7. Muscle Attachments & Actions

TYPES OF ATTACHMENTS

Tendons:       fibrous tissue bands attaching muscle to bone

Aponeuroses:   broad, flat sheets of fibrous tissue attaching muscle to bone or other muscles

ATTACHMENT SITES

Origin:    more stable site; does not move much when muscle contracts

Insertion: site undergoing the most movement when muscle contracts

Agonist (Prime Mover)

directly produces a desired movement

Antagonist

    — directly opposes the action of the agonist

Synergist

   — contracts at same time as agonist to assist its action

Fixator

  — stabilizes joints to allow other movements

• Action 

what the muscle does (e.g., superficial digital flexor)

• Shape  

geometric shape (e.g., deltoid = triangle)

• Location 

where it is found (e.g., biceps brachii = arm)

• Direction of fibers

orientation (e.g., rectus abdominis)

• Number of heads

origins (e.g., biceps = 2, triceps = 3, quadriceps = 4)

• Attachment sites

origin/insertion bones (e.g., sternocephalicus)