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Definition of Joint. the point of connection between two bones or elements of a skeleton (especially if it allows motion). Structural Classification of Joints. Fibrous joints Generally immovable Cartilaginous joints Immovable or slightly moveable Synovial joints Freely moveable.

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definition of joint
Definition of Joint

the point of connection between two bones or elements of a skeleton (especially if it allows motion)

structural classification of joints
Structural Classification of Joints
  • Fibrous joints
    • Generally immovable
  • Cartilaginous joints
    • Immovable or slightly moveable
  • Synovial joints
    • Freely moveable
joints and their classification
Joints and Their Classification
  • Classified by freedom of movement
    • diarthrosis (freely movable)
    • amphiarthrosis (slightly movable)
    • synarthrosis (little or no movement)
  • Classified how adjacent bones are joined
    • fibrous, cartilaginous, bony or synovial
fibrous joints synarthrosis
Fibrous Joints (Synarthrosis)
  • Collagen fibers span the space between bones
    • sutures, gomphoses and syndesmoses
fibrous joint sutures
Fibrous Joint -- Sutures
  • Immovable fibrous joints
    • bind skull bones together
  • Serrate - interlocking lines
    • coronal, sagittal and lambdoid sutures
  • Lap - overlapping beveled edges
    • temporal and parietal bones
  • Plane - straight, nonoverlapping edges
    • palatine processes of the maxillae
fibrous joint gomphoses
Fibrous Joint -- Gomphoses
  • Attachment of a tooth to its socket
  • Held in place by fibrous periodontal ligament
    • collagen fibers attach tooth to jawbone
  • Some movement while chewing
fibrous joint syndesmosis
Fibrous Joint -- Syndesmosis
  • Two bones bound by ligament only
    • interosseus membrane
  • Most movable of fibrous joints
  • Interosseus membranes unite radius to ulna and tibia to fibula
cartilaginous joint synchondrosis
Cartilaginous Joint -- Synchondrosis
  • Bones are joined by hyaline cartilage
    • rib attachment to sternum
    • epiphyseal plate in children binds epiphysis and diaphysis
cartilaginous joint symphysis
Cartilaginous Joint -- Symphysis
  • 2 bones joined by fibrocartilage
    • pubic symphysis and intervertebral discs
  • Only slight amount of movement is possible
synovial joint
Synovial Joint
  • Joint in which two bones are separated by a space called a joint cavity
  • Most are freely movable
features of synovial joints
Features of Synovial Joints
  • Articular cartilage (hyaline cartilage) covers the ends of bones
  • Joint surfaces are enclosed by a fibrous articular capsule
  • Have a joint cavity filled with synovial fluid
  • Ligaments reinforce the joint
general anatomy
General Anatomy
  • Articular capsule encloses joint cavity
    • continuous with periosteum
    • lined by synovial membrane
  • Synovial fluid = slippery fluid; feeds cartilages
  • Articular cartilage = hyaline cartilage covering the joint surfaces
  • Articular discs and menisci
    • jaw, wrist, sternoclavicular and knee joints
    • absorbs shock, guides bone movements and distributes forces
  • Tendon attaches muscle to bone
  • Ligament attaches bone to bone
what is a bursar
What is a Bursar?
  • is a small fluid-filled sac lined by synovial membrane with a inner capillary layer of slimy fluid (similar to that of an egg white).
  • It provides a cushion between bones and tendons and/or muscles around a joint. This helps to reduce any friction between the bones and allows free movement.
  • Bursae are filled with synovial fluid and are found around almost every major joint of the body; when they become inflamed, the condition is called bursitis.
something you should know about joints they act as the fulcum point in a lever system
Something You Should Know About Joints…..They Act As the Fulcum Point in a Lever System..
  • And
components of a lever
Components of a Lever
  • A lever is a rigid object that rotates around a fixed point called a fulcrum
  • Rotation occurs when effort overcomes resistance
    • resistance arm and effort arm are described relative to fulcrum
mechanical advantage of a lever
Mechanical Advantage of a Lever
  • Two kinds of levers
    • lever that helps increase output of force
      • human moving a heavy object with help of crowbar
    • lever move object further and faster
      • movement of row boat with paddle
  • Types of levers produce either increase in speed or force
mechanical advantage
Mechanical Advantage
  • Mechanical advantage is calculated from the length of the effort arm divided by the length of the resistance arm
  • Contraction of the biceps muscle causes the hand to move fast and further (MA <1.0)
first class lever
First-Class Lever
  • Has fulcrum in the middle between effort and resistance
  • Atlantooccipital joint lies between the muscles on the back of the neck and the weight of the face
    • loss of muscle tone occurs when you nod off in class
second class lever
Second-Class Lever
  • Resistance between fulcrum and effort
  • Resistance from the muscle tone of the temporalis muscle lies between the jaw joint and the pull of the diagastric muscle on the chin as it opens the mouth quickly
third class lever
Third-Class Lever
  • Effort between the resistance and the fulcrum
    • most joints of the body
  • The effort applied by the biceps muscle is applied to the forearm between the elbow joint and the weight of the hand and the forearm
range of motion
Range of Motion
  • Degrees through which a joint can move
  • Determined by
    • structure of the articular surfaces
    • strength and tautness of ligaments, tendons and capsule
      • stretching of ligaments increases range of motion
      • double-jointed people have long or slack ligaments
    • action of the muscles and tendons
      • nervous system monitors joint position and muscle tone
axes of rotation
Axes of Rotation
  • Shoulder joint has 3 degrees of freedom = multiaxial joint
  • Other joints – monoaxial or biaxial
condyloid ellipsoid joints
Condyloid (ellipsoid) Joints
  • Oval convex surface on one bone fits into a similarly shaped depression on the next
    • radiocarpal joint of the wrist
    • metacarpophalangeal joints at the bases of the fingers
  • Biaxial joints
gliding joints also called plane joints
Gliding Joints (Also called Plane Joints)
  • Flat articular surfaces in which bones slide over each other
  • Limited monoaxial joint
  • Considered amphiarthroses
hinge joints
Hinge Joints
  • One bone with convex surface that fits into a concave depression on other bone
    • ulna and humerus at elbow joint
    • femur and tibia at knee joint
    • finger and toe joints
  • Monoaxial joint
ball and socket joints
Ball-and-Socket Joints
  • Smooth hemispherical head fits within a cuplike depression
    • head of humerus into glenoid cavity of scapula
    • head of femur into acetabulum of hip bone
  • Multiaxial joint
pivot joints
Pivot Joints
  • One bone has a projection that fits into a ringlike ligament of another
  • First bone rotates on its longitudinal axis relative to the other
    • atlantoaxial joint (dens and atlas)
    • proximal radioulnar joint allows the radius during pronation and supination
saddle joints
Saddle Joints
  • Each articular surface is shaped like a saddle, concave in one direction and convex in the other
    • trapeziometacarpal joint at the base of the thumb
  • Biaxial joint
    • more movable than a condyloid or hinge joint forming the primate opposable thumb
flexion extension and hyperextension
Flexion, Extension and Hyperextension
  • Flexion decreases the angle of a joint
  • Extension straightens and returns to the anatomical position
  • Hyperextension = extension beyond 180 degrees
abduction and adduction
Abduction and Adduction
  • Abduction is movement of a part away from the midline
    • hyperabduction – raise arm over back or front of head
  • Adduction is movement towards the midline
    • hyperadduction – crossing fingers
elevation and depression
Elevation and Depression
  • Elevation is a movement that raises a bone vertically
    • mandibles are elevated during biting and clavicles during a shrug
  • Depression is lowering the mandible or the shoulders
protraction and retraction
Protraction and Retraction
  • Protraction = movement anteriorly on horizontal plane
    • thrusting the jaw forward, shoulders or pelvis forward
  • Retraction is movement posteriorly
  • Movement in which one end of an appendage remains stationary while the other end makes a circular motion
  • Sequence of flexion, abduction, extension and adduction movements
    • baseball player winding up for a pitch
  • Movement on longitudinal axis
    • rotation of trunk, thigh, head or arm
  • Medial rotation turns the bone inwards
  • Lateral rotation turns the bone outwards
supination and pronation
Supination and Pronation
  • In the forearm and foot
  • Supination
    • rotation of forearm so that the palm faces forward
    • inversion and abduction of foot (raising the medial edge of the foot)
  • Pronation
    • rotation of forearm so the palm faces to the rear
    • eversion and abduction of foot (raising the lateral edge of the foot)
movements of head and trunk
Movements of Head and Trunk
  • Flexion, hyperextension and lateral flexion of vertebral column
rotation of trunk and head
Rotation of Trunk and Head
  • Right rotation of trunk; rotation of head
movements of mandible
Movements of Mandible
  • Lateral excursion = sideways movement
  • Medial excursion = movement back to the midline
    • side-to-side grinding during chewing
  • Protraction – retraction of mandible
movement of hand and digits
Movement of Hand and Digits
  • Radial and ulnar flexion
  • Abduction of fingers and thumb
  • Opposition is movement of the thumb to approach or touch the fingertips
  • Reposition is movement back to the anatomical position
movements of the foot
Movements of the Foot
  • Dorsiflexion is raising of the toes as when you swing the foot forward to take a step (heel strike)
  • Plantarflexion is extension of the foot so that the toes point downward as in standing on tiptoe
  • Inversion is a movement in which the soles are turned medially
  • Eversion is a turning of the soles to face laterally