Introduction to Muscles and Muscle Tissue

Flashcards covering skeletal muscle histology, sarcomere anatomy, muscle naming conventions, and specific actions of thoracic and abdominal muscles.

Skeletal muscle

Muscle tissue attached to the skeleton.

Smooth muscle

Muscle tissue that lines hollow organs such as the GI tract and blood vessels.

Cardiac muscle

The muscle tissue specifically found in the heart.

Epimysium

Dense connective tissue that surrounds the entire muscle tissue.

Perimysium

Connective tissue that surrounds each fascicle.

Endomysium

Connective tissue that covers each muscle fiber (cell).

Sarcolemma

The plasma membrane of a muscle cell.

Tendon

Structure made of dense regular connective tissue that attaches muscles to bones.

Sarcoplasmic reticulum

Smooth ER that stores calcium in a resting muscle cell.

Sarcomere

The functional contractile unit of muscle cells, extending from one Z disc to another Z disc.

Triad

A structure consisting of one T tubule and two terminal cisterns of the SR.

T-tubules

Parts of the sarcolemma that fold to allow membrane potential to reach all myofibrils.

Myofibrils

Long threadlike structures in a muscle fiber composed of bundle of myofilaments.

Myosin

Proteins that make up thick filaments.

Actin

Proteins that make up thin filaments.

Tropomyosin

A regulatory protein that runs the length of the thin filament and covers myosin-binding sites at rest.

Troponin

A regulatory protein that interacts with calcium ions to trigger muscle contraction.

Z-disc

Zig-zagging structures at the edges of the sarcomere where thin filaments are attached.

M-line

Structure in the middle of the sarcomere that helps anchor thick filaments together.

H-zone

The middle region in the sarcomere where only thick filaments are present.

A-band

The darker bands in a sarcomere including thick filaments and regions where thin filaments overlap.

I-band

The lighter regions in a sarcomere containing only thin filaments.

Origin

The stationary or less movable attachment of a muscle.

Insertion

The movable attachment of a muscle that moves towards the origin.

Rectus

A term meaning straight or parallel to a bone or body region.

Transversus

A term meaning perpendicular or at a right angle to a bone or body region.

Oblique

A term meaning angled in relation to muscle fiber direction.

Orbicularis

A term meaning around, encircling, or circular.

Flexion

Action where the angle between bones decreases, moving them together.

Extension

Action where the angle between bones increases, moving them apart.

Abduction

Moving a limb or appendage away from the body's midline.

Adduction

Moving a limb or appendage toward the body's midline.

Inversion

Turning the foot medially, such as when rolling an ankle in.

Eversion

Turning the foot laterally, such as when rolling an ankle out.

Dorsiflexion

Moving the toes toward the tibia and fibula.

Plantarflexion

Pushing the toes down toward the ground.

Prime mover

The muscle most responsible for a body movement.

Synergist

A muscle that helps with a body movement.

Antagonist

A muscle that does the opposite movement of the prime mover.

Diaphragm

A muscle of the thorax specifically involved in inhalation.

External intercostals

Thoracic muscles involved in inhalation.

Internal intercostals

Thoracic muscles involved in exhalation.

External obliques

Abdominal muscles that flex the torso laterally.

Rectus abdominis

Abdominal muscle that flexes the torso forward, such as during sit-ups.