How Do Muscles Work: A Complete Guide On Fascicles And Muscle Shapes

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A Complete Guide On How Do Muscles Work:

Muscles are complex tissues that we can often take for granted.

They play a very intricate but important function in the body.

Every movement we perform: blinking the eye, lifting a finger or running a marathon requires the action of muscles.

Our muscles act like the body’s engine. They convert energy into motion which makes the body move.

Muscles work through an intricate communication system which channels signals from the brain and nervous system.

It’s amazing how we go about our business without consciously thinking how our bodies accomplish the movement. Come with me and explore how do muscles work.

The Control Center

Muscles in the body are constantly at work even when we don’t realize it.

Every movement we make is controlled by the brain and the nervous system.

Muscles are voluntary and involuntary. Voluntary muscles are those we can control the hands and feet.

Involuntary muscles are those that work without our help or control, like the heart, stomach, and lungs.

Voluntary muscles receive their orders from the brain and nervous system. Involuntary muscles are controlled by structures within the brain and the brain stem.

The motor cortex on the left side of the brain controls the muscles on the right side of the body. The reverse action is applicable.

We first have to understand how the movement of the body works.

Muscles constantly contract and relax to adjust to all body movements.

Skeletal muscles attach to bones which are attached to tendons. 

As the fibers in the muscles contract, they become short and pull on tendons.

Tendons, in turn, pull on the bones to make them move. The pulling action results in movement.

The Work and Function of Muscles

First of all, we have to know how do muscles work properly.

A muscle is a mass or bundle of cells known as fibers. They resemble long cylinders and are quite big.

Muscle fibers, in turn, contain myofibrils or cylinders of protein.

Protein allows muscle cells to contract. Muscles have three main functions. They maintain the body’s posture.

Muscles contract to hold the body still or they help maintain a particular posture rather than cause a movement.

Without muscles, we would be unable to move, sit or stand, walk or carry out other important bodily functions.

The muscles support the movement of internal organs like the heart to circulate blood and other substances through the body.

Muscles generate body heat. As we engage in a normal activity, small muscles in the body contract to help produce body heat.

During strenuous exercise,  extra muscles contract and increase body temperature.

The exertion in the muscles causes us to perspire.  Muscles release heat as they contract.

If no heat is produced, the normal body temperature would be imbalanced.

Muscles are grouped according to the specific function they perform. Different muscles carry out specific functions in the body.

Flexor muscles are a group of muscles in the forearm that help flex the wrist and fingers.

Supinator muscles are muscles that rotate the wrist by rolling it over to face the palm up.

Adductor muscles move or pull similar body parts together, like the movement of the legs or fingers.

Skeletal Muscles

The skeletal muscles are those muscles we can see and feel. They receive impulses from the brain and nervous systems.

When they receive these signals, they contract and cause groups of muscles to work together to move the skeleton.

Skeletal are voluntary muscles, or muscles that we can control. They control every bodily action that we consciously perform.

Skeletal muscles are attached to the bones, chest, neck, abdomen, arms, legs face and chest.

Muscles keep the skeleton together and give each body its unique shape.

There are close to 700 skeletal muscles in the body. Can you guess how do muscles work?

They do the bulk of the work in holding the skeleton in place and support movement. Muscles also help support the skeleton and support balance and coordination.

The eyes make at least 10,000 movements in one hour of reading in a single day! Skeletal muscles make up almost half of the body’s weight.

Each muscle is made up of muscle tissue, tendons, nerves and blood vessels.

Muscles move various parts of the body by contracting and relaxing.

Skeletal muscles work in tandem with one or other muscles to move our bones in one direction or another.

They heavily depend on other muscles to get the body moving.

While one muscle is moving in a particular direction, the other muscle moves it back in the opposite direction.

The main function of skeletal muscles is to contract. Sensors within the muscles and joints communicate messages back and forth through the nerves and brain.

Messages from the muscles inform the brain about the position and state of each muscle. The brain, in turn, sends signals back to the muscles, commanding them to move accordingly.

Skeletal muscles help move body parts closer to the bone where the muscle is attached.

Skeletal muscles are so called because they connect to the skeleton in at least one area. Many of them are connected to two bones by tendons.

Tendons are very dense, strong bands of connective tissue.

Muscles pull on tendons to move; hence tendons are constantly under a lot of stress to support body movement.

Muscles move by shortening their length, pulling on tendons and moving the bones closer together.

During movement, one of the bones is pulled towards the other, while the other bone remains stationary. The place where the stationary bone connects to the muscles is known as the origin.

Conversely, the place where the moving bone connects is known as the insertion point. The belly of the muscles is the point between the tendons that performs the actual contraction.

A muscle which produces any particular movement of the body is known as a prime mover.

Agonist muscles always team up with an antagonist’s muscle to create movement.

An antagonist’s muscle performs the opposite action of an agonist’s muscle.

For example, movement in the arm requires the biceps to flex the arms at the elbow joint.

Triceps are agonist muscles since they work to extend the arm at the elbow. Much like a chain gang, other muscles work to support agonist and antagonist muscles.

They are called synergists and help stabilize the body to help reduce unnecessary movement.

Synergist muscles are usually found in areas close to an agonist’s muscle. They often connect to the same bone as an agonist’s muscle.

If you exert yourself while lifting a heavy object, synergist muscles will step in to keep your body upright.

They keep the body erect and help maintain your balance from toppling over under the weight.

Skeletal muscles perform much like levers. They work together with bones and joints to form levers.

Muscles produce the force or effort and joints stay in place to lend support.

The bones that are moved by the muscles are much like levers. The parts of the body that move are known as the load.

Smooth or Visceral Muscles

Here we will know How do muscles work smoothly. Smooth muscles are involuntary muscles.

They quietly and methodically go about their work, and we are hardly aware of them.

For example, the stomach and digestive system work around the clock and require no effort on our part.

Smooth muscles are found in our organs and make up the walls of these organs.

The blood vessels, bladder, air passages, digestive system and the uterus in the female body all have smooth organs. Smooth muscles are the weakest among all muscles.

They are controlled by the involuntary nerve impulses or unconscious part of the brain.

Smooth muscles contract and produce wave-like movements that propel substances through the system.

Urine moves through the bladder, and blood and food move through the system.

Cardiac Muscles

Cardiac muscles are involuntary muscles that make up the walls of the heart.

These types of muscles are found only in the heart. They help the heart beat at a steady, rhythmic pulse.

They can stretch and contract with a kind of force similar to skeletal muscles.

Cardiac muscles can twitch only, and contract involuntarily.

Cardiac muscles are responsible for consistency and endurance. They assist the heart in pumping blood through the body by impulses from the brain.

Cardiac muscles also create electrical charges that make the heart contract.

The heart is the hardest working muscle in the body. It is constantly pumping blood around the body in a continuous cycle.

Every heartbeat sends about 2 ounces of blood through the body.

It can amount to as much as 2,500 gallons of blood daily.

Muscle Fibers

Muscles are based on two types of fiber: Fast-twitch and slow-twitch fibers.
Fast-twitch muscles operate by giving the body a burst of energy or speed when needed.

They contract faster and have a greater capacity to operate without the use of oxygen.
Slow- twitch fibers develop force at a slower rate than fast-twitch muscles.

They depend on oxygen and function over a longer period.

Slow-twitch fibers develop force slowly and can maintain contractions longer and have a higher oxygen capacity.

Motor Units

Nerve cells or neurons control the skeletal muscles. Several muscle cells in a group are controlled by a motor neuron.

The group of muscles is called a motor unit. A motor unit receives a signal from the brain to activate muscle movement.

When the signal is received, the neuron stimulates all of the muscles in the motor unit at the same time.

The size of the motor unit varies throughout the body, depending on the specific function of a muscle.

Muscles that perform fine movements like the fingers or eyes have few muscle fibers in each motor unit.

Muscles like the arms and legs require greater muscles strength to function. They have a lot more muscles cells in each motor unit.

The body can control the strength of each muscle. It determines how many motor units are required to activate a given function.

The same muscles that pick up a stick of chalk are also used to pick up a bowling ball.

Muscle Contraction Cycle

Do you know How do muscles work through concentration cycle? Almost all muscles in the body are always slightly contracted.

The tension or muscle tone is at work even while we are sleeping.

The only time our muscles are completely relaxed is when we are unconscious.

Muscle contractions are triggered by electrical impulses.

Muscles act on brain signals that send electrical changes in muscle cells.

Calcium is released into the cells and brings about a short muscle twitch during this process.

These impulses can be external to electrical shock stimulus or internally through the nerve cells.

Electrical signals travel down through the nerve cells.

The cells then send a chemical message or neurotransmitter into the small gap between the nerve and the muscle cells. The gap between the two cells is called a synapse.

The motor neurons contact the muscles cells at a point called the Neuromuscular Junction (NMJ).

The NMJ forms a bond in the cell membrane that allows ions to enter the muscle fiber.

Muscles will continue to contract as long as they are stimulated by neurotransmitters.

When an individual suffers a stroke or some form of nerve damage, the signals become skewed.

The muscle movement is reduced or cut off entirely depending on the severity of the trauma.

All muscles contract, but they do not necessarily move.

The body is sometimes capable of light contractions that do not produce enough force to create movement.

Types of Muscle Contractions

An isometric contraction occurs when you tensed a muscle but did not produce any movement.

Holding an object still while maintaining your posture as in weightlifting, is an isometric contraction.

Muscles require energy to contract. Muscle strength is determined by two actions.

The number of motor units engaged in muscle contraction and the amount of stimulus they receive from the nervous system.

Temporal stimulation occurs when several signals come from the neuron in a short space of time.

The length of time the muscles contract and strength of the contraction increases.

Tetanus stimulation occurs when too many nerve impulses come into the muscles too quickly from the motor neurons. The muscles will come to a state of lasting and or complete contraction.

The muscles can become too tired to maintain tetanus.

They can remain in that state until the rate of the nerve signals normalizes.

How Muscles are Powered

Muscles need a lot of energy to work. Everything you think with your brain requires a muscle movement.

When we blink our eyes, move our lips to speak or lift a finger, it takes energy. When we move a pen to write or move our lips to speak, energy is involved.

The simple action of wiggling the toes, and moving the tongue or turning the head uses up energy.

Dancing, running, walking or even fighting needs loads of energy.

When our muscles are working for long periods of time, they need the energy to keep momentum.

Energy molecules include oxygen, creatinine, and myoglobin.

Creatinine increases muscle strength, power, and size and enhances performance.

Our muscles do not produce creatinine. Creatinine is drawn from reserves in the body and converted into a form that the body can use as energy.

As the creatinine enters the muscles, they receive a quick burst of energy. It then powers muscle contraction especially during exercise or weight training.

Muscle fibers contain reserves of glycogen which the body converts to glucose for added energy.

During a strenuous workout, the muscles can become tired and lose contraction.

Active muscles then draw on glycogen reserves in the body to relieve tiredness and increase energy in the muscles.

Myoglobin is another energy molecule needed for adequate muscle contraction. Myoglobin is a pigment found in the muscles that contain iron.

It stores reserves of oxygen in the muscles similar to what hemoglobin does for the bloodstream.

Oxygen from myoglobin allows the muscles to continue to perform during aerobic respiration when supplies are low.

Muscles also grow through exercise. As activity in the muscles increases, they, in turn, get bigger.

Exercise also stimulates individual muscle cells and cause them to grow.

A Well Oiled Machine

The human body is a remarkable structure with some amazing functions.

Our muscles do a very important work in holding the entire body together.

They depend on bones and joints and allow us to move. When muscles do not work well, the entire body is affected.

Muscles can lose their function if there is a blockage in signals between the nerves and brain to the muscles.

Some diseases affect how muscles work.

Strokes, musculoskeletal conditions or injury may cause temporary or permanent loss of muscle movement in the affected areas.

There are therapeutic options, along with medication that can improve muscle function over time. Exercise is ideal for maintaining muscle tone and overall fitness.

Finally, movement in the body is not an isolated affair.

Muscles, ligaments, tendons, joints, and cartilage all work together to keep us stable and active.

Muscles work from a network of impulses.

They receive signals from the motor and sensory nerves, the brain, and spinal chord and the neuromuscular, and cardiovascular systems.

As we move, whether voluntarily or involuntarily, these systems all work together to make it happen.

In this article, we have tried to discuss how do muscles work accordingly.

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