Anatomy Exam 3

Muscles

Skeletal Muscle

Muscle tissue that pulls on skeletal bones and is under voluntary contraction.

Cardiac Muscle

Muscle tissue that pushes blood through arteries and veins and exhibits rhythmic contractions.

Smooth Muscle

Muscle tissue that pushes fluids and solids along the digestive tract, characterized by involuntary contraction.

Excitability

The ability of muscle tissue to respond to stimuli.

Contractility

The ability of muscle tissue to shorten and exert a pull or tension.

Extensibility

The ability of muscle tissue to be stretched or to increase in length.

Elasticity

The ability of muscle tissue to rebound toward its original length.

Tendons

Connective tissues that connect muscles to bones.

Aponeuroses

Thick, flattened sheets of connective tissue connecting muscles to muscles.

Myofibrils

Structural units within muscle fibers responsible for muscle contraction.

Sarcomere

The main functioning unit of muscle fibers, consisting of overlapping actin and myosin.

The Sliding Filament Theory

A theory explaining muscle contraction where the H band and I band get smaller while Z lines move closer together.

Neuromuscular Junction (NMJ)

The chemical synapse between a motor neuron and a muscle fiber that transmits signals for contraction.

Motor Unit

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

Muscle Tone

The tension of a muscle when it is relaxed, stabilizing the position of bones and joints.

Fast Fibers

Muscle fibers associated with quick bursts of power but fatigue rapidly.

Slow Fibers

Muscle fibers that contract slowly but can sustain activity longer and contain more myoglobin.

Motor Units and Muscle Control

The method of controlling muscle contraction based on the number and frequency of activated motor units.

Origin (in muscles)

The point of muscle attachment that remains stationary during contraction.

Insertion (in muscles)

The point of muscle attachment that moves during contraction.

Prime Movers (Agonists)

Muscles responsible for producing a particular movement.

Antagonists

Muscles that oppose the action of the agonists.

Synergists

Muscles that assist the prime mover in performing an action.

Fixators

Muscles that stabilize joints and maintain a position during movement.

Diaphragm

The major muscle involved in breathing that contracts to increase thoracic cavity volume.

Perineal Region

The area of the pelvic floor, divided into the urogenital triangle and the anal triangle.

Pelvic Diaphragm

Muscular structure forming the foundation of the pelvic cavity.