HumanA&P 10: Joints

3 Functions of Joints

1. Enable movement

2. Provide stability

3. Allow bones to lengthen

3 Joint Classifications by Motion

1. Synarthrosis: no movement between bones

2. Amphiarthrosis: small amount of movement between bones

3. Diarthrosis: freely moveable within ROM

3 Classifications of Joints by Structure

1. Fibrous

   • Joined by dense regular connective tissue

   • No joint space

   • Arthroses or amphiarthroses

2. Cartilaginous

   • Joined together with cartilage

   • No space between articulating bones

   • Arthroses or amphiarthroses

3. Synovial

   • Hyaline articular cartilage on bones

   • Joint space is fluid filled cavity

   • Diarthrosis joints

3 Types of Fibrous Joints

1. Sutures

2. Syndesmoses

3. Gomphoses

Sutures

• Fibrous joints

• Joints of skull

• Allow for growth during youth

• Structures ossify/fuse at middle age

  • syostoses

Gomphoses

• Fibrous joints

• Peg-in-socket

• Periodontal ligament is fibrous connection

Sydesmoses

• Fibrous joints

• Fiber length varies

• Movement varies

2 Types of Cartilaginous Joints

1. Synchondroses

2. Symphyses

Synchondroses

• Type of cartilaginous joint

• Bones joined together by hyaline cartilage

• Immovable joint (synarthrosis)

• Ex

  • Epiphyseal plates

  • First sternocostal & all costochondral joints

Symphyses

• Type of cartilaginous joint

• Bones joined by fibrocartilage

• Partially moveable joints (amphiarthroses)

• Ex

  • Intervertebral joints

  • Pubic symphysis

Synovial Joints

• Bones separated by fluid-filled joint cavity

• Diarthrotic

• 6 Characteristics

6 General Features of Synovial Joints

1. Articular Cartilage

   • hyaline covers ends of bones

2. Joint Cavity

   • fluid filled space

3. Articular Capsule: 2 layers thick

   • External fibrous layer

   • Inner synovial membranes: loose connective tissue; makes synovial fluid

4. Synovial Fluid: viscous, filtrate of plasma & hyaluronic acid

5. Different types of ligaments

   • Capsular

   • Extracapsular

   • Intracapsular

6. Nerves & Blood Vessels:

   • Nerves detect pain

   • Capillary beds

Special Features of Synovial Joints

• Fatty pads

  • cushioning between fibrous layer of capsule & synovial membrane/bone

• Articular discs

  • Fibrocartilage separates articular surfaces

3 Factors that Determine Stability of Joints

1. Shape of articular surface: Shallow surfaces less stable than ball-socket

2. Ligament number & location

3. Muscle tone: keeps tendons taught

Synovial Joints Structure: 4 Stabilizing & Supporting Elements

• Ligaments

• Tendons

• Bursae

• Tendon Sheath

Bursae

• Bags of synovial fluid that act as lubricating “ball bearing”

• Reduce friction where ligaments, muscles, skin, tendons, or bones rub together

Tendon Sheaths

• Elongated bursae wrapped completely around tendons subjected to friction

Muscle Origin

Attachment to immoveable bone

• Muscle contraction causes insertion to move toward origin

Muscle Insertion

Attachment to moveable bone

• Muscle contraction causes insertion to move toward origin

4 Ranges of Motion Allowed by Synovial Joints

• Nonaxial: slipping only

• Uniaxial: movement in 1 plane

• Biaxial: movement in 2 planes

• Multiaxial: movement in 3 planes

3 General Types of Movements

1. Gliding

2. Angular Movements

3. Rotation

Uniaxial Joint Example

Biaxial Joint Example

Multiaxial Joint Example

Gliding Movements

• Movement permitted by synovial joint

• Flat bone surface glides or slips over another similar surface

Angular Movements

• Movement permitted by synovial joint

• Increase or decrease angle between 2 bones

• Flexion: decreases angle

• Extension: increases angle

• Abduction: away from midline

• Adduction: towards midline

• Rotation: medial. lateral

Supination & Pronation

• Movement permitted by synovial joint

Dorsiflexion & Plantar Flexion

• Movement permitted by synovial joint

Inversion & Eversion

• Movement permitted by synovial joint

Protraction & Retraction

• Movement permitted by synovial joint

Elevation & Depression

• Movement permitted by synovial joint

Opposition

• Movement of thumb

• Permitted by synovial joint

6 Types of Synovial Joints

1. Plane

2. Hinge

3. Pivot

4. Condylar

5. Saddle

6. Ball & Socket

Plane Joint

• Synovial joint

• Least mobile

• Between 2 flat surfaces

Hinge Joint

• Synovial joint

• Convex articular surface of one bone interacts with concave depression of second bone

• Uniaxial movement

Pivot Joint

• Synovial joint

• Rounded end surface of bone fits into groove on surface of other bone

• Uniaxial movement

Condylar Joint

• Synovial joint

• Oval, convex surface of bone fits into shallow concave articular surface of other bone

• Biaxial movement

Saddle Joint

• Synovial joint

• Each bone has concave & convex region

• Biaxial movement

Ball & Socket Joint

• Synovial joint

• Articulating surface is spherical, fits into cup-shaped depression in other bone

• Multiaxial movement

Specific Hinge Joints: The Elbow

• 2 Articulations:

  • Humerolunar joint: trochlea of humerus & trochlear notch of ulna

  • Humeroradial joint: capitulum of humerus & head of radius

Specific Hinge Joints: The Knee

• 2 articulation

  • Tibiofemoral joint: condyles of femur & tibia

  • Patellofemoral joint: posterior & patellar surface of femur

6 Primary Supporting Structures of the Knee

• Patellar ligament: distal continuation of quad tendon.
  Connects patella to anterior tibia

• Tibial (medial) collateral ligament: connects femur to tibia
  (medial joint stabilization)

• Fibular (lateral) collateral ligament: connects femur to
  fibula (lateral joint stabilization)

• Anterior Cruciate Ligament: connects anterior tibia to
  posterior femur (prevents tibia from sliding anteriorly,
  prevents hyperextension)

• Posterior Cruciate Ligament: connects posterior tibia to
  anterior femur (prevents tibia from sliding backward)

• Medial and lateral meniscus: C-shaped fibrocartilage pads
  between the femoral and tibial condyles (provide extra
  stability and shock absorption)

Specific Ball & Socket Joints: The Shoulder

• Glenohumeral Joint

  • Head of humerus with glenoid cavity of scapula

  • Biceps brachii tendon: keeps head of humerus in joint

  • 4 rotator cuff muscles

    • supraspinatus,
      infraspinatus, subscapularis,
      Teres minor

Specific Ball & Socket Joints: The Hip

• Articulation between acetabulum & femur

• Main supporting structures:

  • Iliofemoral ligament: connects
    ilium to femur

  • Ischiofemoral ligament: connects
    ischium to femur

  • Pubofemoral ligament: connects
    pubis to femur

  • Ligament of the head of femur:
    found within joint

Sprain

• Common joint injury

• Reinforcing ligaments are stretched or torn

• Partial tears are repair slow due to poor vascularization

Dislocations

• Common joint injury

• Bones forced out of alignment

• Subluxation: partial dislocation

Bursitis

• Inflammation of bursa

• Treated with rest, ice, NSAIDs

Tendonitis

• Inflammation of tendon sheaths

• Symptoms & treatments similar to bursitis

Arthritis

• >100 different types of inflammatory or degenerative diseases that damage joints

• Symptoms: pain, stiffness, and swelling of joint

• Acute forms: caused by bacteria, treated with antibiotics

• Chronic forms: osteoarthritis, rheumatoid arthritis, and gouty arthritis

Osteoarthritis

• Most common type of arthritis

• Irreversible

• Usually normal part of aging process

• Treatment: moderate activity, mild pain relievers, capsaicin creams

Rheumatoid Arthritis

• Chronic, inflammatory, autoimmune disease of unknown cause

  • Immune system attacks own cells

• Inflamed synovial membrane thickens into abnormal pannus tissue that clings to articular cartilage

• Treatment includes steroidal and nonsteroidal anti-inflammatory drugs to decrease pain and inflammation

Gouty Arthritis

• Deposition of uric acid crystals in joints and soft tissues

• More common in men

• Typically affects joint at base of great toe

• In untreated gouty arthritis, bone ends fuse and immobilize join

• Treatment: drugs, plenty of water, avoidance of alcohol and foods high in
  purines, such as liver, kidneys, and sardines

Lyme Disease

• Bacteria transmitted from tick bites

• Symptoms: skin rash, flu-like symptoms, and foggy thinking

• May lead to joint pain and arthritis

• Treatment: long course of antibiotics