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Chapter 9: Articulations (Joints)
•Point of contact between
•Joints structure determines how it functions
•The closer the fit at the point of contact the stronger the joint.
•Joints are the weakest points of the skeleton
JOINTS CLASSIFIED BY:
FUNCTIONAL: (table 9-1)
•Synarthroses – immovable joints
•Amphiarthroses – slightly immovable joints
•Diarthroses – freely immovable joints
STRUCTURAL: (table 9-2)
•Bony fusion: No joint cavity
•Fibrous: No joint cavity
•Cartilaginous: No joint cavity
•Synovial: Has joint cavity
Synarthroses: Bones are held tightly together by fibrous connective tissue
1. Suture:
a) Synostoses (considered a 4th type)
2. Synchondroses: Held together by hyaline cartilage,
temporary:
permanent:
3. Gomphoses
Amphiarthroses: Bones united by cartilage
1. Syndesmoses: bones connected by a ligament
2. Symphyses: hyaline cartilage fused with fibrocartilaginous pad that separates or unites
the bones
(i.e. pubic symphysis, intervertebral discs)
Diarthroses: Freely movable joints
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-presence of a fluid filled joint (synovial) cavity which has 5 Features:
1.) ARTICULAR CARTILAGE: Thin layer of hyaline that covers articular surface on bone.
2.) SYNOVIAL CAVITY: Feature unique to synovial joints
3.) ARTICULAR CAPSULE: Double-layered membrane that surrounds and encloses the
joint.
-Outer layer is
-Fibers joined to
-Inner layer is
4.) SYNOVIAL FLUID: Thick fluid produced by synovial membrane.
*Provides
*Lubricates joint surfaces
*Normally only enough fluid is secreted to form thin film
*Fluid dissipates evenly to
5.) REINFORCING LIGAMENTS:
- intrinsic
- extra/intrcapsular
Other items usually present
Fatty pads and Menisci (improve the fit)
* Capsule and ligaments are richly supplied with
Bursae:
-tendon sheath
*Found where tendons cross joints
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STABILITY OF SYNOVIAL JOINTS:
1. Shape of articular surface
2. Number and position of ligaments
3. Muscle tone
ANGULAR MOVEMENTS: Increase or decrease the angle between two adjoining bones
Origin –
Insertion –
* movements relative to
FLEXION:
*DORSIFLEXION *PLANTAR FLEXION -
EXTENSION:
*HYPEREXTENSION -
ABDUCTION:
ADDUCTION:
CIRCUMDUCTION:
ROTATION:
Special Movements:
PRONATION:
SUPINATION: Palms up
ELEVATION:
DEPRESSION:
PROTRACTION: Movement in anterior direction
(for scapula protraction is synonymous with abduction)
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RETRACTION: Movement in posterior direction
(for scapula retraction is synonymous with adduction)
INVERSION: Sole turns
EVERSION: Sole turns
OPPOSITION: Thumb touches tips of other fingers
TYPES OF SYNOVIAL JOINTS:
Nonaxial Joints: no axis
1. gliding (plane) joints
- between
Uniaxial Joints: 1 axis, 1 plane
2. Hinge joints
3. Pivot joints
Biaxial Joints: movement in 2 planes, 2 axes
4. Condyloid Joints (ellipsoidal): one articular surface concave and the other convex.
5. Saddle:
Triaxial Joints: movement in 3 planes
6. Spheroid (ball & socket):
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HOMEOSTATIC IMBALANCES
Sprain:
Strain:
Cartilage damage:
Dislocation:
Subluxation:
Bursitis:
Tendinitis:
Arthritis:
1. osteoarthritis: most common
-"wear and tear" arthritis
-chronic inflammation causes articular cartilage to degenerate
2. rheumatoid arthritis: autoimmune disease
affects small joints:
inflammation of synovial membrane which causes abnormal
tissue (pannus) to develop over the cartilage
Gout: more common in males
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Intervertebral Articulation
-
superior and inferiorior articular surfaces create gliding joints for little movement
flexion, extension, lateral flexion, rotation
Intervetebral discs – pads of fibrocartilage that separate and cushion vertebrae
- S1 – L5 to C2 – C3
- annulus fibrosus – tough outer layer of fibrocartilage; connected directly to
the the disc bodies of neighboring vertebrae
- nucleus pulposus – soft, elastic, gelatinous core; gives resiliency and
absorbs shock
-
Ligaments
o
o
o
o
o
Ant/Post longitudinal ligament
Ligamentum flavum – laminae
Interspinous ligament
Supraspinous ligament – C7 to Sacrum
Ligamentum nuchae – C7 to base of skull
Shoulder joint (glenohumeral joint)
-
ball-and-socket diarthrosis joint
Glenoid labrum – fibrocartilagenous lip around the glenoid cavity which deepens the
socket
Stability of this joint are mostly provided by the surrounding musculature and a few
ligaments
-
glenohumeral
coracohumeral
coracoacromial
coracoclavicular
acromioclavicular – supports the superior surface of the shoulder
Rotator cuff – tendons of these muscles create the stability of the GH joint
- supraspinatus
- infraspinatus
- teres minor
- subscapularis
Inferior aspect of the capsule is poorly reinforced - dislocations
Bursa in the shoulder can become easily inflamed
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Elbow Joint
-
hinge joint; flexion/extension of elbow and pronation/supination of the forearm
-
humeroulnar joint – largest and strongest of this joint; trochlea of the humerus
and trochlear notch of the ulna
-
humeroradial joint – capitulum of the humerus and the head of the radius
Stable joint because:
1. the bony surfaces of the humerus and ulna interlock
2. the articular capsule is very thick
3. the capsule is reinforced with strong ligaments
-
radial collateral ligament – lateral epicondyle and annular ligament
annular ligament – binds the head of the radius to the ulna
ulnar collateral ligament – medial epicondyle to the coronoid process and
olecranon process
Hip Joint (coxal joint)
-
sturdy ball-and-socket joint; permits flex/ext, abd/adduction, circumduction and
rotation
Acetabular labrum – a thick fibrocartilage rim that deepens the acetabulum
Articular capsule is comprised of four broad ligaments: (attach to the intertrochanteric line)
-
iliofemoral
pubofermoral
regional thickenings of the capsule
ischiofemoral
transverse acetabular ligament – creates the inferior border of the capsule
Ligamentum teres (ligament of the femoral head) – originates along the transverse
acetabular ligament and attached to the femoral head to the fovea capitis (pit)
Knee Joint
-
hinge joint; permits flexion/extension and little rotation
Thin articular capsule that is supported by ligaments and tendons
Medial and Lateral menisci:
1. act as cushions; shock absorbers
2. conform to the shape of the surface of the femur
3. provide some lateral stability to the joint
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Stabilizing ligaments:
-
Tendons of quadriceps muscles converge at the patella. From the level of the
patella to the tibia, the patellar ligament (center) and patellar retinaculae
(lat/med to patellar lig.) attach to the anterior surface of the tibia
-
Two popliteal ligaments posteriorly extend from femur to tibia
-
The anterior and posterior (site of origin on the tibia) cruciate ligaments
inside the joint capsule stabilize the joint from sliding anteriorly and posteriorly
-
Tibial collateral ligament and the fibular collateral ligament support the joint
medially and laterally in extension
“Locking” the knee will allow a person to stand for prolonged periods of time with out using
surrounding musculature
Review table 9-3 on page 271 and 9-4 on page 275