflex: if something—like a finger—is placed in a newborn infant’s palm, they will close their fist around it. We share this reflex with most of our fellow primates.
Other reflexes are protective actions. For instance, if someone throws a ball and it looks like it’s going to hit you in the face, you will reflexively bring up your hands to protect yourself. That’s a learned reflex, and as a result, you wouldn’t think of doing that to a baby!
Likewise, if you touch a hot stove, your skeletal muscles will automatically execute what’s called a withdrawal reflex and pull your hand away before you even know it, and before you even have the chance to say “ouch”. So, from these examples we see that even our voluntary skeletal muscles have some involuntary overrides.
Common Questions about the Different Types of Muscle Tissues
The cardiac muscles make up the walls of the heart chambers and is one of the two types of involuntary muscle, which means that we cannot control its action directly. Although we can increase our physical activity level, and that will cause the heart to beat faster and with more force, but that’s indirect control. When an unfortunate person is suffering from atrial fibrillation, or maybe a heart attack, he or she cannot will their heart back into rhythm, or make it start beating again.
The name smooth muscle is due to the internal appearance of the cells in this type of muscle, but it is also involuntary muscle that we cannot consciously control. Smooth muscle is typically found in the walls of hollow organs, like the stomach, the bladder, the uterus, and the walls of blood vessels—but it’s also found in other locations, like the tiny muscles in the skin that give us goosebumps, or in the iris of the eye to cause the pupil to dilate or constrict.
There are three different types of muscle tissues, namely cardiac muscles, skeletal muscles and smooth muscles. The three muscle tissues are basically differentiated by their microscopic structure as well as by whether we can voluntarily control them or not which corresponds to their relationship with the nervous system.
