Joints I Flashcards
Joint/Articulation
site of contact between bones or between cartilage and bone (bones/joints develop from the same embryonic tissue)
Surfaces of the bone covering the joint is …
articular surfaces, the covering articular cartilage
Role of Joints
to allow movement amongst rigid bones, however not all joints allow movement - e.g. sutures in the skull and temporary joints
Temporary Joint - 4 points
designed to allow growth of bone, found in immature bones with bony epiphysis and a bony diaphysis - epiphyseal plate/growth plate, not designed for movement, eventually obliterated by ossification of growth plate
2 categories for classifying joints
Function and Structure
Function category - 3 types based on the degree of movement
synarthroses, amphiarthroses and diarthroses
synarthroses
immoveable
amphiarthroses
slightly moveable
diarthroses
freely moveable
Structure category - 3 types based on presence/absence of a joint cavity & type of connective tissue
Fibrous, cartilaginous and synovial
Define a fibrous joint
bones connected by fibrous tissue with no joint cavity
Define a cartilaginous joint
bones connected by cartilage with no joint cavity
Define a synovial joint
bones not connected, form joints and have a joint cavity
3 types of fibrous joint
Sutures, Syndesmoses and Gomphoses
Describe sutures - 6 points
connected by fibrous tissue, found only in the skull, bones of the skull vault bound tightly with fibrous tissue = sutural ligaments - this immobility is important to give protection to brain/special sense organs, found where the margins of the bone meet, sutural surfaces = designed to interlock
serrated
saw-like (sutures)
denticulate
tooth-like (sutures)
Describe sutures in a foetus/young child - 3 points
bones of cranial vault have not yet met so there are gaps covered only by fibrous tissue = fontanelles - allow for further growth in size of the brain, when growth is complete the sutural ligament is replaced with bone (late 20s) = synostosis
Describe Syndesmoses - 3 points
held together by fibrous connective tissue but not as firmly as sutures, only 1 true syndesmoses - between the distal ends of the tibia & fibula = inferior tibiofibular joint, permits some movement but no true movement, superior tibiofibular joint and the radius & ulna joints are joined by sheet of fibrous tissue (interosseous membrane) which have much larger fibres and so aren’t true syndesmoses
Describe Gomphosis - 2 points
specialised fibrous joints between teeth and supporting bones of the jaw, tooth root anchored to bony walls of socket by thin fibrous membrane = periodontal membrane
3 types of cartilaginous joints
Primary cartilaginous joints, secondary cartilaginous joints and synovial
Describe primary cartilaginous joints (synchondroses) - 2 points
held together by a plate of hyaline cartilage, mostly temporary joints - allows for growth (e.g. between epiphyses and diaphyses of long bone) and for growth of skull base until about 25 yrs
Example of a primary cartilaginous joint
Between ribs and costal cartilages - cost-chondral joints
Describe secondary cartilaginous joints (symphyses) - 5 points
have articular surfaces and bones are covered by hyaline cartilage, bones held together by plate of fibro-cartilage, allows slight movement, not all are permanent joints, the 2 halves of the mandible are joined by symphyseal joint in midline - united after 1st year of life
Examples of secondary cartilaginous joints
Inter-vertebral discs between vertebral bodies - permanent joint, pubic symphysis forms between 2 pubic bones - permanent joint, joint between manubrium and body of sternum = manubrio-sternum joint - obliterated by bone later in life
Describe synovial joint - 4 points
form the majority of joints in the body, the articular joint capsule is attached around the articular margins and between the articulating bones, bony surfaces covered by articular hyaline cartilage, joint cavity and joint capsule
Joint cavity in synovial joint
v small space and separates articulating bone
Joint capsule in synovial joint
double-layered, outer = strong & fibrous capsule, inner = synovial membrane
Describe the fibres of the fibrous capsule found in a synovial joint - 4 points
firmly joined to periosteum by ligaments holding the bone together, ligaments can be intrinsic (capsular) extrinsic and distinctly separated from the joint capsule (extracapsular), some joints become strengthened internally by having intracapsular ligaments located within the synovial cavity (e.g. knee joint which has the cruciate ligaments) - also has 2 articular discs = medial & lateral menisci inside the joint cavity
Examples of Intra-articular surfaces in synovial joints
e.g. articular discs, tendons & ligaments, all additional features to some synovial joints but not common to all
Smooth synovial membrane in synovial joints - 5 points
found within joint capsule, lines entire joint cavity, doesn’t cover surfaces of articular cartilage, often thrown into folds which project into joint cavity, produces a viscous fluid = synovial fluid which lubricates joint surfaces
