Joint Mechanics DSA Flashcards
Fibrous joints
Synarthroses
Sutures
Syndesmosis
Gomphosis
Type of joint united by dense fibrous tissue
Movement is dependent on the length of the fibers uniting the bones
Cartilaginous joints
Amphiarthroses Hyaline (Synchondrosis) Fibrocartilage (symphysis) strong ligamentous support Small rocking, sliding motion Intervertebral discs Pubic symphysis
Synovial joints
Diarthrosis Spheroid Hinge Condylar Provide free movement Contain synovial fluid, lined with a synovial membrane, some contain fibrocartilage discs or meniscus
Sutures
Fibrous joint Held together by several layers of strong CT Extremely tight, little movement Skull sutures Squamous type: edges overlap Serrate type: edges interlock
Syndesmosis
Bones are united by a sheet of fibrous tissue
Can be ligament or a fibrous membrane
Interosseous membrane between ulna and radius
Movement can be slight up to considerable, depends on distance between the bones and the degree of flexibility of the uniting fibrous tissue
Gomphosis
Fibrous joint
Unique between tooth and the bone In its alveolus (socket)
Primary cartilaginous joints
Hyaline cartilage
Temporary union
Permits slight bending during early life, growth, and then usually fuses when growth is completed
Secondary cartilaginous joints
Surfaces of the articulating bones are covered with hyaline cartilage and the bones are united by strong fibrous CT and/or fibrocartilage
Strong, slightly movable joints
Distinguishing features of synovial joints
Synovial membrane
Joint cavity
Articular cartilage-hyaline
Articular (joint) capsule
Articular cartilage
Hyaline
No blood vessel or nerve supply
Nourished by synovial fluid
Articular (joint) capsule
Fibrous capsule Envelops the articulation or joint Synovial membrane: vascular CT membrane that lines the entire joint cavity (except the articular cartilage) Produces synovial fluid Regeneration
Plane joints
Synovial joint
Permit gliding or sliding movements
AC joint, proximal tibiofibular, intercarpal, SC
Uniaxial joint
Movement limited by tight articular capsules
Hinge joints
Ginglymus Synovial joint Uniaxial joint Strong collateral Ls. Elbow, knee, ankle
Ball and Socket joint
Spheroidal
Multiaxial, highly moveable joints
Spheroidal surface of one bone moves within the socket of another bone
Flexion, extension, abduction, adduction, rotation, circumduction
Pivot joint
Trochoid
Uniaxial joints which allow rotation
Radioulnar
Condyloid and Ellipsoid joints
Partial flattening of both articular surfaces
Modified spheroidal
MCP joint
Radiocarpal
Saddle joints
Sellar synovial
Biaxial with opposing surfaces shaped like a saddle
Flexion/extension, abduction, adduction, circumduction
Carpalmetacarpal joint of thumb
Hilton’s law
Nerves supplying a joint also supply the muscles moving the joint and the skin covering the attachments of these muscles
Wolff’s law
Bone is increased where needed and reabsorbed were it is not
Fibrillation
Early degenerative change of the articular cartilage due to the loss of proteoglycans
Unmasks collagen fibers and increases water content in chondrocytes
Superficial erosion of the cartilage
Ground-glass appearance of affected cartilage
Eburnation
Complete loss (ulceration) of articular cartilage
Thickening of the subchondral bone-osteosclerosis
Exposed bone surfaces take an ivory-like appearance
Permanent lesion
Joint mice
Osteochondromatosis
Fragments of cartilage and/or bone floating free in synovial fluid
Pieces of degenerating cartilage detach from the subchondral bone
