Based on the material that
binds the bones together
Based on the degreee of
movement they permit
Diarthroses: Synovial Joints
• Freely movable
• Each joint contains
a fluid filled joint
cavity called the
synovial cavity
that separates the
articulating bones.
• Arcticular cartilage
covers the ends of
opposing bones but does
not bind them
• Articular capsule
surrounds the joint and
encloses the synovial
cavity
• Outer layer is fibrous
capsule (dense, irreg.
C.T.) which binds
periosteum of the
articulating bone to the
edge of the articular
cartilage
• Synovial membrane is the
inner layer of joint capsule,
only a few cells thick (loose
C.T.)
• Lines all internal joint
surfaces except articular
cartilage
• Richly supplied with
sensory nerve fibers (pain
and stretch) and blood
vessels
• Synovial fluid is secreted
by synovial membrane to fill
cavity
•
Synovial fluid consists
primary of blood filtrate,
protein and glycoprotein
secreted by fibroblasts
•
Functions of fluid:
1. Lubricates and reduces
friction
2. Supplies nutrients to and
removes metabolic wastes
from chondrocytes
3. Contains phagocytic cells
to remove microbes and
debris from wear/tear.
• Ligament
•
Band-like reinforcment which
resists recurrent strain
•
Can be found both capsular and
extracapsular
Articular Discs (meniscus) of fibrocartilage
• Joints containing a disk of
fibrocartilage that extends from
the capsule and divides the
joint cavity in two
• Improves the fit between
articulating bone of different
shapes which helps in stability
Medial and Lateral Meniscus
(semilunar cartilage)
2 fibrocartilage menisci occur
between the femoral and tibial
condyles.
Lateral and medial menisci
attach to the condyles of the
tibia.
They help stabilize the femur in
the joint and absorb some shock
transmitted to the knee.
Tibial Collateral (medial) and Fibular Collateral (lateral) Ligaments
The joint capsule is reinforced by extracapsular ligaments.
These ligaments are taut in the extended position to prevent hypertension
and lateral and medial movement.
Tibial Collateral (medial) and Fibular Collateral (lateral) Ligaments
1. The tibial ligament (medial) runs from the medial epicondyle of the
femur to the medial condyle of the tibia.
2. The fibular ligament (lateral) descends from the lateral epicondyles of the
femur to the head of the fibula.
Anterior and Posterior Cruciate Ligaments
The knee joint is reinforced by
intracapsular ligaments.
The cruciate ligaments form a cross as
each runs from the tibia superiorly to the
femur.
Each is named according to the location
of its attachment to the tibia.
Anterior and Posterior Cruciate Ligaments
The anterior cruciate ligament (ACL) –
Attaches to the anterior portion of the
tibia in the intercondylar area and travels
to attach to the femur on the medial side
of its lateral condyle.
It prevents :
Anterior sliding of the tibia on the femur
when the leg is flexed, and
Hypertension of the leg at the knee.
Anterior and Posterior Cruciate Ligaments
The posterior cruciate ligament (PCL) –
Attaches to the posterior intercondylar
area of tibia and passes anteriorly to
attach to the femur on the lateral side of
the medial condyle.
It prevents:
Forward sliding of the femur, or
Backward displacement of the tibia.
Both ligaments act to lock the knee in
standing position.
The knee is susceptibility to sports injuries because the articular surfaces
offer little stability.
It is especially vulnerable to horizontal blows such as tackling.
Lateral blows are especially dangerous.
The tibial collateral (medial) ligament
and the medial meniscus attached to it,
plus the relatively weak anterior cruciate
ligament can be ripped.
These can often be serious to career
ending injuries.
Movements of Joints
Flat surfaces slip across each
other.
Flexion - Bending that decreases
the angle of the joint and brings
the two bones closer together
e.g. carpal and tarsal joints
Extensions – increases the angle
and is a straightening action
Abduction – movement of limb away
from body mid line.
Rotation – turning movement of bone
around its own long axis.
Adduction – movement towards
Circumduction – moving a limb or finger
so that it describes a cone space.
Pronation – forearm rotates medially Dorsiflexion – lifting the foot so that its
so that the palm faces posteriorly.
superior surface approaches the shin.
Supination – forearm rotates laterally Plantar flexion – depressing the foot
so that palm faces anteriorly.
(pointing the toes)
Eversion – turn the sole of the
foot laterally.
Inversion – turn the sole of the
foot medially.
Protraction – movement of the
mandible or shoulder girdle forward on
a plane parallel to the ground.
Retraction – movement of a protracted
body part backward on a plane
parallel to the ground.
Elevation – lifting of a body part
superiorly.
Depression – moving the elevated part
inferiorly.
• Plane (gliding)
•
Both articular surfaces are essentially
flat planes
•
Short gliding movements are allowed,
nonaxial movement
– e.g. intervertebral, intercarpal,
intertarsal
• Hinge
•
The cylindrical end of one bone fits into
a trough shaped surface on the other
bone
•
Movement allowed in once direction,
uniaxial.
– e.g. elbow, interphalangeal
• Pivot
•
Rounded end of one bone fits into a
ring formed by another bone plus its
ligament
•
Rotating bone on long axis, uniaxial
– e.g. atlas & axis, supinator, radialulnar
• Condyloid
•
Egg-shaped articular surface of 1 bone
fits into an oval concavity in another.
•
Allows side-to-side
adduction/abduction and flex and
extend, biaxial
– e.g. wrist, metacarpophalangeal
• Saddle
• Each articular surface has both
convex and concave areas
– e.g. thumb-carpometacarpal
• Ball and socket
• Spherical head fits into round
socket. Universal movement
• Universal movement, multiaxial
– e.g. shoulder, hip
Medial and Lateral Condyles of Femur and Tibia
This joint is bicondyloid.
The wheel shaped condyles
of the femur roll along the flat
surfaced condyles of the tibia.
It acts primarily as a hinge.
Bursae and Tendon Sheaths
• Flat fibrous bags lined
by synovial membrane
and filled with lubricant
(synovial fluid) which
act like “ball bearings”
to reduce drag.