Your muscles create movement.
There are more than 600 skeletal muscles on your body. In this lesson, you will learn about the major skeletal muscles of the body and terminology associated with important structures of the skeletal muscular system.
Did you know that the word muscle comes from the Latin word mus, which means ‘little mouse?’ That’s right; the person who gave muscles their name thought they looked like little mice scampering under the surface of the skin. If you look at your forearm and wiggle your fingers, you can see how they might have thought that.In reality, your muscles never scamper or scurry, but they do create movement. Every movement within your body, whether it’s the beating of your heart, the rumble of your digestive system or the flexing of your forearm, is created by muscles.
You have three different types of muscles in your body. Cardiac muscle is responsible for keeping your heart beating; smooth muscles control involuntary functions, like digestion and breathing; and skeletal muscles are the muscles that allow you to voluntarily move, like when you bend, squat or lift something up. In this lesson, we’ll introduce you to some of the vocabulary words associated with the gross anatomy, or visible anatomy, of the skeletal muscular system.
Skeletal muscles get their name because they’re attached to your skeleton. But, they don’t directly attach; instead, their ends are gathered together to form tendons. Tendons are strong, cord-like bands of connective tissue that bind muscles to bone.
Some tendons are big and can be seen and even felt under your skin. One of the most prominent tendons in your body is your Achilles tendon, which is the thick tendon you see running up the back of your ankle. It attaches the gastrocnemius and soleus muscles (calf muscles) to your heel bone. When your calf muscles contract, your foot is pulled down allowing you to push off as you walk, run or jump.
The muscles of your calf are only two of the more than 600 skeletal muscles in your body. For this lesson, we don’t have the ability to name every muscle in your body, but we can discuss the major skeletal muscles.If we work up from the calf muscles, we see the back of your upper leg contains the hamstrings.
When I was in college, my anatomy professor told me that the hamstrings got their name because butchers used to string up hams by the muscle tendon behind the pig’s knee, which may help you remember the muscle’s name. Travel up the body a bit farther, and we run into the gluteus maximus, which is the large muscle that maximizes the area you sit on.The front of your upper leg contains the large quadriceps. ‘Quad’ means ‘four,’ and we see that the quadriceps are made up of four muscles that come together to form one tendon in front of the knee.In your chest, you have the pectoral muscles, and they help you push things in front of you, whereas the major back muscles, called the latissimus dorsi help you pull objects.
Think of a scary dorsal fin on the back of a shark to help recall this term.Your biceps are your arm benders. They are the two (bi) muscles in the front of your upper arms, whereas your triceps are your arm extenders. They are the three (tri) muscles in the back of your upper arms.We see that skeletal muscles are able to create movement because they attach across joints, which is simply the name given to the area where two or more bones come together.
So, when a skeletal muscle contracts, or shortens, it pulls one of the attached bones closer to the other. For example, your bicep muscle has tendons on each end that attach it above the elbow joint and below the elbow joint. When your brain tells your bicep to flex, the skeletal muscle fibers that make up your bicep contract, causing your lower arm to move up toward your upper arm.
So, we see that movement is created by muscle fibers. Skeletal muscle fibers are actually elongated cells that contain multiple nuclei. These fibers run the entire length of the muscle, so some of them, like the ones in your thigh, are very long. You could say that the muscle fibers make up the meat of the muscle.
Muscle fibers need a way of staying together. That job is handled by fascia, which is a connective tissue that surrounds muscles and binds them to other structures. Fascia is found throughout your skeletal muscle system. It can be found inside muscles where it helps muscle fibers stay together.It can also extend past the muscle to help bind the muscle to other structures.
When this is the case, the fascia looks like white sheets. For example, we see the white fascia when we look at the abdominal muscles. Another example of fascia extending beyond the muscle is found in the base of your foot, where you have the plantar fascia. If you ever had plantar fasciitis, you might be familiar with this tissue and the pain that can result when it becomes inflamed.
Let’s review. Skeletal muscles are attached to your skeleton by tendons, which are strong, cord-like bands of connective tissue that bind muscles to bone.
Skeletal muscle fibers are elongated cells that contain multiple nuclei. Contraction of the muscle fibers creates movement. Fascia is a connective tissue that surrounds muscles and binds muscles to other structures.
Major skeletal muscles of the lower body include the hamstrings and gluteus maximus in the back and the quadriceps in the front. In your chest, you have the pectoral muscles, whereas your major back muscles are called the latissimus dorsi. Your biceps are in the front of your upper arms, and your triceps are in the back of your upper arms.