Chapter 8 joints Flashcards
joints
the junction of two or more bones
synarthosis
immovable joint
amphiarthorsis
a slightly movable joint
diarthrosis
freely movable joint
fibrous joints
bones joined by fibrous tissue; no joint cavity is present
suture
an immovable fibrous joint; with one exception, all the bones of the skull are united by sutures
synostoses
a completely ossified joint; a fused joint
syndesmosis
a fibrous joint in which the bones are united by a ligament or a sheet of fibrous tissue
gomphosis
a fibrous joint; peg-in-socket fibrous joint, ex. tooth with bony alveolar socket.
cartilaginous joints
bones united by cartilage; no joint cavity
synchondrosis
a cartilaginous joint in which the bones are united by hyaline cartilage; almost all are synarthrotic (immovable)
ex. epiphyseal plates in children
symphysis
a cartilaginous joint in which the bones are connected by fibrocartilage.
plane joint
flat articular surfaces, nonaxial movement, gliding, found in intercarpal joints
hinge joint
cylinder & trough; uniaxial movement, flexion and extension (medial/lateral axis) found in elbow joints
pivot joints
sleeve(bone and ligament) & axle; uniaxial movement (vertical axis) rotation; proximal radioulnar joints
condylar joint
oval articular surfaces, biaxial movement, medial/lateral axis, flexion and extension, adduction and abduction; wrist joints
saddle joint
articular surfaces are both concave and convex; biaxial movement, medial/lateral axis, anterior/posterior axis; adduction and abduction; flexion and extension; carpometacarpal joints of the thumbs
ball-and-socket joint
cup(socket) and spherical head (ball); multiaxial movement, medial/lateral axis, flexion and extension; anterior/posterior axis, adduction and abduction; and vertical axis, rotation, shoulder joints,
synovial joint
freely movable joint exhibiting a joint cavity; also called a diarthrosis
6 synovial joint features
articular cartilage, joint cavity, articular capsule, synovial fluid, reinforcing ligaments, nerves and blood vessels
articular cartilage
hyaline cartilage covering bone ends at movable joints
joint (articular cavity)
potential space that contains a small amount of synovial fluid
articular capsule
double-layered capsule composed of an outer fibrous layer lined by synovial membrane; encloses the joint cavity of a synovial joint.
synovial membrane’s function
make synovial fluid
synovial fluid
fluid secreted by the synovial membrane; lubricates joint surfaces and nourishes articular cartilages.
reinforcing ligaments
synovial joints are reinforced and strengthened by a number of band-like ligaments.
weeping lubrication
a form of hydrostatic lubrication in which the interstitial fluid of hydrated articular cartilage flows into its surface when a load is applied.
capsular ligaments
thickened fibrous structures, lined with synovial membrane and surrounding articulations.
intrascapsular ligaments
ligaments located within and separate from the articular capsule of a synovial joint.
fatty pads
cushioning between fibrous layers and synovial membrane or bone.
menisci (articular discs)
discs or wedges of fibrocartilage separating articular surfaces
bursa
a fibrous sac lined with synovial membrane and containing synovial fluid; occurs between bones and muscle tendons (or other structures) where it acts to decrease friction during movement
tendon sheath
an elongated bursa that wraps completely around a tendon subjected to friction
factors influencing the stability of synovial joints
- the shapes of the articular surfaces
- the number & position of ligaments
- muscle tone (for many, this is most important)
muscle tone
low levels of contractile activity in relaxed muscles that keep the muscles healthy and ready to react to stimulation
origin
attachment of a muscle that remains relatively fixed during muscular contraction (one end)
insertion
(other end) movable attachment of a muscle
body movement happens when
muscles contract across joints and their insertion moves towards their origin.
nonaxial movement
slipping movements only
uniaxial movement
movement in one plane
biaxial movement
movement in two planes
multiaxial movement
movement in or around all three planes of space & axes.
3 general types of movement
gliding, angular movements and rotation
gliding
occurs when one flat or nearly flat, bone surfaces glides or slips over another without appreciable angle and rotation
angular movements
increase or decrease the angle between two bones
flexion
movement that decreases the angle of the joint, ex. bending the knee from a straight to an angled position,
extension
is the reverse of flexion and occurs at the same joints. increases the angle of the joints.
hyperextension
movements beyond the anatomical position.
abduction
to move away from the midline of the body
adduction
moving toward, movement of a limb toward the body midline
circumduction
circular movement of a body part so that it outlines a cone in space.
rotation
the turning of a bone around its own long axis.
pronation
(palm down) radius rotates over ulna, inward rotation of the forearm causing the radius to cross diagonally over the ulna-palms face posteriorly.
supination
(palm up) radius and ulna are parallel, outward rotatiuon of forearm causing palms to face anteriorly
doriflexion
pointing foot up
plantar flexion
pointing foot down
inversion
sole towards midline
eversion
sole towards lateral
protraction
nonangular anterior movement in a transverse plane
retraction
nonangular posterior movement in a transverse plane (mandible)
elevation
lifting a body part superiorly, ex. shrugging shoulders
depression
moving the elevated part inferiorly
opposition
of the thumbs, is the action taken when you touch your thumb to the tips of the other fingers on the same hand
