Anatomy and Physiology: Muscular System

Muscles – “machines” of the body

Muscle make up nearly half the body’s mass. The essential function of muscle is contraction or shortening. This unique characteristic sets muscle apart from other tissues in the body. All body movements depend on the muscles. Thus, muscles can be viewed as the “machines” of the body.

Functions of the muscles

  1. Produces movement. All movements of the human body are result of muscular contraction.
  2. Maintaining posture. The skeletal muscles in the body maintain posture.
  3. Stabilizing joints. Presence of muscle tendons reinforces and stabilizes joints that have poorly fitting articulating surfaces.
  4. Generating heat. Heat is a by-product of muscle activity. This heat is essential in maintaining normal body temperature.

Types of muscles

Skeletal muscles

Also called: voluntary muscle, striated muscle

This type of muscle attaches to the body’s skeleton. Because of their attachment to the bony part of the body smoother contours of the body are formed. Skeletal muscle fibers are cigar-shaped, multi-nucleate cells and are the largest of the muscle fiber types. This is the only muscle type that can be controlled consciously, thus it is a voluntary muscle. Since its fibers appear to be striped it is known as striated muscle.

Summary of the characteristic of Skeletal Muscles:

  1. Subject to conscious control.
  2. Multinucleated.
  3. Cigar-shaped.
  4. Attaches to the body’s skeleton
  5. Soft and fragile.
  6. Its tissue can rapidly contract and with great force.
  7. Tires easily.
  8. Contraction is abrupt and rapid.

What is the reason why skeletal muscles are not ripped apart as they exert effort?

Skeletal muscles do not rip apart after exerting effort because thousands of skeletal muscle fibers are bundled together by connective tissues which are responsible for providing strength and support to the muscle as a whole.

Structure or Parts of Skeletal Muscle

  1. Endomysium – a delicate connective tissue sheath that encloses each skeletal muscle fiber.
  2. Perimysium – a coarse fibrous membrane that wraps the sheathed muscle fibers.
  3. Fascicle – bundle of fibers formed from group of sheathed muscle fibers wrapped by perimysium.
  4. Epimysium – a tough overcoat of connective tissue that bounds together fascicles. This is the connective tissue that covers the entire muscle.
  5. Tendons – these are cordlike structures that are formed from epimysia. These are composed of mostly collagenic fibers that can cross rough bony projections. Aside from anchoring muscles, tendons are very important in providing durability.
  6. Aponeuroses – these are sheet like structures that attaches muscles indirectly to bones, cartilages or connective tissue coverings of each other.

Daisy Jane Antipuesto RN MN

Currently a Nursing Local Board Examination Reviewer. Subjects handled are Pediatric, Obstetric and Psychiatric Nursing. Previous work experiences include: Clinical instructor/lecturer, clinical coordinator (Level II), caregiver instructor/lecturer, NC2 examination reviewer and staff/clinic nurse. Areas of specialization: Emergency room, Orthopedic Ward and Delivery Room. Also an IELTS passer.

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