Classification of joints
Structural - based on the structure connects the articulating surfaces of bones. |
Functional - based on the amount of movement between articulating bones |
Structural Classification
Fibrous
- joined by fibrous connective tissue.
-Functionally are synarthroses or amphiarthroses |
Cartilaginous
- joined by cartilage (hyaline cartilage/fibrocartilage)
-Functionally are synarthroses or amphiarthroses* |
Synovial
- joined within a fluid-filled cavity. (most common joint)
-Functionally are diarthroses |
• Based on the structure of the articulating surfaces
Functional Classification
Synarthrosis - little to no movement (ex., suture of skull) |
Amphiarthrosis - slight movement (ex., pubic symphysis, intervertebral discs) |
Diarthrosis - significant movement |
Three categories based on axes of motion
1. Uniaxial—movement in one plane (ex., elbow)
2. Biaxial—movement in two planes (ex., metacarpophalangeal joints) 3. Multiaxial—movement in three or more planes (ex.,hip) |
• Based on the extent of
joint
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Fibrous Joints
Characterisitics of Fibrous Joints
- NO joint cavity
-Held together by dense (fibrous) connective tissue
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Types
1. Sutures
- Joins the bones of the skull
-synarthroses
-convoluted shape prevents movement between bones
-form when skull bones completely ossify during early childhood
2. Syndesmoses
-Joins two parallel bones using fibrous connective tissue
-Amphiarthroses
-Found between radius and ulna of forearm between tibia and fibula of leg
3. Gomphoses
-Anchors teeth to maxilla
Made of numerous shorts bands of dense connective tissue called periodental ligaments
- Synarthroses |
Cartilaginous Joints
Characteristics of Cartilaginous Joints
-Bones joined by cartilage or fibrocartilage |
Types
• Synchondroses
-Joined by hyaline cartilage
-Found in every long bone to allow increase in skeletal size
-Synarthroses
(Ex., epiphyseal plates, costal cartilage)
• Symphyses
-Joined by fibrocartilage
-Permits strong attachment while allowing limited movement
-Amphiarthroses
(Ex., pubic symphysis, intervertebral symphysis) |
Synovial Joints
Characteristics of Synovial Joints
-Contains a joint cavity (Bones do not directly touch) |
• Articular capsule
-Forms wall of cavity
-Ligaments to attach bones
-Synovial Membrane (secretes synovial fluid to lubricate joints and nourish cartilage)
• Articular cartilage
-Hyaline cartilage at ends of bones
-Diarthroses |
Supporting Structure
1. Ligaments
-Strong bands of fibrous connective tissue
-Strengthen and support joints by anchoring bone together
2. Tendons
-Connective tissue structure that attaches muscle to bone |
Cushioning Structures
• Articular discs and menisci
-Pads of fibrocartilage between bones.
-Provide shock absorption and help smooth movements.
• Bursae and tendon sheaths
-Prevent friction between bone and tendons
• Fat pads
-Provide cushioning |
Pivot Joint
-Rounded portion of a bone enclosed in a ring
-Allows rotation around one axis
- Uniaxial joint
-Atlantoaxial Joint |
Hinge Joint
-Convex end of one bone articulates with the concave end of another
-Allows bending and stretching along one axis
-Uniaxial
-Elbow, knee, ankle, and interphalangeal joints |
Condyloid Joint
-Shallow depression at the end of one bone articulates with rounded structure from nearby bone or bones
-Biaxial Joint
-Allows bending and straightening, anterior-posterior movements
-Metacarpophalangeal joints |
Saddle Joint
-Both articulating surfaces have a saddle shape
-Biaxial joint
-Allows Circulating movement
-First carpometacarpal joint, sternoclavicular joint |
Plane Joint
-Surfaces of the bones are mostly flat
-Bones slide past each other during motion
-Limited motion, but multiaxial joint
-Intercarpal joints, interatrial joints, acromioclavicular joint |
Ball-and-socket Joint
-Rounded head of one bone fits into the bowl-shaped
-Great range of motion
-Multiaxial joint
-Hip joint, shoulder joint |
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Movement at Synovial Joints
Flexion
- reduces the angle of the joint from
Extension
-returns joint to resting position
Hyperextension
-increases joint angle beyond
Lateral Flexion
-bending of neck or body toward |
Abduction
-moves a limb, finger, toe or thumb away from midline of body
Adduction
-moves a limb, finger, toe, or thumb toward midline
Circumduction
-movement in a circular motion
-Combination of flexion, adduction, extension, and abduction at a joint |
Rotation
-Twisting movement
• Medial rotation
-moves anterior of a limb toward midline
• Lateral rotation
-moves anterior of a limb away from midline |
Supination & Pronation
-movements of the forearm
• Supination
-moves palm toward facing posteriorly
• Pronation
-Moves palm toward facing anteriorly |
Dorsiflexion & Plantar Flexion
-Movements of the ankle joint
• Dorsiflexion
moves top of foot towards anterior leg
• Plantar flexion
-Lifts heel away from ground or points toes toward ground |
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Joint Damage
Arthrisis
-Inflamation of a joint
-Leads to pain, swelling, stiffness, and reduced mobility of the joint
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