ch 8 Flashcards
Joints (articulation)
Functions of joints: give skeleton mobility and hold skeleton together
Classification of Joints
Structural: three types based on what material binds the joints and whether a cavity is present
Fibrous
Cartilaginous
Synovial
Functional classifications: three types based on movement joint allows
Synarthroses: immovable joints
Amphiarthroses: slightly movable joints
Diarthroses: freely movable joints
Fibrous Joint
Bones joined by dense fibrous connective tissue
No joint cavity
Most are immovable
Sutures-Rigid, interlocking joints of skull Allow for growth during youth
Syndesmoses- Bones connected by ligaments, bands of fibrous tissue Fiber length varies, so movement varies
Gomphoses- Only examples are the teeth in alveolar sockets
Cartilagenous Joint
Bones united by cartilage
Like fibrous joints, have no joint cavity
Not highly movable
Two types:
Synchondroses-Bones united by hyaline cartilage
Symphyses- Bones united by fibrocartilage
Synovial Joint
Bones separated by fluid-filled joint cavity
All are diarthrotic (freely movable)
Include almost all limb joints
Have six general features Have bursae and tendon sheaths associated with them Stability is influenced by three factors Allow several types of movements Classified into six different types
Synovial joints have six general features
Articular cartilage: consists of hyaline
cartilage covering ends of bones
Prevents crushing of bone ends
Joint (synovial) cavity: small, fluid-filled potential space that is unique to synovial joints
Articular (joint) capsule: two layers thick
External fibrous layer: dense irregular connective tissue
Inner synovial membrane: loose connective tissue that makes synovial fluid
Synovial fluid: viscous, slippery filtrate of
plasma and hyaluronic acid
Lubricates and nourishes articular cartilage
Contains phagocytic cells to remove microbes and debris
Different types of reinforcing ligaments
Capsular: thickened part of fibrous layer
Extracapsular: outside the capsule
Intracapsular: deep to capsule; covered by synovial membrane
Nerves and blood vessels
Nerves detect pain; monitor joint position and stretch
Capillary beds supply filtrate for synovial fluid
Other Synovial Joint feature
Fatty pads
For cushioning between fibrous layer of capsule and synovial membrane or bone
Articular discs (menisci) Fibrocartilage separates articular surfaces to improve “fit” of bone ends, stabilize joint, and reduce wear and tear
Three factors determine stability of joints to prevent dislocations
Shape of articular surface (minor role)
Shallow surfaces less stable than ball-and-socket
Ligament number and location (limited role)
The more ligaments, the stronger the joint
Muscle tone keeps tendons taut as they cross joints (most important)
Extremely important in reinforcing shoulder and knee joints and arches of the foot
Movement allowed by synovial
All muscles attach to bone or connective tissue at no fewer than two points
Origin: attachment to immovable bone
Insertion: attachment to movable bone
Muscle contraction causes insertion to move toward origin
Movements occur along transverse, frontal, or sagittal planes
Range of motion allowed by synovial joints
Nonaxial: slipping movements only
Uniaxial: movement in one plane
Biaxial: movement in two planes
Multiaxial: movement in or around all three planes
Three general types of movements
Gliding
Angular movements
Rotation
Gliding
One flat bone surface glides over another similar surface
Angular movement
Increase or decrease angle between two bones
Movement along sagittal plane (extension, Flexion, circumduction, adduction)
rotation
turning of bone around axis, (pronation, supination)
six different types of synovial joints
Non Axial movement- plane joint
Uniaxial joint- hinge joint/ Pivot joint
Biaxial movement- condylar joint/ saddle joint
multiaxial- ball and socket
Five main synovial joints
Knee Shoulder Elbow Hip Jaw
Knee Joint general
Largest, most complex joint of body
Consists of three joints surrounded by single cavity
Femoropatellar joint
Plane joint
Allows gliding motion during knee flexion
- Lateral joint and 3. Medial joint
Lateral and medial joints together are called tibiofemoral joint
Joint between femoral condyles and lateral and medial menisci of tibia
Hinge joint that allows flexion, extension, and some rotation when knee partly flexed
