Skip to Main Content




acromioclavicular joint

irregular joint between the acromion process of the scapula and the distal clavicle

active insufficiency

condition occurring when a two-joint muscle cannot shorten enough to cause full range of motion at both joints it crosses at the same time

active stretching

stretching of muscles, tendons, and ligaments produced by active development of tension in the antagonist muscles

acute loading

application of a single force of sufficient magnitude to cause injury to a biological tissue


role played by a muscle acting to cause a movement


cessation of menses

anatomical reference position

erect standing position with all body parts, including the palms of the hands, facing forward; considered the starting position for body segment movements

angle of attack

angle between the longitudinal axis of a body and the direction of the fluid flow

angle of projection

the direction at which a body is projected with respect to the horizontal


involving rotation around a central line or point

angular acceleration

rate of change in angular velocity

angular displacement

change in the angular position or orientation of a line segment

angular impulse

change in angular momentum equal to the product of torque and time interval over which the torque acts

angular momentum

quantity of angular motion possessed by a body; measured as the product of moment of inertia and angular velocity

angular velocity

rate of change in the angular position or orientation of a line segment


exhibiting different mechanical properties in response to loads from different directions

annulus fibrosus

thick, fibrocartilaginous ring that forms the exterior of the intervertebral disc


role played by a muscle acting to slow or stop a movement


related to the dimensions and weights of body segments


the highest point in the trajectory of a projectile

appendicular skeleton

bones composing the body appendages

Archimedes' principle

physical law stating that the buoyant force acting on a body is equal to the weight of the fluid displaced by the body

articular capsule

double-layered membrane that surrounds every synovial joint

articular cartilage

protective layer of dense white connective tissue covering the articulating bone surfaces at diarthrodial joints

articular fibrocartilage

soft-tissue discs or menisci that intervene between articulating bones


occurring over a designated time interval


directed along the longitudinal axis of a body

axial skeleton

the skull, vertebrae, sternum, and ribs

axis of rotation

imaginary line perpendicular to the plane of rotation and passing through the center of rotation


a person's ability to control equilibrium

ballistic stretching

a series of quick, bouncing-type stretches

base of support

area bound by the outermost regions of contact between a body and support surface or surfaces


asymmetric loading that produces tension on one side of a body's longitudinal axis and compression on the other side

Bernoulli principle

an expression of the inverse relationship between relative velocity and relative pressure in a fluid flow


application of mechanical principles in the study of living organisms

bone atrophy

decrease in ...

Want remote access to your institution's subscription?

Sign in to your MyAccess profile while you are actively authenticated on this site via your institution (you will be able to verify this by looking at the top right corner of the screen - if you see your institution's name, you are authenticated). Once logged in to your MyAccess profile, you will be able to access your institution's subscription for 90 days from any location. You must be logged in while authenticated at least once every 90 days to maintain this remote access.


About MyAccess

If your institution subscribes to this resource, and you don't have a MyAccess profile, please contact your library's reference desk for information on how to gain access to this resource from off-campus.

Subscription Options

AccessPhysiotherapy Full Site: One-Year Subscription

Connect to the full suite of AccessPhysiotherapy content and resources including interactive NPTE review, more than 500 videos, Anatomy & Physiology Revealed, 20+ leading textbooks, and more.

$595 USD
Buy Now

Pay Per View: Timed Access to all of AccessPhysiotherapy

24 Hour Subscription $34.95

Buy Now

48 Hour Subscription $54.95

Buy Now

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.