Transcript Microscopic Anatomy and Organization of Skeletal Muscle

EX 14

Skeletal Muscle
 Most numerous
 Voluntary
 Striated
 Gives you shape, allows for facial
expressions, movement, and manipulation
Cells of the Skeletal Muscle
Long cylindrical cells called fibers
 Multinucleated
 Composed of myofibrils

 Myofilaments
○ Made of actin and myosin alternating to
produce the banding pattern (I and A bands)
Sacrolema- “plasma membrane”
 Sacroplasm- “cytoplasm”

Skeletal Muscle Fibers
Figure 10–2a The Formation of a Multinucleate Skeletal Muscle
Fiber.
Copyright © 2009 Pearson Education,
Inc., publishing as Pearson Benjamin
Cummings
Skeletal Muscle Fibers
Figure 10–2 The Formation of a Multinucleate Skeletal Muscle
Fiber.
Copyright © 2009 Pearson Education,
Inc., publishing as Pearson Benjamin
Cummings

Sarcomeres
 Contractile units
 Made up of bundles of myofibrils
 Extend from middle of I band to middle of
next myofibril
Organization of Skeletal Muscle
Cells into Muscles
Endomysium – areolar connective tissue
sheath that covers muscle fibers
 Perimysium – encloses sheathed
muscle
 Fascicle-bundle of perimysium
 Epimysium-bundle of fasciles
 Epimysium blend into deep fascia
 Fascia blends into tendons

Skeletal Muscle Structures
Figure 10–1 The Organization of Skeletal Muscles.
Copyright © 2009 Pearson Education,
Inc., publishing as Pearson Benjamin
Cummings

Tendons provide
 durability and
 conserve space
 Provide route of entry for blood vessels
Neuromuscular Junction
Junction between a nerve fiber and a
muscle cell
 Axons stimulate many muscle fibers
 Both neuron and muscle fibers make up
the motor unit
 Neurotransmitters cause a change in Na
and K concentration which causes
muscle contraction
