Chapter 3
Articular System
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Objectives
Differentiate types of joints
Describe structures associated with
synovial joints
State the plane and axis for joint
movements
Identify the degrees of freedom for
various joints
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Joint
Connection between two bones
Functions:
Allow motion
Bear weight
Provide stability
Contain synovial fluid
⌧Lubricate joint
⌧Nourishes Cartilage
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Fibrous Joint
Thin layer of fibrous periosteum between
the two bones
Three types
Synarthrosis = Suture Joint
Syndesmosis = Ligamentous Joint
Gomphosis = “bolting together,” tooth and
dental socket
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Fibrous: Synarthrodial = Suture
Thin layer of fibrous
periosteum between
the two bones
Bone ends interlock
No movement
Purpose:
Provide shape
Provide stability
Example:
Sutures of the skull
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Fibrous:
Syndesmosis = Ligamentous
Great deal of fibrous tissue
Ligaments and interosseous
membranes hold joint
together
Small amount of twisting or
stretching movement can
occur
Examples:
Distal tibiofibular joint
Distal radioulnar joint
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Cartilaginous = Amphiarthrodial
Hyaline cartilage or fibrocartilage
between the two bones
Allow a small amount of motion
Bending
Twisting
Compression
Provide a great deal of stability
Examples:
Symphysis pubis - fibrocartilage
between
First sternocostal joint - hyaline
cartilage between
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Synovial = Diarthrodial
No direct union between the bone ends
Allows free motion
Components
Cavity filled with synovial fluid
Sleeve-like capsule
⌧Outer layer strong fibrous tissue
⌧Inner layer synovial membrane secretes
synovial fluid
Articular surface smooth
⌧Covered with hyaline or articular cartilage
Example: Hip, elbow, knee
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Joint Classification
Type
Synarthrosis
Motion
None
Structure
Fibrous-suture
Example
Bones in the skull
Syndesmosis
Slight
Fibrous-ligamentous
Distal tibiofibular
Amphiarthrosis Little
Cartilaginous
Symphysis pubis,
vertebrae
Diarthrosis
Synovial
Hip, elbow, knee
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Free
Joint Classifications By Axes
Nonaxial
Linear movement (not
angular)
Gliding motion
Joint surfaces flat
example: Intercarpal
Biaxial
2 axes, 2 planes
Condyloid or saddle
example: Metacarpophalangeal
and radiocarpal
Uniaxial
1 axis, 1 plane
Hinge or pivot
example: elbow and
interphalangeal joints
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Triaxial or Multiaxial
3 axes, 3 planes
Ball and socket
example: hip and shoulder
Synovial Joints
Components
Bones
Ligaments
Joint Capsule
Synovial Fluid
Cartilage
Muscles
Bursae
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Types of Synovial Joints
Plane
Hinge
Pivot
Condyloid
Saddle
Ball and Socket
Plane Joint
Synovial/Diarthrodial
Nonaxial
Relatively flat joint surfaces
Glide over one another
No degrees of movement
Example: Intercarpal or intertarsal joints
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Hinge or Ginglymus Joint
Synovial/Diarthrodial
Uniaxial
One plane, one axis
One degree of freedom
Example: Elbow, knee, or interphalangeal
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Pivot or Trochoid Joint
Synovial/Diarthrodial
Uniaxial
One plane, one axis
One degree of freedom
Example: Radioulnar joint or A-A joint of C1-C2
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Condyloid or Ellipsoidal Joint
Synovial/Diarthrodial
Biaxial
Two planes, two axes
Two degrees of freedom
Example: Wrist
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Saddle Joint
Synovial/Diarthrodial
Biaxial
Rotation component is not active
Active motion around two axes
Bones fit like a horseback rider in a saddle
Example: Carpometacarpal (CMC) joint of the thumb
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Ball and Socket Joint
Synovial/Diarthrodial
Triaxial or Multiaxial
Three planes, three axes
Three degrees of freedom
Example: Shoulder or hip
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Joint Structure
of Synovial Joints
Bones
Ligaments
Synovial Fluid
Cartilage
Muscles
Bursae
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Joint Structure
(cont’d)
Bones - two articulating
Ligaments - holds bones together
Bands of fibrous connective tissue
⌧Provide attachment for cartilage, fascia, and muscle
Flexible but not elastic
Allows joint motion
Capsular ligaments surround and protect joints
⌧Example: Anterior talofibular ligament
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Joint Structure
(cont’d)
Capsule - surrounds and
encases the joint
Protects the articular
surfaces of the bone
Example: shoulder joint
encases and create a partial
vacuum
Two layers
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Joint Structure
(cont’d)
Capsule -Two layers
Outer Layer
⌧Fibrous tissue
⌧Provides support and
protection
Inner Layer
⌧Lined with synovial membrane
⌧Thick vascular connective
tissue
⌧Secretes synovial fluid
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Joint Structure
(cont’d)
Synovial Fluid
Thick, clear fluid, like the white of an egg
Lubricates the articular cartilage
⌧Reduces friction
⌧Helps to keep the joint moving freely
Provides some shock absorption
Major source of nutrition for articular
cartilage
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Joint Structure
(cont’d)
Cartilage
Dense fibrous connective tissue
Withstanding a great amount of pressure
and tension
Three types:
⌧Hyaline = Articular
⌧Fibrocartilage
⌧Elastic
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Joint Structure
(cont’d)
Cartilage - Three Types
Hyaline = Articular Cartilage - Ends of opposing bones
Smooth articular surface
No blood supply or nerve supply
Nutrition from synovial fluid
Fibrocartilage
Shock absorption, important in weight bearing joints
⌧Example: menisci knee, disk between sternum and clavicle,
labrum, IV disks
Elastic Cartilage
Certain amount of motion
⌧Example: symphysis pubis, larynx
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Joint Structure
(cont’d)
Cartilage - Three Types
Fibrocartilage
Labrum of shoulder
⌧Deepens the shallow
glenoid fossa
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Joint Structure
(cont’d)
Muscles
Provide the contractile force that causes joints
to move
Attach to bone through tendon
⌧Cylindrical cord or flattened band
⌧In certain locations in tendon sheaths
• Fibrous sheaths surround tendon when subject to
pressure or friction
• When passing between muscles and bones or through a
tunnel between bones
• Lubricated by fluid secreted from their lining
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Joint Structure
Muscles
(cont’d)
Aponeurosis - broad, flat tendinous sheet
Found in several places where muscles
attach to bones
Examples:
⌧Latissimus dorsi
⌧Abdominal muscles - linea alba
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Joint Structure
Bursa
(cont’d)
Small padlike sacs
In areas of excessive friction
Under tendons or over bony prominences
Example: Olecranon bursa
Two-types
Natural
Acquired - develop where excessive friction
Example: “Student’s bursa” - third finger
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Planes of
Action
Fixed lines of
reference along
which the body is
divided
There are 3 planes,
each at right angles
of perpendicular to
the other 2 planes
(Adapted from Lehmkuhl, LD and Smith, LK: Brunnstrom’s Clinical
Kinesiology, ed 4. FA Davis, Philadelphia, 1983, with permission.)
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Sagittal Plane
Divides the body into
right and left sides
Motions of flexion and
extension occur in
this plane
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Frontal/Coronal Plane
Movement abduction
and adduction
Passes through the
body from side to
side
Divides the body into
front and back
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Transverse/Horizontal Plane
Divides the body into
top and bottom parts
Passes through the
body horizontally
Movement rotation
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Cardinal Plane
When a plane
passes through
midline of a part
Center of gravity
is the intersection
of three cardinal
planes
(Adapted from Lehmkuhl, LD and Smith, LK:
Brunnstrom’s Clinical Kinesiology, ed 4.
FA Davis, Philadelphia, 1983, with permission.)
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Axes
Points that run through each of the
cardinal planes
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Axes
(cont’d)
A. Sagittal Axis - runs from front to back
B. Frontal Axis - runs from side to side
C. Vertical/ Longitudinal Axis - runs from top to bottom
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Joint Motions
PLANE
AXIS
MOVEMENT
Sagittal
Frontal
Flexion/extension
Frontal
Sagittal
Abduction/adduction
Radial/ulnar deviation
Inversion/eversion
Transverse
Vertical
Medial/lateral rotation
Supinate/Pronate
Horizontal abduction/
adduction
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Joint Classifications by
Degrees of Freedom
Joints can be
classified by the
number of planes in
which the segments
of the joint move or
the number of axes
the joint possesses
One Degree of Freedom
1 axis, 1 plane
Example: elbow and IP
Two Degrees of Freedom
2 axes, 2 planes
Example: MCP and RC
Three Degrees of Freedom
3 axes, 3 planes
Example: hip and shoulder
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