Muscles Important A muscle that is primarily responsible

Muscles

Important! A muscle that is primarily responsible for producing a movement is called a prime mover or an agonist. n The muscle that is designed to produce the opposite or reverse of that movement is called an antagonist. n

Synergists and Fixators Synergists- Assist prime movers. They add extra force and reduce undesirable and unnecessary movement. An example of a synergist would be muscles that stabilize the wrist when you make a fist. n Fixators- muscles that immobilize a bone. An example of fixator muscles are the muscles that hold the scapula to the axial skeleton. n

Example of synergistic muscles n n The muscles in the fingers are stabilized by other muscles in the fingers and wrists. Hold your hand straight out and with your fingers spread, try and flex just your middle finger straight down.

Naming Skeletal Muscles n When we name a skeletal muscle, we use the following criteria to name that muscle: Location n Shape of muscle n Relative size of the muscle n Direction of muscle fibers n Number of origins n Location of attachments n Action n

Muscle Mechanics: Fascicle Arrangement n Muscles can be described based on the arrangement of the fascicles (muscle fiber bundles) in the muscle.

Arrangement types n n Circular: fascicles arranged in rings. Example: sphincter muscles. Convergent: Muscle converge toward a single insertion. Example: pectoralis muscles. Parallel: long axis of the fascicles run parallel to the long axis of the muscle. Example: Thigh muscles. Pennate: muscle attach obliquely (in a slanting or inclined direction) to a central muscle or tendon. Example: deltoid muscle.

Lever systems: relationships between the skeletal and muscular system. n Mechanical Advantage: Occurs when the effort is further from the load being moved than the fulcrum (pivot point). n Mechanical disadvantage: occurs when effort is closer to the load being moved than the fulcrum.

Skeletal Muscles in the human body n There are several major muscles that you will need to learn for the muscular system. The proceeding lists are the muscles you need to locate.