Week 2 - Joints

Question 1

Name all the types of joints

Answer 1

• synovial joints
• syndesmosis
• synchondrosis
• synostosis
• symphysis
• gomphosis

Question 2

What is a synovial joint and where is it found?

Answer 2

Joint with two opposing surfaces covered by cartilage, bathed in synovial fluid within a joint capsule

• found in most appendicular joints
• posterior joints of spine

Question 3

What is a syndesmosis and where is it found?

Answer 3

Joint where two bones are joined by fibrous tissue only.

• found in skull sutures
• found between distal end of tibia and fibula

Question 4

What is a synchondrosis and where is it found?

Answer 4

Two bones are joined by cartilage.

• found in physis (joins epiphysis & metaphysis)

Question 5

What is a synostosis and where is it found?

Answer 5

Bones are fused together obliterating joint.

• found in bones of the pelvis

Question 6

What is a symphysis and where is it found?

Answer 6

Two bones joined by cartilage but with no synovial fluid (and therefore very little movement).

• found at symphysis pubis
• found between vertebrae

Question 7

What is a gomphosis and where is it found?

Answer 7

Fibrous connection between a tooth and its socket. Blood vessels and nerves cross the joint

Question 8

When do synovial joints begin to develop?

Answer 8

At 6-9 weeks in development.

Question 9

Which develops first: upper or lower extremity?

Answer 9

upper extremity

Question 10

What are the 4 stages of joint development?

Answer 10

1. Homogenous Interzone
2. Three-layer interzone
3. Early liquefaction of middle layer
4. Full separation and joint cavitation

Question 11

What is found in the homogenous interzone of developing bone?

Answer 11

Mesenchymal cells

Question 12

What will the mesenchymal interzone develop into?

Answer 12

• articular cartilage
• meniscus
• cruciate ligaments
• collateral ligaments

(these happen before development of synovial fluid

Question 13

What is found in the three-layered interzone?

Answer 13

• two layers of densely packed cells (become articular surfaces).
• one layer of loosely packed undifferentiated cells in between the dense layers.

Question 14

What is the tiny sesamoid bone located BEHIND the knee called?

Answer 14

flabella

Question 15

What are the layers of the synovium?

- briefly decribe each

Answer 15

Outer: rich supply of blood vessels, nerves, and lymph
Inner: thin syncytium

Question 16

What cells are found in the inner layer of the synovial membrane?

Answer 16

Type A –> cells specialized to clear waste material

Type B –> cells specialized to synthesize hyaluronic acid

Question 17

What is synovial fluid composed of?

Answer 17

dialyzed plasma with glycoprotein and hyaluronic acid

Question 18

Approximately how much synovial fluid would you find in the knee?

Answer 18

~5 cubic cm

Question 19

What is the joint capsule?

Answer 19

tough fibrous tissue that joins the two bones of a joint

Question 20

What is a bone bruise?

Answer 20

Injury to the subchondral bone

Question 21

Name a couple examples of tendons that are intra articular.

Answer 21

Biceps; popliteus

Question 22

What happens when a joint is injured?

Answer 22

• injury (twist/fall/etc)
• inflammation (redness, swelling, pain, heat)
• effusion (increase in joint fluid volume)
• healing/resolution

Question 23

What is immediate joint swelling after an injury indicative of?

Answer 23

hemarthrosis

• -> fracture
• -> significant ligament/capsular injury

Question 24

What is development of a bruise indicative of?

Answer 24

bleeding into subdermal tissue

Question 25

What is the healing response for a synovial joint injury?

Answer 25

substitution of collagen into hemorrhagic tissue

Question 26

What are the two main mechanisms for injury to joint cartilage?

Answer 26

Abnormal force on normal joint (seen more often in younger patients involved in high-intensity sports)

Normal force on abnormal joint (seen more often in older patients)

Question 27

How does articular cartilage heal?

Answer 27

Doesn’t heal except in very young patients.

Instead will get replaced with fibrocartilage (Type I collagen) but this is not as durable

Question 28

Why does blood not clot within the knee capsule?

Answer 28

The synovial fluid mixes with the blood and has factors that prevent clotting

Question 29

How do extraarticular ligaments heal?

Answer 29

With a fibrin clot

• fibroblasts proliferate & secrete matrix
• forms early tissue type III collagen
• remodels to resemble normal ligament (Type I collagen)
• contraction of healing tissue

Question 30

What are the extra articular ligaments of the knee?

Answer 30

MCL & LCL

Question 31

What are the effects of decreased loading on a joint?

Answer 31

Loss of PGs

Muscle, tendon, & bone become deconditioned

Question 32

What are the components of a synovial joint?

Answer 32

• bone
• Articular cartilage
• two opposing bones
• fibrous capsule & ligaments
• synovial membrane
• synovial fluid
• supportive fibrocartilage (tissue inside a specific joint for stability)
• tendons
• associated nerves and vessels

Question 33

What are the categories of intrinsic causes of joint pain?

Answer 33

Articular & Non-articular

Question 34

What are the categoris of extrinsic causes of joint pain?

Answer 34

Generalized, Neurologic, & Referred pain

Question 35

What are some examples of articular causes of joint pain?

Answer 35

• arthritis
• neoplasm
• trauma

Question 36

What are some examples of non-articular causes of intrinsic joint pain?

Answer 36

• bursitis
• tendonitis
• myositis

Question 37

What are some examples of neurologic causes of joint pain?

Answer 37

• nerve root compression

- HCV

Question 38

What are some examples of generalized causes of joint pain?

Answer 38

• fibromyalgia

- dermatomyositis