Anatomy of Skeletal Muscles

Study Notes

Also known as striated muscles
Voluntary muscles, meaning they can be controlled consciously
Attached to bones and help move the body's skeleton
Responsible for movement, posture, and balance
Examples:
- Biceps and triceps in the arm
- Quadriceps and hamstrings in the leg
- Pectoralis major in the chest

Muscle Fiber: The basic structural unit of a muscle
- Composed of:
  - Myofibrils (containing actin and myosin filaments)
  - Sarcoplasm (cytoplasm of the muscle fiber)
  - Sarcoplasmic reticulum (smooth endoplasmic reticulum)
  - Mitochondria (for energy production)
Muscle Belly: The main part of the muscle, where contraction occurs
Tendons: Connective tissue that attaches muscles to bones
Aponeurosis: A type of tendon that is flat and sheet-like, often found in muscles of the back and abdomen
Muscle Origins: The point where a muscle attaches to a bone, usually a fixed point
Muscle Insertions: The point where a muscle attaches to a bone, usually a movable point

Also known as striated muscles, they are voluntary muscles that can be controlled consciously
Attached to bones, they help move the body's skeleton and are responsible for movement, posture, and balance
Found in the arm, leg, and chest, examples include biceps and triceps, quadriceps and hamstrings, and pectoralis major

A muscle fiber is the basic structural unit of a muscle, composed of myofibrils, sarcoplasm, sarcoplasmic reticulum, and mitochondria
Myofibrils contain actin and myosin filaments, which are essential for muscle contraction
Sarcoplasm is the cytoplasm of the muscle fiber, while sarcoplasmic reticulum is a type of smooth endoplasmic reticulum
Mitochondria are responsible for energy production in the muscle fiber
The muscle belly is the main part of the muscle where contraction occurs
Tendons are connective tissue that attaches muscles to bones, allowing for movement
Aponeurosis is a type of tendon that is flat and sheet-like, often found in muscles of the back and abdomen
Muscle origins are the points where a muscle attaches to a bone, usually a fixed point
Muscle insertions are the points where a muscle attaches to a bone, usually a movable point

Muscle tissue consists of muscle fibers, connective tissue, and nerve endings
Muscle fibers contain myofibrils, which are contractile units
Myofibrils contain myosin and actin filaments that slide past each other during contraction

Slow-twitch (red) muscles: for endurance, slow contraction, and high oxygen supply
Fast-twitch (white) muscles: for speed and power, rapid contraction, and low oxygen supply

Concentric contraction: muscle shortens during contraction (e.g., bicep curl)
Eccentric contraction: muscle lengthens during contraction (e.g., lowering a weight)
Isometric contraction: muscle contracts without moving the joint (e.g., wall sit)