Generating Movement in the Human Body

Comprehensive vocabulary flashcards covering human skeletal structure, movement terminology, anthropometry, connective tissues, muscular contractions, levels systems, and the sliding filament theory.

Axial skeleton

The portion of the skeleton that includes the skull, vertebral column, and rib cage, providing central support and protection for vital organs.

Appendicular skeleton

The portion of the skeleton consisting of the limbs and their connecting girdles (shoulder and pelvic) that enables movement and manipulation of the environment.

Superior

A positional term meaning above relative to the head.

Inferior

A positional term meaning below relative to the head.

Proximal

A positional term meaning closer to the trunk.

Distal

A positional term meaning farther from the trunk.

Anterior

A positional term meaning front of the body.

Posterior

A positional term meaning back of the body.

Medial

A positional term meaning toward the midline of the body.

Lateral

A positional term meaning away from the midline of the body.

Intermediate

A positional term meaning between two structures.

Sagittal plane

An anatomical plane that divides the body into right and left halves (anterior-posterior).

Frontal/coronal plane

An anatomical plane that divides the body into anterior and posterior portions.

Transverse/horizontal plane

An anatomical plane that divides the body into superior and inferior portions.

Flexion

Movement that decreases the angle between bones.

Extension

Movement that increases the angle between bones.

Abduction

Movement moving away from the midline of the body.

Adduction

Movement moving toward the midline of the body.

Pronation

Rotation of the forearm that turns the palm down or backward.

Supination

Rotation of the forearm that turns the palm up or forward.

Protraction

Forward movement in a horizontal plane.

Retraction

Backward movement in a horizontal plane.

Opposition

Thumb moving toward the little finger.

Reposition

Thumb moving away from the little finger.

Inversion

Sole of the foot turning inward.

Eversion

Sole of the foot turning outward.

Elevation

Moving a structure superiorly (upward).

Depression

Moving a structure inferiorly (downward).

Circumduction

Circular movement combining flexion, extension, abduction, and adduction.

Rotation

Turning around the longitudinal axis of a bone.

Plantarflexion

Movement at the ankle that points the foot downward.

Dorsiflexion

Movement at the ankle that brings the top of the foot toward the shin.

Horizontal flexion/extension

Moving the arm horizontally toward or away from the midline.

Anthropometry

The scientific study of standardized measurements and proportions of the human body, including stature, mass, and limb lengths.

Ergonomic design

Design principles using anthropometric data to optimize the fit between equipment and user to enhance efficiency and reduce injury risk.

Bone

Rigid tissue providing structural support and attachment points for muscles.

Ligament

Bands of dense regular connective tissue connecting bones to other bones, enhancing joint stability.

Cartilage

Firm but flexible tissue reducing friction at joints and absorbing shock.

Fascia

Fibrous connective tissue providing structural support and force transmission between muscles.

Tendon

Dense regular connective tissue connecting muscles to bones and transmitting force.

Fibrous joints

Articulations with minimal or no movement, connected by fibrous tissue such as skull sutures.

Cartilaginous joints

Articulations with limited movement, connected by cartilage such as intervertebral discs.

Synovial joints

Freely movable joints characterized by a fluid-filled cavity, articular cartilage, and a fibrous capsule.

Ball and socket joint

A multiaxial synovial joint allowing movement in many directions, such as the hip or shoulder.

Hinge joint

A uniaxial synovial joint allowing movement in one plane, such as the elbow or knee.

Pivot joint

A synovial joint allowing rotation around a central axis, such as the atlanto-axial joint.

Condyloid joint

A biaxial synovial joint allowing movement in two planes, such as the wrist.

Saddle joint

A modified condyloid synovial joint allowing freer movement, such as the thumb carpometacarpal joint.

Gliding/plane joint

A synovial joint allowing sliding movements, such as the intercarpal joints.

Motor unit

A functional unit consisting of a single motor neuron and all the muscle fibers it innervates.

All-or-none principle

The concept that when a motor unit is activated, all its muscle fibers contract fully or not at all.

ATP

Adenosine triphosphate, the immediate energy currency of cells used for muscular contraction.

Type I (slow oxidative) fiber

Muscle fiber characterized by high fatigue-resistance, aerobic metabolism, and low force production.

Type IIa (fast oxidative-glycolytic) fiber

Muscle fiber with moderate fatigue resistance using both aerobic and anaerobic metabolism.

Type IIx (fast glycolytic) fiber

Fast-contracting muscle fiber with high force production and quick fatigue, using anaerobic metabolism.

Size principle

The recruitment pattern where smaller motor units (Type I) are recruited first, and larger units (Type IIx) are recruited last as force requirements increase.

Isometric contraction

A muscle contraction where tension develops but the muscle length remains unchanged.

Isotonic concentric contraction

A muscle contraction where the muscle shortens while generating tension to accelerate movement.

Isotonic eccentric contraction

A muscle contraction where the muscle lengthens while generating tension to decelerate or control movement.

Isokinetic contraction

A muscle contraction performed at a constant velocity regardless of the force applied.

Agonist

The muscle primarily responsible for producing a particular movement (also called prime mover).

Antagonist

The muscle that produces an action opposite to the agonist and relaxes during agonist contraction.

Reciprocal inhibition

The neurological process where activation of the agonist muscle causes inhibition of the antagonist muscle.

Hypertrophy

An increase in muscle size due to enlarged muscle fibers.

Atrophy

A decrease in muscle size.

Sarcomere

The basic functional and contractile unit of a muscle fiber, consisting of actin and myosin filaments.

Sliding filament theory

The explanation of muscle contraction where thin (actin) and thick (myosin) filaments slide past each other.

Actin

The protein that forms thin filaments and contains binding sites for myosin.

Myosin

The protein that forms thick filaments with heads that bind to actin during contraction.

Troponin

A regulatory protein complex that binds calcium to initiate the contraction sequence.

Tropomyosin

A protein that blocks myosin binding sites on actin when the muscle is at rest.

Power stroke

The phase of contraction where myosin heads pivot, pulling actin filaments toward the center of the sarcomere.

Fulcrum

The fixed point around which a lever rotates.

First class lever

A lever system where the fulcrum is located between the effort and the load, such as nodding the head.

Second class lever

A lever system where the load is between the fulcrum and the effort, providing a mechanical advantage, such as standing on toes.

Third class lever

A lever system where the effort is between the fulcrum and the load, providing a mechanical disadvantage but increasing speed, such as the biceps flexing the elbow.

Mechanical advantage

The ratio of output force to input force in a machine; values greater than $1$ indicate force multiplication.