Definition of joint
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Definition of Joint - PowerPoint PPT Presentation

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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 l.jpg
Definition of Joint

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

Structural classification of joints l.jpg
Structural Classification of Joints

  • Fibrous joints

    • Generally immovable

  • Cartilaginous joints

    • Immovable or slightly moveable

  • Synovial joints

    • Freely moveable

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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

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Fibrous Joints (Synarthrosis)

  • Collagen fibers span the space between bones

    • sutures, gomphoses and syndesmoses

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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

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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

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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

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Cartilaginous Joint -- Synchondrosis

  • Bones are joined by hyaline cartilage

    • rib attachment to sternum

    • epiphyseal plate in children binds epiphysis and diaphysis

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Cartilaginous Joint -- Symphysis

  • 2 bones joined by fibrocartilage

    • pubic symphysis and intervertebral discs

  • Only slight amount of movement is possible

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The Synovial Joint

Figure 5.28

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Synovial Joint

  • Joint in which two bones are separated by a space called a joint cavity

  • Most are freely movable

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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

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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

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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 l.jpg
Something You Should Know About Joints…..They Act As the Fulcum Point in a Lever System..


  • And


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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

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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

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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)

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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

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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

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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

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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

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Axes of Rotation

  • Shoulder joint has 3 degrees of freedom = multiaxial joint

  • Other joints – monoaxial or biaxial

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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

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Gliding Joints (Also called Plane Joints)

  • Flat articular surfaces in which bones slide over each other

  • Limited monoaxial joint

  • Considered amphiarthroses

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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

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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

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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

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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

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Flexion, Extension and Hyperextension

  • Flexion decreases the angle of a joint

  • Extension straightens and returns to the anatomical position

  • Hyperextension = extension beyond 180 degrees

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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

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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

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Protraction and Retraction

  • Protraction = movement anteriorly on horizontal plane

    • thrusting the jaw forward, shoulders or pelvis forward

  • Retraction is movement posteriorly

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  • 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

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  • Movement on longitudinal axis

    • rotation of trunk, thigh, head or arm

  • Medial rotation turns the bone inwards

  • Lateral rotation turns the bone outwards

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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)

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Movements of Head and Trunk

  • Flexion, hyperextension and lateral flexion of vertebral column

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Rotation of Trunk and Head

  • Right rotation of trunk; rotation of head

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Movements of Mandible

  • Lateral excursion = sideways movement

  • Medial excursion = movement back to the midline

    • side-to-side grinding during chewing

  • Protraction – retraction of mandible

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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

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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