You know that when you need to visit your massage therapist when your muscles ache. You know that after your massage, the pain you feel is lessened. You know that your muscles move your body. But do you know what your muscles actually look like? Do you know how they do the things that they do? I mean, you’re probably not lying awake at night wondering this, but it’s important to know! The more you know about your body, the more you can help your body feel better. This week, we’re examining the anatomy of a skeletal muscle – the ones that move your body!
You may think of your muscles as big groups of tiny, contractile cylindrical fibers. Your muscles are made up of specialized cells called myofibers, or just fibers. Each singular fiber is surrounded by the endomysium (meaning within the muscle), a thin protective layer of connective tissue. A collection of these singular fibers is then bunched together in parallel fashion, and this bunch is called a fascicle. Fascicles are enclosed by a layer of connective tissue called the perimysium. A complete muscle is made up of many fascicles held together by a thick layer of connective tissue called the epimysium. The epimysium extends past the muscle and creates the tendon, which attaches to the bone and holds the muscle in place.
Muscles receive their blood supply from arteries, veins, and capillaries that run through them. Nerves also interact with muscles, hence why you feel pain when your muscles get tight. Muscles can also cause compression on nerves of the body, such as the median nerve that runs through the carpal tunnel or the sciatic nerve that runs down the leg.
A muscle contraction is caused by the shortening of muscle fibers. When the muscle contracts, it moves a particular joint in a certain direction. It’s pretty easy to determine which muscle will move which joint in which direction. All you have to do is think about where the muscle is on your body, and what would happen if the fibers of that muscle were to shorten.
Let’s use the biceps brachii muscle as an example. This is the muscle in your arm that you probably know simply as the biceps muscle. The biceps muscle lays on the anterior side of the humerus bone of the upper arm, and it crosses the anterior aspects of both the shoulder and elbow joint. So, given that information, what actions do you think the biceps performs?
The main action of the biceps is to flex the shoulder joint (think raising your hand in the air.) It also flexes your elbow joint, bringing your forearm closer to your upper arm.
If you don’t know where your muscle attaches to the bone, you can try placing your hand on it and moving the joint. If you feel the muscle tense up with a certain movement, then you know that the muscle is causing that movement.
Knowing the anatomy of your muscle can be very beneficial when they start to ache. Mainly, if a certain muscle is sore or tired, you can pretty much guess that you’ve been doing too much of one activity, or you haven’t been doing the activity properly. If your biceps muscle is achey, you probably lifted something that was too heavy, or you lifted something too many times.
Of course, if you don’t know what would be causing pain in a certain muscle, ask your massage therapist! She will work with you to evaluate your daily routine and your posture to help you figure out what’s causing your pain, and what you can do to decrease stress on the area!
Korthuis, RJ. Skeletal Muscle Circulation, Ch. 2. San Rafael (CA): Morgan & Claypool Life Sciences. 2011. [Accessed on 2016, November 13]. Available from https://www.ncbi.nlm.nih.gov/books/NBK57140/
Ruths, M. 2016, January 6. How Does Blood Get to the Muscles in the Human Body?. [Accessed on 2016, November 13]. Available from http://www.livestrong.com/article/292708-how-does-blood-get-to-the-muscles-in-the-human-body/
Biceps Brachii Muscle by GetBodySmart