Synovial Joints - Valencia

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					                                          Joints Notes

Learning Objectives:
   1. Define joint or articulation.
   2. Classify joints structurally and functionally.
   3. Describe the general structure of fibrous joints. Name and give an example of each of the
      three common types of fibrous joints.
   4. Describe the general structure of cartilaginous joints. Name and give an example of each
      of the two common types of cartilaginous joints.
   5. Describe the structural characteristics of synovial joints.
   6. List three natural factors that stabilize synovial joints.
   7. Compare the structures and functions of bursae and tendon sheaths.
   8. Name and describe (or perform) the common body movements.
   9. Name and provide examples of the six types of synovial joints based on the movement(s)
      allowed.



I. Joints (Articulations)
      A. Weakest parts of the skeleton
      B. Articulation – site where two or more bones meet
      C. Functions of joints
           1. Give the skeleton mobility
           2. Hold the skeleton together


      D. Classification of Joints: Structural
           1. Structural classification focuses on the material binding bones together and
             whether or not a joint cavity is present
           2. The three structural classifications are:
                       a. Fibrous
                       b. Cartilaginous
                       c. Synovial


      E. Classification of Joints: Functional
             1. Functional classification is based on the amount of movement allowed by the
                joint
             2. The three functional classes of joints are:
              a. Synarthroses – immovable
              b. Amphiarthroses – slightly movable
              c. Diarthroses – freely movable


F. Fibrous Structural Joints
       1. The bones are joined by fibrous tissues
       2. There is no joint cavity
       3. Most are immovable (synarthrosis)
       4. There are three types:
              a. Sutures
                      i. Occur between the bones of the skull
                      ii. Comprised of interlocking junctions completely filled with
                           connective tissue fibers
                      iii. Bind bones tightly together, but allow for growth during youth
                      iv. In middle age, skull bones fuse and are called synostoses

              b. Syndesmoses
                      i. Bones are connected by a fibrous tissue ligament
                      ii. Movement varies from immovable to slightly variable
                      iii. Examples include the connection between the tibia and fibula,
                           and the radius and ulna

              c. Gomphoses
                      i. The peg-in-socket fibrous joint between a tooth and its alveolar
                          socket
                      ii. The fibrous connection between the tooth and alveolar socket is
                          the periodontal ligament


G. Cartilaginous Joints
       1. Articulating bones are united by cartilage
       2. Lack a joint cavity
       3. Amphiarthoses and synarthoses
       4. Two types – synchondroses and symphyses
                      a. Synchondroses
                            i. A bar or plate of hyaline cartilage unites the bones
                            ii. All synchondroses are synarthrotic
                            iii. Examples include:
                                      a. Epiphyseal plates of children
                                      b. Joint between the costal cartilage of the first rib and the
                                          sternum


                      b. Symphyses
                            i. Hyaline cartilage covers the articulating surface of the bone and
                                 is fused to an intervening pad of fibrocartilage
                            ii. Amphiarthrotic joints designed for strength and flexibility
                            iii. Examples include intervertebral joints and the pubic symphysis
                                 of the pelvis


II. Synovial Joints
      A. Those joints in which the articulating bones are separated by a fluid-containing joint
          cavity
      B. All are freely movable diarthroses
      C. Examples – all limb joints, and most joints of the body


      D. General Structure: Synovial joints all have the following
             1. Articular cartilage
             2. Joint (synovial) cavity
             3. Articular capsule
             4. Synovial fluid
             5. Reinforcing ligaments


      E. Articular cartilage
             1. On ends – like sponge holding fluid
             2. Provides smooth surface
             3. In contact with synovial fluid
F. Joint (synovial) cavity
       1. Filled with synovial fluid


G. Articular capsule - Surrounds the joint
       1. Double layer
              a. Outer layer – fibrous capsule continuous with periosteum
              b. Inner layer
                       i.   Synovial membrane composed of loose CT
                       ii. Forms capsule secreting synovial fluid
                       iii. Lines all internal parts that aren’t hyaline cartilage
H. Synovial fluid
       1. Viscous fluid – because of hyaluronic acid
       2. Contains phagocytes


I. Reinforcing ligaments
       1. Also known as Intrinsic ligaments
       2. Thickened parts of fibrous capsule
       3. Parallel bundle of fibers

J. Friction-Reducing Structures
       1. Bursae – flattened, fibrous sacs lined with synovial membranes and
          containing synovial fluid
              a. Common where ligaments, muscles, skin, tendons, or bones rub
                    together
       2. Tendon sheath – elongated bursa that wraps completely around a tendon


K. Stability is determined by:
       1. Articular surfaces – shape determines what movements are possible
       2. Ligaments – unite bones and prevent excessive or undesirable motion
       3. Muscle tone and Tendons:
              a. Muscle tendons across joints acting as stabilizing factors
              b. Tendons that are kept tight at all times by muscle tone
L. The two muscle attachments across a joint are:
      1. Origin – attachment to the immovable bone
      2. Insertion – attachment to the movable bone


M. Range of Motion
      1. Nonaxial – slipping movements only
      2. Uniaxial – movement in one plane
      3. Biaxial – movement in two planes
      4. Multiaxial – movement in or around all three planes

N. Gliding Movements
      1. One flat bone surface glides or slips over another similar surface
      2. Examples – intercarpal and intertarsal joints, and between the flat articular
          processes of the vertebrae

O. Angular Movement
      1. Flexion — bending movement that decreases the angle of the joint
      2. Extension — reverse of flexion; joint angle is increased
      3. Dorsiflexion and plantar flexion — up and down movement of the foot
      4. Abduction — movement away from the midline
      5. Adduction — movement toward the midline
      6. Circumduction — movement describes a cone in space
      7. Rotation
             a. The turning of a bone around its own long axis
             b. Examples: Between first two vertebrae and Hip and shoulder joints

P. Special Movements
      1. Supination and pronation
      2. Inversion and eversion
      3. Protraction and retraction
      4. Elevation and depression
      5. Opposition
Q. Types of Synovial Joints
       1. Plane joints
              a. Articular surfaces are essentially flat
              b. Allow only slipping or gliding movements
              c. Only examples of nonaxial joints


       2. Hinge joints
              a. Cylindrical projections of one bone fits into a trough-shaped surface on
                   another
              b. Motion is along a single plane
              c. Uniaxial joints permit flexion and extension only
              d. Examples: elbow and interphalangeal joints


       3. Pivot Joints
              a. Rounded end of one bone protrudes into a “sleeve,” or ring, composed
                   of bone (and possibly ligaments) of another
              b. Only uniaxial movement allowed
              c. Examples: joint between the axis and the dens, and the proximal
                   radioulnar joint

R. Condyloid or Ellipsoidal Joints
       1. Oval articular surface of one bone fits into a complementary depression in
          another
       2. Both articular surfaces are oval
       3. Biaxial joints permit all angular motions
       4. Examples: radiocarpal (wrist) joints, and metacarpophalangeal (knuckle)
          joints

S. Saddle Joints
       1. Similar to condyloid joints but allow greater movement
       2. Each articular surface has both a concave and a convex surface
       3. Example: carpometacarpal joint of the thumb
T. Ball-and-Socket Joints
      1. A spherical or hemispherical head of one bone articulates with a cuplike
          socket of another
      2. Multiaxial joints permit the most freely moving synovial joints
      3. Examples: shoulder and hip joints

U. Synovial Joint: Knee
      1. Largest and most complex joint of the body
      2. Allows flexion, extension, and some rotation
      3. Three joints in one surrounded by a single joint cavity
             a. Femoropatellar joint
             b. Lateral and medial tibiofemoral joints
      4. Knee Ligaments and Tendons – Anterior View
             a. Tendon of the quadriceps femoris muscle
             b. Lateral and medial patellar retinacula
              c. Fibular and tibial collateral ligaments
             d. Patellar ligament
      5. Other Supporting Structures
             a. Anterior cruciate ligament
             b. Posterior cruciate ligament
              c. Medial meniscus (semilunar cartilage)
             d. Lateral meniscus
      6. Posterior Superficial View
             a. Adductor magnus tendon
             b. Articular capsule
              c. Oblique popliteal ligament
             d. Arcuate popliteal ligament
             e. Semimembranosus tendon

V. Synovial Joints: Shoulder (Glenohumeral)
      1. Ball-and-socket joint in which stability is sacrificed to obtain greater freedom
          of movement
      2. Head of humerus articulates with the glenoid fossa of the scapula
W. Synovial Joints: Elbow
       1. Hinge joint that allows flexion and extension only
       2. Radius and ulna articulate with the humerus
       3. Annular ligament
       4. Ulnar collateral ligament
       5. Radial collateral ligament

X. Shoulder Stability
       1. Weak stability is maintained by:
              a. Thin, loose joint capsule
              b. Four ligaments – coracohumeral, and three glenohumeral
              c. Tendon of the long head of biceps, which travels through the
                  intertubercular groove and secures the humerus to the glenoid cavity
              d. Rotator cuff (four tendons) that encircles the shoulder joint and blends
                  with the articular capsule

Y. Synovial Joints: Hip (Coxal) Joint
       1. Ball-and-socket joint
       2. Head of the femur articulates with the acetabulum
       3. Good range of motion, but limited by the deep socket and strong ligaments
       4. Acetabular labrum
       5. Iliofemoral ligament
       6. Pubofemoral ligament
       7. Ischiofemoral ligament
       8. Ligamentum teres

				
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posted:12/4/2011
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