Functional Anatomy - Introduction to the Muscular System

Flashcards based on Functional Anatomy lecture notes, focusing on the muscular system, muscle terminology, muscle tissues, and skeletal muscle structures.

Origin

Muscle attachment to the more stationary bone, usually at the most proximal end of the muscle.

Insertion

Muscle attachment to the bone with greatest movement, usually at the most distal end of the muscle.

Agonist

A muscle that, when it contracts, causes the movement.

Antagonist

A muscle that, when it contracts, opposes the movement.

Synergists

Muscles that work together to produce the movement.

Prime Mover

A muscle that plays a major role in producing a movement (its main role).

Fixator / Stabilizer

Muscles that stabilize joints crossed by prime movers; prevents movement of the origin of the primer mover.

Concentric contraction

Contraction with shortening of muscle size, where muscle torque is greater than external torques.

Eccentric contraction

Contraction with lengthening of muscle size, where muscle torque is less than external torques.

Isometric contraction

Contraction with no change in length, where muscle torque equals external torques.

Belly

Largest portion of a muscle between the origin and insertion (usually at mid-distance).

Aponeurosis

A very broad tendon.

Fascia

Membrane that covers/surrounds anatomical structures, such as muscles, and contributes to transmit forces from the origin to the insertion.

Smooth muscle tissue

Also called involuntary muscles; long and slender cells with 1 nucleus that contract slowly and automatically. Found covering internal organs and the digestive system.

Cardiac muscle tissue

Small cells with 1 nucleus that contract without neural stimulation (automaticity). Includes pacemaker cells and functions to move blood in the vascular system.

Skeletal muscle tissue

Also called voluntary muscles; large, multinucleate cells that contract with neural stimulation. Functions include movement, posture maintenance, promoting blood return, producing heat, and converting chemical energy into mechanical and thermic energy.

Nucleus (muscle cell)

Control center of the muscle cell that contains genetic material.

Sarcolemma

Cytoplasmic membrane of the muscle cell.

Sarcoplasm

Cytoplasm of the muscle cell.

Mitochondrion (muscle cell)

Organelle in the sarcoplasm responsible for energy production (aerobic only).

Myofibril

Unit containing contractile proteins (myofilaments) that are responsible for muscle contraction, making up 80% of muscular volume.

Sarcomere

Smallest functional unit of a muscle delimited by Z discs.

Actin

Thin myofilament within the sarcomere.

Myosin

Thick myofilament with a head that pulls on the actin to shorten muscle.

Tendons

Connect muscles to bones & ligaments. Passive tissue comprised of collagen & elastic fibers. Respond to mechanical stress by hypertrophying / atrophying.