| sarcomere | the smallest functional unit of muscle tissue |
| myofibril | a series of sarcomeres |
| muscle fiber | a single muscle tissue cell |
| fascicle | a bundle of muscle fibers |
| sliding filament theory | theory of how muscles generate force |
| myosin proteins | thick filaments |
| actin proteins | thin filaments |
| titin | maintains the position of the myosin in the center of the sarcomere & prevents the sarcomere from being pulled apart |
| active tension | tension due to muscle contraction |
| passive tension | tension due to muscle stretch |
| active insufficiency | muscles aren't able to generate as much force in a shortened or lengthened position |
| passive insufficiency | the motion of a joint may be limited by the length of a joint muscle because it's unable to stretch across both joints |
| strap, fusiform, rhomboidal, & triangular muscles | types of muscles with fibers parallel to the tendon |
| unipennate, bipennate, & mutipennate muscles | types of muscles with fibers oblique to the tendon (feather-like) |
| agonist | main muscle used to produce a movement |
| antagonists | muscles that oppose the movement of the agonist |
| synergists | muscles that assist the action of the agonist |
| fixators | muscles that stabilize the proximally to allow the agonist to work effectively |
| type I muscle fibers | these muscle fibers are slow twitch, built for endurance, and are red |
| type IIa muscle fibers | these muscle fibers are fast twitch, and can be trained to act like the other types |
| type IIb muscle fibers | these muscle fibers are fast twitch, built for power, and are white |
| genetics | fiber type is determined by this |
| muscle spindles | lie parallel to the muscle fibers, detect changes in muscle length and the speed of the length change, they're responsible for deep tendon reflexes |
| golgi tendon organs | located in the tendon, detect changes in tendon tension |
| paresis | muscle weakness or partial paralysis |
| paralysis | complete loss of muscle function |
| hemiplegia | partial or complete loss of muscle function on 1 side of the body |
| paraplegia | paralysis of all or some of the muscles in the trunk & lower extremities |
| tetraplegia/quadriplegia | paralysis of the trunk & lower extremities & some or all of the upper extremities |
| atrophy | loss of muscle mass due to lack of use or loss of innervation |