lec exam 2

Skeletal Muscle

Striated, voluntary muscle attached to bones; responsible for body movement, posture, and heat production.

Cardiac Muscle

Striated, involuntary muscle found in heart walls, responsible for pumping blood.

Smooth Muscle

Non-striated, involuntary muscle located in walls of hollow organs, responsible for moving substances through these organs.

Muscle Tissue Hierarchy

Organization of muscle tissue from muscle to myofilaments, including epimysium, perimysium, endomysium, and myofibrils.

Sliding Filament Theory

Process where myosin heads pull actin filaments toward the sarcomere center, causing muscle contraction.

Slow Oxidative Fibers (Type I)

Muscle fibers that contract slowly, are fatigue-resistant, and used for endurance activities.

Fast Oxidative-Glycolytic Fibers (Type IIa)

Muscle fibers that contract quickly and are moderately fatigue-resistant, used for moderate-intensity activities.

Fast Glycolytic Fibers (Type IIb or IIx)

Muscle fibers that contract very quickly, fatigue rapidly, and are used for short, powerful bursts.

Motor Unit

A motor neuron and the muscle fibers it controls, with small units for fine movements and large units for powerful actions.

Agonist

The primary muscle responsible for a given movement; e.g., biceps brachii flexing the elbow.

Antagonist

Muscle that opposes the agonist and relaxes during the main action; e.g., triceps brachii during elbow flexion.

Synergist

Muscle that assists the agonist and stabilizes movements; e.g., brachialis during elbow flexion.

Fixators

Muscles that stabilize a body part, allowing smooth movement of other muscles; e.g., shoulder muscles during writing.

Fascicle Arrangement

The arrangement of muscle fibers affecting movement range and strength, including parallel, pennate, convergent, and circular.

Neuromuscular Junction

The synapse where a motor neuron communicates with a muscle fiber, initiating contraction.

Tendon of Origin vs. Insertion

The origin is the fixed attachment of a muscle, while the insertion is the movable attachment that moves when the muscle contracts.

Mobility vs. Strength

Parallel fibers favor mobility and range of motion, while pennate fibers favor strength and force production.

Rotator Cuff Muscles

Muscles that stabilize the shoulder joint, including supraspinatus, infraspinatus, teres minor, and subscapularis.

Quadriceps Muscles

Muscles located in the front of the thigh, including rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius.

Hamstrings Muscles

Muscles located in the back of the thigh, including biceps femoris, semitendinosus, and semimembranosus.