The Muscular System

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The Muscular System

• Muscles are responsible for all types of body
  movement
• Muscle Functions
• Movement
• Maintain posture
• Stabilize joints
• Heat
• Three basic muscle types found in the body
• Smooth muscle (Visceral)
• Cardiac muscle
• Skeletal muscle

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Characteristics of Muscles

• Muscle cells are elongated
• Contraction of muscles is due to the movement of
  microfilaments many cells contracting at the
  same time
• All muscles share some terminology
• Prefix myo refers to muscle

3
Smooth Muscle Characteristics How blood and
food move

• No striations
• Spindle-shaped cells
• Single nucleus
• Involuntary no conscious control
• Found mainly in the walls of hollow organs (blood
  vessels, intestines)

Figure 6.2a
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Cardiac Muscle CharacteristicsWhat makes your
heart beat?

• Striations
• Usually only one nucleus
• Cells joined to each other at an intercalated
  disc
• Involuntary
• Found only in the heart

Figure 6.2b
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Skeletal Muscle CharacteristicsMoving your
bones!

• Most are attached by tendons to bones
• Remember tendons tug
• Cells have more than one nucleus
• Striated have visible banding
• Voluntary subject to conscious control
• Cells are surrounded and bundled by connective
  tissue

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Connective Tissue Wrappings of Skeletal Muscle

• Endomysium around single muscle fiber
• Perimysium around a bundle of fibers
• Epimysium covers the entire skeletal muscle

Figure 6.1
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Skeletal Muscle Attachments

• Epimysium blends into a connective tissue
  attachment the tendon a cord-like structure
• Sites of muscle attachment
• Bones
• Cartilages
• Connective tissue coverings
• Animation http//www.wisc-online.com/objects/inde
  x_tj.asp?objIDAP13904

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Contraction of a Skeletal Muscle

• Video
• Muscle fiber contraction is all or none
• Within a skeletal muscle, not all fibers may be
  stimulated during the same interval
• Different combinations of muscle fiber
  contractions may give differing responses
• Graded responses different degrees of skeletal
  muscle shortening
• Must have ATP in order to contract

10
Muscle Response to Strong Stimuli

• Muscle force depends upon the number of fibers
  stimulated
• More fibers contracting results in greater muscle
  tension
• Muscles can continue to contract unless they run
  out of energy (ATP)

11
Muscle Fatigue and Oxygen Debt

• When a muscle is fatigued, it is unable to
  contract
• The common reason for muscle fatigue is oxygen
  debt
• Oxygen must be returned to tissue to remove
  oxygen debt
• Oxygen is required to get rid of accumulated
  lactic acid
• Increasing acidity (from lactic acid) and lack of
  ATP causes the muscle to contract less

12
Muscles and Body Movements

• Movement is attained due to a muscle moving an
  attached bone
• Muscles are attached to at least two points
• Origin attachment to an immoveable bone
• Insertion attachment to a movable bone

Figure 6.12
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Ordinary Body Movements

• Flexion decreases the angle between two
  adjacent body segments
• Extension increases the angle between two
  adjacent body segments
• Rotation the bone distal to the joint is moved
  either toward (medial) or away from (lateral) the
  midline
• Abduction movement of a body part away from the
  midline
• Adduction movement of a body part back toward
  the midline
• Circumduction a combination of flexion,
  abduction, extension, and adduction

http//www.med.umich.edu/lrc/hypermuscle/hyper.htm
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Body Movements
Figure 6.13ac
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Body Movements
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Body Movements
Figure 6.13d
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Naming of Skeletal Muscles

• Direction of muscle fibers
• Example rectus (straight)
• Relative size of the muscle
• Example maximus (largest)
• Location of the muscle
• Example many muscles are named for bones (e.g.,
  temporalis)
• Number of origins
• Example triceps (three heads)

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Naming of Skeletal Muscles

• Location of the muscles origin and insertion
• Example sterno (on the sternum)
• Shape of the muscle
• Example deltoid (triangular)
• Action of the muscle
• Example flexor and extensor (flexes or extends a
  bone)

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Head and Neck Muscles
Figure 6.15
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Trunk Muscles
Figure 6.16
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Deep Trunk and Arm Muscles
Figure 6.17
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Muscles of the Pelvis, Hip, and Thigh
Figure 6.19c
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Muscles of the Lower Leg
Figure 6.20
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Superficial Muscles Anterior
Figure 6.21
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Superficial Muscles Posterior
Figure 6.22
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Movement Worksheet p.1

• Standing on your toes as in ballet is (1) of
  the foot. Walking on your heels is (2) .
• Winding up for a pitch (as in baseball) can
  properly be called (3) . To keep your seat when
  riding a horse, the tendency is to (4) your
  thighs.
• In running, the action at the hip joint is
  (5) in reference to the leg moving forward and
  (6) in reference to the leg in the posterior
  position. When kicking a football, the action at
  the knee is (7) . In climbing stairs, the hip
  and knee of the forward leg are both (8) .

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• You have just touched your chin to your chest
  this is (9) of the neck.
• Using a screwdriver with a straight arm requires
  (10) of the arm. Consider all the movements of
  which the arm is capable. One often used for
  strengthening the upper arm and shoulder muscles
  is (11) .
• Moving the head to signify no is (12) .
  Action that moves the distal end of the radius
  across the ulna is (13) . Raising the arms
  laterally away from the body is called (14) of
  the arms.When you are cupping your hands in order
  to hold a bowl of soup, the position is called
  __(15)__.