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Skeletal muscle is the most common type of muscle in the human body, comprising between 30% and 40% of total body mass. It is a highly organised tissue made up of thousands of muscle fibres, which contract to produce movement, maintain posture, control body temperature, and stabilise joints. Skeletal muscles are attached to bones by tendons and are under voluntary control, receiving neural inputs from the brain that allow conscious movement.
| Characteristics | Values |
|---|---|
| Type of Muscle Tissue | Skeletal Muscle |
| Part of the Body | Musculoskeletal System |
| Controlled By | Voluntary |
| Consists of | Muscle Fibers |
| Muscle Fiber Composition | Actin, Myosin, Support Proteins |
| Muscle Fiber Diameter | 10-100 Micrometres |
| Muscle Fiber Length | 2-3 Centimetres |
| Connective Tissue | Endomysium, Perimysium, Epimysium |
| Muscle Composition | Myofibers, Myofibrils, Sarcomeres |
| Muscle Movement | Contraction |
| Muscle Functions | Movement, Posture, Temperature Control, Nutrient Storage, Joint Stabilisation |
| Muscle Mass | 30-40% of Total Body Mass |
| Number of Muscles | 600+ |
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What You'll Learn
Skeletal muscle is the most common type of muscle in the body
Skeletal muscles are composed of bundles of muscle fibres called myofibers, which contain several myofibrils. Each myofiber is a muscle cell with its basic cellular unit, the sarcomere. The sarcomeres are functional units created by the arrangement of actin and myosin, which gives skeletal muscle its microscopic striated appearance. Skeletal muscle fibres are typically 2-3cm long and range from 10 to 100 micrometres in diameter. Each muscle can contain thousands of fibres, and these fibres contract, allowing the muscles to move bones and produce a wide range of movements.
The functions of skeletal muscles include producing movement, maintaining body posture, controlling body temperature, and stabilizing joints. They also play a role in swallowing, chewing, breathing, and producing body heat. Skeletal muscles are essential for converting chemical energy into mechanical energy, generating force and power. Additionally, they serve as storage sites for essential substrates such as carbohydrates, amino acids, and proteins.
The tissue of skeletal muscle is unique among muscle tissues due to its striated appearance, voluntary nature, and long, straight muscle fibres. Skeletal muscle disorders typically manifest as muscle weakness, and it is important to maintain skeletal muscle strength and health.
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Skeletal muscles are voluntary muscles
Skeletal muscle is one of the three types of vertebrate muscle tissue, the others being cardiac and smooth muscle. Skeletal muscles are attached to bones by tendons and allow us to perform a wide range of movements and functions. They make up around 30% to 40% of our total body mass and are the most common type of muscle in our bodies.
The skeletal muscle cells are multinucleated, with nuclei located along the inside of the cell membrane. These nuclei are termed myonuclei. Skeletal muscles produce adenosine triphosphate (ATP) molecules, which power the movement of the myosin heads. They also keep a storage form of glucose in the form of glycogen, which can be rapidly converted to glucose when energy is required for sustained, powerful contractions.
Nerves in the somatic nervous system send signals to make skeletal muscles function. These nerves communicate with muscles through the release of neurotransmitters at the neuromuscular junction, the space between a nerve cell and muscle fibre. Weakness or an inability to control voluntary skeletal muscles can signal a health issue, such as a neuromuscular disorder or electrolyte imbalance.
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Skeletal muscles are attached to bones by tendons
Skeletal muscles are a vital part of the musculoskeletal system, comprising 30% to 40% of the human body weight. They are attached to bones by tendons, which are fibrous connective tissues that act as levers to move the bones when the muscles contract and relax. Tendons are highly resistant to tearing but are not stretchy, making them susceptible to strain injuries when overstretched. Tendons also work to connect muscles to structures such as the eyeball.
Skeletal muscles are composed of bundles of muscle fibres called myofibers, which contain several myofibrils. Each myofiber represents a muscle cell, with its basic cellular unit being the sarcomere. These muscle fibres contract, allowing the muscles to move bones and perform a wide range of movements. The contraction of skeletal muscles also helps to produce body heat, which is a by-product of muscular activity.
The musculoskeletal system includes bones, joints, muscles, tendons, ligaments, and cartilage. Skeletal muscles are attached to bones by tendons at specific points of connection called junctions. The point where the tendon attaches to the muscle is called the musculotendinous junction (MTJ), and the point where the tendon attaches to the bone is the osteotendinous junction (OTJ). Tendons of the hand or foot are held in place by sliding through a connection called a reflection pulley.
Tendons are made up of collagen fibres, one of the most abundant proteins in the body. They are flexible, strong, and resistant to damage. The bundling of collagen fibres reinforces the tendon, making it even stronger. Tendons also contain Sharpey fibres, which are collagen fibres that attach the tendon to the bone. Additionally, tendons contain blood vessels and nerves.
The skeletal muscles' attachment to bones via tendons allows for a wide range of movements and functions. For example, when you contract your bicep, your tricep lengthens, demonstrating the coordinated pairing of skeletal muscles. This contraction of skeletal muscles also plays a role in regulating blood sugar levels by taking up glucose from the blood as fuel or storing it for later use.
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Skeletal muscles help with digestion and breathing
Skeletal muscles are the most common type of muscle in the body, comprising 30% to 40% of total body mass. They are voluntary muscles, meaning we can control how and when they move. Skeletal muscles are attached to bones by tendons, allowing us to perform a wide range of movements and functions.
These muscles are vital to the process of breathing. The thoracic cage, a component of the thoracic wall, encloses most of the respiratory system's structures and provides a framework for breathing. While the thoracic cage offers protection and flexibility for ventilation, breathing would be impossible without the action of the skeletal muscles. These muscles expand and contract the chest cavity, allowing air to move in and out during inhalation and exhalation.
Skeletal muscles also play a role in digestion. Chewing and swallowing are the first parts of digestion that skeletal muscles facilitate. Additionally, skeletal muscles in the abdominal region, such as the rectus abdominis, are involved in the breathing process and aid in pulling the ribs down during active expiration.
Furthermore, the muscular system works in conjunction with the digestive system. The muscular system helps break down food into smaller pieces, both mechanically and chemically, to facilitate the extraction of nutritional molecules. The smooth muscles of the stomach contract irregularly, grinding food and moving it through the digestive tract. Regular, rhythmic contractions of the small intestine, which are also involuntary, propel food toward the exit of the digestive tract.
Therefore, skeletal muscles are essential for breathing and digestion, contributing to vital bodily functions and overall health.
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Skeletal muscles make up 30-40% of total body mass
Skeletal muscle is the most common type of muscle in the body, comprising around 30% to 40% of an individual's total body mass. There are more than 600 skeletal muscles in the human body, and they are present in various parts of the body, including the tongue, diaphragm, eye socket, and upper oesophagus.
Skeletal muscles are attached to bones by tendons, allowing for a wide range of movements and functions. They are voluntary muscles, meaning that individuals have control over how and when they move. These muscles are composed of bundles of muscle fibres called myofibers, which contain several myofibrils. Each myofiber represents a muscle cell, and bundles of these form fascicles, which further group together to form muscle tissue.
The skeletal muscle cells are much longer than other types of muscle tissue cells, and they exhibit a striped appearance due to the arrangement of sarcomeres. This arrangement of actin and myosin proteins within the cells forms myofibrils, which are responsible for the skeletal muscles' strength and ability to generate force and power. Each muscle fibre can contain hundreds to thousands of nuclei, which are necessary for the production of large amounts of proteins and enzymes required for normal cell functioning.
The contraction of skeletal muscles produces movement, sustains body posture, controls body temperature, stores nutrients, and stabilises joints. From a metabolic perspective, skeletal muscles contribute to basal energy metabolism and serve as storage sites for essential substrates such as carbohydrates and amino acids. They also produce body heat as a byproduct of muscular activity.
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