Kinese exam 1 MUSCULAR KINEMATICS

Muscle Fiber Type 1 (Slow Twitch)

Small aerobic fibers; slow contraction, high endurance, fatigue resistant.

Muscle Fiber Type 2 (Fast Twitch)

Large anaerobic fibers; strong and fast contractions, fatigue quickly.

Muscle Fiber Type 2a (Intermediate)

Mixed fibers; moderate speed and endurance, fatigue delayed with training.

Henneman’s Size Principle

Motor units recruit from smallest to largest; Type 1 fibers are activated first.

Innervation Ratio (Low)

One nerve controls few fibers; high precision movement (example: eye or hand muscles).

Innervation Ratio (High)

One nerve controls many fibers; powerful gross movement (example: quadriceps).

Parallel Muscle Shape

Fibers run parallel to tendon; greater ROM and speed, less force.

Fusiform Muscle

Spindle-shaped muscle; example: biceps brachii.

Flat Muscle

Thin, broad muscle often from aponeurosis; example: rectus abdominis.

Radiate (Convergent) Muscle

Fan-shaped fibers converge to tendon; example: pectoralis major.

Strap Muscle

Long fibers with uniform diameter; example: sartorius.

Sphincter Muscle

Circular muscle controlling openings; example: orbicularis oculi.

Pennate Muscle Shape

Fibers angled to tendon; more fibers, increased strength and power.

Unipennate Muscle

Fibers attach on one side of tendon.

Bipennate Muscle

Fibers attach on both sides of tendon.

Multipennate Muscle

Multiple tendons with diagonal fibers.

Muscle Origin

Proximal, more stable attachment point.

Muscle Insertion

Distal, more movable attachment point.

Concentric Contraction

Muscle shortens while producing force.

Eccentric Contraction

Muscle lengthens while controlling movement.

Isometric Contraction

Muscle tension with no joint movement (example: plank).

Isotonic Contraction

Joint movement with relatively constant resistance.

Isokinetic Contraction

Movement at constant speed with equal resistance throughout ROM.

Agonist

Primary muscle producing concentric contraction (example: biceps in curl).

Antagonist

Muscle opposing the agonist; often eccentric (example: triceps in curl).

Synergist

Assists agonist or compensates to improve movement.

Force Couple

Two muscles act in opposite directions to create control or stability.

Stabilizer

Muscle providing posture or joint support.

Neutralizer

Prevents unwanted movement during action.

Lombard’s Paradox

Opposing muscles contract simultaneously to produce movement.

Muscle Optimal Length (lo)

Length where maximal cross bridges form and force production is greatest.

Proprioception

Sensory feedback about muscle length, tension, and body position.

Kinesthesia

Sensory feedback related to force, speed, and joint movement.

Muscle Spindle

Detects stretch and rate of stretch; causes reflex contraction.

Patellar Reflex

Stretch reflex causing muscle contraction.

Golgi Tendon Organ

Detects excessive tension; causes reflex relaxation.

Factors Affecting Muscle Force Production

Muscle fiber type, fiber arrangement, muscle size, motor unit recruitment, contraction type, proprioceptors, length-tension relationship, contraction velocity, time history of activation.