joints Honors Anatomy & Physiology - PowerPoint Presentation

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joints

Honors Anatomy

& Physiology

Chapter 8

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JOINTS

aka Articulations

2 Functions:

Hold Bones Together

Allows otherwise rigid skeleton to have some flexibility

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Classification of Joints

Functionally

Named according to how much movement allowed @ joint

Structurally

Named according to presence of fibrous tissue, cartilage, or a joint cavity separate the articulated bones

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Functional Joints

Synarthrosis

Immovable joints

Skull bones

Amphiarthrosis

Slightly movable joints

Symphysis

pubis

Diarthrosis

Freely movable joints

Ball & Socket or Hinge Joints

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Structural Joints

Fibrous Joints

Bones united by fibrous tissue

Joint connecting distal tibia & fibula

Cartilaginous Joints

Bone ends connected by cartilage

Pubic

symphysis

Synovial Joints

Articulating ends of bone separated by joint cavity

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4 Features of Synovial Joints

Articular

Cartilage

Hyaline cartilage covers ends of bones

Fibrous

Articular

Capsule

Joint surfaces enclosed by capsule of fibrous CT

Capsule lined by synovial membrane

Joint Cavity

Contains synovial fluid

Reinforcing Ligaments

Reinforce fibrous

articular

capsule

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General Structure

of a

Synovial Joint

Articular

Cartilage

Joint Cavity

Articular

Capsule

Synovial Fluid

Reinforcing Ligaments

Nerves & Blood Vessels

Some also have: menisci,

bursae

, tendon sheaths outside the joint proper

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Factors Influencing Stability of Synovial Joints

Joints must be stabilized to avoid dislocation

Stability of a joint depends on 3 factors:

Articular

surfaces: overall minor role

Ligaments: prevent excessive or undesirable motion at the joint

Muscle tone: muscle tendons that cross the joint most stabilizing factor

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Types of Synovial Joints

PLANE JOINT

Articular

surfaces flat

Allow gliding movement (w/out rotation)

Example:

intercarpal

joints of wrist & ankle

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Types of Synovial Joints

2. HINGE JOINT

cylindrical end of bone fits into trough-shaped surface of another bone

Angular movement allowed in 1 plane

Examples: elbow, knee,

interphalangeal

joints

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Types of Synovial Joints

3. PIVOT JOINT

Rounded end of 1 bone fits into sleeve or ring of another bone

allows 1 bone to rotate along its long axis

Example: joint between atlas & dens of axis

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Types of Synovial Joints

4.CONDYLOID JOINT

“knuckle-like”

Egg-shaped end of 1 bone fits into oval concavity in another bone

Allows for moving bone to travel side-to-side & back-and-forth but cannot rotate along its long axis

Example:

metacarpophalangeal

joint

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4. CONDYLOID JOINT

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Types of Synovial Joints

5. SADDLE JOINTS

Each

articular

surface has convex & concave areas

Same movements as

condyloid

joints

Example: twiddling your thumbs

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Types of Synovial Joints

6. BALL & SOCKET JOINTS

Spherical head of 1 bone fits into a round socket formed by 1 or more bones

Allows movement is 3 dimensions(most freely moving of synovial joints)

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Types of Movements

@

Synovial Joints

1. Gliding

relatively flat surfaces move back-and-forth & side-to-side

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Types of Movements

@

Synovial Joints

2. flexion/extension/ hyperextension:

opposite movements

flexion: decrease in angle between articulating bones

extension: increase in angle between articulating bones

hyperextension: continuation of extension beyond the anatomical position

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Types of Movements

@

Synovial Joints

3. abduction/adduction/

circumduction

abduction: movement of bone away from midline

adduction: movement of bone toward midline

circumduction

: movement of distal end of a body part in a circle

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Types of Movements

@

Synovial Joints

4. elevation/depression:

elevation: upward movement of part of body (closing mouth, shrugging shoulders)

depression: downward movement of part of body (opening mouth, returning elevated shrugged shoulders to anatomical position)

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Types of Movements

@

Synovial Joints

5. protraction/retraction

protraction: movement of part of body

anteriorly

in transverse plane

retraction: returning a protracted part of body to anatomical position

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Types of Movements

@

Synovial Joints

6. inversion/

eversion

inversion: movement of soles medially @

intertarsal

joints (soles face each other)

eversion

: movement of soles laterally @

intertarsal

joints

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Types of Movements

@

Synovial Joints

7.

dorsiflexion

/ plantar flexion

dorsiflexion

: bending foot @ ankle in direction of dorsum (superior surface)

plantar flexion: bending foot @ ankle in direction of plantar surface

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Types of Movements

@

Synovial Joints

8.

supination

/

pronation

supination

: movement of forearm in which palm is turned

anteriorly

pronation

: movement of forearm in which distal end of radius crosses over distal end ulna & palm is turned

posteriorly

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Types of Movements

@

Synovial Joints

9. opposition

movement of thumb in which thumb moves across palm to touch tips of the fingers on same hand

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Ball - & - Socket Joint

ball-like surface of one bone fits into a cuplike depression of another bone

permits movement around 3 axis + all directions in between

flexion

extension

abduction

adduction

circumduction

rotation

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SPRAINS

Ligaments or tendons reinforcing a joint are damaged by excessive stretching or tearing

Both have poor blood supply so heal slowly

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ARTHRITIS

“inflammation of a joint”

General term for >100 different diseases

Most wide-spread, disabling disease in USA

Onset: same symptoms: joint stiffness & swelling

Synovial membrane

inflammed

 thickens  less synovial fluid  increased friction

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Rheumatoid Arthritis

Autoimmune disorder

Adult onset or Juvenile onset

Women 3x more often than men

Any synovial joint could be affected, often symmetrical involvement

disfiguring

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Rheumatoid Arthritis

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Osteoarthritis

Most common form of arthritis

Chronic degenerative condition: “wear-and-tear”

Affects

articular

cartilage (eventually breaks down)

 increased friction  bone spurs develop  restricts movement

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Osteoarthritis

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