Joint Capsule, Synovium, Movement & Innervation

Question 1

The joint capsule is a ____ layer of tissue

Answer 1

fibrous

Question 2

What is the quality of vascularization and innervation of the joint capsule?

Answer 2

high

Question 3

____ blend with the joint capsule

Answer 3

ligaments
(hence, ligamentous sleeve)

Question 4

The majority of ligament fibers of a joint capsule run in the ____ direction

Answer 4

same

Question 5

What is the joint capsule comprised of?

Answer 5

closely packed collagen fibers

Question 6

What is the function of the joint capsule?

Answer 6

• limit stretch
• proprioception

Question 7

Why would someone experience chronic/repeated ankle sprains?

Answer 7

destroyed joint capsule ligaments -> decreased proprioception

Question 8

The internal portion of the joint capsule is lined by ____

Answer 8

synovial membrane (synovium)

Question 9

What parts of a joint are covered by synovium?

Answer 9

all internal joint structures (including fat pad on post. knee) except bare area & articular cartilage

Question 10

What is the synovial membrane comprised of?

Answer 10

2-3 layers of synoviocytes (type A and B)

Question 11

What are type A synoviocytes?

Answer 11

macrophages with lysosomal enzymes

Question 12

What are type B synoviocytes?

Answer 12

fibroblast-like cells

Question 13

What type of synoviocytes help to clean up joints?

Answer 13

type A

Question 14

What type of synoviocytes produce synovial fluid components?

Answer 14

type B

Question 15

What are the components of synovial fluid?

Answer 15

• hyaluronate
• collagens
• fibronectin
• glycoproteins

Question 16

Synovial tissue is arranged in ____ and ____

Answer 16

villi (folds)
microvilli

Question 17

What is the consistency of synovial fluid?

Answer 17

thick, viscous, egg-like

Question 18

What is the function of villi and microvilli of synovium?

Answer 18

^surface area for fluid production and waste resorption

Question 19

What are the functions of synovium?

Answer 19

1. diffusion of nutrients (fluid –> cartilage) & waste products (cartilage –> fluid)
2. ingestion of joint debris
3. secrete hyaluronate, Ig’s (immune function), lysosomal enzymes, proteoglycans
4. lubrication

Question 20

What components secreted by synovium provide the lubricative function of synovium?

Answer 20

• hyaluronate
• proteoglycans (eg. chondroitin sulfate)
  (large, negatively charged, hydrophilic molecules)

Question 21

What changes to synovium occur due to Rheumatoid arthritis?

Answer 21

• less lubrication
• less lysosomal enzymes = less breakdown of waste –> jt adhesions
• less diffusion of nutrients –> starve & breakdown cartilage

Question 22

How much synovial fluid is in a joint?

Answer 22

1-4 mL

Question 23

What happens to the amount of synovial fluid with inflammation?

Answer 23

increases (eg. ACL tear)

Question 24

Why is synovial fluid non-clotting?

Answer 24

comes from plasma with NO clotting factors (thromboplastin, fibrinogen)

Question 25

Movement is essential for joint ____ and ____

Answer 25

development maintenance

Question 26

Synovium and other vascularized structure require ____ to maintain optimal function

Answer 26

regular activity

Question 27

What is the effect of moderate exercise on articular cartilage?

Answer 27

decreased fibrillation and chondrocyte necrosis (strengthens cartilage)

Question 28

What is the effect of immobilization on articular cartilage?

Answer 28

decreased proteoglycans & ^atrophy

Question 29

What is arthrogryposis?

Answer 29

multiple congenital joint contractures (fibrosis) resulting in lack of joint mobility in utero

Question 30

What is the clinical presentation of arthrogryposis?

Answer 30

- abnormal CT (fibrosis) deposited around jts = stiffness - muscle weakness due to underdeveloped mm & tendons - flattened & incongruent jt surface

Question 31

What is Hilton's law?

Answer 31

every peripheral nerve supplying a **muscle** sends a branch to the **joint** moved by the muscle and to the **skin** overlying the joint

Question 32

What law explains the superficial sensations felt with pathology?

Answer 32

Hilton's law

Question 33

What are the 4 types of nerve endings in a joint?

Answer 33

- encapsulated endings - Pacinian corpuscles - golgi tendon organs (GTOs) - free nerve endings

Question 34

What type of nerve endings respond to mechanical stimuli such as **pressure and stretch**?

Answer 34

encapsulated (eg. ligament/joint capsule proprioception)

Question 35

What type of nerve endings respond to initiation and cessation of movement (acceleration & deceleration), and are considered dynamic?

Answer 35

Pacinian corpsucles

Question 36

What type of nerve endings are a stretch receptor responding to tension generated at the musculotendinous junction?

Answer 36

golgi tendon organs (eg. deep tendon reflex)

Question 37

What type of nerve endings mediate pain?

Answer 37

free nerve endings