How muscles move

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How muscles move
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It all starts in the nervous system

• Neuro dealing with the CNS
• Transmitter sends messages
• A neurotransmitter sends messages from the brain
  or CNS

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Acetycholine (ACh)

• ACh is sent from the nervous system down to the
  muscles that need to be used for a particular
  job.
• ACh leaves the neuron and crosses the synaptic
  cleft
• There are receptors on the sarcolemma just for
  the ACh.

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Movement, part II

• The ACh causes a series of electrical conditions
  to occur causing the muscle to shorten
• The actin and myosin walk across one another
  much like tiny oars in the water, attaching and
  releasing to cause the shortening
• They release and it all begins again.

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Skeletal muscles

• Almost always function in groups
• Prime mover the muscle responsible for
  contracting a muscle
• Synergists muscles that contract and aid a
  prime mover
• Antagonists resist a prime movers action and
  cause movement in the opposite direction

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Tone, tonus, tonic

• A sustained partial contraction
• Characterized by a waking individual as opposed
  to an unconscious one

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Isotonic

• Involves the actual shortening of muscles. Most
  exercises, games, etc., usually involve movement,
  therefore are isotonic

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Isometric

• The length of the muscle remains the same but
  tension increases.
• A gymnast on the rings, wall sits, trying single
  handed to pick up something very heavy
• Muscle filaments are trying to slide but the
  muscle is pitted against some more or less
  immoveable object.

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Twitch

• A quick, jerky contraction in response to a
  stimulus

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Tetany

• Tetanus, a sustained twitch
• Muscle is stimulated so fast no evidence of
  relaxation is seen
• Prolonged and continuous

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Good tetany

• Incomplete
• Normal body movements, starting and stopping
• Smooth because of constant barrage of nerve
  messages

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Bad tetany

• These are complete contractions
• Cramps
• Too much water loss
• Loss of electrolytes
• Blood supply cut off due to contractions
• Convulsion - Could lead to death as a result
  seizures (like an all over cramp)
• Fibrillation - Convulsions in the muscles of the
  heart (heart attack)

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All or nothing

• You cannot make all of your muscles fibers all
  contract at one time
• When a fiber does contract, it contracts 100,
  not part of the way

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Hernia

• The protrusion of a body part or organ through a
  weakness in the muscular abdominal wall
• Hietal when you eat too much and the stomach
  pushes up in a weak spot at the diaphragm
• Inguinal the intestines protrude into the
  scrotum or a separation in the abdominal muscles
  in the groin area. Common in infant boys and can
  also be caused by heavy lifting

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Charley Horse

• An injury to muscle resulting in tearing, leading
  to intense, prolonged pain
• Bleeding into adjacent tissues usually follows
  forming (bruises)
• This is a common injury in contact sports and
  frequently occurs at the quads

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Strain

• Overuse injuries that result when the muscle is
  stretched usually because of not warming up

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Cramp

• A painful involuntary contraction of a muscle.
• Can be caused by
• Overexertion and dehydration electrolyte
  imbalance
• Inactivity (reason not known)
• Blood being cut off from muscle

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Myalgia

• A condition of muscle pain that accompanies many
  infectious diseases such as influenza, measles
  and rheumatic fever

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Shin splints

• A common term for the irritation of the anterior
  tibialis of the leg. This occurs following
  excessive exercise and leads to inflammation of
  the muscle.

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RICE

• Rest
• Ice
• Compression
• Elevation

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Muscle fatigue

• When the muscle is unable to contract even though
  it is still being stimulated.
• If no rest is given, the muscle begins to tire
  and contracts more and more weakly until it can
  no longer contract.

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Oxygen debt

• A person is unable to take in oxygen fast enough
  to keep the muscles supplied with all the oxygen
  they need when they are working vigorously.