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Major Skeletal Muscle Functions

Chapter 14 / Lesson 2
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  • 0:05 Skeletal Muscle Functions
  • 0:50 Support and Movement
  • 2:48 Homeostasis
  • 4:30 Lesson Summary
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Lesson Transcript
Instructor: John Simmons

John has taught college science courses face-to-face and online since 1994 and has a doctorate in physiology.

Did you know that skeletal muscle does more than just move our body parts? This lesson describes how skeletal muscles are used for movement, posture, swallowing, defecation, urination and homeostasis.

Skeletal Muscle Functions

A sphincter is a muscular organ that surrounds a hollow organ
Sphincter Diagram

Our skeletal muscles serve a variety of functions. Through contraction and relaxation, skeletal muscles help to support and move our body. Additionally, skeletal muscles help with nutrition and temperature regulation. For the purposes of this study, skeletal muscle functions will be divided into two general categories - that is, support and movement and homeostasis.

In this lesson, we will describe the major functions performed by skeletal muscle. But before we get into that discussion, let's quickly define skeletal muscle. A skeletal muscle is a contractile organ that is directly or indirectly attached to bone.

Support and Movement

Skeletal muscles move the body. Skeletal muscle contractions pull on tendons, which are attached to bones. If contraction of the muscle causes the muscle to shorten, the bone and, thus, the body part will move. For example, the biceps brachii is attached to the shoulder and the forearm bones. Contraction and, thus, shortening, of the biceps brachii pulls on the tendons attached to the bones. Since the shoulder is stationary, the forearm moves. Skeletal muscle contraction, however, doesn't always result in the movement of a body part.

In many cases, skeletal muscle contraction maintains body posture and position; for example, holding your head still while you are watching this lesson. The muscles in our abdominal wall and pelvis contract to maintain our abdominal organs in position.

The energy from skeletal muscle contractions produces heat and regulates body temperature
Skeletal Muscles Produce Heat

A special type of skeletal muscle called a sphincter regulates opening of our digestive and urinary systems. A sphincter is an organ composed of muscle that surrounds a hollow organ. Much like a rubber band would wrap around a plastic tube. Our intestines and blood vessels are examples of hollow organs. The sphincters at the ends of our digestive and urinary systems are composed of skeletal muscle and provide conscious control of swallowing, defecation and urination. For example, the anus contains a sphincter that, when contracted, prevents defecation. Let me make a quick note that sphincters are not only composed of skeletal muscles. There are smooth muscle sphincters, as well. And they're under the influence of the autonomic system, or involuntary nervous system.

Homeostasis

In addition to providing support and movement, skeletal muscles are necessary for some homeostatic functions. Homeostasis is the maintenance of a relatively constant internal environment. If you have ever shivered in the cold, you are familiar with one of these functions - that is, temperature regulation.

Let's talk about how our skeletal muscles help. As we know, muscular contraction requires energy. As energy is used to contract muscle, much of that energy is converted to heat, and heat helps to maintain a relatively constant body temperature. As much of our body is skeletal muscle, these organs provide an effective means of temperature regulation.

In fact, shivering thermogenesis is the rapid contraction of our muscles for the purpose of generating heat. Therefore, skeletal muscle helps with homeostatic regulation of body temperature.

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