Skeletal muscle


In order to fully understand the way in which the body movements of both humans and animals work, it is necessary to know the musculoskeletal system and the way in which it works. It is also known by the name of the locomotor system , and as its name indicates in this case, it is responsible for moving us from one place to another, but it also has many vital functions for the human body.


What is skeletal muscle?

Skeletal muscle is a system that is responsible for making the body move so that it interacts with the environment and is made up of two parts, the skeletal system and the muscular system , which work together to allow movement .

  • Skeletal muscle characteristics
  • Classification
  • Skeletal muscle function
  • Parties
  • Skeletal muscle location
  • Disorder
  • Skeletal muscle contraction
  • Examples

Skeletal muscle characteristics

Among its main features are the following:

  • It is responsible for overall the body movement
  • It is completely regulated by the central nervous system .
  • It is closely related to the skeletal , cardiac , respiratory , digestive, and endocrine systems .
  • It is made up of a large number of muscle fibers and also has connective tissue which surrounds the fibers and the muscle.
  • It is a vitally important system for exercise and physical activity .
  • It is made up of several types of fibers
  • They are attached to the skeleton.
  • They are made up of fibers that are long and also have several cores .
  • It has a reddish appearance which is caused thanks to the blood supply that gives it nutritional contributions and helps them eliminate waste.
  • They give protection to all the internal organs that make up the human body.


The classification of skeletal muscle is quite extensive and is divided into groups depending on the type of muscle. In this way we can find the following classification:

  • According to its shape:
    • Fusiform : they have an elongated shape, they are wide in their central part and narrower at the ends.
    • Unipenniform : their muscle fibers come out on one side of the tendons and are shaped like a half feather.
    • Bipenniform : its fibers come from a central tendon following it longitudinally.
    • Multipenniform : their fibers have a more complex organization depending on the function they perform.
    • Widths : they have similar diameters and sizes.
    • Flat : they are fan-shaped, flat and broad longitudinally.
    • Short : they are muscles made up of smaller fibers.
  • According to the action they perform:
    • Flexors
    • Extenders
    • Abductors
    • Adductors
    • Rotators
    • Fixers
  • According to the action they do together:
    • Agonists : are those that are in the same direction and produce a large amount of force when an action is performed.
    • Antagonists : they are opposite to the main muscle and control the speed and the range of movement avoiding the involuntary actions and the injuries.
    • Synergist : Produces quite a bit of force.
    • Fixator : it is responsible for preventing the bone from moving, making it remain firm.

Skeletal muscle function

The role of skeletal muscles is of vital importance to the human body and there are many. In the first place, they are responsible for the movement of the body thanks to the nervous system that sends signals so that the muscles can react either by contracting or elongating. They produce a type of displacement movement that allows the body to move without having to return to the original point.

Through them, mechanical energy can be obtained , a necessary process to be able to carry out the movement. They provide the body with stability in the joints by keeping them in their correct place. They also help maintain good body posture and act in temperature regulation processes when the body is faced with extreme temperatures. A function that is also very important is that they intervene in the process of blood supply since, thanks to their contraction, the pumping of blood to the muscles is promoted.


The musculoskeletal system is made up of several parts. One of them is the osteoarticular system which involves organs such as bones , cartilage and the different joints that make up the body. On the other hand is the muscular system that involves all the muscles , the ligaments that attach to the bones and tendons. In total there are 206 bones in the human body, all of them with different shapes and functions. Approximately a total of 650 muscles are forming part of this system which have connective tissues and fibers.

Skeletal muscle location

The musculoskeletal system is located in approximately 40% of the human body and 10% of cardiac muscle and viscera . They are directly attached to the skeleton of the body and due to their location are generally referred to as the “flesh of the human body.”


Skeletal muscle disorders are very common and affect thousands of people around the world. The main problems usually occur in the neck , shoulders, and lower and upper extremities , including problems related to the joints. This situation produces pain and a series of discomforts that if not treated in time can cause more complicated and difficult to treat diseases. There are several risk factors that can trigger them, including mentioning:

  • Inadequate handling of heavy loads .
  • Very energetic and repetitive movements .
  • Incorrect or forced postures .
  • Sitting for long periods of time without a break.

It is common to observe in people who suffer from inflammation , pain , bodily discomfort , a reduction in sensitivity and strength. This type of musculoskeletal disorder has a high incidence especially at work and this causes that in many cases the normal performance of a person is quite affected. Some of the most common disorders are:

  • De Quervain’s tenosynovitis : affects the tendon sheaths of the muscles that are responsible for extending and separating the thumb.
  • Stenosing tenosynovitis of the fingers : affects the flexor tendons of the fingers.
  • Osteoarthritis : a degenerative disorder that affects cartilage and the underlying bone structure.
  • Trauma : caused mainly by accidents or injuries can considerably affect the mechanics and circulation of the body.
  • Tendinitis : directly affects the Achilles tendon and can be caused by poor use of footwear, poor alignment and weakness.
  • Fibromyalgia : a disease whose cause is unknown that produces a feeling of fatigue mainly in the morning.
  • Rheumatoid arthritis : arthritis causes inflammation in different joints

Skeletal muscle contraction

Skeletal muscle contraction occurs thanks to a series of different nervous stimuli that are produced by the Central Nervous System and which are then transmitted through neurons which carry them directly to the muscle. Neurons are responsible for making a muscle contract . The contraction is also the result of an action that is carried out voluntarily thanks to the signals that are produced in the brain. The union that exists between the neuron and the muscle fibers forms the motor plate which, in turn, has the ability to carry impulses from the neuron to produce thedepolarization of the muscle fiber membrane .


Some examples of skeletal muscles are as follows:

  • Quadriceps femoris
  • Deltoid
  • Gastrocnemius

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