Name: muscle fibers, tendons, and contraction
Uploaded: 2025-10-23T11:49:18.000Z
Duration: 55 s
Channel: JoVE

Skeletal muscles, striated tissues under the voluntary control of the somatic nervous system, are attached to bones through collagenous fibers called tendons. They are enclosed in a connective tissue called epimysium, which distinguishes the muscle from surrounding structures.

Within each skeletal muscle, like the biceps brachii, are numerous cell bundles, called fascicles, that are also surrounded by connective fascia, perimysium. Each fascicle contains multiple muscle cells, which are individually-enclosed in a plasma membrane known as the sarcolemma. A single muscle cell can be further broken down into myofibrils, filaments composed of actin and mysosin, the functional unit referred to as the sarcomere.

skeletal muscle anatomy

Skeletal muscle is the most abundant type of muscle in the body. Tendons are the connective tissue that attaches skeletal muscle to bones. Skeletal muscles pull on tendons, which in turn pull on bones to carry out voluntary movements.

Skeletal muscles are surrounded by a layer of connective tissue called epimysium, which helps protect the muscle. Beneath the epimysium, an additional layer of connective tissue, called perimysium, surrounds and groups together subunits of skeletal muscle called fasciculi.

Each fascicle is a bundle of skeletal muscle cells, or myocytes, which are often called skeletal muscle fibers due to their size and cylindrical appearance. Between the muscle fibers is an additional layer of connective tissue called endomysium.

The muscle fiber membrane is called the sarcolemma. Each muscle fiber is made up of multiple rod-like chains called myofibrils, which extend across the length of the muscle fiber and contract. Myofibrils contain subunits called sarcomeres, which are made up of actin and myosin in thin and thick filaments, respectively.

Actin contains myosin-binding sites that allow thin and thick filaments to connect, forming cross bridges. For a muscle to contract, accessory proteins that cover myosin-binding sites on thin filaments must be displaced to enable the formation of cross bridges. During muscle contraction, cross bridges are repeatedly broken and formed at binding sites further along the actin.

Skeletal Muscle Anatomy

Skeletal muscle is the most abundant type of muscle in the body. Tendons are the connective tissue that attaches skeletal muscle to bones. Skeletal ...

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muscle fibers, tendons, and contraction

Skeletal muscle moves the body by pulling on bones through tendons. Tendons are the connective tissue that attaches skeletal muscle to bones. When skeletal muscles contract, they create voluntary movement.

Skeletal muscle is wrapped in layers of connective tissue. The outer layer is the epimysium, which helps protect the muscle. Beneath it, the perimysium surrounds and groups fasciculi, which are bundles of skeletal muscle cells called myocytes. These cells are also called skeletal muscle fibers because of their long, cylindrical shape.

Between muscle fibers is another connective tissue layer called endomysium. Each muscle fiber is surrounded by a membrane called the sarcolemma. Inside each fiber are many rod-like chains called myofibrils. They run the length of the fiber and contract.

Myofibrils contain sarcomeres, the subunits made of actin and myosin. Actin forms the thin filaments, and myosin forms the thick filaments. Actin has myosin-binding sites that let the thin and thick filaments connect and form cross bridges. For contraction to begin, accessory proteins that block these binding sites must move away. The cross bridges then break and reform at new binding sites farther along the actin.

Muscle Fibers, Tendons, and Contraction

what is the skeletal system?

Human Skeleton: Bones, Cells, and Disease

The human skeleton is a living framework made of 206 bones in adults. Bones connect with cartilage, tendons, and ligaments. This system gives the body support, protects organs, and helps with movement and locomotion. The skeleton has two main parts: the axial skeleton and the appendicular skeleton. The axial skeleton has 80 bones and includes the skull, the vertebral column, and the rib cage. The cranium, or upper skull, has eight bones that enclose the brain, while the lower part of the skull...

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Skeletal muscle moves the body by pulling on bones through tendons. Tendons are the connective tissue that attaches skeletal muscle to bones. When skeletal muscles contract, they create voluntary movement. Skeletal muscle is wrapped in layers of connective tissue. The outer layer is the epimysium, which helps protect the muscle. Beneath it, the perimysium surrounds and groups fasciculi, which are bundles of skeletal muscle cells called myocytes. These cells are also called skeletal muscle...

classification of skeletal muscle fibers

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Skeletal muscle fibers can be grouped by how fast they contract and how they make ATP, the energy cells use for movement. These differences also shape their physical features. Most human muscles contain all three fiber types, but in different amounts. Slow oxidative fibers, also called slow-twitch fibers, appear red because they have many capillaries and high levels of myoglobin, an oxygen-storing protein. They also contain more mitochondria, which make ATP through oxidative phosphorylation,...

muscle contraction

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Nerve signals trigger muscle contraction in both skeletal and smooth muscle, but the two muscle types use different control systems. In skeletal muscle, the signal begins at the motor end plate, which is the synapse between a motor neuron and a muscle fiber. In smooth muscle, contraction is controlled by the autonomic nervous system and happens without conscious control. In skeletal muscle, motor nerve terminals release acetylcholine. This neurotransmitter binds to receptors on the sarcolemma,...

cross-bridge cycle

Calcium Control in Muscle Contraction

Calcium control in muscle contraction depends on ATP, motor neurons, and the sliding action of actin and myosin. As a muscle contracts, the thin and thick filaments overlap more, and the sarcomere, which is the contractile unit of the muscle, becomes shorter. This process uses energy from ATP and happens in a repeating cycle at the molecular level. Myosin drives the movement of actin through a cross-bridge cycle. When ATP attached to the myosin head is hydrolyzed to ADP, myosin shifts into a...

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key terms and concepts

Explore how skeletal muscle attaches to bones, how muscle fibers are organized, and how actin and myosin work together during contraction.

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Muscle Fibers, Tendons, and Contraction

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