MUSCLES

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MUSCLES

• CHAPTER 9

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MUSCLE TYPES

• SKELETAL-striations,voluntary, multinucleated
• SMOOTH-involuntary, non-striated, visceral
• CARDIAC-involuntary, striated, branched

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MUSCLE FUNCTIONS

• Producing Movement-pull on bones which act as
  levers
• Maintaining Posture
• Stabilizing Joints
• Generating Heat

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FUNCTIONAL CHARACTERISTICS

• Excitability-the ability to receive and react to
  a stimulus
• Contractibility-the ability to shorten forcibly
  when stimulated
• Extensibility-the ability to stretch or extend
• Elasticity-the ability to resume normal length
  after stretching

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GROSS ANATOMY OF SKELETAL MUSCLE

• Endomysium-areolar connective tissue binding each
  muscle fiber
• Fascicles-bundles of muscle fibers
• Perimysium-collagenic sheath binding fascicles
• Epimysium-dense fibrous connective tissue that
  surrounds the entire muscle
• Deep Fascia-coarse sheet of fibrous connective
  tissue that binds muscles into functional groups
  as well as other organs

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Motorunit 1
Motorunit 2
Spinal cord
Nerve
Motor neuroncell body
Motor neuronaxon
Neuromuscularjunctions
Nuclei
Muscle fibers(cells)
Muscle
Tendon
Bone
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SKELETAL MUSCLE..MORE GROSS ANATOMY

• Nerve and Blood Supply-Each muscle is served by
  an artery and one or more veins as well as a
  nerve ending that controls activity
• Attachments-insertion origin
• direct-epimysium fused to periosteum or
  perichondrium of cartilage
• indirect-ct wrappings extend as a rope to
  attach to connective tissue surrounding bone or
  cartilage(aponeurosis) or to another muscle

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MICROSCOPIC ANATOMY OF SKELETAL MUSCLE

• Sarcolemma--plasma membrane of a muscle cell
• Sarcoplasm-similar to cytoplasm of the other
  cellsbut contains large amounts of glycogen and
  myoglobin(similar to hemoglobin-oxygen storage)
• Myofibrils-super organelles that run parallel and
  extend the entire length of the cell-80 of cell
  volume-other organelles are squeezed in around
  them.contractile units
• Sarcomeres-chains of these make up myofibrils
• Striations-repeating light and dark bandslight
  bands-I dark bands-A they give the cell its
  striped appearance.

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Motor neuronaxon
Action potential
Mitochondrion
Tubule
Endoplasmicreticulum (ER)
Myofibril
Ca2 releasedfrom ER
Plasma membrane
Sarcomere
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MICROSCOPIC ANATOMY,contd

• H-Zone, Z-Lines-midline interruptions in the band
  or striations
• M-Line-an interruption in the H zone
• T-Tubules-found at the A-1 junction,an
  invagination of the sarcolemma into the cell.They
  serve as connectors for all the myofibrils as
  well as a transport system.
• Myofilaments-at the molecular level, thick and
  thin filaments-what the myofibrils are made of
  and they are found in the sarcomeres
• Thick-Myosin-have heads (cross bridges) and tails
• Thin-Actin-coin-shaped molecules reinforced by
  tropomyosin strands

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Muscle Vocab List

• Gluteus Maximus
• Gastrocnemius
• Latissimus Dorsi
• Deltoid
• Semitendinosus
• Trapezius
• Rectus Femoris
• Triceps Biceps Brachii
• Gracilis
• Flexor Carpi Ulnaris
• Platysma
• Sternohyoid
• Transversus Abdominus

• Occipitalis
• Sternocleidomastoid
• Bracialis
• Obicularis Oris
• Obicularis Oculi
• Frontalis
• Pectoralis Major
• External Oblique
• Rectus Femoris
• Sartorius
• Masseter
• Temporalis
• Extensor Carpi Ulnaris