Joints (Q2,P1) Flashcards
Possible Articulations of Joints
Bone to bone
Bone to cartilage
Teeth in bony sockets
Structure of Joints
Enables resistance to crushing, tearing, and other forces
Functional Classiffications of Joints
Functional classification is based on the amount of movement
- Synarthroses
- Amphiarthroses
- Diarthroses
Structural Classifications of Joints
Structural classifications are based on:
1) Material that binds bones together
2) Presence or absence of a joint cavity
- Fibrous
- Cartilaginous
- Synovial
Fibrous Joints
- Bones are connected by fibrous connective tissue
- Do not have a joint cavity
-Most are immovable or slightly movable
3 types
Types of Fibrous Joints
sutures,
syndesmoses
gomphoses
Sutures
- Type of Fibrous Joint
- Bones are tightly bound by a minimal amount of fibrous tissue
- Only occur between the bones of the skull
- Allow bone growth so that the skull can expand with brain during childhood
- Fibrous tissue ossifies in middle age
Synostoses
closed sutures
Syndesmoses
Type of fibrous joint
Bones are connected exclusively by ligaments
Amount of movement depends on length of fibers
Ex. Tibiofibular joint, Interosseous membrane, freely movable diathrosis
Cartilaginous Joints
Bones are united by cartilage
Lack a joint cavity
2 types: synchondroses and symphyses
Types of Cartilaginous Joints
synchondroses and symphyses
Synchondroses
Type of cartilaginous joint
Hyaline cartilage unites bones; immovable
ex. Epiphyseal plates
(made from hyaline
cartilage)
Symphyses
Fibrocartilage unites bones – resists tension and compression
Slightly movable joints that provide strength with flexibility
Hyaline cartilage – also present as articular cartilage
ex. Intervertebral discs
Pubic symphysis
Synovial Joints
Most movable type of joint
All are diarthroses
Each contains a fluid-filled joint cavity
Synovial joints are Richly supplied with sensory nerves that Detect pain
lubricating devices
Are subjected to compressive forces
Friction could overheat and destroy joint tissue
Have a rich blood supply
General Structure of Synovial Joints
- All have Articular cartilage (Ends of opposing bones are covered with hyaline cartilage)
- Joint cavity (synovial cavity)
- Articular capsule
- Synovial fluid
- Reinforcing ligaments (either inta- or extracapsular ligaments)
Articular capsule
joint cavity is enclosed in a two-layered capsule
Articular capsule is composed of…
Fibrous capsule – dense irregular connective tissue – strengthens joint
Synovial membrane – loose (far apart) connective tissue
Lines joint capsule and covers internal joint surfaces
Functions to make synovial fluid
Synovial fluid
A viscous fluid similar to raw egg white
A filtrate of blood
Contains glycoprotein molecules secreted by fibroblasts
Bursa
a flattened fibrous sac lined by a synovial membrane
- closed bags of lubricant
reduce friction between body elements
- not synovial joints
Tendon sheath
an elongated bursa that wraps around a tendon
Factors Influencing Joint Stability
Articular surfaces – seldom play a major role in joint stability
Ligaments – the more ligaments in a joint, the stronger it is
~~Muscle tone – the most important factor in joint stability (keeps tension on muscle tendons)
Three basic types of movement by synovial joints
- Gliding – one bone across the surface of another
- Angular movement – movements change the angle between bones
- Rotation – movement around a bone’s long axis
Gliding
- one bone across the surface of another
- Flat surfaces of two bones slip across each other
- Gliding occurs between Carpals, Articular processes of vertebrae, Tarsals
Angular Movements
movements change the angle between bones
Flexion and Extension
Abduction and Adductionon
Circumduction
Flexion
decrease the angle between two bones
Extension
increase the angle between bones
Abduction (A.B duction)
moving a limb away from the body midline
Adduction (A.D duction)
moving a limb toward the body midline
Circumduction
moving a limb or finger so that it describes a cone in space
Rotation
turning movement of a bone around its long axis
The only movement allowed between atlas and axis vertebrae
Occurs at the hip and shoulder joints
Supination
forearm rotates laterally – palm faces anteriorly
special movement
Pronation
– forearm rotates medially – palm faces posteriorly
special movement
Supine
face up
Prone
face down
Dorsiflexion
lifting the foot so its superior surface approaches the shin
Plantar Flexion
depressing the foot – pointing the toes
Inversion
turning the sole medially
Eversion
turning the sole laterally
Protraction
nonangular movement of jutting out the jaw
Retraction
opposite movement to protraction
Elevation
lifting a body superiorly
Depression
moving the elevated part inferiorly
Opposition
– movement of the thumb to touch the tips of other fingers
Plane joint
Articular surfaces are flat planes
Short gliding movements are allowed
Intertarsal and intercarpal joints
Movements are nonaxial
Gliding does not involve rotation around any axis
Hinge joints
Cylindrical end of one bone fits into a trough on another bone
Angular movement is allowed in one plane
Elbow, ankle, knee and joints between phalanges
Movement is uniaxial – allows movement around one axis only
Pivot Joints
Classified as uniaxial – rotating bone only turns around its long axis
allow rotation
Examples
Proximal radioulnar joint
Joint between atlas and axis
Condyloid Joints
Allow moving bone to travel:
Side to side – abduction-adduction
Back and forth – flexion-extension
Classified as biaxial – movement occurs around two axes
Saddle joints
Each articular surface has concave and convex surfaces
Classified as biaxial joints
Ball and Socket Joint
Spherical head of one bone fits into round socket of another
Classified as multiaxial – allow movement in all axes
Examples: shoulder and hip joints
