Chapter 15: The Muscular System

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15.1:

The Muscular System

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Anatomy and Physiology

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The Muscular System

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15.2: Fascicle Arrangement in Skeletal Muscles

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The muscular system includes the skeletal, smooth, and cardiac muscles that coordinate with each other to carry out functions like movement, digestion, and circulation. Of the three muscle types, the skeletal muscles are the most predominant. They form the musculoskeletal system, a complex network of muscles, bones, and associated connective tissues that produce voluntary movements, such as standing, walking, or running. When a skeletal muscle contracts, it generates force to move one of the articulating bones while keeping the other relatively stationary. Let's consider the example of the biceps brachii. Its two proximal ends called the origins, are attached to the scapula, a stationary bone. In contrast, the distal end called the insertion, is attached to a movable bone, which is the radius in this case. The muscle's origin and insertion are separated by a fleshy region called the belly or the gaster. During elbow flexion, the origin of the bicep pins the muscle to the stationary bone, supporting its insertion to pull the radius for movement.

15.1:

The Muscular System

The muscular system is essential to the body's overall structure and function, playing a crucial role in movement, stability, and internal processes. It consists of three distinct types of muscle tissue: the skeletal, the smooth, and the cardiac muscles.

Skeletal Muscles: These muscles are under our conscious control and enable movement. They are attached to bones by tendons, and their contraction and relaxation allow us to move. Additionally, they generate heat during physical activity, helping maintain body temperature.
Smooth Muscles: Unlike skeletal muscles, smooth muscles operate without conscious control. They are located in the walls of hollow organs such as the stomach, intestines, blood vessels, and airways. The contraction of these muscles aids in processes like digestion, by propelling food through the gastrointestinal tract.
Cardiac Muscle: Found exclusively in the heart, this type of muscle contracts rhythmically and continuously, pumping blood throughout the body without fatigue.

The Musculoskeletal System

As the name suggests, the musculoskeletal system is a complex network of muscles and bones. It is critical in facilitating movement and providing structural support to the body.

The skeletal component of the system is primarily made up of bones and associated elements like cartilage, tendons, and ligaments. Bones provide our bodies with basic structure and shape and protect vital organs. For instance, the skull shields the brain, while the ribcage safeguards the heart and lungs. The cartilage, tendons, and ligaments further aid mobility and stability by connecting bones and cushioning joints.

The muscular component, on the other hand, consists of various types of muscle tissues. These include skeletal muscles, which are directly attached to bones and are responsible for voluntary movements such as walking or lifting; smooth muscles, which control involuntary actions like digestion and blood flow; and cardiac muscle, found only in the heart, which pumps blood throughout the body. Together, the muscular and skeletal components work harmoniously to allow locomotor functions.