Joints and Their Classification

•Arthrology = study of the joints

•Kinesiology = study of musculoskeletal movement

• Classified how adjacent bones are joined • Fibrous – by fibrous connective tissue with no space between• Cartilaginous – by pad or bridge of cartilage• Synovial – bones separated by fluid- filled cavity covered by connective

tissue

• Classified by freedom of movement• Synarthrosis (little or no movement) – fibrous or cartilaginous• Amphiarthrosis (slightly movable) – fibrous or cartilaginous• Diarthrosis (freely movable) – always synovial

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Synarthroses - immobile joints

1. Synostosis - Bony Joint •Gap between two bones ossifies• frontal and mandibular bones in infants• cranial sutures in elderly• attachment of first rib and sternum

• Can occur in either fibrous or cartilaginous joint

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Synarthroses -Fibrous Joints• Collagen fibers span the space between bones

1. Sutures - bind skull bones together• Serrate - interlocking lines• coronal, sagittal and lambdoid sutures

• Lap - overlapping beveled edges• temporal and parietal bones

• Plane - straight, non-overlapping edges• palatine processes of the maxillae

2. Gomphosis• Attachment of a tooth to its socket • Held in place by fibrous periodontal ligament• collagen fibers attach tooth to jawbone

• Some movement while chewing

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Synarthroses -Cartilaginous Joint• Synchondrosis• Bones are joined by hyaline cartilage• rib attachment to sternum• epiphyseal plate in children binds epiphysis and diaphysis

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Amphiarthroses - fibrous joint

• Syndesmosis• Two bones bound by ligament only• interosseus membrane

• Most movable of fibrous joints• Interosseus membranes unite radius to ulna and tibia to

fibula

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Amphiarthroses - cartilaginous joint

• Symphysis• 2 bones joined by fibrocartilage• pubic symphysis and intervertebral discs

• Only slight amount of movement is possible

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Diarthrosis - Synovial Joint

Joint in which two bones are separated by a space called a joint cavity

Most are freely movable7-7

General Anatomy

•Articular cartilage = hyaline cartilage covering the joint surfaces• Synovial cavity •Articular capsule encloses joint cavity• continuous with periosteum• lined by synovial membrane

• Synovial fluid = slippery fluid; feeds cartilages

•Articular discs and menisci• jaw, wrist, sternoclavicular and knee

joints• absorbs shock, guides bone

movements and distributes forces• Tendon attaches muscle to bone• Ligament attaches bone to bone

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Tendon Sheaths and Bursae

• Bursa = saclike extension of joint capsule • between nearby structures so slide more easily past each other

• Synovial tendon sheaths = cylinders of connective tissue lined with synovial membrane and wrapped around a tendon

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Range of Motion

•Degrees through which a joint can move• Nonaxial – vertebrocostal, sacroiliac• Monoaxial – elbow, knee,ankle, interphalangeal• Biaxial – radiocarpal• Triaxial (multiaxial) – sholder, hip

•Determined by• structure of the articular surfaces• strength and tautness of ligaments, tendons and capsule• stretching of ligaments increases range of motion• double-jointed people have long or slack ligaments

• action of the muscles and tendons• nervous system monitors joint position and muscle tone

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Types of Synovial Joints

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