Skeletal Muscle Actions
Movements:
Flexion of a joint
- Moves two bones closer together; muscles that do this are called flexors.
Extension of a joint
- Moves two bones further apart; muscles that do this are called extensors.
Abdudction
- Moves limb away from midline
Adduction
- Moves limb towards midline
Lateral rotation
- Turns limbs away from the midline of the body
Medial rotation
- Turns limbs towards the midline of the body
Skeletal muscle function
Agonist
- Produces the movement
Synergist
- Contributes to the movement
Antagonist
- Opposes the movement
Basis of Muscle Nomenclature:
- Orientational terminology (superior is on top and inferior is below; anterior is in front and posterior is behind)
- Depth (superficial means closer to the surface; deep means further from the surface)
- Anatomical Region (named for bony landmarks, etc.)
- Origin/Insertion (origin means that the bone that remains stable upon muscle contraction; insertion means that the bone moves upon muscle contraction).
- Fiber Direction (rectus = straight; brevis = short; longus = long; minor/minimus = small; quadratus = rectangular)
- Action (adductor, abductor, extensor, flexor)