3: Joint Structure and Function

Question 1

define a synarthrosis joint

Answer 1

• essentially no movement
• functions to bind and transfer forces b/w bones
• reinforced by a combo of cartilaginous and connective tissues

Question 2

define a diarthrosis (synovial) joint

Answer 2

• allows moderate to extensive motion

- synovial fluid-filled cavity

Question 3

what are 2 types of synarthroses?

Answer 3

• fibrous joints

- cartilaginous joints

Question 4

what are some examples of fibrous joints?

Answer 4

• sutures of the skull
• distal tibiofibular joint (syndesmosis)
• radioulnar interosseous membrane

Question 5

what are some examples of cartilaginous joints?

Answer 5

• pubic symphysis
• interbody joint of spine
• manubriosternal joint (in the young)

Question 6

what are some examples of diarthroses (synovial joints)?

Answer 6

• GH joint
• apophyseal (facet) joints of the spine
• knee
• ankle

Question 7

what elements are always associated with synovial joints?

Answer 7

• synovial fluid
• articular cartilage
• joint capsule
• synovial membrane
• ligaments
• blood vessels
• sensory nerves

Question 8

what elements are sometimes associated with synovial joints?

Answer 8

• intra-articular discs or menisci
• peripheral labrum
• fat pads
• bursa
• synovial plicae (overlapped pleats of tissue)

Question 9

describe the articular capsule of a synovial joint

Answer 9

• composed of CT that encloses the joint
• fibrous layer
• synovial layer or membrane

Question 10

describe the synovial membrane of a synovial joint

Answer 10

internal layer of articular capsule

Question 11

describe synovial fluid

Answer 11

• produced by cells within synovial membrane

- coats surfaces of joints, decreases friction, and provides nourishment

Question 12

what is the function of synovial joint ligaments?

Answer 12

protect from excessive movement

Question 13

intra-articular discs increase ____ and improve ____

Answer 13

• congruency

- force dispersion

Question 14

describe the peripheral labrum of a synovial joint

Answer 14

• deepens concave joint

- supports attachment of joint capsule

Question 15

describe the fat pads of a synovial joint

Answer 15

• reinforce internal aspects of capsule

- fill non-articulating joint spaces

Question 16

describe the bursa of a synovial joint

Answer 16

• extension of synovial membrane
• filled with synovial fluid
• absorb force
• protect periarticular connective tissue

Question 17

what are the 3 main functions of synovial joints?

Answer 17

• allow for motion
• bear body weight
• provide stability

Question 18

what 5 things does connective tissue form?

Answer 18

• capsules
• ligaments
• tendons
• articular cartilage
• fibrocartilage

Question 19

connective tissue components

Answer 19

• fibrous proteins
• ground substance
• cells

Question 20

fibrous proteins

Answer 20

• collagen (type I and II)

- elastin

Question 21

ground substance

Answer 21

• glycosaminoglycans (GAGs)
• water
• solutes

Question 22

cells

Answer 22

• fibroblasts

- chondrocytes

Question 23

types of periarticular connective tissue

Answer 23

• dense CT
• articular cartilage
• fibrocartilage

Question 24

dense CT includes…

Answer 24

• ligaments
• fibrous layer of joint capsule
• tendons

Question 25

dense CT has a limited ____

Answer 25

blood supply

Question 26

primary function of dense CT

Answer 26

resist tension

Question 27

ligaments and joint capsules ____ and ____ the joint

Answer 27

protect and bind

Question 28

tendons transfer forces between ____ and ____

Answer 28

muscle and bone

Question 29

describe irregular dense CT

Answer 29

- irregular and haphazard orientation of collagen within ground substance - suited to resist tensile force in multiple directions - ex: joint capsule

Question 30

describe regular dense CT

Answer 30

- more orderly | - nearly parallel orientation of collagen fibers

Question 31

collagen fibers function most effectively when stretched parallel to _____

Answer 31

- long axis of ligament | - ex: ligaments and tendons

Question 32

in tendons, the arrangement of collagen fibers is suited to...

Answer 32

high directional tensile loads

Question 33

in ligaments, the arrangement of collagen fibers is suited to....

Answer 33

variable load direction

Question 34

hyaline cartilage

Answer 34

- articular cartilage - distributes and absorbs joint forces and reduces joint friction - varies in thickness (1-4mm in low compression, 5-7mm in high compression) - classified as avascular and aneural - receives nutrition with compression

Question 35

fibrocartilage

Answer 35

- mixture of dense and articular cartilage - includes mensici, labrum, discs - aneural - limited blood supply (outer rims of some fibrocartilage do have direct blood supply)

Question 36

primary functions of fibrocartilage

Answer 36

- supports and mechanically stabilizes joints - dissipates loads across multiple planes - guides complex arthrokinematics

Question 37

bone consists of...

Answer 37

- type I collagen - osteoblasts - hard ground substance

Question 38

primary function of bone

Answer 38

- rigid support to body | - systems of levers for muscles

Question 39

bone can accept tremendous ____ loads

Answer 39

compressive

Question 40

bone is richly ____ and ____

Answer 40

vascularized and innervated

Question 41

compact bone

Answer 41

outer cortex of long bones

Question 42

cancellous bone

Answer 42

end of long bones w thinner layer of compact bone surrounded by a network of cancellous bone

Question 43

wolff's law

Answer 43

bone is laid down in areas of high stress and reabsorbed in areas of low stress

Question 44

define anisotropic

Answer 44

cortical bone responds differently depending on the direction of the force applied

Question 45

an immobilized joint will demonstrate changes in ____ and ____ of connective tissues if immobilized for prolonged time

Answer 45

structure and function

Question 46

rate of decline of CT is dependent on ____ of the tissue

Answer 46

metabolic activity

Question 47

rapid loss of ____ occurs with prolonged reduced loading and recovery is ____

Answer 47

- strength | - slower