Major Muscles ofthe 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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Anterior Chest MusclesDeeper:pectoralis minorserratus anteriorsubclavius

Superficial:sternocleidomastoidpectoralis 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

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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

Posterior compartment of leg

Superficial: these plantarflex foot

Gastrocnemius

Soleus

Plantaris