Articulations

The place of union or junction between two or more bones of the The place of union or junction between two or more bones of the skeleton (also between cartilage and bones/teeth and bonesskeleton (also between cartilage and bones/teeth and bones

- allow for movement- allow for movement

- structure of joint determines the range of movement- structure of joint determines the range of movement

- the closer the fit, the stronger the joint; the looser the fit, - the closer the fit, the stronger the joint; the looser the fit, the the more movement more movement

ARTHROLOGY – The science concerned with the study of joints, ARTHROLOGY – The science concerned with the study of joints, includes function, structure, classification and any dysfunctions includes function, structure, classification and any dysfunctions

KINESIOLOGY – the science concerned with the functional KINESIOLOGY – the science concerned with the functional relationship, or biomechanics, of the skeleton, joints and muscles relationship, or biomechanics, of the skeleton, joints and muscles as they work together to produce coordinated movement.as they work together to produce coordinated movement.

I.I. Classification of jointsClassification of joints

A.A. Structural classification – based on the presence or Structural classification – based on the presence or absence of a joint cavity and the kind of supportive tissue absence of a joint cavity and the kind of supportive tissue surrounding the joint.surrounding the joint.

Three types:Three types:

1. Fibrous joints – lack a joint cavity; fibrous connective tissue 1. Fibrous joints – lack a joint cavity; fibrous connective tissue connects articulating jointsconnects articulating joints

2. Cartilaginous joints – lacks a joint cavity; cartilage binds 2. Cartilaginous joints – lacks a joint cavity; cartilage binds articulating bonesarticulating bones

3. Synovial joints – has a joint cavity; ligaments help support 3. Synovial joints – has a joint cavity; ligaments help support articulating bonesarticulating bones

B. Functional classification – based on the degree of movement B. Functional classification – based on the degree of movement permitted within the jointpermitted within the joint

Three types:Three types:

1.1. Synarthrosis – immoveable jointsSynarthrosis – immoveable joints

2.2. Amphiarthrosis – slightly moveable jointsAmphiarthrosis – slightly moveable joints

3.3. Diarthrosis – freely moveable jointsDiarthrosis – freely moveable joints

II. Breakdown by functional II. Breakdown by functional classificationclassification

A.A. Synarthroses (immoveable Synarthroses (immoveable joints)joints)

1.Suture – strongest joint by 1.Suture – strongest joint by structurestructure

- fibrous joints found between - fibrous joints found between flat bones of the skullflat bones of the skull

- irregular structure that gives - irregular structure that gives strength and reduces fracturesstrength and reduces fractures

2.Gomphoses 2.Gomphoses

- fibrous joints that occur - fibrous joints that occur between teeth and the between teeth and the supporting bones of the jaw.supporting bones of the jaw.

- located where the root of a - located where the root of a tooth is attached to the tooth is attached to the periodontal ligament of the periodontal ligament of the alveolus (socket) of the bone.alveolus (socket) of the bone.

3. Synchondroses 3. Synchondroses

- cartilaginous joint with hyaline cartilage as the connective - cartilaginous joint with hyaline cartilage as the connective tissuetissue

- some are temporary and form the epiphyseal growth plates - some are temporary and form the epiphyseal growth plates between the diaphysis and epiphysis in the long bones of between the diaphysis and epiphysis in the long bones of childrenchildren

B. Amphiarthroses – slightly B. Amphiarthroses – slightly moveable jointmoveable joint

1.1. SyndesmosesSyndesmoses

- Fibrous joint found only in the Fibrous joint found only in the forearm and leg where adjacent forearm and leg where adjacent bones are held together by bones are held together by collagenous fiberscollagenous fibers

- Characteristic of the side-to-Characteristic of the side-to-side joints between tibia-fibula side joints between tibia-fibula and the radius-ulna (allows and the radius-ulna (allows rotation)rotation)

2. Symphyses (symphysis pubis, 2. Symphyses (symphysis pubis, and intervertebral discs) and intervertebral discs)

- Cartilaginous joint separated by Cartilaginous joint separated by a pad of fibrocartilage; allows a pad of fibrocartilage; allows for limited movementfor limited movement

- Only limited motion is possible Only limited motion is possible at each joint, the combined at each joint, the combined movement allows for extensive movement allows for extensive movement (vertebrae)movement (vertebrae)

C. Diarthroses – freely moveableC. Diarthroses – freely moveable

1.1. Characteristics:Characteristics:

a. provides a wide range of precise, a. provides a wide range of precise, smooth movements while maintaining smooth movements while maintaining stability, strength, and some rigidity stability, strength, and some rigidity in the bodyin the body

b. most complex and varied of the b. most complex and varied of the three major typesthree major types

c. range of movement is limited by c. range of movement is limited by three factors:three factors:

- structure of the bones participating in the articulation- structure of the bones participating in the articulation- the strength and tautness of the associated ligaments, - the strength and tautness of the associated ligaments, tendons and joint capsuletendons and joint capsule- the size, arrangement and action of the muscles that span - the size, arrangement and action of the muscles that span the joint (“double jointed” is a misnomer; not two joints, but the joint (“double jointed” is a misnomer; not two joints, but extreme maneuverability due possibly to loose ligaments extreme maneuverability due possibly to loose ligaments and tendons) and tendons)

2. Structure of the synovial joint2. Structure of the synovial joint

a. Synovial Cavity – space between the a. Synovial Cavity – space between the articulating bones refers to the structural articulating bones refers to the structural classificationclassification

b. Articular Cartilage – present in all b. Articular Cartilage – present in all diarthrotic joints (2 mm thick), hyaline diarthrotic joints (2 mm thick), hyaline cartilage covers the articulating surfacecartilage covers the articulating surface

c. Articular Capsule – surrounds the entire c. Articular Capsule – surrounds the entire diarthrotic joint (two layers):diarthrotic joint (two layers):

FIBROUS LAYER – outer layer FIBROUS LAYER – outer layer - dense, irregular connective tissue- dense, irregular connective tissue- attaches to periosteum of bones- attaches to periosteum of bones- permits movement and resists - permits movement and resists

dislocationdislocation- fibers from ligaments; hold bones - fibers from ligaments; hold bones

togethertogether

SYNOVIAL MEMBRANE – Inner layerSYNOVIAL MEMBRANE – Inner layer

- secretes synovial fluid (looks,feels like uncooked egg - secretes synovial fluid (looks,feels like uncooked egg white)white)

- lubricates joints and nourishes cartilage- lubricates joints and nourishes cartilage

- houses phagocytic cells that remove microbes and - houses phagocytic cells that remove microbes and debrisdebris

d. Accessory ligaments – some outside of d. Accessory ligaments – some outside of articular capsule, some within articular capsule, some within

e. Articular discs – pads of fibrocartilage e. Articular discs – pads of fibrocartilage called menisci (meniscus = singular)called menisci (meniscus = singular)

-Stabilize joint by forming tighter fitStabilize joint by forming tighter fit

-Tearing of these is called torn cartilageTearing of these is called torn cartilage

f. Bursae – sac-like structures between f. Bursae – sac-like structures between moving parts (help cushion and reduce moving parts (help cushion and reduce frictionfriction

-Filled with synovial fluidFilled with synovial fluid

-Found between skin and bone, tendon Found between skin and bone, tendon and bone, muscle and bone, ligaments and bone, muscle and bone, ligaments and boneand bone

3. Types of synovial joints3. Types of synovial joints

a.a. Gliding joint – simplest typeGliding joint – simplest type

- Allow only side-to-side and back-and-- Allow only side-to-side and back-and-forth movements with minimal rotationforth movements with minimal rotation

- Surfaces are usually flat or slightly Surfaces are usually flat or slightly concave/convexconcave/convex

- EX: Intercarpal/intertarsal, EX: Intercarpal/intertarsal, sternoclavicular, between adjacent sternoclavicular, between adjacent vertebrae vertebrae b. Saddle joint- looks like a saddleb. Saddle joint- looks like a saddle

-Each articular process has a Each articular process has a concave surface in one direction, concave surface in one direction, convex in the otherconvex in the other

-Is a modified condyloid joint Is a modified condyloid joint allowing a wider range of movementallowing a wider range of movement

-EX: only associated with the thumb EX: only associated with the thumb (located at the articulation of the (located at the articulation of the trapezium of the carpus with the first trapezium of the carpus with the first metacarpal bone)metacarpal bone)

c. Hinge joint – permits bending in only one direction c. Hinge joint – permits bending in only one direction

(similar to the hinge of a door)(similar to the hinge of a door)

-One surface is always concave and the other is convexOne surface is always concave and the other is convex

-Most common type of synovial jointMost common type of synovial joint

-EX: knee, humeroulnar, phalangesEX: knee, humeroulnar, phalanges

d. Pivot – movement is limited to rotation about a central axisd. Pivot – movement is limited to rotation about a central axis

-One surface is rounded and fits into a depression of anotherOne surface is rounded and fits into a depression of another

-EX: proximal articulation of the radius and ulna, articulation EX: proximal articulation of the radius and ulna, articulation between atlas and axisbetween atlas and axis

e. Ball-and socket – formed by e. Ball-and socket – formed by articulation of a rounded articulation of a rounded convex surface with a cuplike convex surface with a cuplike cavitycavity

-Provides the greatest range of Provides the greatest range of movement of all jointsmovement of all joints

-EX: hip and shoulder jointsEX: hip and shoulder joints

f. Condyloid or ellipsoid – structured so that an oval, convex f. Condyloid or ellipsoid – structured so that an oval, convex surface of one bone fits into an elliptical, concave depression of surface of one bone fits into an elliptical, concave depression of another boneanother bone

- Allows for angular movement in two directions (up and down and - Allows for angular movement in two directions (up and down and side-to-side motion)side-to-side motion)

- EX: radiocarpal joint - EX: radiocarpal joint

III. ProblemsIII. Problems

A.A. Clinical considerationsClinical considerations

1. Hyperextension1. Hyperextension

2. Strained joint2. Strained joint

3. Sprain3. Sprain

4. Luxation4. Luxation

5. Bursitis5. Bursitis

6. Tendonitis6. Tendonitis

B. Diseases of jointsB. Diseases of joints

Arthritis -Arthritis -

1. Rheumatoid arthritis1. Rheumatoid arthritis

2. Osteoarthritis2. Osteoarthritis

3. Gouty arthritis 3. Gouty arthritis

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