joint mechanics

Question 1

3 types of joints and their composition

Answer 1

– Fibrous joint
• Synarthrosis
– Cartilaginous joint
• Amphiarthrosis
– Synovial joint
• Diarthrosis

JOINTS MAKE ME S.A.D.

Question 2

fibrous joint examples

Answer 2

– Example
• Cranial Articulations
– Greater motion in infants –fontanelle
• Sydesmosis
– Joint united by a ligamentous fibrous sheet
– Distal tibiofibular articulation
– Movement is slight to considerable
• Gomphosis
– A conical process fitting into a socket in an
immovable joint
– Periodontal ligament anchoring the tooth

Question 3

Cartilaginous joints description

Answer 3

– Two contiguous surfaces united by
fibrocartilaginous disks
– There is no cavity between the bones
– Strong ligamentous support
– Small amount of rocking and sliding
motion

Question 4

subtypes of cartilaginous joints

Answer 4

hyaline

fibrocartilage

Question 5

Hyaline cartilage - type of joint and functions

Answer 5

– Synchondroses
– Permits slight bending during early life
– Temporary union in long bone growth
» Epiphyseal plate

Question 6

fibrocartilage - type of joint and functions

Answer 6

Symphyses
– Cartilage fuses into a pad of fibrocartilage that is
compressible and allows some movement
– Center of each pad, or disc, is the nucleous
pulposus

Question 7

synovial joint

Answer 7

The most common joint
– Articulating bones do not
touch
– Separated by a fluidcontaining
joint cavity
– Freely mobile
– Some contain fibrocartilage
discs or meniscus

Question 8

types of synovial joints 6 main, and subtypes

Answer 8

• Plane
• Hinge
– Ginglymus
• Saddle
• Condyloid
• Ball and Socket
– Ellipsoid
– Condylar
• Pivot

Question 9

Triquetreum-pisiform is an example of this type of synovial joint

Answer 9

plane synovial

Question 10

ginglymus synovial - type of joint, fx and example

Answer 10

• Hinge
• Allows for large degree of freedom of motion
in one plane
• Example
– Elbow

Question 11

condylar (spheroidal) synovial joint - description, motion, example

Answer 11

» Partial flattening of both articular surfaces
» Limits motion
» Example – metacarpal- phalangeal

Question 12

ellipsoid (spheroidal) synovial joint - description, motion, example

Answer 12

» Head is ellipsoid (football shaped)
» Greater motion than condylar, less than
spheroid
» Example - radiocarpal

Question 13

trochoid synovial - description, primary motion, example

Answer 13

• Composed of a ball shape that is
surrounded by a circle composed of bone
and ligament
• Primary motion is rotation
• Example
– Atlas and axis

Question 14

sellar synovial joint - description, moiton, example

Answer 14

Composed of one concave and one convex
bone
• Allows for greater motion in all planes
• Example
– Thumb

Question 15

Hilton’s law

Answer 15

Nerves supplying a joint also
supply the muscles moving the joint and the
skin covering the attachments of these muscles

Question 16

Main type of sensation, which provides
information concerning the movement and
position of the joint

Answer 16

proprioception

Question 17

nerve endings within a joint are primarily found within this part of the joint:

Answer 17

articular capsule

Question 18

3 basic forms of joint degeneration

Answer 18

• inflammatory (most commonly rheumatoid arthritis)
• osteoarthritis
• traumatic

Question 19

traumatic arthritis definition and why it causes pain

Answer 19

From an injury which leads to a condition called avascular necrosis: blood supply to the bone is cut off
- Lack of blood supply causes the surrounding cartilage’s deterioration and bones grind or rub together

Question 20

osteoarthritis definiiton and and why it causes pain

Answer 20

Definition
Joint disease that gets worse over time; does not cause swelling in joints (not inflammatory)
- Cartilage that cushions the bones of the hip starts to erode, eventually allows the bones of the joint to grind or rub together

Question 21

fibrillation - mechanism, what it looks like, cartilage appearance

Answer 21

• Early degenerative change of the articular cartilage due to the loss of proteoglycans
• Unmasks collagen fibres and increases water content in chondrocytes
• Equivalent of a superficial erosion of the cartilage.
• Affected cartilage becomes dull with a yellowish discolouration taking a characteristic ground-glass appearance

Question 22

eburnation

Answer 22

Complete loss (ulceration) of articular cartilage
Accompanied by a thickening of the subchondral bone
Osteosclerosis
Exposed bone surfaces take an ivory-like appearance (hard and polished)
It is a permanent lesion since lost cartilage cannot be repaired
Pain on weight bearing

Question 23

Term used to describe fragments of cartilage and/or bone floating free in synovial fluid
- HOW DOES IT OCCUR? what is it associated with? which disease conditions is it seen in?

Answer 23

Term used to describe fragments of cartilage and/or bone floating free in synovial fluid
Occurs when pieces of degenerating cartilage detach from the subchondral bone
Often associated with “Catching” or “Locking” of joint
Commonly seen in degenerative joint diseases
Particularly in “Osteochondrosis Dissecans” (OCD)

Question 24

most common type of rheymatoid arthritis, gender ratio, age

Answer 24

rheumatoid arthritis!

- 75% women, most often 30-60 but cna begin at any age

Question 25

Definition 
Inflammatory condition (causes joint swelling) in which the immune system mistakenly attacks the synovium and cartilage of  the joints

Answer 25

rheumatoid arthritis

Question 26

why does rheumatoid arthritis cause main

Answer 26

Why it causes pain
Cartilage wears away and the cushioning fluid in the joint (from the synovium) becomes inflamed (swollen) inflammation causes chemicals to be released that damage the cartilage and bone of the affected joint