Based on the degreee of movement they permit - Based on the material that binds the bones together

Based on the degreee of
Based on the material that    movement they permit
 binds the bones together

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   Flexion - Bending that decreases
other.                           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   Rotation – turning movement of bone
from body mid line.                 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    Protraction – movement of the
foot laterally.                    mandible or shoulder girdle forward on
                                   a plane parallel to the ground.
Inversion – turn the sole of the
foot medially.                     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, radial-
       ulnar

• 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.