Download synovial joint

Chapter
9
Articulations
PowerPoint® Lecture Slides
prepared by Jason LaPres
Lone Star College - North Harris
Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Copyright © 2009 Pearson Education, Inc.,
publishing as Pearson Benjamin Cummings
An Introduction to Articulations
 Articulations
 Body movement occurs at joints
(articulations) where two bones connect
 Joint Structure
 Determines direction and distance of
movement (range of motion)
 Joint strength decreases as mobility increases
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Classification of Joints
 Two methods of classification
 Functional classification is based on range
of motion of the joint
 Structural classification relies on the
anatomical organization of the joint
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Functional Classifications
Synarthrosis (immovable joint)
 No movement and very strong
 Fibrous or cartilaginous connections
 May fuse over time
 Four types:
– 1. Suture – located between the bones of the skull.
– 2. Gomphosis – bind the teeth to bony sockets
– 3. Synchondrosis – rigid, cartilaginous bridge between two
articulating bones. Ex) epiphyseal cartilage
– 4. Synostosis – totally rigid, immovable joint created when two
bones fuse and the boundary between them disappears ex)
epiphyseal lines of mature long bones
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Functional Classifications
 Amphiarthrosis (slightly movable joint)
 Little movement
 Stronger than freely movable joints
 Fibrous or cartilaginous connections
 Two types:
 1. syndesmosis – bones are connected by a
ligament
– ex) distal articulation between the tibia and fibula
 2. symphysis – bones separated by fibrous cartilage
– ex) articulation between the bodies of vertebrae and the
connection between the two pubic bones
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Functional Classifications
 Diarthrosis (freely movable joint)
 More movement
 Also called synovial joints
 Located at the ends of long bones
 Subdivided by type of motion
 A synovial joint is surrounded by a fibrous articular
capsule and a synovial membrane that lines the walls
of the articular cavity. The membrane does not cover the
articulating surfaces within the joint.
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Synovial Joints
 Components of Synovial Joints
 Articular cartilages
 Pad articulating surfaces within articular capsules:
– prevent bones from touching
 Smooth surfaces lubricated by synovial fluid:
– reduce friction
 Normal synovial joint function cannot continue if this cartilage
is damaged.
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Synovial Joints
 Components of Synovial Joints
 Synovial fluid
 Clear viscous solution with consistency of
molasses
 Functions of synovial fluid:
– lubrication
– nutrient distribution
– shock absorption
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Synovial Joints
 Components of Synovial Joints
 Accessory structures
 Cartilages:
– cushion the joint:
» Fibrous cartilage pad called a meniscus
(articular disc)
 Fat pads:
– superficial to the joint capsule
– protect articular cartilages
– packing material to fill in the spaces created as
the joint cavity change shape when you move.
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Synovial Joints
 Ligaments:
– support, strengthen joints
– sprain: when a ligament is stretched to the point at which some of the
collagen fibers are torn, but the ligament survives and the joint is not
damaged.
 Tendons:
– attach to muscles around joint
– help support joint
 Bursae:
– pockets of synovial fluid
– They form where a tendon or ligament rub against other tissues to
reduce friction and act as shock absorbers
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Synovial Joints
[INSERT FIG. 9.1a]
Figure 9–1a The Structure of a Synovial Joint.
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Synovial Joints
Figure 9–1b The Structure of a Synovial Joint.
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Synovial Joints
 A joint cannot be both highly mobile and very strong. The
greater the range of motion at a joint, the weaker it
becomes.
 Prevent injury by limiting range of motion
 The collagen fibers of the joint capsule and any accessory or extrinsic
ligaments
 The shapes of the articulating surfaces and menisci, which may
prevent movement in specific directions
 The presence of other bones, skeletal muscles, or fat pads around
the joint
 Tension in tendons attached to the articulating bones
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Synovial Joints
 Injuries
 Dislocation (luxation)
 Articulating surfaces forced out of position
 Damages articular cartilage, ligaments, joint capsule
 Subluxation
 A partial dislocation
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Movements
 Types of Movements at Synovial Joints
 Linear, angular, rotation
 Linear motion
 Also called gliding
 Two surfaces slide past each other:
– between carpal or tarsal bones
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Movements
 Angular Motion
 Tip remains stationary but shaft changes angle relative to surface
 Flexion
– Anterior–posterior plane
– Reduces angle between elements
– Flexing your bicep
 Extension
– Anterior–posterior plane
– Increases angle between elements
– Extending arm
 Hyperextension
– Extension past anatomical position
– Holding head back
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Movements
 Angular Motion
 Abduction
 Frontal plane
 Moves away from
longitudinal axis
 Stretching fingers out
 Adduction
 Angular motion
 Frontal plane
 Moves toward longitudinal axis
 Bringing fingers together
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Movements
 Angular Motion
 Circumduction
 Circular motion without
rotation
 Moving arm in loop
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Movements
Rotation
 Direction of rotation from anatomical position
 Relative to longitudinal axis of body
 Left or right rotation
– Medial rotation (inward rotation):
» rotates toward axis
– Lateral rotation (outward rotation):
» rotates away from axis
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Movements
 Types of Movements at Synovial Joints
 Rotation
 Pronation:
– rotates forearm, radius over ulna
– Palm facing down
 Supination:
– forearm in anatomical position
– Palm facing up
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Movements
 Types of Movements at Synovial Joints
 Special movements
 Inversion:
– twists sole of foot medially
 Eversion:
– twists sole of foot laterally
 Dorsiflexion:
– flexion at ankle (lifting toes)
 Plantar flexion:
– extension at ankle (pointing toes)
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Movements
 Special Movements at Synovial Joints
 Opposition
 Thumb movement toward fingers or palm (grasping)
 Protraction
 Moves anteriorly
 In the horizontal plane (pushing forward)
 Ex) pushing jaw forward
 Retraction
 Opposite of protraction
 Moving anteriorly (pulling back)
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Movements
 Special Movements at Synovial Joints
 Elevation
 Moves in superior direction (up)
 Ex) closing your mouth
 Depression
 Moves in inferior direction (down)
 Ex) opening the moth
 Lateral flexion
 Bends vertebral column from side to side
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Movements
Figure 9–5 Special Movements.
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Movements
Figure 9–5 Special Movements.
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Movements
 Classification of Synovial Joints by Shape






Gliding
Hinge
Pivot
Ellipsoid
Saddle
Ball-and-socket
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Movements
 Gliding Joints
 Flattened or slightly curved faces
 Limited motion - side-to-side or back-and-forth (nonaxial)
 Ex) acromioclavicular joint
 Hinge Joints
 Angular motion in a single plane (monaxial)
 Ex) elbow
 Pivot Joints
 Rotation only (monaxial)
 Ex) atlas and axis
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Movements
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Movements
 Ellipsoid Joints
 Oval articular face within a depression
 Motion in two planes (biaxial)
 Ex) radiocarpal joint
 Saddle Joints
 Permits angular and circumduction motion, not rotation (biaxial)
 Fit together like a rider in a saddle
 Ex) first carpometacarpal joint
 Ball-and-Socket Joints
 Round articular face in a depression (triaxial) – all angular and
rotational movements possible
 Ex) shoulder and hip
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Movements
Figure 9–6 Movements at Synovial Joints.
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Movements
 A joint cannot be both mobile and strong
 The greater the mobility, the weaker the
joint
 Mobile joints are supported by muscles
and ligaments, not bone-to-bone
connections
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Intervertebral Articulations
 The articulations between the superior and
inferior articular processes of adjacent
vertebrae are gliding joints that permit small
movements associated with flexion and
rotation of the vertebral column. Little gliding
occurs between adjacent vertebral bodies.
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Intervertebral Articulations
 Intervertebral Articulations
 C2 to L5 spinal vertebrae articulate
 Intervertebral discs:
– pads of fibrous cartilage
– separate vertebral bodies
– anulus fibrosus:
» tough outer layer of intervertebral disc that surrounds nucleus pulposus
» attaches disc to vertebrae
– nucleus pulposus:
» elastic, gelatinous core
» absorbs shocks
 As vertebral column moves
 Nucleus pulposus shifts
 Disc shape conforms to motion
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Intervertebral Articulations
Figure 9–7 Intervertebral Articulations.
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Intervertebral Articulations
 Intervertebral Ligaments
 Bind vertebrae together
 Stabilize the vertebral column
 Ligaments interconnecting adjacent vertebrae include the following:
 a. anterior longitudinal ligament – connects the anterior surfaces of
adjacent vertebral bodies
 b. posterior longitudinal ligament – parallels the anterior longitudinal
ligament and connects the posterior surfaces of adjacent vertebral bodies
 c. ligamentum flavum – connects the laminae of adjacent vertebrae
 d. interspinous ligament – connects the spinous processes of adjacent
vertebrae
 e. supraspinous ligament – interconnects the tips of the spinous
processes from C7 to the sacrum
 f. ligamentum nuchae – extends from C7 to the base of the skull.
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Intervertebral Articulations
 Damage to Intervertebral Discs
 Slipped disc
 Bulge in anulus fibrosus
 Invades vertebral canal
 Herniated disc
 Nucleus pulposus breaks through
anulus fibrosus
 Presses on spinal cord or nerves
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The Shoulder Joint
 Permits the greatest range of motion of
any joint
 Most frequently dislocated joint
 Joint is a ball-and-socket diarthrosis
formed by the articulation of the head of
the humerus with the glenoid cavity of
the scapula
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The Elbow Joint
 A complex hinge joint that involves the humerus,
radius, and ulna
 The largest and strongest articulation at the elbow
is the humeroulnar joint
 Permits only flexion and extension
 The elbow joint is extremely stable because:
 the bony surfaces of the humerus and ulna interlock
 a single, thick articular capsule surrounds both the
humeroulnar and proximal radioulnar joints
 the articular capsule is reinforced by strong ligaments
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The Hip Joint
 Also called coxal joint
 Strong ball-and-socket diarthrosis
 Wide range of motion
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The Knee Joint
 A complicated hinge joint
 Transfers weight from femur to tibia
 Articulations of the knee joint
 Two femur–tibia articulations
 At medial and lateral condyles
 One between patella and patellar surface of femur
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The Knee Joint
 Menisci of the Knee
 Medial and lateral menisci
 Fibrous cartilage pads
 At femur–tibia articulations
 Cushion and stabilize joint
 Give lateral support
 Locking knees
 Standing with legs straight:
– “locks” knees by jamming lateral meniscus between tibia
and femur
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The Knee Joint
The menisci have three functions:
 act as cushions
 conform to the shape of the
articulating surfaces as the femur
changes position
 provide lateral stability to the joint
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The Knee Joint
 Seven Ligaments of the Knee Joint
 Patellar ligament (anterior)
 Two popliteal ligaments (posterior)
 Anterior and posterior cruciate ligaments (inside joint
capsule)
 Tibial collateral ligament (medial)
 Fibular collateral ligament (lateral)
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The Knee Joint
Figure 9–12a The Knee Joint.
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The Knee Joint
Figure 9–12b The Knee Joint.
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