Muscle Anatomy and Physiology Notes

Flashcards for reviewing muscle anatomy and physiology.

Latissimus dorsi or pectoralis major

Muscle that adducts the arm back to the body

Quadriceps femoris

Agonist for knee extension

Hamstrings

Agonist for knee flexion

Flexor

Indicates that the muscle flexes a joint or body part

Extensor

Indicates that the muscle extends or straightens a joint or body part

Rectus abdominis

A superficial axial muscle involved in trunk flexion

Triceps brachii

A superficial appendicular muscle used for elbow extension

Skeletal muscle

Voluntary, striated muscle attached to bones

Functions of skeletal muscle

Movement, posture, heat production

Cardiac and smooth muscle

Involuntary muscle types

Muscle organization

From largest to smallest: Muscle > Fascicle > Muscle fiber > Myofibril > Sarcomere

Perimysium

Connective tissue that wraps a fascicle

Sarcolemma

The muscle cell membrane

Myosatellite cells

Stem cells that repair damaged muscle fibers

Sarcomere

The smallest contractile unit of muscle

Actin (thin) and Myosin (thick)

Proteins responsible for muscle contraction

A band

Band that stays the same during contraction

Lack of ATP after death

Cause of rigor mortis

Cross-bridge

Connection between actin and myosin

Acetylcholine (ACh)

Neurotransmitter released at the neuromuscular junction

Acetylcholinesterase (AChE)

What breaks down ACh after it's used

Down the T-tubules to the SR

Where action potential travels after ACh binds

Calcium

Released by the SR

Troponin

What Calcium binds to during contraction

ATP

Breaks the cross-bridge and re-cocks myosin during muscle contraction

Power stroke

Myosin pulling actin toward the center of the sarcomere

Fast fibers

Fibers that contract quickly and fatigue fast

Slow fibers

Fibers that are slow but fatigue-resistant

Low ATP, low calcium, or pH drop

Causes of muscle fatigue

Hypertrophy

Muscle growth from training

Atrophy

Muscle shrinkage from disuse or damage

Oxygen debt

Extra oxygen needed after exercise to restore balance

4 main fascicle arrangements

Parallel, Convergent, Pennate, Circular

Pennate

Most powerful fascicle type

Parallel

Fascicle type that allows the most movement

Circular

Muscle shape that surrounds body openings

Origin

Fixed end of a muscle, usually proximal

Insertion

Movable end of a muscle, usually distal

Agonist (prime mover)

Muscle mainly responsible for a movement

Antagonist

Muscle that opposes the action of the agonist

Synergist

Muscle that assists the agonist

Fixator

Stabilizing muscle that prevents movement at another joint

Isometric contraction

Tension increases but length stays the same

Isotonic contraction

Tension remains but muscle changes length

Triceps brachii

Antagonist to the biceps brachii during forearm flexion

Triceps brachii

Agonist during elbow extension

Deltoid

Muscle that abducts the arm at the shoulder