Joints Flashcards
What kind of joints allow for very limited or no movement?
Synarthroses
What type of synarthrotic joint unites the skull bones in adults?
Synostosis (no mvt - connected by bone)
What type of joint connects the first rib to the sternum? What tissue connects them?
Synchondroses (connected by hyaline cartilage)
What type of joint forms the pubic symphysis? What tissue type connects them?
Syndesmosis (connected by dense connective tissue)
What type of joint allows for slight movement? Give an example
Amphiarthroses - intervertebral discs
What joint allows for relatively free movement? What’s another name for this joint? Give an example
Diarthroses or synovial joint - knees and elbows
What’s the anatomy of the amphiarthrotic intervertebral disc?
The disc consists of concentric layers of fibrocartilage called the annulus fibrosus.
The annular fibrosus surrounds the nucleus pulposus which allows each intervertebral
disc to function as a shock absorber within the spinal column.
Describe diarthroses joints.
Generally unite long bones. Connective tissue capsule encloses a synovial fluid-filled cavity. Joint cavity lined by synovial membrane and secretes synovial fluid as a lubricant.
What is synovial fluid derived from and what does it have a high concentration of?
Derived from blood plasma and produced by cells of synovial membrane - has high [hyaluronic acid]
What type of cartilage is found at the tips of long bones in diarthrosis joints? How does it distribute forces?
Articular cartilage - contains gothic arches of collagen fibers that distribute forces perpendicular, then parallel to surface.
Proteoglycan aggregates bound to hyaluronic acid and collagen bind a large amount of water in collagen fiber network and function as a biomechanical spring. When pressure is applied, water is forced out of cartilage matrix and into synovial fluid. As water is expelled, electrostatic repulsion of negative groups in GAGs occurs, separating GAGs again and creating space for return of water. When pressure is relaxed, water is attracted back into GAG matrix. No perichondrium exists b/c wouldn’t allow water to move in and out.
Describe synovial membrane and the two prominent cell types there.
The membrane has folds that extend into the synovial cavity and secrete the lubricative synovial fluid. No basement membrane or other epithelial features.
Consists of macrophage-like and fibroblast-like cells.
The “synoviocytes” in
contact with the synovial cavity are phagocytes and remove wear and tear debris from the
synovial fluid.
The other fibroblastic synoviocytes produce GAGs which they secrete
along with plasma from the capillaries into the synovial fluid.
Name a few joint disorders associated with aging.
Herniated disc (degeneration of vertebral disc), osteoarthristis, rheumatoid arthritis
