Forces and movement in the human body Flashcards
Describe linear movement and how it is created
Linear movement is the movement of an object in a straight line. Force has to be applied at the centroid of an object.
Describe angular movement and how it is created
Angular movement is the movement of an object in a circular motion. Force has to be applied away from the centroid of the body.
Describe angular velocity
Rate at which a rotating body changes position
Describe angular acceleration
Rate at which angular velocity changes
What do each of the components of the lever systems represent?
Lever = bone Effort = muscle Fulcrum = joints Load = other forces (weight, gravity)
Describe a 1st class lever system and give an example
Fulcrum is in the middle and the load and effort are situated on either side.
E.g = nodding your head
Describe a 2nd class lever system and give an example
Fulcrum is to one end of the lever, with load in the middle and effort at the opposite end.
E.g = plantar flexion
Describe a 3rd class lever system and give an example
Fulcrum is at one end of the lever, with effort in the middle and load at the other end.
E.g = bicep curl
How do you calculate mechanical advantage and disadvantage of lever systems.
Effort arm length / load arm length
>1 = mechanical advantage
<1 = mechanical disadvantage
Do first class lever systems have a mechanical advantage or disadvantage?
They can have either, depending on the arm lengths.
Do second class lever systems have a mechanical advantage or disadvantage?
They always have a mechanical advantage (>1), so requires less effort to move the equivalent load
Do third class lever systems have a mechanical advantage or disadvantage?
They always have a mechanical disadvantage (<1)
Require more effort to move the equivalent load, but they move at a greater speed and has a larger range of motion
What are internal forces
Forces produced by muscles
What are external forces
Forces made outside the body (being hit)
How do tendons and ligaments help to prevent injury
They help prevent joints and muscles from being taken beyond their normal range of motion, helping to reduce injury
Define stress
Pressure exerted on an object
Define strain
The amount of deformation of a material caused by stress
How can ligaments and tendons become damaged
Ligaments and tendons take a finite amount of stress and/or strain, but if the force is greater than their tensile, compressive or shear stress they become damaged
Describe active movement
Movement carried out by the individual, with no help
Describe passive movement
Movement carried out by someone/ something else
What factors is range of motion affected by
Shape of joint
Ligaments
Length of muscle and tendon
Magnitude of force applied
Define flexibility
Ability to move your joint, or series of joints, through the full ROM
What factors affect flexibility
Age Gender Genetics Use Training ROM
Describe degrees of freedom
Degrees of freedom refer to the number of planes in which they can move
One degree of freedom = movement in one plane
Two degrees of freedom = movement in two planes
Three degrees of freedom = movement in three planes
Define the following words:
- Pronation
- Supination
- Radial deviation
- Ulna deviation
- Opposition
- internal rotation of forearm/forefoot (palm up)
- external rotation of forearm/forefoot (palm up)
- abduction of the wrist
- adduction of the wrist
- combination of the thumb towards the fingertips
Define the following words:
- Dorsiflexion
- Plantar flexion
- Inversion
- Eversion
- flexion of the ankle
- extension of the ankle
- rotation in the frontal plane that moves the foot inwards
- rotation in the frontal plane that moves the foot outwards
