Lecture 10: Movement of Synovial Joints

Question 1

What determines the amount and direction of movement?

Answer 1

• Joint Structure

Question 2

What is the structure of synovial joints?

Answer 2

• Bone ends
• Articular Cartilage (covering bone ends)

Purpose: Smooth, shiny, frictionless

• Capsule

Purpose: To keep two bony ends together, made of DFCT, sleeve-like continuation of periosteum

• Cavity

Allows actual movement of joints, allowing space for it to occur

• Synovial Membrane

Fluid that fills joint space and helps create frictionless environment, articular cartilage does not have blood supply so can not heal quickly, it gets rid of its waste through synovial fluid

• Ligaments

So close together with capsule that we can’t dissect them out, made out of DFCT, purpose is to resist separation of bone ends

Question 3

Any additional features of Synovial Joints?

Answer 3

• Articular Cartilage
• Ligaments on outside of joint AND inside joint - intracapsular (cruciate) ligaments to prevent movement of tibia in one direction and femur in the other
• Menisci

Made of fibrocartilage, little shock absorbers, crescent like discs. Top of tibia is like a plate, distal end of femur is like a ball - would make a poor joint. Meniscus cups condyles of femur and gives a better fit / bony congruence.

Question 4

How do we see things using camera inside body?

Answer 4

Fluid is injected in

Question 5

What is Bursa / House Maid Knee?

Answer 5

Tiny little fluid filled sacs, located behind (quadriceps) tendon, sometimes they become inflamed

Question 6

What is the joint design principle?

Answer 6

There has to be a trade-off between stability and mobility

Question 7

How many axes are there?

Answer 7

3:

• Uniaxial
• Biaxial
• Multiaxial

Question 8

What determines range of movement?

Answer 8

• Bone end shape
• Ligaments
• Body Surface Contact

Question 9

How much movement is possible?

Answer 9

By using a big protractor,

Question 10

What are the different synovial joint shapes?

Answer 10

• Hinge
• Pivot
• Saddle
• Ellipsoid
• Condylar
• Plane
• Ball and Socket

Question 11

What does the hinge joint do? Give examples

Answer 11

• Allows movement in one plane (uniaxial)

- Ankle, elbow (humerus + ulna)

Question 12

What does the pivot joint do? Give examples

Answer 12

• Rotation in transverse plane
• eg. proximal and distal radioulnar joint
  Fibrous on the inside, keeps bones together

Question 13

What does the saddle joint do? Give an example

Answer 13

• Biaxial (+) : circumduction
• Obligatory rotation (because of opposition
• Looks like two saddles
• eg. Base of first metacarpal + first carpal bone (carpometacarpal)

Question 14

What does the ellipsoid joint do? Give examples

Answer 14

• Convex and concave surfaces, radius + carpal, radiocarpal joint
• Biaxial : circumduction
• NO rotation

Question 15

What does the condylar joint do? Give examples

Answer 15

• Biaxial : flexion / extension
• Rotation
• e.g. knee, TMJ (jaw + skull joint)

Question 16

What is a plane joint? Give examples

Answer 16

• Multiaxial: sliding and gliding can occur in any direction
• Flat articular surfaces
• e.g. intercarpal and intertarsal joints

Question 17

What is the ball and socket joint? Give examples

Answer 17

• Multiaxial : circumduction
• Rotation
• Shoulder / hip joint