Muscle Structure and Function

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Muscle Structure and Function

• Chapter 9

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Muscle Types

• Skeletal Muscle
• Primarily links to bone through tendon
• Enabling through levers of the bones of the human
  skeleton, allows for posturing, upright stance
  under atmospheric pressure, and voluntary
  movements.
• Heat production- 85 of body heat is generated by
  muscles providing the proper environment for
  enzymes and therefore metabolism

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Muscle Types

• Smooth Muscle
• Found in parts of the body where it conveys
  action without conscious intent.
• Majority of this type of muscle tissue is found
  in the Digestive and Urinary systems where it
  acts by propelling forward food and feces
• Other places smooth muscle can be found are
  within the uterus, where it helps facilitate
  birth, and the eye, where the pupillary sphincter
  controls pupil size.
• Cardiac Muscle
• Specific to the heart.
• Involuntary in its movement, and is additionally
  self-excitatory, contracting without outside
  stimuli.

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Characteristics of all Muscle

• Excitability
• Respond to stimuli
• Contractility
• Actively shorten to exert a pull
• Extensibility
• Continue to contract over range of resting
  lengths
• Ex smooth muscle can be stretched to several
  times its original length and still contract on
  stimulation
• Elasticity
• Return to original length after contraction

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Location
Function
Frontalis Frontal bone
Femoris Femur
Gluteus Posterior of hip/thigh
Oculi Eye
Oris Mouth
Radialis Radius
Ulnaris Ulna
Brachialis Arm
Abductor Moves part away from body
Adductor Moves part toward body
Depressor Lowers a part
Extensor Extends a part
Flexor Flexes a part
Levator Elevates a part
Rotator Rotates a part

Shape
Fiber Direction
Deltoid Shaped like delta ?
Orbicularis Circular
Platy Flattened platelike
Quadratus Square
Rhomboideus Diamond-shaped
Trapezius Trapezoidal
Oblique Diagonal to midline
Rectus Parallel to midline
Sphincter Circling an opening
Transversus Right angle to midline
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Number of divisions
Bicep Two heads
Tricep Three heads
Quadricep Four heads
Size
Brevis Short
Longus Long
Magnus Large
Maximus Largest
Medius Moderately sized
Minimus Smaller
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Structures of a skeletal muscle fiber
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Sarcomere The repeating patterns formed in
muscle striations
Sacromere
Z Line
H Zone
M Line
I Band
A Band
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Muscle Fiber Arrangement
Parallel
Pennate
Bipennate
Sphincter
Convergent