Lecture on Muscle Types

Introduction to Muscles

• Muscles are associated with movement.
• Think broadly about different movements in the body.

Types of Muscles

1. Skeletal Muscle

   • Example: Leg muscles moving while playing soccer.
   • Attachment: Typically attached to bones via tendons.
     • Not all skeletal muscles attach to bones via tendons.
     • Example: External oblique muscle attaches via aponeurosis, a flat tendon-like structure.
   • Identification: Visible muscles on the body.

2. Cardiac Muscle

   • Found exclusively in the heart.
   • Specialized cells unique to the heart.

3. Smooth Muscle

   • Found in hollow organs (e.g., stomach, intestines) and blood vessels (e.g., aorta).
   • Located in the walls of these structures to aid movement (e.g., food through stomach).

Control of Muscle Movement

• Skeletal Muscle: Voluntary control (e.g., choosing to move).
• Cardiac Muscle: Involuntary control (automatic, heart beats without conscious effort).
• Smooth Muscle: Involuntary control (automatic, slow movements in organs and vessels).

Speed of Muscle Movement

• Smooth Muscle: Slowest.
• Cardiac Muscle: Intermediate speed.
• Skeletal Muscle: Fastest, allowing quick, voluntary movements.

Structure and Appearance of Muscle Cells

1. Smooth Muscle Cells

   • Shape: Eye or almond-shaped, also known as spindle-shaped.
   • Nuclei: One, centrally located.

2. Cardiac Muscle Cells

   • Shape: Branched.
   • Nuclei: One or two, centrally located.

3. Skeletal Muscle Cells

   • Shape: Straight, not branched.
   • Nuclei: Many, located on the periphery.
   • Striations: Skeletal and cardiac muscles have striations (stripes visible under a microscope), whereas smooth muscles do not.

Conclusion

• Muscles have varying similarities and differences:
  • Skeletal & Cardiac: Both are striated.
  • Cardiac & Smooth: Both are involuntary.
  • Each muscle type has unique characteristics and functional roles in the body.