L5.2.1: Overview of the Skeletal System

• THE SKELETAL MUSCLE

  ● Skeletal muscle fibers - packaged into organs called skeletal muscles that attach to the skeleton

  ○ Large, cigar-shaped, and multinucleated

  ○ Most are attached by tendons to bones

  ○ Largest muscle fibers ranging up to 30 cm
• THE SKELETAL MUSCLE

  ● Skeletal muscle is also known as:

  ○ Striated muscle - because of its obvious stripes

  ○ Voluntary muscle - because it is the only muscle tissue subject to conscious control

  ● Are surrounded and bundled by connective tissues
• Can skeletal muscles move without our willed command?

  The answer is yes. Remember, skeletal muscles can be activated by reflexes.
• CONNECTIVE TISSUE WRAPPINGS OF SKELETAL MUSCLE

  Endomysium

  ● Encloses a single muscle fiber

  Perimysium

  ● Encloses each muscle fiber wrapped by endomysium to form bundles known as fascicles

  Epimysium

  ● Covers the entire skeletal muscle

  Fascia

  ● On the outside of the epimysium
• Each muscle fiber is enclosed by endomysium. Several sheathed muscle fibers are then wrapped by a coarser fibrous membrane called perimysium to form a bundle of fibers called a fascicle. Many fascicles are bound together by an even tougher overcoat of connective tissue called epimysium which covers the entire muscle.
• The epimysium blends into a connective tissue attachment

  ● TENDONS - cordlike structures

  ○ Mostly collagen fibers

  ○ Often cross a joint because of their toughness and small size
• The epimysium blends into a connective tissue attachment

  ● APONEUROSIS - sheetlike structures

  ○ Attach muscles indirectly to bones, cartilages, or connective tissue coverings

  ○ Covers a substantial portion of the muscle surface

  ○ The close association within the muscles suggest that any changes in the shape that occurs in the muscles during contraction also stretches the aponeurosis in the transverse direction perpendicular to the muscle lines of

  axion

  ○ May be subject to sprain along multiple axis