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Plane (Gliding) Joints
Plane joints have apposing flat to slightly
curved articular surfaces that slide
over one another. The movement is slight.
Examples of plane joints include intertarsal
and intercarpal joints and the joints
between the articular facets of vertebrae. |
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Hinge Joints
These joints permit angular movement
in a single plane. Examples include
the elbow and knee joints. |
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Pivot Joints
Pivot joints only permit rotation.
The joint between the atlas and the axis is
an example. |
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Condylar (Ellipsoidal) Joints
In
condylar joints, an oval convex
articular surface moves in an oval
depression. This permits angular
movement in two planes. Condylar
joints exist between the proximal phalangeal
bones and the metatarsal and metacarpal
bones in the hands and feet. |
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Saddle Joints
In
saddle joints, two saddle-shaped articular
surfaces, orient at right angles to one
another, appose one another in an
interlocking fashion. This kind of joint
permits a wider range of angular movement
than the condylar joint. The joint at the
base of the thumb is an example. |
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Ball-and-Socket Joint
In
this joint the hemispherical articular
surface of one bone fits into the cup-shaped
depression of the other. Angular and
rotational movements are permitted. The
shoulder and hip joints are examples.
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Knee Joint
The
knee joint will serve as an example of a
synovial joint. The knee joint is a complex
joint in which the wheel-shaped femoral
condyles "roll" on the flat tibial
articular surfaces. The knee joint can be
divided into three separate joints with
there own separate joint capsules:
the femoral medial condyles articulate
with the tibial medial condyles; |
the femoral lateral condyles
articulate with the tibial lateral
condyles; and |
the patella articulates with the
patellar surface of the femur. |
Menisci
The medial and lateral condylar
articulations between the femur
and tibia have between them pads
of fibrocartilage called the medial
and lateral menisci. These
menisci
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1. absorb
the compressive forces
generate at this
weight-bearing joint; |
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2. more
evenly distribute the
force transferred from the
femoral articulations to
the tibial; and |
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3. provide
lateral stability. |
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Supporting
Ligaments
Seven
major ligaments support the knee
joints:
The patella (knee cap) is
present in the tendon of
the muscle that extends
the knee. The patella
ligament extends from
the patella to its
attachment to the tibia
and supports the anterior
side of the knee joint. |
The
remaining ligaments are
classified as either extracapsular
or intracapsular depending
on their position relative
to the fibrous joint
capsule. The
extracapsular ligaments
are: |
The tibial collateral
ligament reinforces
the medial side of the
knee joint and the fibular
collateral ligament
reinforces the lateral
side of the knee joint.
Two
popliteal ligaments reinforce
the posterior side of the
knee joint. |
The
intracapsular ligaments
are: |
The anterior cruciate
ligament (ACL) and the
posterior cruciate
ligament (PCL) limit
the anterior and posterior
movement of the femur. The
names of these ligaments
derive from the way they
cross one another and
their relative attachments
on the tibia.
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