joint mechanics Flashcards
3 types of joints and their composition
– Fibrous joint • Synarthrosis – Cartilaginous joint • Amphiarthrosis – Synovial joint • Diarthrosis
JOINTS MAKE ME S.A.D.
fibrous joint examples
– 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
Cartilaginous joints description
– Two contiguous surfaces united by fibrocartilaginous disks – There is no cavity between the bones – Strong ligamentous support – Small amount of rocking and sliding motion
subtypes of cartilaginous joints
hyaline
fibrocartilage
Hyaline cartilage - type of joint and functions
– Synchondroses
– Permits slight bending during early life
– Temporary union in long bone growth
» Epiphyseal plate
fibrocartilage - type of joint and functions
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
synovial joint
The most common joint – Articulating bones do not touch – Separated by a fluidcontaining joint cavity – Freely mobile – Some contain fibrocartilage discs or meniscus
types of synovial joints 6 main, and subtypes
• Plane • Hinge – Ginglymus • Saddle • Condyloid • Ball and Socket – Ellipsoid – Condylar • Pivot
Triquetreum-pisiform is an example of this type of synovial joint
plane synovial
ginglymus synovial - type of joint, fx and example
• Hinge • Allows for large degree of freedom of motion in one plane • Example – Elbow
condylar (spheroidal) synovial joint - description, motion, example
» Partial flattening of both articular surfaces
» Limits motion
» Example – metacarpal- phalangeal
ellipsoid (spheroidal) synovial joint - description, motion, example
» Head is ellipsoid (football shaped)
» Greater motion than condylar, less than
spheroid
» Example - radiocarpal
trochoid synovial - description, primary motion, example
• Composed of a ball shape that is surrounded by a circle composed of bone and ligament • Primary motion is rotation • Example – Atlas and axis
sellar synovial joint - description, moiton, example
Composed of one concave and one convex bone • Allows for greater motion in all planes • Example – Thumb
Hilton’s law
Nerves supplying a joint also
supply the muscles moving the joint and the
skin covering the attachments of these muscles
Main type of sensation, which provides
information concerning the movement and
position of the joint
proprioception
nerve endings within a joint are primarily found within this part of the joint:
articular capsule
3 basic forms of joint degeneration
- inflammatory (most commonly rheumatoid arthritis)
- osteoarthritis
- traumatic
traumatic arthritis definition and why it causes pain
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
osteoarthritis definiiton and and why it causes pain
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
fibrillation - mechanism, what it looks like, cartilage appearance
- 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
eburnation
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
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?
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)
most common type of rheymatoid arthritis, gender ratio, age
rheumatoid arthritis!
- 75% women, most often 30-60 but cna begin at any age
Definition Inflammatory condition (causes joint swelling) in which the immune system mistakenly attacks the synovium and cartilage of the joints
rheumatoid arthritis
why does rheumatoid arthritis cause main
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
