Joints Flashcards
What are the two classes of joints
Synarthroses
Diarthrosis/synovial
What are the five types of synarthroses
synostosis
synchondrosis
symphysis
syndesmosis
gomphosis
Synostosis
two bones connected by bone (fused)
mature skull, mature pelvis
Synchondrosis
two bones connected by cartilage
growth plate
Symphysis
Two bones connected fibrocartilage
early pelvic, mandibular
Syndesmosis
two bones connected by fibrous tissue
early skull, distal tibio-fibular
Gomphosis
fibrous joint between tooth and socket
What are the six types of synovial joints
ball and socket
Ellipsoidal
Saddle
Hinge
Pivot
Planar/sliding
What separates synarthroses from diarthrosis joints
diarthrosis are more mobile joints
Ball and socket
enarthrosis
hip
3 axis
Ellipsoidal
no rotation, more restricted than ball and socket
2 axis
Saddle
sellar
interphalangeal
2 axis
‘‘2 pringles on top of each other’’
Hinge
ginglymus
hock, elbow
1 axis
Pivot
trochoid
C1/C2
cat radioulnar
1 axis
Planar/sliding
arthrosis
intercarpal, intertarsal
unusual - translation not rotation
Synovial membrane
glistening pink, many vessels and nerves
often incomplete, no basement membrane
folded or tufted
often large pouches to allow movement
Cells in the synovial membrane
synoviocytes type A = phagocytic
Synoviocytes type B = secretory (of synovial fluid)
Synovial Fluid
secreted by type B synoviocytes
plasma ultrafiltrate + hyaluronate
(long chains of glycosaminoglycan)
lubricate, nutritive
What position is the high energy state in snap joints of horses
intermediate position
as collateral ligaments are stretched rather than relaxed
How is articular cartilage fed
fed by diffusion from fluid>capsule>underlying bone
no vessels or nerves
What is the physical structure of articular cartilage
arcade of arches arrangement of collagen
What is the molecular structure of articular cartilage
based on glycosaminoglycan (GAG)
proteoglycans are attached to long GAG chains
Proteoglycans are a core protein with a shorter GAG sidechain
What are the two matrix meshes of articular cartilage
Type II collagen protein mesh - resits tension
Hyaluronate polysaccharide mesh - resist compression
How does the Hyaluronate polysaccharide mesh resist compression
Hydrophilic proteoglycans are negatively charged so repel each other and attract water
What is the effect of retaining water in articular cartilage
water will weep in and out of joint space in varying pressures so:
- lubricates joint
- carries dissolved nutrients and gases to the articular cartilage
Capsules
fibrous capsule attaches to periosteum
continuous with articular cartilage
supports joint
Collateral ligaments
restrict the movement of the joint to one plane (sagittal plane) - hinge movements
Much innervation - proprioception, respiratory reflexes
Menisci
fibrocartilage ingrowths from capsule
incomplete, c-shaped, 2 in each stifle joint
Discs
fibrocartilage ingrowths from capsule
allocate different movements to different compartments (separate joint in two)
1 in each jaw joint
Labra
fibrocartilaginous extension to the joint surface
hip joint
Fat pads
lie between synovial membrane and capsule - padding the joint
Bursae
small spaces between bones and the:
- tendon -biceps and humerus in horses
- occasional muscles
What clinical condition can reduce joint function
degeneration of either the collagen or glycosaminoglycan meshes
