Lecture 4 - Articulations and Frames Flashcards
What is an articulation?
- a place where two or more bones meet
what are the three types of articulations?
- synarthrodial
- amphiarthrodial
- diarthrodial
what are synarthrodial articulations?
- immovable joints
- where two bones “fuse” together
- ex: suture of the skull
what are amphiarthoridal articulations?
- cartilaginous joints
- connected via fibrocartilage
- a small range of motion
- ex: intervertebral discs
what are diarthrodial articulations?
- joints that allow the most forceful motions
- large range of motion
- ligaments and tendons are present
- ex: knees, hips, elbows
what is articular cartilage?
- covers bearing surfaces of bones
- protects bones where they hit to reduce friction (heat and wear)
what is synovial fluid?
- fluid found in the joint space
- lubricates and nourishes cartilage
- keeps friction low
what is the joint capsule?
- a watertight enclosure on the joint
- keeps the synovial fluid in
- pressurized
what are ligaments?
- hold bone to bone
- tension only
- strain = elongation
- stress = load
- sustains less stress
what are tendons?
- hold muscle to bone
- tension only
- strain = elongation
- stress = load
- sustains more stress
how are tendons and ligaments affected by age?
- stiffer with age
- warming up becomes more important with age (to prevent strains)
what is “stability”?
- how easy it is to disrupt or injure a joint
- less stability = more likely to injure
what are the three factors that influence joint stability?
- bony congruency (how well the bones fit together)
- tightness and strength of ligaments
- strength and angles of muscle attachments
what is bony congruency?
- how well the bones fit together
- stable joints have good bony congruency
what is tightness and strength of ligaments?
- lots of ligaments = tight and strong
- high stability
- once injured, unstable and difficult to fix
what is strength and angles of muscle attachments?
- direction of pull
- surfaces muscles are attached to
- muscles surrounding joints assist in stability
- once injured, very hard to keep stable
what is mobility?
- how far the joint can translate and rotate
- range of motion on each degree of freedom
- assessing end feel to find the limits to ROM
how are stability and mobility related?
- more stable = less mobile (and vice versa)
- more mobile = more degrees of freedom
what is the normal end feel of bone-to-bone?
- hard
- unyielding
- not painful
what is normal end feel of soft-tissue approximation?
- mushy
- soft tissues are compressed
- slight yield when overpressured
what is normal end feel of tissue stretch?
- springy
- slight yield when overpressured
- less yield than soft-tissue
what is a frame of reference?
- attached to the part of the system
- can be within or outside the body
- measures linear translation, angular rotation or a combination of both
- contains 1 origin and 3 axes (x,y,z)
