Types of Muscles and Their Characteristics
The muscular system consists of three main types of muscles, each with distinct functions and locations in the body:
- Skeletal muscles: Found attached to bones
- Cardiac muscles: Located exclusively in the heart
- Smooth muscles: Present in organs and blood vessels
Skeletal and cardiac muscles are both striated, meaning they have a striped appearance under a microscope.
Vocabulary: Sphincter muscles are special circular muscles that open and close to allow substance passage, such as the urethral sphincter for liquid waste and the anal sphincter for solid waste.
The muscular system exhibits several key characteristics:
- Contractability: Allows muscle tissue to pull or shorten
- Extensibility: The ability to stretch or expand
- Excitability: Capacity to respond to stimuli e.g.,afirealarm
- Elasticity: Ability to return to its original state e.g.,theuterus
Highlight: Atrophy refers to the lack of muscle development or wasting away of muscle tissue.
Key terms related to muscle movement and function include:
- Abduction: Movement away from the midline
- Adduction: Movement toward the midline
- Aerobic: Requiring oxygen
- Anaerobic: Requiring no oxygen
- Agonist: Contracts muscle to cause movement
- Antagonist: Produces movement in the opposite direction of the prime mover
- Circumduction: Circular movement of a joint
- Extension: Increasing the angle between two bones
- Flexion: Decreasing the angle between two bones
Definition: Fascia is a thin, flexible band of connective tissue that holds, separates, or binds muscles.
Other important terms include:
- Insertion: Attachment point for skeletal muscle to bone after crossing a joint
- Origin: Attachment site for muscle to bone that does not move during contraction
- Isometric: Contraction of a muscle without joint movement
- Isotonic: Maintains constant tension as the muscle changes length
- Prime mover: Produces movement of a muscle in a single direction
- Synergist: Muscles that help support a joint
Vocabulary: Pronation refers to the rotation of the hand and forearm so that the palm faces downward, while supination is the opposite movement.
