Muscle Anatomy and Physiology- Skeletal Muscle Structure and Contraction

Fascia

A sheet of connective tissue that surrounds muscles, blood vessels, and nerves, binding some structures together while allowing others to slide smoothly over each other.

Aponeurosis

A flat, broad tendon that connects muscles to each other or to bone.

Cardiac muscle

Found only in the heart; involuntary, striated, with intercalated discs.

Skeletal muscle

Voluntary, striated muscle attached to bones for movement

Smooth muscle

Involuntary, non-striated muscle found in walls of hollow organs.

Aponeuroses

Plural form of aponeurosis.

Epimysium

Connective tissue surrounding the entire muscle.

Perimysium

Connective tissue surrounding groups of muscle fibers (fascicles).

Fascicles

Bundles of muscle fibers within a muscle.

Endomysium

Connective tissue surrounding each individual muscle fiber.

Muscle fiber

A single muscle cell.

Myofiber

A single muscle cell.

Myofibril

Rod-like units within muscle fibers, made of repeating sarcomeres.

Actin

A thin filament protein involved in muscle contraction; works with myosin.

Myosin

A thick filament protein with "heads" that bind to actin to produce contraction.

Sarcolemma

The cell membrane of a muscle fiber.

Sarcoplasmic reticulum

A specialized endoplasmic reticulum that stores and releases calcium ions to trigger muscle contraction.

Troponin

A regulatory protein that binds to calcium and moves tropomyosin, exposing binding sites on actin.

Tropomyosin

A protein that blocks the binding sites on actin until moved by troponin.

Cross bridge

The connection formed when myosin heads bind to actin during muscle contraction.

Synapse

Junction between a neuron and another cell (e.g., muscle cell).

Neurotransmitter

Chemical that transmits a signal across the synapse.

ACh- acetylcholine

The neurotransmitter that stimulates skeletal muscle contraction.

Sarcoplasm

The cytoplasm of a muscle fiber.