Major Muscles of the Body

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

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

 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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6 Anterior Chest Muscles Deeper: pectoralis minor serratus anterior subclavius Superficial: sternocleidomastoid pectoralis major

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 **

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

Posterior compartment of leg  Superficial: these plantarflex foot  Gastrocnemius  Soleus  Plantaris