Chapter 8 Joints

Question 1

Joints are classified based on amount of movement

Answer 1

• synarthroses = immovable joints
  
  • amphiarthroses = slightly moveable
  • diarthroses = freely moveable

Question 2

Join movement: Synarthroses

Answer 2

synarthroses = immovable joints

Question 3

Join movement: Amphiarthroses

Answer 3

amphiarthroses = slightly moveable

Question 4

Join movement: Diarthroses

Answer 4

diarthroses = freely moveable

Question 5

Fibrous joints characteristics

Answer 5

• Fibrous joints = bones joined by collagen fibers of connective tissue and no joint cavity is present
  - most immoveable
  
  • sutures – interlocking junction with minimal amount of very short connective tissue fibers
  • cranial bones of skull
  • syndesmosis = bones connected by ligaments, cords or bands of fibrous tissue
  • radius and ulna
  *gomphosis = tooth in bone alveolar socket – connected by periodontal ligament

Question 6

Fibrous joints: Suture

Answer 6

Sutures – interlocking junction with minimal amount of very short connective tissue fibers
-cranial bones of skull

Question 7

Fibrous joints: Syndesmosis

Answer 7

Syndesmosis = bones connected by ligaments, cords or bands of fibrous tissue
-radius and ulna

Question 8

Fibrous joints: Gomphosis

Answer 8

Gomphosis = tooth in bone alveolar socket – connected by periodontal ligament

Question 9

Cartilaginous joints

Answer 9

• synchondrosis = immovable joints joined by hyaline cartilage
  
  • epiphyseal plate
  • symphysis = limited movement designed for strength and flexibility and joined by fibrocartilage
  • intervertebral discs, pubic symphysis

Question 10

Cartilaginous joints: Synchondrosis

Answer 10

Synchondrosis = immovable joints joined by hyaline cartilage

-epiphyseal plate

Question 11

Cartilaginous joints: Symphysis

Answer 11

Symphysis = limited movement designed for strength and flexibility and joined by fibrocartilage
-intervertebral discs, pubic symphysis

Question 12

Synovial joints: Classification and Features

Answer 12

• articular cartilage
  
  • joint cavity
  • articular capsule
    - fibrous layer
    - synovial membrane
  • synovial fluid
  • reinforcing ligaments
    
    • capsular ligaments
  • intracapsular ligaments
  • nerves and blood vessels – in the capsule
  *other features – cushion structures and improve fit of joint

Question 13

Synovial joints: Articular cartilage

Answer 13

Articular cartilage = hyaline cartilage that covers opposing bone surfaces

Question 14

Synovial joints: Joint cavity

Answer 14

Space that contains small amount of synovial fluid

Question 15

Synovial joints: Articular capsule

Answer 15

Articular capsule – two-layer

* fibrous layer = outer layer of dense regular connective tissue
* synovial membrane = inner layer of loose connective tissue and makes synovial fluid

Question 16

Synovial joints: Synovial fluid

Answer 16

Synovial fluid – contains hyaluronic acid = slippery weight-bearing film

Question 17

Synovial joints: Reinforcing ligaments

Answer 17

• reinforcing ligaments
• capsular ligaments = thickenings of fibrous layer of capsule
• intracapsular ligaments – covered with synovial membrane so do not lie within capsule

Question 18

Synovial joints: Nerves and blood vessels

Answer 18

-Nerves and blood vessels – in the capsule: provide sensory information and nourish synovial membrane

Question 19

Synovial joints: Other features

Answer 19

–Cushion structures and improve fit of joint

* fat pads 
* articular discs or menisci

Question 20

Synovial joints: Stability depends on?

Answer 20

Stability depends on

* shapes of articular surfaces
* number and positioning of ligaments
* muscle tone

Question 21

Synovial joints: Types of movement

Answer 21

• gliding
  * angular
  
  • rotation
  • special movements (Fig 8.6)

Question 22

Synovial joints - Types of movement: Gliding

Answer 22

*gliding – bony surfaces slip over one another

Question 23

Synovial joints - Types of movement: Angular

Answer 23

Angular – increases or decreases the angle between two bones

* flexion – along sagittal plane - decreases angle of joint – brings articular bones closer together
* extension – increases angle of joint or straightens
      - hyperextension = increase in joint angle beyond anatomical position

* abduction – movement away from midline along frontal plane
* adduction – movement toward midline
* circumduction – movement that describes a cone in space - distal end of a limb moves in a circle while proximal portion remains stationary

Question 24

Synovial joints - Types of movement: Rotation

Answer 24

Rotation = turning a bone around its own long axis

-first two cervical vertebrae, shoulder, hip

Question 25

Joints diseases: Bursa and Tendon sheaths

Answer 25

• Bursa and Tendon sheaths – often associated with synovial joints *Bursa = flattened fibrous sacs lined with synovial membrane and small amount of synovial fluid *Tendon sheath = elongated bursa that wraps completely around a tendon subject to friction

Question 26

Knee Joint

Answer 26

* largest and most complex joint of body * one joint cavity but have femoropatellar and tibiofemoral joints * tibial surface = articular cartilage plus C-shaped medial and lateral menisci (fibrocartilage) * articular capsule present on sides and posterior aspects of knee * anteriorly – three broad ligaments run from patella to tibia * many bursae – subcutaneous prepatellar bursa often damaged when knee bumped anteriorly * capsular and extracapsular ligaments act to prevent hyperextension of knee and are stretched tight when knee is extended * cruciate ligaments = intracapsular ligaments cross each other forming an X between the femoral condyles * most susceptible to sports injuries – can absorb vertical force nearly 7 x body weight but very susceptible to HORIZONTAL blows - most ACL injuries occur when a runner changes direction quickly, twisting a hyperextended knee

Question 27

Knee Joint: Menisci

Answer 27

Menisci = shock absorbers that deepen articular surface and prevent side-to-side rocking of bones * tears when subjected to compression and shear (twisting) stress at the same time * avascular so repairs poorly * cartilage fragments (loose bodies) can interfere with joint function * arthroscopic surgery – small instrument with tiny lens and fiber-optic light source that allows surgeon to remove cartilage fragments or repair a ligament through one or more small slits

Question 28

Knee Joint - Anteriorly three broad ligaments run from patella to tibia:

Answer 28

* Patellar ligament, and | * Medial and lateral retinacula (merge with articular capsule)

Question 29

Knee Joint: Capsular and Extracapsular ligaments

Answer 29

*capsular and extracapsular ligaments act to prevent hyperextension of knee and are stretched tight when knee is extended

Question 30

Knee Joint: Cruciate ligaments

Answer 30

Intracapsular ligaments cross each other forming an X between the femoral condyles * anterior cruciate ligament (ACL)– prevents forward sliding of tibia on femur * posterior cruciate ligament – prevents backward displacement of tibia

Question 31

Shoulder (Glenohumoral) joint

Answer 31

* glenoid cavity shallow – deepened by glenoid labrum (rim of fibrocartilage) * few ligaments reinforce joint and mainly located on anterior surface * rotator cuff = four tendons that encircle shoulder joint and blend in with articular capsule * dislocations (luxations) – fairly common due to shallow joint cavity and weak anterior and inferior reinforcements

Question 32

Shoulder (Glenohumoral) joint: Rotator cuff

Answer 32

- Four tendons that encircle shoulder joint and blend in with articular capsule * can be severely stretched or torn when arm is vigorously circumducted – pitchers, tennis players

Question 33

Shoulder (Glenohumoral) joint: Dislocations (luxations)

Answer 33

Fairly common due to shallow joint cavity and weak anterior and inferior reinforcements * forward and downward into axillary area * usually accompanied by sprains, inflammation and difficulty moving joint

Question 34

Temporomandibular joint (TMJ)

Answer 34

- Modified hinge joint just anterior to ear * hinge-like depression and elevation of mandible * gliding from side to side – grinding = lateral excursion -Dislocations common – shallow joint that dislocates anteriorly

Question 35

Temporomandibular joint (TMJ): Dislocation

Answer 35

Dislocations common – shallow joint that dislocates anteriorly

Question 36

TMJ disorders

Answer 36

- Often found in people who grind their teeth, following jaw trauma, poor occlusion of teeth * symptoms: pain in the ear and face, tenderness of jaw muscles, popping sounds when mouth opens and joint stiffness * treatment – relaxation of jaw muscles using massage, muscle-relaxants, heat or cold, stress reduction techniques, and bite plate for use during sleep for teeth grinders

Question 37

Joints Diseases: Sprains

Answer 37

Sprains – occur when ligaments reinforcing a joint are stretched or torn * most common sites = ankle, knee, and lumbar area of spine * pain, immobilizing and heal slowly

Question 38

Joints Diseases: Bursitis

Answer 38

Inflammation of a bursa – usually caused by a blow or friction *severe cases treated by injection of anti-inflammatory drugs into bursa

Question 39

Joints Diseases: Tendonitis

Answer 39

Inflammation of tendon sheath – typically caused by overuse * symptoms: pain, swelling and may getting tingling (if compresses sensory nerves) * treatment: rest, ice, anti-inflammatories

Question 40

Joints Diseases: Arthritis

Answer 40

100 different types of inflammatory or degenerative diseases that damage joints * symptoms: pain, stiffness, and swelling of joint * acute forms usually result from bacterial infection and are treated with antibiotics * chronic forms include: osteoarthritis, rheumatoid arthritis, and gouty arthritis * osteoarthritis (OA) = most common chronic arthritis = chronic degenerative * rheumatoid arthritis * gouty arthritis

Question 41

Joints Diseases - Arthritis: Osteoarthritis

Answer 41

- Most common chronic arthritis = CHRONIC DEGENERATIVE CONDITION * wear-and-tear disease as most common in elderly * produces softened, roughened, pitted and eroded articular cartilages * exposed bone thickens and forms osteophytes – bony spurs that enlarge bone ends and may restrict movement * most affected joints = cervical and lumbar spine, fingers, knuckles (juntas), knees and hips * most controllable with mild pain relief (aspirin, acetaminophen) and moderate activity * can be crippling when knees or hips are involved - total knee and hip replacements with metal and plastic prostheses last about 10-15 years - done to reduce pain and restore about 80% of original joint function

Question 42

Joints Diseases - Arthritis: Rheumatoid arthritis

Answer 42

- Chronic inflammatory AUTOIMMUNE DISORDER * usually occurring between 30-50 years of age * many joints – especially small joints of fingers, wrists, ankles and feet bilaterally affected * in addition to pain and swelling – can include anemia, osteoporosis, muscle weakness and cardiovascular disease * *pannus = thickened synovial membrane that clings to and degrades articular cartilage - scar tissue forms and connects bone ends - ANKYLOSIS = fusion of bone ends that deform and immobilize joint * steroidal and non-steriodal anti-inflammatory drugs, immune suppressants

Question 43

Joints Diseases - Arthritis: Rheumatoid arthritis

Answer 43

Pannus = thickened synovial membrane that clings to and degrades articular cartilage - scar tissue forms and connects bone ends - ANKYLOSIS = fusion of bone ends that deform and immobilize joint

Question 44

Joints Diseases - Arthritis: | Gouty arthritis

Answer 44

Resulting from excessive uric acid production (waste product of nucleic acid metabolism) and deposition of uric acid crystals (needle-shaped crystals) into soft tissues of joints * inflammatory response accompanied with pain – usually starting in one joint – base of great toe * more common in men * several drugs that terminate or prevent gout attacks available and patients advised to drink plenty of water, avoid alcohol consumption (promotes uric acid overproduction) and foods high in purine-containing nucleic acids (liver, kidneys, sardines)