Joints Flashcards
What is a joint?
an articulation between two or more bones
What are the three classes of joints? (by structural classification)
fibrous, cartilaginous or synovial
Give examples of fibrous joints?
sutres of skull, inferior tibiofibial joints, sacroiliac joints, joints at base of teeth and manidble
- all immobile
What is a primary cartilaginous joint? Give an example
Two bones united by hyaline cartilage
- 1st sternocostal joint
- epiphyseal growth plates
What is a secondary cartilaginous joint? give an example
aka symphysis- articulating bones are covered in hyaline cartilage with pad of fibrocartilage between them
- pubic symphysis
- intervertebral discs
- mandubriosternal joints
What is a synovial joint?
a highly mobile joint with a cavity between the two bones that contains synovial fluid
What type of cartilage covers the articulating surfaces of synovial joints? What is its role?
hyaline cartilage- reduces friction and absorbs shock
What two synovial joints have fibrocarilage instead of hyaline cartilage covering the joint surfaces?
sternoclavicular joint and acromioclavicular joint
describe the membranes that line a joint
- fibrous capsule encloses the whole joint and helps stabilise it
- beneath this is a synovial membrane which helps enclose the synovial fluid
- synovial fluid is found within the synovial membrane
- hyaline cartilage covers the articulating surfaces of the bones
Are intervertebral discs and minisci enclosed within the synovial membrane or are synovial membranes found on top of the minisci?
The synovial fluid is found in top of the joint minisci
What is the name for the sac of synovial fluid created by the synovial membrane?
the bursa
What is the role of the bursa? Are they always found within the joint cavity?
To reduce friction around a joint, to absorb shock and transport waste and nutrients. They are not always in communication with the joint (eg. supra platella bursa)
What is synovial fluid made of?
hyaluronic acid, lubricin, proteinase and collagenase
What is the appearance of synovial fluid?
clear/ pale yellow liquid, it is alkaline at rest
How much synovial fluid is found within an avg bursa?
0.5ml
Where are miniscal discs found? what are they made of
fibrocartilage found at knee and vertebrae
What type of joints have fat pads?
synovial joints
is the vascular supply to articular catrilage, capsule and associated ligaments and synvial membranes good or bad?
- articular cartilage avascular
- capsule and ligaments poor blood supply
- synovial membrane good blood supply
Do joint capsules have a nervous supply?
yes for pain and proprioception, the same nerves which supply the capsule will supply the muscles moving the joint and the skin above the joint
What types of synovial joints are there?
- planar
- hinge
- pivot
- chondyloid/ ellipsoidal joint
- saddle joint
- ball and socket
Describe and give an example of a planar joint
gliding movements- side to side and back and forth.
- eg sternoclavicular joints
Describe a hinge joint and give an example
movement in one axis, pully shaped
- knee, elbow
Describe and give an example of a pivot joint
- pivot point articulated with a ring, causing rotational movement
- one axis of movement
- eg radioulnar joint
Describe and give an example of a condyloid joint
- in between a hinge and a ball and socket joint, main movement is flexion and extension but also allows some abduction and aduction
- 2 axis of movement
- metacarple phalangeal joints, wrist joint
Describe a saddle joint
- one bones end is saddle shaped the other is complementary
- allows circumduction
- eg thumb and trapezium
What factors affect stability and ROM of a normal joint?
- structure/ shape of the bones
- length and tension on ligaments
- arrangement and tone of muslces
- neighbouring soft tissues
- hormones (ligaments tend to relax in pregnancy)
- use/ dis use of the joint
What is the theory to why joints crack as you stretch them?
- bones pull away from each other
- synovium expands
- fluid volume is constant
- vaccume is produced
- gasses dissolved in synovial fluid are pulled out of solution
- makes a popping sound
What effect does ageing have on joints?
- decreased synovial fluid production
- cartilage wears out
- ligaments shorten and weaken
