Synovial Joints

Topics: Synovial joint, Knee, Bone Pages: 6 (621 words) Published: December 21, 2014
SYNOVIAL JOINTS
Torie Shultz, Noelle Henniger, Chris Scanlon

Synovial Joint
Freely moveable (diarthroic)
Most complex
Consists of:
Articular cartilage
Joint capsule
Synovial membrane which
secrets synovial fluid
Ligaments
Bursae
Menisci

Articular Cartilage
Hyaline cartilage covers the bones
surface is known as articular
cartilage
Resists wear and minimizes friction
Subchondral plate- bone beneath
articular cartilage that contains elastic
cancellous bone
Absorbs shock, protects from stress
by body weight and force of
contracting muscles
Excessive mechanical stress (obesity
or athletics) may cause fractures

Joint Capsule
Tubular joint capsule (articular
capsule): two articular cartilage layers
that encloses joint cavity
Outer layer: dense connective tissue
that attaches to periosteum
Inner layer: shiny, vascular lining of
loose connective tissue called synovial
membrane
Outer fibrous layer of capsule
Encloses joint
Flexible for movement
Strong to prevent pulling apart of
articular surfaces

Synovial Membrane
Inner lining layer of loose
connective tissue of joint
capsule
Surrounds closed sac called
synovial cavity
Secrets clear, viscous fluid called
synovial fluid
Stores adipose tissue and forms
moveable pads within joints
Resorbs fluid
Extensions (projections and folds)
fill spaces of joint and increase
surface area of membrane

Synovial Fluid
Synovial fluid moistens and
lubricates smooth cartilage
surfaces within joint
Supplies articular
cartilage with nutrients
obtained from blood
vessels
Reduces friction between
bones
Helps with shock
absorption

Ligaments
Bundles of collagenous fibers
called ligaments reinforce joint
capsule and bind articular ends
of bones
Located in fibrous layer of
capsule or accessory
structures outside capsule
Surrounds the joint cavity
Prevent excessive movement
at joint
Inelastic and tighten when
joint stressed

Menisci
Synovial Joints divided into two
compartments by disc of
fibrocartilage called menisci which is
rim of white fibrous cartilage located
between articular surfaces
Each meniscus attaches to fibrous
layer of joint capsule and the free
surface projects into joint cavity
Knee joint contains crescentshaped menisci that cushions and distributes body weight
Shock absorber
Protection of edges
Facilitates movement

Bursae
Fluid-filled sacs called
bursae are the inner lining of
synovial membrane
Contains synovial fluid
Located between skin and
bony prominences (knee,
elbow)
Cushions and aids
movement of tendons

Six Types of Synovial Joint
Classified according to arrangement of articular surfaces and types of movement:
Ball-and-socket
Condyloid
Gliding
Hinge
Pivot
Saddle

Ball-and-Socket Joint
Egg-shaped head articulates
with a cup shaped cavity of
another bone.
Allows for a wider range of
motion than any other joint.
Permits rotational movement
around a central axis.

Ex: Hip and shoulder

Condyloid Joint
The ovoid condyle of a bone
fits into the elliptical cavity of
another
Allows movement in
different planes
Rotational movement is
NOT possible
Ex: Joints between
metacarpals and phalanges

Gliding Joint
Nearly flat or slightly curved
Allow sliding, twisting, and
back-and-forth motion
Ex: Most joints in wrist and
ankle

Pivot Joint
Cylindrical surface of one
bone rotates within a ring of
bone and a ligament
Limited to rotation around a
central axis

Ex: First and Second cervical
vertebrae allow head to move
from side to side

Hinge Joint
Convex surface fits into the
concave surface of another
Permits movement in one
plane only
Ex: Elbow

Saddle Joint
Surface of one bone fits into
the surface of another
Articulating surfaces have
convex and concave surfaces
Allows movement in two
planes only
Ex: Metacarpal of the thumb

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