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  • acceleration The rate of change in velocity.

  • accessory motion The actual change in relationship between the articular surface of one bone relative to another, characterized as roll, spin and glide.

  • action potential Electrical signal transmitted from the brain and spinal cord through axons to the muscle fibers in a particular motor unit providing the stimulus to contract.

  • active insufficiency Point reached when a muscle becomes shortened to the point that it cannot generate or maintain active tension.

  • active tension Tension in muscles that is generated via an active contraction of the respective muscle fibers in that muscle.

  • afferent nerves Nerves that bring impulses from receptors in the skin, joints, muscles and other peripheral aspects of the body to the central nervous system.

  • aggregate muscle action Muscles working together in groups rather than independently to achieve given joint motions.

  • agonist A muscle or muscle group that is described as being primarily responsible for a specific joint movement when contracting.

  • all or none principle States that regardless of the number involved, the individual muscle fibers within a given motor unit will fire and contract either maximally or not at all.

  • anatomical position The position of reference in which the subject is in the standing position, with feet together and palms of hands facing forward.

  • angular displacement The change in location of a rotating body.

  • angular motion Motion involving rotation around an axis.

  • arthrokinematics Motion between the actual articular surfaces of the bones at a joint.

  • arthrosis Joint or articulation between two or more bones.

  • Articular Pertaining to the hyaline cartilage covering at the end of bones where diarthrodial joints move upon one another.

  • axis of rotation The point in a joint about which a bone moves or turns to accomplish joint motion.

  • axon An elongated projection that transmits impulses away from the neuron cell body.

  • balance The ability to control equilibrium, either static or dynamic.

  • basal ganglia A group of neuron clusters (nuclei) located deep beneath the cerebral cortex in the brain.

  • biomechanics The study of mechanics as it relates to the functional and anatomical analysis of biological systems, especially humans.

  • brain stem The most basic region of the brain which is a tube-shaped mass of nervous tissue located at the base of the brain to form the connection between the brain and the spinal cord.

  • cancellous bone Spongy, porous bone that lies under cortical bone.

  • cardinal plane Specific planes that divide the body exactly into two halves.

  • carpal tunnel syndrome A condition characterized by swelling and inflammation with resultant increased pressure in the carpal tunnel, which interferes with normal function of the median nerve, leading to reduced motor and sensory function of its distribution; particularly common with repetitive use of the hand and wrist in manual labor and clerical work such as typing and keyboarding.

  • carpal tunnel A three-sided arch, concave on the palmar side and formed by the trapezium, trapezoid, capitate and hamate. It is spanned by the transverse carpal and ...

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