Which type of muscle is the most common in the human body? A. Skeletal muscle B. Cardiac muscle C. Smooth muscle D. Autonomic muscle
The correct answer and explanation is:
The correct answer is A. Skeletal muscle.
Explanation:
The human body contains three primary types of muscle tissue: skeletal muscle, cardiac muscle, and smooth muscle. Each type has distinct characteristics and functions.
- Skeletal Muscle
- These muscles are attached to bones by tendons and are responsible for voluntary movements like walking, lifting, and facial expressions.
- They are striated (have a striped appearance under a microscope) due to the organized arrangement of muscle fibers.
- Skeletal muscles are the most abundant muscle type in the human body, making up about 40-50% of total body weight.
- They are controlled consciously by the somatic nervous system, meaning you decide when to move them.
- Cardiac Muscle
- Found only in the heart, cardiac muscle is also striated but involuntary—you do not consciously control it.
- It contracts rhythmically and continuously to pump blood throughout the body.
- Though vital, cardiac muscle is much less abundant than skeletal muscle because it is limited to the heart.
- Smooth Muscle
- Found in the walls of internal organs such as the intestines, blood vessels, bladder, and uterus.
- Unlike skeletal and cardiac muscles, smooth muscle is non-striated and involuntary.
- It helps move substances through internal passageways (e.g., food in the digestive tract, blood in arteries).
- Although smooth muscle is widespread, its overall mass in the body is less than skeletal muscle.
- Autonomic Muscle
- This is not a recognized muscle type. The term “autonomic” relates to the autonomic nervous system, which controls involuntary functions, including those of smooth and cardiac muscles, but it is not a distinct muscle type.
Summary:
- Skeletal muscle is the most common muscle type in the human body by mass and volume.
- It is primarily responsible for voluntary movements and posture.
- Cardiac and smooth muscles are crucial but less abundant overall.
This makes A. Skeletal muscle the correct answer.