chapter 9 - Joints

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Chapter 9 Notes

*Joints: Where two bones come together.

Basic Terminology:

Synarthrosis: No Movement

Amphiarthrosis: Slight Movement

Diarthrosis: Freely Moveable

Arthro: Joint  Syn: Together Amphi: Slight  

Chondro: Cartilagenous Dia: Through

Classification of Joint: Structural and Functional:

• • Structural Classification
  

  • Based on type of tissue between the bones
    

  • Fibrous, cartilaginous, synovial
    

• • Functional Classification
  

  • Based on amount of movement
    

  • Synarthrosis, Amphiarthrosis, Diarthrosis
    

Structural Classification: Type of Tissue

• • Fibrous:  
  

  • Sutures, Gomphosis, Syndesmosis
    

• • Cartilagenous:  
  

  • Symphysis & intervertebral discs (fibrocartilage)  
    

  • epiphyseal plate , 1st rib & sternum (Hyaline)
    

• • Synovial
  

  • Always diarthrotic joints
    

Fibrous joints:  Made of collagen fibers (Sutures, Gomphosis, Syndesmosis)

Cartilaginous joints

-Fibrous cartilage

-Costochondral joints

-Symphyses

-Intervertebral discs

-Hyaline cartilage

-Epiphyseal cartilage

- 1st rib & sternum

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Synovial Joint (Diarthrotic Joints)

• • Fibrous Capsule
  

  • Dense irregular CT; continuous with periosteum
    

• • Synovial Membrane
  

  • Areolar CT covered by a few scattered cells
    

• • Synovial Fluid
  

  • Secreted by synovial membrane
    

  • Slippery  
    

  • Reduces friction between bones forming the joint
    

  • Composed of proteoglycans
    

Bursa and Tendon Sheath:

• • Bursa
  

  • Membrane bound pocket filled with synovial fluid
    

  • Found where tendons or ligaments rub against bone or other tissue
    

  • Reduces friction, shock absorption
    

• • Tendon Sheath
  

  • A bursa that extends along a tendon for some distance. It permits the tendon to stretch and not adhere to the surrounding fascia.
    

Classifying Joints By Movement:

*Synarthrotic, Amphiarthrotic and Diarthrotic  

Synarthrotic joints (Immovable Joints)

- Epiphyseal plate

- Gomphosis

- Sutures / synostoses

Amphiarthrotic Joints (Slightly Moveable/A Little Movement)

- Symphysis

- Syndesmosis

Diarthrotic joints (Freely Moveable/These are always Synovial Joints)

Movement at a joint is affected by:

- Soft tissue

- Shapes of condyles

- Ligaments

Types of Movements at Joints: (Be familiar with movement of all joints of the human body!)

*Angular Movement (Flexion/Extension of upper and lower extremities)

*Angular Movement (Hyperextension/Flexion of torso; Hyperextension/Extension/Flexion of    

 Neck; Flexion/Extension/Hyperextension of wrist(hand))

*Angular Movement (Abduction/Adduction of wrists; Dorsiflexion/Plantarflexion of foot;  

 Abduction/Adduction of Arm; Circumduction of Arm).

*Rotation of Neck; Rotation of Arm (Medial and Lateral)

*Supination (Radius and Ulna are Parallel); Pronation (Radius rotates over Ulna).

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Special Movements:

*Inversion and Eversion of the foot.

*Opposition (Thumb and Fingers)

Types of Synovial Joints:

• 1. Gliding 2. Hinge  3. Ball and Socket     4. Pivot
  

• 1. Gliding Joints:
  

-Slight non-axial or multi-axial movement.

* Flat Surfaces slide across one another with very little movement.

-Examples: Intercarpal, Intertarsal, Acromioclavicular, Sacroiliac

     2. Pivot Joint:

-Movement: Mono-axial (Rotation)

 *Examples: C1/C2, Proximal radio-ulnar

    3. Hinge Joints:

-Movement: Mono-axial

          -Permit angular motion in a single plane, Allows Flexion/Extension

          -Examples: Elbow, Knee, Ankle, Interphalangeal

     4. Ball and Socket Joints:

-Triaxial (Movement)

-Allows: Flexion/Extension, Abduction/Adduction, Rotation, Circumduction.

-Examples: Shoulder, Hip
     5. Ellipsoid Joint:    

-Biaxial (Movement)

-Allows: Flexion/Extension; Abduction/Adduction; Circumduction

-Example: Radiocarpal Joint; Metacarpophalangeal Joints (2-5); Metatarsal Phalangeal  

                             Joints.

    6. Saddle Joints:

-Biaxial (Movement)

-Allows: Flexion/Extension; Abduction/Adduction; Circumduction; Opposition

-First Carpometacarpal Joint (Thumb)

Knee Joint:

• • Lateral & Medial Collateral Ligaments
  

-Reinforce the lateral and medial surfaces of the joint

• • ACL & PCL
  

  • Limit anterior and posterior movements
    

• • Lateral & Medial Meniscus
  

Act as cushions

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Shoulder Joint:

-Ball & socket joint

• - Unstable
  

• - Shallow
  

-    Held in place by Ligaments

-    Stabilized by Rotator cuff muscles

     - Rotator Cuff Muscles: Supraspinatus, Infraspinatus, Teres minor & Subscapularis.

       (The “SITS” muscles)

Hip Joint:

• • Ball and Socket Joint.
  

• • The ligaments and supporting muscles stabilize the joint.
  

▪    Dislocation usually occurs posteriorly

Sprain/Dislocation:

• • Sprain: Ligaments at joints stretch and some of collagen fibers are torn
  

• • Strain: Tendons stretch and some of collagen fibers are torn
  

• • Dislocation: The articulating surfaces are forced out of place