week 3: Musculoskeletal levers Flashcards
three types of muscle tissue
skeletal, cardiac, smooth
muscle origin
fixed point of attachement,
proximal to body
muscle insertion
point of attachment that moves ussually distal to origin
at joints that permit flexion and extension, muscles whose line of action crosses the anterior side of a joint are
flexors of joint
at joints that permit flexion and extension, muscles whose line of action crosses the posterior side of a joint are
extensors of joint
bones and the muscles attached to them function as
levers
lever
rigid structure that moves on a fixed point called a fulcrum
fulcrum in human lever systems
the joint
an applied force results in
an exerted force
lever systems change (3)
change the direction of the applied force
change distance and speed of movement of applied force
change the magnitude of the exerted force relative to the applied force
First-class lever system
fulcrum lies in-between applied force and load
human neck
second-class lever system
load (exerted force) in the middle between the fulcrum and the effort (applied force)
e.g wheelbarrow
third class- lever system
fulcrum remains at end effort located between the fulcrum and load
most common in human body
third class lever system in body
fulcrum: elbow
applied force: biceps brachii
load: in hand
human example of first-class lever systme
fulcrum: skull vertical column
load: head
applied force: muscles in neck
