Chapter 9
Articulations
Articulations
• Point of contact between bones.
• Joint- mostly very movable but some are
immovable or only allow limited motions.
• Movable joints allow complex, highly
coordinated movements.
Classifications
• Structural classification- joints are named
according to:
– Type of connective tissue
– Presence of fluid filled joint capsules
• Functional classification– Synarthroses- immovable
– Amphiarthroses- slightly movable
– Diarthroses- freely movable
Fibrous Joints
• Synarthroses
• Bones of joints fit together closely, allowing
little or no movement.
– Syndesmoses- joints in which ligaments connect
two bones.
– Sutures- found only in skull; toothlike projections
from adjacent bones interlock with each other.
– Gomphoses- between root of a tooth and the
alveolar process of mandible and maxilla.
Cartilaginous joints
• Bones of joints are joined together by hyaline
cartilage of fibrocartilage; allow very little
motion.
Synovial joints
• Freely movable joints
– Structures:
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Joint capsule
Synovial membrane
Articular cartilage
Joint cavity
Menisci
Ligaments
Bursae
Types of Synovial Joints
• Uniaxial joints
– Hinge joints- knee, elbow
– Pivot joints- neck/vertebrae, radius
• Biaxial joints
– Saddle joints- thumbs
– Condyloid joints- hips, shoulders
Types of Synovial Joints
• Multiaxial joints
– Ball and socket joint- shoulder, femur
– Gliding joint- wrists, vertebrae
Humeroscapular Joint
• Shoulder joint
• Most mobile joint because of glenoid cavity
• Glenoid labrum
Elbow Joint
• Humeroradius joint
• Humeroulnar joint
• Both components of elbow joint surrounded
by single joint capsule and stabilized by
collateral ligaments.
Hip Joint
• Stable joint
Knee Joint
• Largest and one of the most complex and
most frequently injured joints.
• Tibiofemoral joint- supported by joint capsule,
cartilage, ligaments, and tendons.
• Permits flexion and extension
Ankle Joint
• Hinge type of synovial joint
• Articulation between lower ends of tibia and
fibula and upper part of talus.
• Joint is “mortise” or wedge-shaped.
– Lateral malleolus lower than medial.
Measuring Range of Motion
• Range of motion (ROM) assessment used to
determine extent of joint injury.
• ROM can be measured actively or passively;
results of both by instrument called
goniometer.
Angular Movement
• Change in the size of angle between
articulating bones.
– Flexion- decreases angle between bones; bends or
folds one part on another.
– Extension- increases angle between two bones.
– Hyperextension- extension between bones of a
joint that is greater than normal.
– Plantar flexion- increases angle between top of
foot and front of leg.
Angular Movement
– Dorsi flexion- decreases angle between top of foot
and front of leg.
– Abduction- moves part away from median plan of
body.
– Adduction- moves a part toward median plane of
body.
Circular Movements
• Rotation- pivoting a bone on its own axis.
• Circumduction- moves a part so that its distal
end moves in a circle.
• Supination- turns the hand palm side-up.
• Pronation- turns the hand palm side-down.
Gliding Movements
• Simplest of all movements; articular surface of
one bone moves over articular surface of
another without any angular or circular
movement.
Special Movements
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Inversion- turning sole of foot inward.
Eversion- turning sole outward.
Protraction- moves a part forward.
Retraction- moves part backward.
Elevation- moves part up.
Depression- lowers a part.