The muscular system consists of various types of muscle that each play a crucial role in the function of the body. Some muscular system functions include mobility, stability, posture, and circulation.

Muscles allow a person to move, speak, and chew. They control heartbeat, breathing, and digestion. Other seemingly unrelated functions, including temperature regulation and vision, also rely on the muscular system.

This article explores how the muscular system works and its 11 main functions.

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The muscular system contains more than 650 muscles that work together to enable the full functioning of the body.

There are three types of muscles in the body:

Skeletal muscle

Skeletal muscles are the only muscles that a person can consciously control. They are attached to bones, and contracting the muscles causes movement of those bones.

Any action that a person consciously undertakes involves the use of skeletal muscles. Examples of such activities include running, chewing, and writing.

Smooth muscle

Smooth muscle lines the inside of blood vessels and organs, such as the stomach, and is also known as visceral muscle.

It is the weakest type of muscle but has an essential role in moving food along the digestive tract and maintaining blood circulation through the blood vessels.

Smooth muscle acts involuntarily and cannot be consciously controlled.

Cardiac muscle

Located only in the heart, cardiac muscles pump blood around the body. Cardiac muscle stimulates its own contractions that form the heartbeat. Signals from the nervous system control the rate of contraction.

This type of muscle is strong and acts involuntarily.

The main functions of the muscular system are as follows:

1. Mobility

The muscular system’s main function is to allow movement. When muscles contract, they contribute to gross and fine movement.

Gross movement refers to large, coordinated motions and includes:

  • walking
  • running
  • swimming

Fine movement involves smaller movements, such as:

  • writing
  • speaking
  • facial expressions

The smaller skeletal muscles are usually responsible for this type of action.

Most muscle movement of the body is under conscious control. However, some movements are reflexive, such as withdrawing a hand from a source of heat.

2. Stability

Tendons connect muscles to bones and contribute to joint stability. The tendons in the knee and shoulder joints are crucial in stabilization.

The core muscles are those in the abdomen, back, and pelvis. They stabilize the body and assist in tasks such as lifting weights.

3. Posture

Skeletal muscles help keep the body in the correct position when someone is sitting or standing. This is known as posture.

Neutral posture relies on strong, flexible muscles. Stiff, weak, or tight muscles contribute to problems with posture and body misalignment.

Long term problems with posture lead to joint and muscle pain in the shoulders, back, neck, and elsewhere.

4. Circulation

The heart is a muscle that pumps blood throughout the body. The movement of the heart is outside of conscious control, and it contracts automatically when stimulated by electrical signals.

Smooth muscle in the arteries and veins plays a further role in the circulation of blood around the body. These muscles maintain blood pressure and circulation in the event of blood loss or dehydration.

They expand to increase blood flow during times of intense exercise when the body requires more oxygen.

5. Respiration

Breathing involves the use of the diaphragm muscle.

The diaphragm is a dome-shaped muscle located below the lungs. When the diaphragm contracts, it pushes downward, causing the chest cavity to get bigger. The lungs then fill with air. When the diaphragm muscle relaxes, it pushes air out of the lungs.

When someone wants to breathe more deeply, it requires help from other muscles, including those in the abdomen, back, and neck.

6. Digestion

Smooth muscles in the gastrointestinal (GI) tract control digestion. The GI tract stretches from the mouth to the anus.

Food moves through the digestive system with a wave-like motion called peristalsis. Muscles in the walls of the hollow organs contract and relax to cause this movement, which pushes food through the esophagus into the stomach.

The upper muscle in the stomach relaxes to allow food to enter, while the lower muscles mix food particles with stomach acid and enzymes.

The digested food moves from the stomach to the intestines by peristalsis. From here, more muscles contract to pass the food out of the body as stool.

7. Urination

The urinary system comprises both smooth and skeletal muscles, including those in the:

The muscles and nerves must work together to hold and release urine from the bladder.

Urinary problems, such as difficulty with bladder control or urinary retention, are caused by damage to the nerves that carry signals to the muscles.

8. Childbirth

Smooth muscles in the uterus expand and contract during childbirth. These movements push the baby through the vagina. Also, the pelvic floor muscles help to guide the baby’s head down the birth canal.

9. Vision

Six skeletal muscles around the eye control its movements. These muscles work quickly and precisely, and allow the eye to:

  • maintain a stable image
  • scan the surrounding area
  • track moving objects

If someone experiences damage to their eye muscles, it can impair their vision.

10. Organ protection

Muscles in the torso protect the internal organs at the front, sides, and back of the body. The bones of the spine and the ribs provide further protection.

Muscles also protect the bones and organs by absorbing shock and reducing friction in the joints.

11. Temperature regulation

Maintaining typical body temperature is an important function of the muscular system. Almost 85% of the heat a person generates in their body comes from contracting muscles.

When body heat falls below optimal levels, the skeletal muscles increase their activity to generate heat. Shivering is one example of this mechanism. Muscles in the blood vessels also contract to maintain body heat.

Body temperature can be brought back within typical range through the relaxation of smooth muscle in the blood vessels. This action increases blood flow and releases excess heat through the skin.

Muscles play a part in all bodily functions, from heartbeat and breathing to running and jumping. Muscle damage can impact movement, speech, and much more.

A person should contact a doctor if they notice signs of muscular weakness or pain that do not have a clear cause. A doctor can work out the underlying cause and recommend an appropriate treatment plan, if necessary.