Joint Biomechanics - Intro Flashcards
Sagittal Plane
Runs parallel to the sagittal suture of the skull, dividing the body into right and left sections.
Flexion/extension.
Transversal axis.
Frontal Plane
Runs parallel to the coronal suture of the skull, dividing the body into front and back sections.
Abduction/adduction.
Antero-posterior axis.
Horizontal (Transverse) Plane
Courses parallel to the horizon and divides the body into upper and lower sections.
Rotation, horizontal abduction/adduction.
Longitudinal axis.
Osteokinematics
Describes the motion of bones relative to the three cardinal (principal) planes of the body: Sagittal, Frontal and Horizontal.
Degrees of Freedom
Indicates the number of permitted planes of angular motion at a joint.
We have three degrees of freedom illustrated by a tennis ball in space.
Accessory Movements
Or joint “play” refers to the slight passive translation that occurs in most joints and are commonly defined in three linear directions.
Arthrokinematics
Refers to the movement of joint surfaces.
Joint angular motions (e.g. knee flexion) of bones in the human body occurs as a result of a combination of rolling, sliding and spinning. Without a combination of these movements, simple and complex tasks would not be possible.
Roll
Multiple points along one rotating articular surface contact multiple points on another articular surface.
E.g. a tire rotating across a stretch of pavement.
Slide
A single point on one articular surface contacts multiple points on another articular surface. E.g. A nonrotating tire skidding across a stretch of icy pavement.
Spin
A single point on one articular surface rotates on a single point on another articular surface.
Concave Motion Rule
Concave surface moving on a convex surface.
E.g. tibia on femur condyles, ulna and radius on humerus. MCP and IP joints.
Roll and glide in the same direction.
Convex Motion Rule
Convex surface moving on a concave surface.
E.g. head of humerus on the glenoid fossa, carpal bones on the radius.
Roll and glide in the opposite direction.
Agonist
The muscle or muscle group that is most directly related to the initiation and execution of a particular movement, regardless of contraction type.
Antagonist
The muscle or muscle group that is considered to have the opposite action of a particular agonist and is relaxed during the movement.
Synergists
Muscles that cooperate to produce the same movement. E.g.:
- Infraspinatus and teres minor for external rotation.
- Rhomboids helping teres major in shoulder adduction.
