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Joints & Articulations
Classification Of Joints

Classification By Function (degree of
movement possible):
1. Synarthroses (Syn=connected, immovable)


Joints with little or no movement
Skull sutures, cranium (minus the mandible)
2. Amphiarthroses (Amphi = on both sides, between)
 Slightly moveable joints
 Intervertebral discs, costosternal joints, cartilaginous
joints(vertebrate between spine)
3. Diarthroses (Diar=passing through, free moving)
 Freely moveable joints
 Shoulder, knee, hip, elbow, interphalangeal, tarsal,
and carpal joints
Joint Classification

Classification by
structure:
1. Synovial joints:


Bones separated
by a joint cavity;
lubricated by
synovial fluid;
enclosed in a
fibrous joint
capsule.
Shoulder, hip,
elbow, knee,
carpal,
interphalangeal
How would we classify these
joints functionally?
Joint Classification
2. Fibrous joints:


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Bones held together
by collagenous
fibers extending from
the matrix of one
bone into the matrix
of the next.
No joint cavity
Skull sutures, teeth
in joints, distal
radioulnar joints &
tibiofibular joints
Joint Classifications
3. Cartilaginous joints:


Bones held together by cartilage; no joint cavity
Epiphyseal plates of long bones, costosternal joints,
pubic symphysis, intervertebral discs
Structure and Function
 Joints are designed
for their function.
 Let’s look at sutures
as our 1st example:
 Name 4 sutures!
 What function do you
suppose sutures are
designed for?
Types of Joints in the
Human Body
(1) Immovable: fixed joint such as the cranium
(2) Ball-and-socket joints: such as the shoulder and hip joints, allow
backward, forward, sideways, and rotating movements.
(3) Hinge joints: such as in the fingers, knees, elbows, and toes,
allow only bending and straightening movements.
(4) Pivot joints: such as the neck joints, allow limited rotating
movements.
(5) Sliding Joint: found in the vertebral column and allows small
sliding movements. The vertebrae have pads of cartilage between
them, and the bones slide over these pads. This is what makes the
backbone so flexible.
(6) Ellipsoidal Joint: similar to a ball and socket joint. They allow
the same type of movement to a lesser magnitude such as the wrist
Structure and Function

Now let’s talk about
synovial joints.

5 main structural
characteristics:
1. Articular cartilage

What kind of
cartilage is it?


Where do we find it?
What does it do?
Structure and Function
2. Articular capsule



2 layered. Surrounds both
articular cartilages and the
space btwn them.
External layer is made of
dense irregular CT & is
continuous w/ the
perisoteum.
Inner layer is a synovial
membrane made of loose
connective tissue.

It covers all internal joint
surfaces except for those
areas covered by the
articular cartilage.
Structure and Function
3.
Joint (Synovial) Cavity

4.
The potential space within
the joint capsule and
articular cartilage
Synovial Fluid



A small amount of slippery
fluid occupying all free
space w/i the joint capsule
Formed by filtration of
blood flowing thru
capillaries in the synovial
membrane
Synovial fluid becomes
less viscous as joint
activity increases.
Structure and Function
5.
Reinforcing Ligaments



What kind of tissue are
they?
What do you suppose
their function is?
Double-jointed-ness
results from extrastretchy ligaments and
joint capsules. Is this
necessarily a good
thing?
Other Synovial Structures
 The knee and hip joints
have cushioning fatty
pads btwn the fibrous
capsule and the synovial
membrane or bone.
 Discs of fibrocartilage
(i.e., menisci) which
improve the fit between
bone ends, thus
stabilizing the joint.
 Found in the knee, jaw, and
sternoclavicular joint.
 Bursae are basically bags
of lubricant - fibrous
membrane bags filled with
synovial fluid. Often
found where bones,
muscles, tendons, or
ligaments rub together.
Types of
Synovial Joints
1.
Plane joints


2.
Articular surfaces are flat and
allow short slipping or gliding
movements.
Intercarpal and intertarsal
joints
Hinge joints



A cylindrical projection of one
bone fits into a troughshaped surface on another
(like a hotdog in a bun)
Movement resembles a door
hinge.
Elbow joint – ulna and
humerus; Interphalangeal
joints
Type of
Synovial Joints
3.
Pivot joints



4.
Rounded end of one bone
protrudes into a ring formed by
another bone or by ligaments of
that bone.
Proximal radioulnar joint
Atlas-axial joint
Condyloid joints



Oval articular surface of one
bone fits into a complementary
depression on another.
Radiocarpal joints
Metacarpophalangeal joints
Types of
Synovial Joints
5. Saddle joints


Each articular surface has convex
and concave areas. Each
articular surface is saddleshaped.
Carpometacarpal joints of the
thumbs.
6. Ball-and-Socket joints



Spherical or semi-spherical head
of one bone articulates with the
cuplike socket of another.
Allow for much freedom of
motion.
Shoulder and hip joints.
The Knee
 Largest and most complex
diarthrosis in the body.
 Primarily a hinge joint, but
when the knee is flexed, it is
also capable of slight rotation
and lateral gliding.
 Actually consists of 3 joints:
 Patellofemoral joint
 Medial and lateral tibiofemoral
joints
 The joint cavity is only partially
enclosed by a capsule – on
the medial, lateral, and
posterior sides.
 The lateral and medial
condyles of the femur
articulate with the
lateral and medial
condyles of the tibia.
 Between these
structures, we have the
lateral and medial
menisci.
 Anteriorly, the patellar
ligament binds the
tibia (where?) to the
inferior portion of the
patella. The superior
portion of the patella
is then connected to
the quadriceps
femoris muscle
The Knee
 At least a dozen
bursae are associated
with the knee.
 Multiple ligaments are
present.
 The fibular collateral
ligament extends from
the lateral epicondyle
of the femur to the
head of the fibula.
 The tibial collateral
ligament connects
medial epicondyle of
the femur to the medial
condyle of the tibial
shaft and is also fused
to the medial
meniscus.
 Both of these ligaments
prevent excessive
rotation
The Knee
 The anterior and posterior
cruciate ligaments are
also very important.
 ACL connects the anterior
intercondylar area of the
tibia to the medial side of the
lateral femoral condyle.
 Prevents forward sliding of
the tibia and hyperextension
of the knee.
 PCL connects the posterior
intercondylar area of the
tibia to the lateral side of the
medial femoral condyle.
 Prevents backward
displacement of the tibia or
forward sliding of the femur.
The Knee
ACL Videos
http://video.about.com/sportsmedicine/Anterior-Cruciate-Ligament.htm
http://video.about.com/sportsmedicine/Medial-Meniscus-Injury.htm
Articulations (Movements)
Clinical
Conditions
 Arthritis describes about
100 different types of
inflammatory or
degenerative joint
diseases.
 Osteoarthritis
 Most common arthritis.
 Normal joint use prompts
the release of cartilagedamaging enzymes. If
cartilage destruction
exceeds cartilage
replacement, we’re left with
roughened, cracked,
eroded cartilages.
 Eventually bone tissue
thickens and forms spurs that
can restrict movement.
 Most common in C and L
spine, fingers, knuckles,
knees, and hips.
 Rheumatoid arthritis
 Chronic inflammatory
disorder
 Marked by flare-ups
 Autoimmune disease.
 Body creates antibodies
which attack the joint
surfaces
 The synovial membrane
can inflame and eventually
thicken into a pannus – an
abnormal tissue that clings
to the articular cartilage.
Clinical
Conditions
Clinical
Conditions
 Gouty arthritis
 When nucleic acids are metabolized uric
acid is produced. Normally uric acid is
excreted in the urine.
 If blood [uric acid] rises due to decreased
excretion or increased production, it may
begin to form needle-shaped crystals in
the soft tissues of joints.
 Inflammation ensues causing painful
arthritis.