Classification Of Joints Flashcards
Fibrous Joints
Bones concerned are bound by tough fibrous tissue- strength joints.
Further classified into sutures, gomphoses, and syndesmoses.
Sutures
Type of fibrous joint.
These are immovable joints only found bw the flat plate-like bones of the skull.
Limited movement until about 20yrs of age, after which they become fixed. They are most important at birth as at that stage they are not fused, allowing deformation of the skull as it passes through the birth canal.
Gomphoses
Immovable joints and are found where the teeth articulate with their sockets in the maxillae (upper teeth) or the mandible (lower teeth)
The fibrous connection that binds the tooth and socket is the periodontal ligament
Syndesmoses
Slightly movable joints. Structure is comprised of bones held together by an interosseous membrane.
Key in providing strength along long bones, preventing them from separating
Eg: Middle radio-ulnar and middle tibio-fibular joint
Cartilaginous
In cartilaginous joints, the bones are attached by fibrocartilage or hyaline cartilage.
There are 2 main types: Primary cartilaginous and cartilaginous secondary joints.
Cartilage is an excellent shock absorber as it is essentially a thick gel. Important in the pelvis and spine.
Synchondroses
Also known as primary cartilaginous joints. They only involve hyaline cartilage. The joints can by immovable or slightly movable.
Eg: joint bw the diaphysis and epiphysis of a growing long bone.
Symphyses
Also know as a secondary cartilaginous joint, it can involve fibrocartilage or hyaline cartilage.
These joints are slightly movable
Eg: pubic symphysis
Synovial
Joint filled with synovial fluid. These joints tend to be fully movable and are the main type of joint found around the body.
Allow a huge range of movements, which are defined by the arrangement of their surfaces and the supporting ligaments and muscles.
Often classified by their movement: hinge, saddle, plane, pivot, condyloid, ball and socket.
Hinge joint
Permits flexion and extension
Eg: Elbow
Saddle Joint
Concave and convex joint surfaces unite at saddle joints.
Eg. Metatarsophalangeal joint (toes)
Plane Joint
Permit gliding or sliding movements
Eg: acromioclavicular joint ( collarbone to shoulder blade)
Pivot joint
Allows rotation. A round bony process fits into a bony ligamentous socket.
Eg: Atlantoaxial (top of neck) and proximal radio-ulnar joint (elbow)
Condyloid
Permits flexion, extension, addiction, abduction, and circumduction
Eg: metacarpophalangeal joint
Ball and socket joint
Permits movement in several axis; a rounded head fit into a concavity
Eg: Glenohumeral joint (shoulder)
Stability of joints- Shape, size, and arrangement of articular surfaces.
Most important factor is the relative proportion of 2 articulating surfaces. For example, in the shoulder joint, the humeral head is disproportionately larger than the glenoid fossa or the scapula that it sits in making the joint more unstable as there is less contact bw bones.
In contrast the acetabulum of the pelvis fully encompasses the femoral head which makes the hip more stable. However, while the hip is more stable, the should has more ROM.