Muscle Anatomy and Physiology

1. Muscle Functions

• Movement: Muscles produce movement necessary for activities such as walking and breathing.
• Posture: They maintain body posture and position providing stability.
• Joint Stabilization: Muscles help stabilize joints, preventing dislocation or injury during movement.
• Heat Generation: Muscles generate heat during activity, which is vital for maintaining body temperature.

2. Diagram of a Muscle

• Components of Skeletal Muscle:
  • Muscle
  • Fascicle
  • Muscle Fiber
  • Myofibril
  • Sarcomere
• (A diagram can enhance understanding of these components. Request if needed.)

3. Details of Muscle Components

• Muscle (Organ):
  • Composed of bundles of fascicles.
• Fascicle:
  • A bundle of muscle fibers (cells).
• Muscle Fiber:
  • Long cylindrical cells housing multiple nuclei and mitochondria.
• Myofibrils:
  • Rod-like structures within the muscle fiber containing sarcomeres.
• Sarcomere:
  • The contractile unit of the muscle, composed of actin and myosin.

4. Key Connective Tissues and Proteins

• Ligaments:
  • Tissue connecting bone to bone, crucial for joint stability.
• Tendons:
  • Tissue connecting muscle to bone, aiding in force transfer from muscles to bones.
• Actin:
  • Thin protein filament playing a key role in muscle contraction.
• Myosin:
  • Thick protein filament that interacts with actin to facilitate contraction.

5. Detailed Explanation of a Sarcomere

• Sarcomere:
  • The functional unit of muscle fibers; spans from Z line to Z line.
• Components:
  • Z-lines: Boundaries defining the sarcomere limits.
  • A band: Dark band containing myosin (thick filaments).
  • I band: Light band where only actin can be found (thin filaments).
  • H zone: Region within the A band containing only myosin.
  • M line: The central part of the sarcomere.
• Contraction Mechanism: Contraction occurs via actin sliding over myosin, resulting in sarcomere shortening.

6. Types of Muscle (Identification and Characteristics)

• Skeletal Muscle:
  • Appearance: Striated, long
  • Control: Voluntary
  • Location: Attached to bones
  • Function: Movement
• Cardiac Muscle:
  • Appearance: Striated, branched
  • Control: Involuntary
  • Location: Heart
  • Function: Pumps blood
• Smooth Muscle:
  • Appearance: No striations
  • Control: Involuntary
  • Location: Walls of organs
  • Function: Moves substances through organs.

7. Sliding Filament Theory (Overview)

• Contraction Process:
  • Myosin heads attach to actin forming cross-bridges.
  • Utilize ATP to pull actin inward resulting in muscle shortening.
  • This process continues in a ratchet-like manner facilitating sustained contraction.

8. Muscles of the Body

• Labeling Practice: Study and label the muscles from:
  1. Head muscles
  2. Anterior body muscles
  3. Posterior body muscles
• (A detailed labeling quiz can assist in mastering muscle identification.)

9. Muscle Action Table: Face Muscles

Chest Muscles

Shoulder/Back Muscles

Arm Muscles

Leg/Gluteal Muscles