Muscles Anatomy and Physiology

Muscles

• Muscles are soft tissues found in both animals and humans.
• The cells of the muscles comprise protein filaments of actin and myosin that slide past one another, producing contraction and changing both the length and the shape of the cell.

Origin of the Term "Muscle"

• The term "muscle" is derived from the Latin word "musculus," which refers to a little mouse, due to the shape of certain muscles or the contraction of muscles that look like a moving mouse.

Functions of Muscles in Humans

• Muscles function by producing force and motion and are primarily responsible for:
  • Locomotion
  • Maintaining and changing body posture
  • Circulation of blood cells throughout the body
  • Movement of internal organs, such as the contraction of the heart and the movement of food through the digestive system via peristalsis

Human Muscular System

• The human muscular system includes more than 600 muscles, making up about 40 to 50 percent of the total body weight.
• Muscles are attached to bones, blood vessels, and other internal organs of the body and are mainly composed of skeletal muscles, tissue, tendons, and nerves.
• The muscles of the human muscular system are composed of a kind of elastic tissue.

Types of Muscles

• There are three types of muscles, mainly classified based on their movements and structures:
  • Skeletal or striated muscles
  • Cardiac muscles
  • Smooth muscles

Classification of Muscles

• Muscles are further classified into:
  • Voluntary muscles
  • Involuntary muscles

Skeletal Muscles

• Skeletal muscle is a muscle tissue that is attached to the bones and is involved in the functioning of different parts of the body.
• Skeletal muscles are also called voluntary muscles as they come under the control of the central nervous system in the body.
• Skeletal muscles are cylindrically shaped with branched cells attached to the bones by an elastic tissue or collagen fibers called tendons.
• The end of each skeletal muscle has a tendon, which connects the muscle to bone and connects directly to the collagenous, the outer covering of skeletal muscle.
• There is a group of muscle fibers, present below the epimysium, which are collectively called the fascicles.
• These muscle fibers are surrounded by another protective shield formed from collagen.
• The perimysium, a sheath of connective tissue surrounding the muscle fibers, allows nerve and blood vessels to make their way through the muscle.

Functions of Skeletal Muscle

• It maintains body posture.
• It regulates body temperature.
• It connects to and controls the motions of the skeleton.
• It is responsible for performing muscular involuntary movements.
• It is responsible for body movements such as breathing, extending the arm, typing, writing, etc.
• It is responsible for the erect posture of the body.
• The sartorius muscles in the thighs are responsible for body movement.
• Skeletal muscles protect the internal organs and tissues from any injury and also provide support to these delicate organs and tissues.
• They also support the entry and exit points of the body.