Joint Summary

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  • Topic: Knee, Synovial joint, Joints
  • Pages : 10 (1520 words )
  • Download(s) : 131
  • Published : July 13, 2012
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Articulations or Joints
•  Articulation or Joint

–  Place where two bones (or bone and cartilage) come together –  Can be freely movable, have limited, or no apparent movement –  Structure correlated with movement

•  Naming Joints
–  According to bones or parts united at joint- temporomandibular –  According to only one of articulating bones- humeral –  By Latin equivalent of common name- cubital 8-2

Classes of Joints
•  Structural: based on major connective tissue type that binds bones –  Fibrous –  Cartilaginous –  Synovial

•  Functional: based on degree of motion
–  Synarthrosis: non-movable –  Amphiarthrosis: slightly movable –  Diarthrosis: freely movable 8-3

Fibrous Joints
•  Characteristics

–  United by fibrous connective tissue –  Have no joint cavity –  Move little or none

•  Types: Sutures, Syndesmoses, Gomphoses

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Fibrous Joints: Sutures

•  Opposing bones interdigitate. •  Periosteum of one bone is continuous with the periosteum of the other. •  Sutural ligament: two periostea plus dense, fibrous, connective tissue between. •  In adults may ossify completely: synostosis. •  Fontanels: membranous areas in the suture between bones. Allow change in shape of head during birth and rapid growth of the brain after birth. 8-5

Fibrous Joints: Syndesmoses
•  Bones farther apart than suture and joined by ligaments •  Some movement may occur •  Examples: radioulnar (interosseus membrane)

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Fibrous Joints: Gomphoses
•  Specialized joints •  Pegs that fit into sockets •  Periodontal ligaments: hold teeth in place •  Inflammations –  Gingivitis leads to… –  Periodontal disease

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Cartilaginous Joints

•  Unite two bones by means of cartilage •  Types
–  Synchondroses: hyaline cartilage –  Symphyses: fibrocartilage

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Cartilaginous Joints: Synchondroses
•  Joined by hyaline cartilage •  Little or no movement •  Some are temporary and are replaced by synostoses •  Some are permanent •  Some like costochondral joints develop into synovial joints •  Examples: Epiphyseal plates, sternocostal, sphenooccipital

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Cartilaginous Joints: Symphyses
•  Fibrocartilage uniting two bones •  Slightly movable •  Examples: symphysis pubis, between the manubrium sternum and the body of the sternum, intervertebral disks.

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Synovial Joints
•  Contain synovial fluid •  Allow considerable movement •  Most joints that unite bones of appendicular skeleton reflecting greater mobility of appendicular skeleton compared to axial •  Complex 8-11

Synovial Joints
•  Articular cartilage: hyaline; provides smooth surface •  Joint cavity: synovial; encloses articular surfaces •  Capsule –  Fibrous capsule: dense irregular connective tissue, continuous with fibrous layer of the periosteum. Portions may thicken to form ligaments. –  Synovial membrane and fluid: membrane lines inside of joint capsule except at actual articulation of articular cartilages. Thin, delicate. Sometimes separated from fibrous capsule by areolar C.T. and fat, sometimes merged with fibrous.

• Synovial fluid: complex mixture of polysaccharides, proteins, fat and cells. Hyaluronic acid- slippery. • No blood vessels or nerves in articular cartilages; nutrients from nearby blood vessels and synovial fluid 8-12 • Nerves in capsule help brain know position of joints (proprioception)

Accessory Structures
•  Bursae
–  Pockets of synovial membrane and fluid that extend from the joint. Found in areas of friction –  Bursitis

•  Ligaments and tendons: stabilization
•  Articular discs: temperomandibular, sternoclavicular, acromioclavicular •  Menisci: fibrocartilaginous pads in the knee. •  Tendon sheaths: synovial sacs that surround tendons as they pass near or over bone 8-13

Types of Synovial joints
•  Uniaxial: occurring around one axis •  Biaxial: occurring around two axes at right angles to each other •  Multiaxial: occurring around several axes

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