Skeletal Muscle Design

Skeletal Muscle Structure

By Andrew Nelson

Objectives

• Identify the structures that make up a skeletal muscle

• Identify the major parts of a skeletal muscle fiber

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• Layers of connective tissue enclose and separate all parts of a skeletal muscle

• Fascia (covering) separate muscles from each other​

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Tissue​s​

• Epimysium: The outermost layer of tissue surrounding the entire muscle.

• Perimysium: The middle layer surrounding bundles of muscle fibers.

• Endomysium: The innermost layer surrounding individual muscle fibers.

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​3 Fascia​

• External connective tissue

• Protects the muscle from friction against other muscles or bones

• Extends past the muscle and forms tendon to attach to bone

Epimysium

• Fascicles are bundles of muscle fibers

• Many fasciculi make up a muscle

• Surrounded by second layer, perimysium​

Fasciculi

• Multiple fibers make up fasciculi (can be many or few depending on muscle)

• Each fiber has a connective covering called the​ endomysium

Muscle cells

Muscle Fibers

• ​Cell Membrane: Sarcolema

• Cell Cytoplasm: Sarcoplasm​

• Organelle called Myofi​brils

• Each myofibril is made of actin and myosin proteins

Muscle Fibers

• ​Surrounding the myofibril organelle is the sarcoplasmic reticulum where calcium is stored

• Each fiber is broken into sections called sarcomeres​