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Joint Structure and Function
Objectives¡G After studying this topic, the students will be able to
- identify types of the joints and their characteristics
- describe the definition and characteristics of a synovial joint
- distinguish arthrokinematic movements from osteokinematic movements and explain their relationship
Classification of Joints
Synovial Joint
Joint Mobility
Joint Stability
- Neumann, DA (2002)¡G Getting Started. in Neumann DA (ed)¡G
Kinesiology of the Musculoskeletal System - Foundations for Physical Rehabilitation.
Philadelphia¡G Mosby. pp.4-11
- Threlkeld AJ (2002). Basic Structure and Function of the Joints.
In Neumann DA: Kinesiology of the Musculoskeletal System: Foundations for
Physical Rehabilitation. Philadelphia: Mosby. pp. 25-40
- Smith L.K., Weiss E.L., Don Lehmkuhl L., 1996.
Brunnstrom's Clinical Kinesiology, 5th ed. Philadelphia: FA Davis. pp.11-17.
Classification of Joints
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Classification based on anatomic structure and movement potential
diarthrosis¡G
an articulation
that contains an articular cavity between two bones
synarthrosis¡G
an articulation between bones that is held together by
dense irregular connective tissues
amphiarthrosis¡G
an articulation between bones that is formed primarily by fibrocartilage and/or
hyaline cartilage
| ¡@ |
Diarthrosis |
Synarthrosis |
Amphiarthrosis |
| prefix |
di = double |
syn = together |
amphi = both |
articular cavity
capsule
synovial membrane |
presence |
no |
no |
| articular surfaces |
hyaline cartilage or fibrocartilage |
linked by fibrocartilage, fibrous tissues, or ligaments |
linked by fibrocartilage and/or hyaline cartilage |
functions¡G
to connect two bones
to transmit forces
to allow motions |
yes
yes
maximum |
yes
yes
no or little |
yes
yes
some |
| examples |
most joints in the extremities |
cranial suture or distal tibiofibular ligament |
intervertebral joint or pubis symphysis |
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Classification of diarthrosis
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Classificaiton of synarthrosis
cartilaginous (synchondrosis)
fibrocartilage
bending and twisting
fibrous (suture)
fibrous tissue
no movement
ligamentous (syndesmosis)
ligaments
limited or no movement
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Synovial Joint
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Components of synovial joint
bone and subchondral bone
intra-articular tissues
articular cartilage (hyaline cartilage)
joint capsule and capsular ligament
synovial membrane
synovial cavity
rheumatoid arthritis
synovial fluid¡G
to provide nutrition and lubrication for the articular cartilage
extra-articular tissues
ligament
exception¡G anterior/ posterior cruciate ligaments of the knee are intra-articular
muscle and tendon
meniscus or disc
bursa
labrum
fat pads
synovial plica
vascular or lymphatic vessels
nerves
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Functions of synovial joint
to provide motion (joint mobility)to maintain stability (joint stability)
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Factors affecting structure and function of synovial joint
aging
immobilization
trauma
disease
habit
psychological status
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Joint Mobility
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Osteokinematic movements¡G
movements between 2 bony segments
synonym¡G physiological movements
types
swing¡G
rotary motion about a fixed
axis at the proximal segment e.g. knee flexion
spin¡G
axial rotation about a
longitudinal axis
of the distal segment e.g. forearm pronation
description of osteokinematic movements
plane of motion
axis of rotation
degree of freedom
range of motion
open vs. closed kinematic chain
concentric vs. eccentric contraction
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Arthrokinematic movements¡G
movements between 2 articular surfaces
synonym¡G accessory movements¡F
joint play
types
distraction (traction)¡G
separation of two articular surfaces along the longitudinal axis of the distal segment
compression¡G
meeting together of two articular surfaces along the longitudinal axis of the distal segment
glide¡G
a combination of roll and slide between two incongruent joint surfaces
roll¡G
new points on one rotating articular surface meet new points on another articular surface
slide¡G
same point on one rotating articular surface meet new points on another articular surface
In Neumann's book, three fundamental arthrokinematic movements was classified.
(Neumann 2002, p.8)
roll¡G not really found in human joints
slide¡G not really found in human joints
spin
What if only the roll movement occurs without any slide for the glenohumeral joint?
-- shoulder impingement syndrome
description of arthrokinematic movements
joint morphology to establish
concave-convex rule
plane of motion
direction of motion
amplitude of motion
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Concave-convex rule
concave on convex (concave surface moving on convex surface) movement¡G
The concave articular surface moves in the same direction as the moving bone
Glide occurs in the same direction as the physiological movement
e.g. tibia on femur motion: knee flexion with posterior glide
convex on concave (convex surface moving on concave surface) movement¡G
The convex articular surface moves in the opposite direction of the moving bone
Glide occurs in the direction opposite to the physiological movement
e.g. humerus on scapula motion: shoulder abduction with inferior glide
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Joint Stability
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Factors affecting joint stability
configuration of the bone
components of ligament¡G depending on proportion of different types of fibers in ligament
collagen fibers¡G for strength
94% of the anterior cruciate ligament of the knee is composed of collagen fibers
60% of the ligamentum of flavum are elastin fibers
elastin fibers¡G for flexibility
rectin fibers¡G for mass
muscular arrangement
fascia and skin
atmosphere pressure
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Close-packed position
definition¡G the position that both of the articular surfaces are in the maximum congruency status for a joint,
resulting in the greatest mechanical stability for that joint
In the close-packed position, most ligaments and capsules surrounding to the joint are taut
example¡G for the glenohumeral joint the close-packed position is abduction of 90º and full external rotation
loose-packed position¡G
all positions other than close-packed position
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