Articulations

1
Components of Synovial Joints

• Accessory Structures
• Cartilages and Fat Pads
• - meniscus a crescent pad of fibrous cartilage
  situated between opposing bones within a synovial
  joint
• - subdivide a synovial cavity
• - channel the flow of synovial fluid
• - allow for variations in shape of articular
  surfaces
• - fat pads localized masses of adipose tissue
  covered by a layer of synovial membrane
• - protect articular cartilage
• - act as packaging material by filling spaces
  as
• cavity changes

2
Components of Synovial Joints Cont.

• Ligaments
• - intrinsic localized thickenings of the joint
  capsule
• - extrinsic separate from joint capsule
• - support, strengthen, and reinforce synovial
  joints
• - can become sprained with excesses
  stretching damaging collagen fibers
• Tendons
• - not part of the articulation, pass across or
  around joint
• - may limit ROM
• - provide mechanical support

3
Components of Synovial Joints Cont.

• Bursae
• - small fluid filled pockets in connective
  tissue
• - contain synovial fluid lined with membrane
• - can be connected or separate from joint
  cavity
• - form where tendons/ligaments rub against
  tissues
• - reduce friction
• - act as shock absorbers
• - if develop in abnormal locations or
  conditions called adventitious

4
(No Transcript)
5
Factors that Stabilze Synovial Joints

• - collagen fibers of the joint capsule and any
  accessory, extracapsular, or intracapsular
  ligament
• - shapes of the articulating surfaces and
  menisci, which may prevent movement in specific
  directions
• ex. hip joint (head of femur projects into
  acetabulum)
• - presence of other bones, skeletal muscles, or
  fat pads around the joint
• ex. elbow
• - tension in tendons attached to the articulating
  bones

6
Injuries to Joints

• Dislocation or luxation
• - joint experiences extreme stress, articular
  surfaces ar forced out of position
• - can damage cartilage, tear ligaments, or
  distort capsule
• - very painful
• Subluxation
• - partial dislocation

7
Types of Synovial Joints

• Gliding (planar)
• Hinge
• Pivot
• Ellipsoid (condylar)
• Saddle (sellaris)
• Ball-and-socket

8
Types of Synovial Joints

• Ellipsoid (condylar)
• - oval articular surface nestles into an
  elliptical cavity of another bone
• - biaxial along or across the length of the
  oval
• ex. radiocarpal joint, metacarpophalangeal
  joints 2-5, metatarsophalangeal joints
• Saddle(sellaris)
• - each articular surface is concave along one
  axis and convex along the other
• - biaxial, permits angular motion, and
  circumduction
• - no rotation
• ex. 1st carpometacarpal joint
  (trapezium/pollex)

9
Types of Synovial Joints

• Gliding
• - flattened or slightly curved
• - flat articular surfaces glide across one
  another
• - movement is minimal
• ex. sacroiliac joint, intercarpal/tarsals,
  acromioclavicular and claviculosternal joints
• Hinge
• - convex surface of one bone fits into the
  concave surface of another
• - permit angular motion in a single plane
• ex. elbow, knee, ankle, interphalangeal joints

10
Types of Synovial Joints

• Pivot
• - cylindrical surface of one bone rotates within
  a ring formed of bone and ligament
• - monoaxial rotation
• ex. atlas/axis, proximal radioulnar joint
• Ball-and-socket
• - round head of one bone rests within a
  cup-shaped depression in another.
• - all movements allowed
• ex. shoulder, hip joint

11
(No Transcript)
12
Describing Dynamic Motion

• Linear Motion
• - two lines of reference
• - gliding forward to backward, side to side or
  diagonal
• Angular Motion
• - two lines of reference
• - change in angle of bone
• - circumduction
• Rotation
• - shaft of bone spins around its longitudinal
  axis

13
Dynamic Motion Cont.

• Monaxial
• - movement permitted along only one axis
• Biaxial
• - movement permitted along two axis
• Triaxial
• - movement permitted in combination of angular
  and rotation

14
Types of Movement Synovial Joints

• Linear gliding
• - two opposing surfaces slide past one another
• - any direction
• - movement is slight, rotation is generally
  prevented by capsule and ligaments
• ex. between carpals/tarsals
• between the clavicle and sternum

15
Types of Movement Synovial Joints

• Angular Motion
• Flexion Extension
• - flexion
• - movement in the anterior-posterior plane -
  reducing the angle between bones
• ex. head to chest
• - extension
• - movement in the anterior-posterior plane -
  increasing the angle
• ex. all major joints in anatomical position
• - past anatomical position called
  hyperextension

16
Types of Movement Synovial Joints

• Abduction Adduction
• - abduction movement away from the longitudinal
  axis in the frontal plane
• ex. swinging upper limb to the side
• - adduction movement towards the body
• ex. bringing heel of hand and finger
  towards body
• Circumduction
• - moving in a circular motion
• ex. drawing a large circle on the chalkboard