Lecture 6- Joint classifications( synovial joints)

Question 1

synovial joint structure

Answer 1

Articular Cartilage
Joint capsule
Joint cavity
synovial fluid
Ligaments

Question 2

Articular cartilage

Answer 2

protects the ends of the bone and allows for frictionless movement.
absorbs shock( resists compression) and allows heavy load to be carried.
covers bone ends where they articulate(meet)

Question 3

Joint capsule

Answer 3

all synovial joint are surrounded by a joint capsule.
- loose enough to allow movement, tight enough to keep bones together.
OUTER LAYER: DFCT
- Thicker parts- capsular ligaments for more support.
looser parts- where movement is allowed
Function-to resist tension( movement), hold bone ends together. protect joint and synovial membrane
INNER LAYER-SYNOVIAL MEMBRANE
inner layer of loose connective tissue
lines all non-articulating areas inside the joint
secreted synovial fluid
nutrients to avascular structures
IN SOME JOINTS
capsular ligaments- thickenings of capsule where more support is needed.
Intracapsular ligaments–>additional bands of DFCT located internally to hold bones together.

Question 4

Fibrocartilaginous pads

Answer 4

• In some joints, small
  structures made of
  fibrocartilage
  — fill in space
  — provide cushioning/shock
  absorption
  and/or deepen articulations
• E.g. menisci (pl.)/meniscus
  (sing.) in the knee
  — half-moon shaped structures
  that sit between femur and
  tibia

Question 5

joint cavity and synovial fluid

Answer 5

Inside the joint capsule is the joint cavity. Its a potential space filled with no more than 1ml of synovial fluid.
SYNOVIAL FLUID:
clear fluid, lubricates joint, shock absorption, supplies nutrients, overall maintence.

Question 6

Stability vs Mobility

Answer 6

There’s a trade off between the two. The more stable the joint, the less mobile.
As a joint becomes more stable mobility is lost.

Question 7

Joint movement

Answer 7

Joint movement
* Range of movement/motion (ROM) determined by joint structure
— type and amount of movement
* Determined by:
— bone end shape
— ligament location and length
— body surface contact
— muscles (see L 10)
high articulation= more stable

Question 8

Synovial joint movements

Answer 8

movement can occur in diff planes, among diff axes
uniaxial( 1 axis)
Biaxial( two axes)
Multiaxial( many axes)
Axis- side to side
Plane- back and forth

Question 9

Plane joint

Answer 9

Multiaxial
sliding and gliding
flat articular surfaces sliding over each other
eg intercarpal joints

Question 10

Hinge joint

Answer 10

uniaxial- movement in 1 direction, eg elbow joint, movement are flexion and extension,
THINK door hinge, moves back and forth in one place

Question 11

Pivot joint

Answer 11

Uniaxial, movement is rotation
eg radioulnar joints

Question 12

Condylar joint

Answer 12

Biaxial- flexion and extension, rotation when flexed eg knee.

Question 13

Ellipsoid joint

Answer 13

Biaxial, flexion, extension, adduction, abduction= circumduction BUT no rotation
Eg - wrist joint

Question 14

Saddle joint

Answer 14

Biaxial, flexion, extension, abduction, adduction= circumduction
obligatory (forced) rotation
eg base of thumb

Question 15

Ball and socket joint

Answer 15

Multiaxial, flexion, extension, adduction, abduction= circumduction
THERES ALSO ROATION- most movable joint
eg shoulder and hip