Articulations
The place of union or junction between two or more bones of the skeleton
(also between cartilage and bones/teeth and bones
- allow for movement
- structure of joint determines the range of movement
- the closer the fit, the stronger the joint; the looser the fit, the
more movement
ARTHROLOGY – The science concerned with the study of joints, includes
function, structure, classification and any dysfunctions
KINESIOLOGY – the science concerned with the functional relationship,
or biomechanics, of the skeleton, joints and muscles as they work
together to produce coordinated movement.
I.
Classification of joints
A. Structural classification – based on the presence or absence of a joint
cavity and the kind of supportive tissue surrounding the joint.
Three types:
1. Fibrous joints – lack a joint cavity; fibrous connective tissue connects
articulating joints
2. Cartilaginous joints – lacks a joint cavity; cartilage binds articulating
bones
3. Synovial joints – has a joint cavity; ligaments help support articulating
bones
B. Functional classification – based on the degree of movement permitted
within the joint
Three types:
1. Synarthrosis – immoveable joints
2. Amphiarthrosis – slightly moveable joints
3. Diarthrosis – freely moveable joints
II. Breakdown by functional
classification
A. Synarthroses (immoveable joints)
1.Suture – strongest joint by
structure
- fibrous joints found between flat
bones of the skull
- irregular structure that gives
strength and reduces fractures
2.Gomphoses
- fibrous joints that occur between
teeth and the supporting bones of
the jaw.
- located where the root of a tooth is
attached to the periodontal ligament
of the alveolus (socket) of the bone.
3. Synchondroses
- cartilaginous joint with hyaline cartilage as the connective tissue
- some are temporary and form the epiphyseal growth plates between
the diaphysis and epiphysis in the long bones of children
B. Amphiarthroses – slightly moveable
joint
1. Syndesmoses
- Fibrous joint found only in the
forearm and leg where adjacent
bones are held together by
collagenous fibers
- Characteristic of the side-to-side
joints between tibia-fibula and the
radius-ulna (allows rotation)
2. Symphyses (symphysis pubis, and
intervertebral discs)
- Cartilaginous joint separated by a
pad of fibrocartilage; allows for
limited movement
- Only limited motion is possible at
each joint, the combined
movement allows for extensive
movement (vertebrae)
C. Diarthroses – freely moveable
1. Characteristics:
a. provides a wide range of precise,
smooth movements while maintaining
stability, strength, and some rigidity in
the body
b. most complex and varied of the three
major types
c. range of movement is limited by three
factors:
- structure of the bones participating in the articulation
- the strength and tautness of the associated ligaments, tendons
and joint capsule
- the size, arrangement and action of the muscles that span the joint
(“double jointed” is a misnomer; not two joints, but extreme
maneuverability due possibly to loose ligaments and tendons)
2. Structure of the synovial joint
a. Synovial Cavity – space between the
articulating bones refers to the structural
classification
b. Articular Cartilage – present in all diarthrotic
joints (2 mm thick), hyaline cartilage covers the
articulating surface
c. Articular Capsule – surrounds the entire
diarthrotic joint (two layers):
FIBROUS LAYER – outer layer
- dense, irregular connective tissue
- attaches to periosteum of bones
- permits movement and resists
dislocation
- fibers from ligaments; hold bones
together
SYNOVIAL MEMBRANE – Inner layer
- secretes synovial fluid (looks,feels like uncooked egg white)
- lubricates joints and nourishes cartilage
- houses phagocytic cells that remove microbes and debris
d. Accessory ligaments – some outside of
articular capsule, some within
e. Articular discs – pads of fibrocartilage called
menisci (meniscus = singular)
-Stabilize joint by forming tighter fit
-Tearing of these is called torn cartilage
f. Bursae – sac-like structures between
moving parts (help cushion and reduce
friction
-Filled with synovial fluid
-Found between skin and bone, tendon and
bone, muscle and bone, ligaments and bone
3. Types of synovial joints
a. Gliding joint – simplest type
- Allow only side-to-side and back-and-forth
movements with minimal rotation
- Surfaces are usually flat or slightly
concave/convex
- EX: Intercarpal/intertarsal, sternoclavicular,
between adjacent vertebrae
b. Saddle joint- looks like a saddle
-Each articular process has a concave
surface in one direction, convex in the
other
-Is a modified condyloid joint allowing a
wider range of movement
-EX: only associated with the thumb
(located at the articulation of the
trapezium of the carpus with the first
metacarpal bone)
c. Hinge joint – permits bending in only one direction
(similar to the hinge of a door)
-One surface is always concave and the other is convex
-Most common type of synovial joint
-EX: knee, humeroulnar, phalanges
d. Pivot – movement is limited to rotation about a central axis
-One surface is rounded and fits into a depression of another
-EX: proximal articulation of the radius and ulna, articulation between
atlas and axis
e. Ball-and socket – formed by
articulation of a rounded convex
surface with a cuplike cavity
-Provides the greatest range of
movement of all joints
-EX: hip and shoulder joints
f. Condyloid or ellipsoid – structured so that an oval, convex surface of
one bone fits into an elliptical, concave depression of another bone
- Allows for angular movement in two directions (up and down and sideto-side motion)
- EX: radiocarpal joint
III. Problems
A. Clinical considerations
1. Hyperextension
2. Strained joint
3. Sprain
4. Luxation
5. Bursitis
6. Tendonitis
B. Diseases of joints
Arthritis -
1. Rheumatoid arthritis
2. Osteoarthritis
3. Gouty arthritis
www.crnasomeday.com/anatpages/joints.htm
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www.mnsu.edu/.../humananatomy/images/body.jpg
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commons.bcit.ca/.../pics/symphysis.jpg
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content.answers.com/.../dental/f0475-01.jpg
www.hawaii.edu/.../pediatrics/pemxray/v1c18f.jpg
academic.wsc.edu/faculty/jatodd1/351/joints2.jpe
www.daviddarling.info/images/synovial_joint.jpg
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sciencefun4all.net/.../Images/Joints/GLIDING.jpg
www.shockfamily.net/skeleton/SADDLE.JPG
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sciencefun4all.net/.../Images/Joints/HINGE.jpg