major muscles of the body. interactions of skeletal muscles muscles can only pull, they can’t...
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Major Muscles ofthe Body
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Interactions of Skeletal Muscles
Muscles can only pull, they can’t push
Actions must be “undone” by a different muscle
Muscles that produce opposite movements usually lie on opposite sides of a given joint
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Interactions, continued
Agonist: prime mover, major responsibility for producing a specific movement
Antagonist: oppose or reverse a particular movement Usually contract a little to prevent overshooting the
mark or slow the agonist’s action near the end Are being stretched or can remain relaxed when
agonist works
Antagonists for one movement can be agonists for another
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Synergists help prime movers
Add a little extra force to the same movement
Or reduce undesirable extra movements (e.g. making a fist without flexing at wrist)
Fixators: hold a bone firmly so agonist has a stable base on which to move a body part (e.g. fixing scapula when arm moves)
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Anterior Chest MusclesDeeper:pectoralis minorserratus anteriorsubclavius
Superficial:sternocleidomastoidpectoralis major
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Muscles of the abdominal wall
Note inguinal ligament- from anterior superior iliac spine to pubic symphysis: lower border of external oblique rolls up on itself to form it
From more superficial to deep: External oblique Internal oblique Transversus abdominis
Nearer midline: Rectus abdominis
The rectus abdominis is the medial pair of muscles; it is ensheathed by the aponeurosis of the lateral muscles, which don’t come to the midline
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Muscles of the abdominal wall from the side
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Abductors of thigh
Buttocks muscles that lie lateral to hip joint
Gluteus medius
Gluteus minimus (under medius)
Tensor fascia lata
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Posterior compartment of leg
Superficial: these plantarflex foot
Gastrocnemius
Soleus
Plantaris