CHAPTER 8: JOINTS Flashcards
Joints (articulations)
Articulation: site where 2 or more bones meet
Function of joints:
- give skeleton mobility
- hold skeleton together
*Classified by structure and function
Functional classification of joints
- based on the amount of movement allowed by the joint
- Three functional classifications:
- synarthrosis: immovable (ex: sutures in skull)
- amphiarthrosis: slightly moveable (sacroiliac joint)
- diarthrosis: freely movable (fingers, wrists, elbows)
Structural classification of joints
Whether there’s a joint cavity or not
Three structural classifications:
1. fibrous
2. cartilaginous
3. synovial
Synovial joints
*1 of 4 membranes (serous, mucous, cutaneous)
*Include all limb joints, most joints of the body
Synovial joints distinguishing features
- hyaline cartilage
- synovial cavity: small potential space (fibrous membrane around joint)
- articular (joint) capsule: outer fibrous capsule of dense irregular connective tissue; Inner synovial membrane of loose connective
- synovial fluid:
- between hyaline joints
- lubricates hyaline cartilage
- weeping lubrication - rich nerve and blood vessel supply
- nerve fibers monitor joint position and stretch and detect pain
Friction reducing structures in synovial joints: Bursae
Bursae:
- flattened fibrous sacs lined with synovial membranes
- act as “ball bearings”, where ligaments, tendons, skin, muscles, or bones rub together
Friction reducing structures in synovial joints: tendon sheath
Tendon sheath:
- Elongated bursa that wraps completely around a TENDON
Stabilization of synovial joints
- Shapes of articular surfaces
- Ligament number and lcoation
- Muscle tone, which keeps tendons that cross the joint taught
Stabilization of synovial joints
- Shapes of articular surfaces
- Ligament number and location
- Muscle tone, which keeps tendons that cross the joint taught
Synovial joints: range of motion
Nonaxial- little slipping movements (carpals)
Uniaxial- movement in one plane (elbow)
Biaxial- movement in two planes (finger)
Multiaxial- movement in three planes
Movements at synovial joints
gliding:
one flat bone surface glides or slips over another similar surface (carpals, tarsals, vertebrae)
angular movements:
- flexion, extension, hyperextension
- abduction, adduction
- circumduction
rotation:
medial and lateral rotation (turning of a bone around its own long axis)
classification of synovial joints
based on shape of articular surface:
1. hinge
2. plane (glide)
3. pivot
4. condyloid (cup and flask)
5. saddle (carpals)
6. ball and socket
Plane joints
nonaxial joints
flat articular surfaces
short gliding movements
hinge joints
uniaxial joints
motion along a single plane
flexion and extension only
