Origin Classification and Naming The Muscular System Origin Classification and Naming

Anatomy of the Muscular System Origins, Insertions, and Actions Origin Muscle attachment that remains fixed Insertion Muscle attachment that moves Action What joint movement a muscle produces

Anatomy of the Muscular System A single skeletal muscle, such as the triceps muscle, is attached at its origin to a large area of bone; in this case, the humerus.

Anatomy of Skeletal MuscleAnatomy of the Muscular System At its other end, the insertion, it tapers into a glistening white tendon which, in this case, is attached to the ulna, one of the bones of the lower arm.

Anatomy of the Muscular System Extensor – Any muscle that opens a joint increasing the angle between components of a limb, such as straightening the knee or elbow and bending the wrist or spine. Flexor – A skeletal muscle whose contraction bends a joint, decreasing the angle between components of a limb, such as bending the knee or elbow. This action is known as flexion. Antagonistic Pair- Muscles that are functional opposites, if one produces flexion, then the other's primary action is extension

Anatomy of the Muscular System Primary Action Categories Prime mover (agonist)- muscle with the major responsibility for a certain movement Synergist - muscle that aids a prime mover in a movement and helps prevent rotation Antagonist - Opposed muscle to an action Fixator – stabilizes the origin of a prime mover

Naming of Skeletal Muscles Direction of muscle fibers Example: rectus (straight) Relative size of the muscle Example: maximus (largest) Location of the muscle Example: many muscles are named for bones (e.g., temporalis) Number of origins Example: triceps (three heads)….

Naming of Skeletal Muscles Location of the muscles origin and insertion Example: sterno (on the sternum) Shape of the muscle Example: deltoid (triangular) Action of the muscle Example: flexor and extensor (flexes or extends a bone)