Chapter #8: Joints Flashcards
Joints
(articulations) the site where two bones meet (may or may not allow movement)
What are the general functions of joints?
Mobility & Stability
Mobility
Allow movement of various body parts
Stability
hold the skeleton together (holds bones in place and prevent damage to internal structures)
Which skeleton has more mobility?
Appendicular skeleton
Which skeleton has more stability?
Axial skeleton
Structural Classifications of Joints
Fibrous, cartilaginous, and synovial
Fibrous joints
joints composed of collagen fibers of connective tissue (no joint cavity present; movement allowed with mostly synarthroses and a few amphiarthroses)
Types of fibrous joints
sutures, syndesmoses, and gomphoses
Sutures
Found only between bones of the skull (composed of bundles of very short & strong collagen fibers) and permits very little movement
Why do you want little movement with sutures?
don’t want anything injuring your brain
What happens to sutures over time?
ossifies over time in adults to form syntoses
Syndesmoses
bones are connected to each other only by ligaments (movement allowed by joint depends on the length of the ligament bands)
Ligaments
bands of fibrous tissue that join bone to bone
What is the relationship between length and movement allowed within ligaments?
more length = more movement
Gomphoses
only joint type that does not join bone to another bone (joins tooth to bony alveolar socket)
-fibers of joint are very short, providing very limited movement (exception: braces)
Periodontal Ligament
joins the bone of the mandible/maxilla to the tooth
Cartilaginous Joints
bones joined by cartilage
-no joint cavity
-movement allowed: synathroses & amphiarthroses
Types of cartilaginous joints
Synchondroses & symphyses
Synchondroses
bones unites with a plate of hyaline cartilage
-mostly synathroses
-ex. epiphyseal plate in long bones, costal cartilage
Symphyses
fibrocartilage joins bone
-some movement allowed, but limited (see this with joints that bear a lot of weight)
-ex. intervertebral joints (discs can herniate)
-ex. pubic symphysis
What is the benefit of fibrocartilage at symphyses joints?
Permitting small amount of movement prevents injury
Synovial joints
possesses joint cavity, diarthroses, most joints fall under this category
Why are almost all synovial joints found in the appendicular skeleton?
we need lots of movement
Structures found in synovial joints
articular cartilage, joint cavity, articular capsule, synovial fluid, reinforcing ligaments, innervation & vascularization
Articular Cartilage
hyaline cartilage covering bone ends
What is the function of articular cartilage?
prevents bone from rubbing on bone
Joint cavity
small space between articulating bones
What is the function of a joint cavity?
responsible for temporarily storing synovial fluid
Articular capsule
two-layered capsule that encloses the joint cavity
What two layers make up the articular capsule?
Fibrous layer and synovial membrane
Fibrous layer
outer layer that is continuous with periosteum of bones
What is the function of the fibrous layer?
connects one bone to the bone it joins with; reinforces structure