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Muscles are the engines of movement. They contract and relax to produce motion, maintain
posture, and support vital functions like breathing and circulation. Broadly, muscles are
classified into three types:
(a) Skeletal Muscles
• Structure: Long, cylindrical, striated (striped) fibers attached to bones.
• Control: Voluntary (we can consciously control them).
• Function:
o Responsible for body movements like walking, running, lifting.
o Maintain posture and balance.
o Generate heat during activity.
• Examples: Biceps, triceps, quadriceps, hamstrings.
Narrative Example: When you decide to pick up a book, your skeletal muscles in the arm
contract, pulling the bones and allowing your hand to grasp the book.
(b) Smooth Muscles
• Structure: Spindle-shaped, non-striated fibers.
• Control: Involuntary (we cannot consciously control them).
• Function:
o Found in internal organs like stomach, intestines, bladder, and blood vessels.
o Help in digestion, circulation, and other automatic processes.
• Examples: Muscles of the digestive tract, urinary bladder, and arteries.
Narrative Example: When you eat food, smooth muscles in your stomach and intestines
automatically contract to push the food along for digestion—without you even thinking
about it.
(c) Cardiac Muscles
• Structure: Striated like skeletal muscles but branched and interconnected.
• Control: Involuntary (work automatically).
• Function:
o Found only in the heart.
o Responsible for pumping blood throughout the body.
o Work tirelessly without fatigue.
• Example: Heart muscle (myocardium).
Narrative Example: Your heart beats continuously, day and night, because cardiac muscles
contract rhythmically without rest, keeping you alive.
3. Comparison of Muscle Types