CHAPTER 9

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CHAPTER 9Joints

• COMMON COURSE OBJECTIVES
• Joints Structural and functional classification
• Structure of a typical synovial joint
• Types of synovial joints
• Terms for descriptions of movements

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JOINTS

• Defined any place where two bones come together
• General Function of Joints
• - Hold the skeleton together
• - Allow for increased mobility and flexibility
  of skeleton

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CLASSIFICATION OF JOINTS

• Joints can be classified based on
• -function (what kind of movement they allow)
• -structure (what material is found in the joint
  and if is there a joint cavity present).
• You are required to know each of these
  categories.

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Functional classification

• Synarthroses joints that have NO movement.
• Examples sutures of the skull, gomphoses- teeth
• Amphiarthroses partially movable joints.
• Examples intervertebral disc and pubic symphysis
• Diarthroses freely movable joints.
• The most common type of functional joint in
  the body.
• Examples knee joint, shoulder joint,finger
  joints,ankle and wrist joints, etc.

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Structural Classification

• Bony joints (synostoses) immovable joint formed
  when the gap between 2 bones ossifies.
• Fibrous joints (synarthroses) adjacent bones are
  joined by collagen fibers. 3 kinds
• - sutures, gomphoses and syndesmoses.
• Cartilaginous joints (amphiarthroses) two bones
  are joined by cartilage. 2 kinds
• - synchondroses and symphyses
• Diarthroses freely movable and most common joint
  in the body. Synovial joints are diarthrodial.

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Fibrous joints (synarthroses)

• Suture immovable fibrous joints that fuse skull
  bones
• Syndesmoses fibrous joint where 2 bones are
  joined by longer collagen fibers more movable.
• Gomphoses attachment of teeth to tooth socket by
  a periodontal ligament.

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Synovial Joints (diarthroses)

• this type of joint is defined by the presence of
  a joint cavity filled with fluid.
• Most joints of the body fall into this class.
• Examples knee joint, elbow joint, shoulder and
  hip joints and the phalanges of hands and feet,
  etc.

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Structures in a Synovial Joint

• articular capsule external and internal
• joint/synovial cavity filled with synovial
  fluid
• articular cartilage Hyaline cartilage
• synovial fluid viscous/ clear colorless fluid
• ligaments give the joint reinforcement and
  strength
• Nerves provide feelings of pain and stretch
• 7. Vessels - provide nutrients to joint

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Typical Synovial Joint

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Additional joint structures

• Ligaments- join bones to bones
• Consists of dense regular connective tissue.
• Tendons- join muscles to bone
• Consists of dense regular connective tissue.
• Bursae- fibrous sac lined with synovial membrane
  and containing synovial fluid
• Occurs between bones and tendons or muscles
• Acts to decrease friction during movement

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Accessory joint structures

1. fatty pads - cushioning
2. menisci tough fibrocartilage
3. bursae -flattened fibrous sac lined by synovial
   membrane.
4. tendon sheaths -fibrous tissue connecting a
   muscle to a bone

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Knee joint structures

1. Articular capsule
2. Synovial membrane
3. Medial and lateral menisci
4. Suprapatellar, infrapatellar and prepatellar
   bursae
5. Anterior and posterior cruciate ligaments
6. Tibial and fibular collateral ligaments
7. Patellar capsule
8. Articular cartilage
9. Tendon of quadriceps femoris

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Knee Joint

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Types of Synovial Joints

1. Plane (gliding) Joints
2. Hinge Joints
3. Pivot Joints
4. Condyloid Joints
5. Saddle Joints
6. Ball and Socket Joints

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Movements allowed by Synovial Joints

• 1. gliding - bony surfaces of bone slide or
  glide over each other
• 2. flexion - bending movement that decreases the
  angle
• 3. extension movement the increases the angle,
  opposite of lexion
• 4. abduction moving away from longitudinal axis
• 5. adduction movement toward the longitudinal
  axis
• 6. circumduction movement of the limb such that
  it describes a cone
• 7. rotation turning the bone or limb around its
  long axis
• 8. supination rotating the forearm laterally
  such that the palm faces superiorly

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Movements allowed by Synovial Joints

• 9. pronation - rotating the forearm medially
  such that the palm faces inferiorly
• 10. inversion - sole of the foot faces or turns
  medially
• 11. eversion - sole of the foot turn laterally
• 12. protraction -juttting out of the jaw
• 13. retraction - moving the jaw backward
• 14. elevation - lifting the limb or body
  superiorly
• 15. depression - moving the body part inferiorly
• 16. opposition - to bring the thumb and index
  finger tips together

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Body movements

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• Extension and flexion
  

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• Abduction and adduction

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• Elevation/Depression Protraction/Retraction
• Inversion/Eversion Pronation/Supination
  

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• Circumduction