Overview
This lecture provides an introduction to the muscular system, covering its main functions, key properties, types of muscle tissue, movements, and supportive structures.
Functions of the Muscular System
- The primary purpose of the muscular system is to provide movement for the body.
- Muscles receive their ability to move through signals from the nervous system.
Major Properties of Muscles
- Muscles are excitable (able to receive and respond to nerve stimulation).
- Muscles are contractable (can shorten after stimulation).
- Muscles are extensible (can be stretched without damage).
- Muscles have elasticity (return to original shape after stretching or contracting).
- Muscles are adaptable (can change in size based on use, such as hypertrophy or atrophy).
Types of Muscle Movements
- Adduction: moving a body part toward the midline.
- Abduction: moving a body part away from the midline.
- Flexion: bending a joint to decrease the angle between two body parts.
- Extension: straightening a joint to increase the angle between two body parts.
- Rotation: moving a body part around an axis.
Types of Muscles
- Cardiac muscle: found in the heart, involuntary control, pumps blood.
- Visceral (smooth) muscle: found in organs, involuntary control, assists organ systems.
- Skeletal muscle: attached to bones, voluntary control, enables body movement.
Support Structures
- Tendons attach muscles to bones.
- Fascia connects muscles to other muscles.
- Tendons and fascia support movement with muscles.
Interaction with the Nervous System
- The nervous system controls voluntary skeletal muscle movement.
- Loss of nerve communication causes paralysis (quadriplegia).
- Cardiac muscle is not directly dependent on the nervous system for function.
Key Terms & Definitions
- Excitable — a muscle's ability to receive and respond to stimuli.
- Contractable — the ability of muscle to shorten.
- Extensible — the ability of muscle to stretch.
- Elasticity — the ability to return to original shape after stretching or contracting.
- Hypertrophy — muscle enlargement with use.
- Atrophy — muscle wasting due to lack of use.
- Adduction — movement toward the body’s midline.
- Abduction — movement away from the body’s midline.
- Flexion — bending to decrease joint angle.
- Extension — straightening to increase joint angle.
- Rotation — movement around an axis.
- Tendon — tissue attaching muscle to bone.
- Fascia — tissue connecting muscles to each other.
- Quadriplegia — paralysis caused by loss of nerve control to muscles.
Action Items / Next Steps
- Watch future CTE videos for details on major muscle groups and muscular system diseases.
- Review key properties and movement types for a foundational understanding.