skeletal muscle gross anatomy

Learning Objectives

• Review gross anatomy of skeletal muscle

• Understand key vocabulary: fascia, epimysium, perimysium, endomysium, tendon, and aponeurosis

• Reference: Saladin, pages 308-310, Chapter 10 (focused on whole muscles)

Overview of Skeletal Muscle Anatomy

• Imagined transverse section through a skeletal muscle attached to a bone

• Tendon:

  • Cord of connective tissue attaching muscle to bone

  • Formed from connective tissue wrappings present within the muscle

Organization of Muscle

• Muscle organized into fascicles:

  • Bundles of muscle cells

  • Example: Pulled pork shreds along fascicles, indicative of muscle structure

• Fascicle:

  • Contains individual muscle cells or fibers

Muscle Fibers and Myofibrils

• Each muscle fiber (muscle cell) is composed of:

  • Myofibrils:

    • Contractile elements within the muscle cell

Connective Tissue Wrappings

• Epimysium:

  • Connective tissue covering the entire muscle organ

  • Described as regular or coarse connective tissue

• Perimysium:

  • Connective tissue surrounding each fascicle

• Endomysium:

  • Connective tissue covering each individual muscle cell

  • Composed of areolar (loose) connective tissue

  • Sits superficial to muscle cells, not the same as plasma membrane

Function of Connective Tissue in Muscles

• All connective tissue coverings (epimysium, perimysium, endomysium) converge to form:

  • Tendon: attaches muscle to bone

  • Fascia: connective tissue wrappings that separate organs

    • Keeps organs organized and aids efficiency of muscular system

Conclusion

• Transitioning to microanatomy of individual skeletal muscle cells in next section