Understanding the primary functions of the muscular system

April 08, 2023 5 min read

Muscular /Skeletal image

Each of the various types of muscle pay an important role in the body’s function; this forms the muscular system. A person is able to speak, move and chew due to their muscles which further control breathing, heartbeat and digestion. Other functions which we take for granted such as temperature regulation are also reliant on our muscular system, therefore our muscles play a significant role in all functions of the body. As a result, our speech and movement along with much more are impacted when our muscles become damaged. 

The smooth running of the muscular system can be interfered by multiple conditions such as Parkinson’s disease, multiple sclerosis and fibromyalgia. If you notice pain that you are unable to explain or notable signs of muscular weakness, you should visit a doctor who can diagnose the problem in order to come up with an appropriate treatment. 

Muscular system facts: 

  • The body’s largest muscle is the gluteus maximus which is located in the buttocks, helping to maintain an upright posture 
  • The smallest muscles are found in the ear, these hold the ear together and are connected to the eardrum. The smallest bones in the body are also found in the ear. 
  • Approximately 40% of your total weight is made up of muscles 
  • By weight, the strongest muscle is in the jaw and is called the masseter which allows the teeth to close with a force of up to 200 pounds on the molars and 55 pounds on the incisors 
  • The hardest working muscle in the body is the heart which pumps 5 quarts of blood every minute, and 2,000 gallons per day 

How does the muscular system work?

More than 600 muscles are within the muscle system; these work together in order to enable the body to fully function. 

In the body there are 3 types of muscle:-

Skeletal muscle -  These are the only muscles which can be consciously controlled. As they are attached to bones, contracting muscles will cause these bones to move.  Skeletal muscles are used in any action which a person consciously undertakes for example, chewing or walking.

Smooth muscleThis type of muscle is also referred to as visceral muscle and lines the inside of organs such as the stomach and blood vessels. Due to this, smooth muscle has an important role in digestion along with maintaining blood circulation throughout the blood vessels. Smooth muscle is the weakest type of muscle; in comparison to skeletal muscle, smooth muscle cannot be controlled consciously and thus acts involuntarily. 

Cardiac muscle - Cardiac muscle is strong and located in the heart and therefore its function is to pump blood around the body. The contractions of the cardiac muscle are stimulated by itself, forming our heartbeat. The rate of contraction is controlled by signals from our nervous system and thus acts involuntarily.  

The eleven main functions of the muscular system:

1. Mobility – this is the muscular system’s main function. As muscles contract, they contribute to fine and gross movement. Large, coordinated motions are referred to as gross movement. Examples include walking and swimming.

Whilst smaller movement are known as fine movements such as writing and speaking. This type of action is usually due to smaller skeletal muscles. 
The majority of muscle movement is under conscious control, yet some movements are of a reflective nature. For example, moving your hand away from the flame of a candle. 

2. Stability - over the joints, muscle tendons are stretched and these contribute to the stability of joints. In stabilization, muscle tendons located in the shoulder and knee joints are crucial. 

The body is also stabilised through the core muscles. These are in the pelvis, back and abdomen. The core muscles further assist in everyday tasks such as lifting heavy objects and are therefore crucial when lifting weights during exercise. 

3. Posture – when you are either standing or sitting, it is the skeletal muscles which help to keep the body in the correct position; this is referred to as posture. Having good posture is reliant on flexible and strong muscles. Poor posture is caused by tight, weak or stiff muscles and this further leads to misalignment of the body. Bad posture over a long period of time can lead to muscle and joint pain felt in the neck, back and shoulders most notably but in other areas as well.

4. Circulation – blood is pumped throughout your body through your heart. The movement of this muscle is not controlled consciously and therefore when it is stimulated by electrical signals, it contracts automatically. 

The circulation of blood through the body is also dependent on smooth muscle within the arteries and veins because it is these muscles which maintain blood circulation and pressure should your body experience dehydration or a loss of blood. During intensive exercise intervals, the body requires more oxygen and these muscles are able to expand in order to increase blood flow.

5. Respiration – the diaphragm muscle is used when you breathe. The diaphragm is located below the lungs and is shaped like a dome. It pushes downward when the diaphragm contracts and this causes the chest cavity to expand. Next, your lungs are filled with air. As your diaphragm relaxes, air is as a result pushed out of the lungs. 

Should you want to breathe more deeply, other muscles are needed, which include those found in the neck, back and abdomen.

6. Digestion – digestion is controlled by small muscles in the gastrointestinal or GI tract; this muscle stretches from the mouth to the anus. Peristalsis is the wave-like motion in which food travels through the digestion system. This movement is caused by the contracting and relaxing of the muscles in the walls of the hollow organs. This then causes food to be pushed through the esophagus into the stomach muscle. 

Food is allowed to enter the stomach when the upper muscle relaxes, whilst food particles are mixed with stomach acid and enzymes by the lower muscles. 
Once again through peristalsis, digested food is moved from the stomach to the intestines. Further muscles contract to move the food from the body through stool.

7. Urination – both smooth and skeletal muscles form the urinary system, including those in the:

  • Prostate
  • Bladder
  • Ureters
  • Penis or vagina
  • Urethra
  • Kidneys

In order to both hold and release urine from the bladder, nerves and muscles must work together. When damage to the nerves which carry signals to the muscles occurs, this causes urinary problems. These can include; poor bladder retention or control of urine. 

8. Childbirth – during childbirth, smooth muscles in the uterus both expand and contract; it is these movements which push the baby through the vagina. The pelvic floor muscles additionally assists in guiding the baby’s head through the birth canal. 

9. Vision – the movements of the is controlled by six skeletal muscles which work both precisely and quickly. Therefore, if damage is done to eye muscles, vision can be affected. 

These muscles enable the eye to;
  • scan the surrounding environment 
  • retain a stable image
  • track the motion of moving objects 

10. Organ protection – the internal organs at the back, front and sides of the body are protected by muscles in the torso. Further protection is provided by the bones of the ribs and spine. Absorbing shock in addition to reducing friction in the joints is another way in which muscles protect the organs and bones in the body. 

11. Temperature regulation – A significant function of the muscular system is maintaining normal body temperature. Contracting muscles accounts for almost 85% of the heat which a person generates throughout their body. 

The skeletal muscles increase their activity in order to make heat when body temperature falls below the optimal levels; an example of this is shivering. To maintain body heat, it is the muscles located in the blood vessels contract. 
When smooth muscles in the blood vessels begin to relax, body temperature can then return to within its normal range. This then increases blood flow, releasing additionally heat through the skin. 

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