Njds: Histology - Joints

Front 1

Question:
What is the definition of joints?

Back 1

Answer:
The regions of skeleton where bones articulate, sometimes allows movement between bones and facilitate growth of bones

Front 2

Question:
What is the definition of a synarthrosis joint?

Back 2

Answer:
A type of joint characterized by limited or no movement between opposing bones

Front 3

Question:
What are the 3 types of synarthrosis joints?

Back 3

Answer:
1. Synostosis
2. Synchondrosis
3. Syndesmosis

Front 4

Question:
What is a synostosis joint?

Back 4

Answer:
- bones joined with bone
- does not allow movement to take place
- stablizes parts of skeleton after cessation of bone

Front 5

Question:
What is an example of a synostosis joint?

Back 5

Answer:
Cranial bones

Front 6

Question:
What is a synchondrosis joint?

Back 6

Answer:
- bones connected by hyaline cartilage
- allow little movement
- pertmits bone growth and expansion by endochondral ossification

Front 7

Question:
What are 2 examples of a synchondrosis joint?

Back 7

Answer:
1. epiphyseal plates
2. union of first rib at sternum

Front 8

Question:
What is a syndesmosis joint?

Back 8

Answer:
- bones that are far apart united by a ligament composed of dense CT
- allows limited movement
- functions as shock absorbers and sites of appositional bone growth

Front 9

Question:
What is an example of syndesmosis joints?

Back 9

Answer:
The union between the distal tibia and fibula

Front 10

Question:
What is an amphiarthrosis joint?

Back 10

Answer:
- a type of joint found where fibrocartilage is the interosseous medium
- capable of slight movement

Front 11

Question:
What are 2 examples of amphiarthrosis joints?

Back 11

Answer:
1. intervertebral joints
2. pubic symphysis

Front 12

Question:
What is a diarthrosis joint (synovial joint)?

Back 12

Answer:
- a type of joint usually found between long bones
- permits wide range of movements

Front 13

Question:
The diarthroidal joint is organized into 3 articular structures. What are they?

Back 13

Answer:
1. Articular capsule
2. Articular cavity
3. Articular cartilage

Front 14

Question:
The bones of a diarthroidal joint are linked by ligaments and an outer capsule that are composed of 2 layers. What are they?

Back 14

Answer:
1. Fibrous Layer
2. Synovial membrane (synovium)

Front 15

Question:
Describe the Fibrous Layer of a diarthroidal joint.

Back 15

Answer:
- an outer layer made of dense CT continuous with periosteum
- contains blood vessels and nerves

Front 16

Question:
Describe the synovial membrane (synovium) of the diarthroidal joint.

Back 16

Answer:
- an inner layer lined by 1-3 layers of synovial cells (synovocytes)
- function is to produce and resorb synovial fluid and to remove material shed into the articular cavity

Front 17

Question:
Describe the structure of synovial membrane (synovium) of the diarthroidal joint.

Back 17

Answer:
- a loose sheet of vascularized and innervated CT facing the articular cavity and arranged in fold and villi
- does not line the articular cartilage

Front 18

Question:
Describe the cells type of the synovial membrane (synovium) of the diarthroidal joint.

Back 18

Answer:
1. Type A (macrophage-like cells) - light staining phagocytic cells
2. Type B (fibroblast-like) cells - dark staining cells that secrete hyaluronic acid and glycoprotein lubricant in the synovial fluid

Front 19

Question:
What are the bones of a diarthroidal joint surfaced with?

Back 19

Answer:
articular cartilage

Front 20

Question:
The articular cartilage of the diarthroidal joint is what type of cartilage?

Back 20

Answer:
hyaline cartilage

Front 21

Question:
The articular cartilage of the diarthroidal joint is characterized in part by the absence of what?

Back 21

Answer:
Perichondrium

Front 22

Question:
Describe how the collagen fibers of the diarthroidal joint are arranged.

Back 22

Answer:
- the collagen fibers of the articular cartilage form wide arches
- the collagen fibers are perpendicular to the surface of the bone
- they are parallel to the articular surface when near the articular surface

Front 23

Question:
Desrcibe what is stacked near the osseous surface of the articular cartilage of the diarthroidal joint.

Back 23

Answer:
chondrocytes - found near the articular surface and are solitary and flat in shape

Front 24

Question:
What makes the articular cartilage of the diarthroidal joint so resilient?

Back 24

Answer:
The cartilage is an efficient absorber of mechanical pressures

Front 25

Question:
What is the articular cartilage of the diarthroidal joint consist of?

Back 25

Answer:
- type II collagen
- proteoglycans
- 8o% water

Front 26

Question:
What do the proteoglycans of the articular cartilage of the diarthroidal joint contain and what does this enable them to do?

Back 26

Answer:
- these molecules contain large amounts of water, enabling them to function as a biomechanical spring

Front 27

Question:
Describe how the proteoglycan molecules of the articular cartilage works as a spring.

Back 27

Answer:
- when pressure is applied, water is forced out of the matrix into the synovial fluid
- reciprocal elctrostatic repulsion of negatively charged carboxyl and sulfate groups in the GAG molecule occurs
- this separates the GAG branches and creates spaces to be occupied by water
- when pressure is released, water is attracted back into these spaces.

Front 28

Question:
Water movements brought about by use of the diarthroidal joint is responsible for what?

Back 28

Answer:
This is responsible for the resiliency of the cartilage and for its nutrition

Front 29

Question:
What are the 3 zones in the articular cartilage?

Back 29

Answer:
1. superficial zone
2. middle (transitional) zone
3. deep zone

Front 30

Question:
Describe the superficial zone of the articular cartilage.

Back 30

Answer:
- chondrocytes are small and flattened
- collagen fibers arranged parallel to the surface

Front 31

Question:
Describe the middle (transitional) zone of the articular cartilage.

Back 31

Answer:
- chondrocytes arranged in columns
- collagen fibers begin to change their orientation from horizontal to vertical

Front 32

Question:
Describe the deep zone of the articular cartilage.

Back 32

Answer:
- contains calcified cartilage with small chondrocytes
- located adjacent to the subchondral bone
- collagen fibers run perpindicular to the surface

Front 33

Question:
Describe the intra-articular menisci (discs).

Back 33

Answer:
- cushions of fibrocartilage or dense CT
- may be free or transverse the joint

Front 34

Question:
Describe the 2 classifications of the articular cartilage.

Back 34

Answer:
- simple: two articulating surfaces (ex. knee joint)
- compound: three or more articulating surfaces (ex. TMJ)

Front 35

Question:
The TMJ is a type of what kind of joint?

Back 35

Answer:
This is a type of gliding-hinge synovial joint found in mammals

Front 36

Question:
Describe the articulation of the TMJ

Back 36

Answer:
This is the articulation of the mandibular condyle with the temporal bone, by way of the glenoid fossa

Front 37

Question:
Describe the mandibular condyles of the TMJ.

Back 37

Answer:
These are ovoid structures with long axes oriented medially

Front 38

Question:
Identify the 5 layers of the TMJ.

Back 38

Answer:
The layers of this structure are
1. dense fibrous CT
2. proliferative zone
3. fibrocartilage (hyaline during growth period)
4. calcified cartilage
5. sub-articular bone

Front 39

Question:
Describe the proliferative zone of the TMJ.

Back 39

Answer:
this zone consists of a layer of cells acting as a replicating pool for underlying cartilage

Front 40

Question:
Describe the layers of the articular eminence of the TMJ from superficial to deep.

Back 40

Answer:
1. dense CT (fibrous layer)
2. proliferative layer
3. fibrocartilage
4. bone

Front 41

Question:
What is the glenoid fossa?

Back 41

Answer:
- This is the concave depression in the squamous portion of the temporal bone.
- Covered by thin film fibrous layer (periosteum)

Front 42

Question:
What is the capsule of the TMJ?

Back 42

Answer:
This is the fibrous membrane that surrounds the joint and incorporates the articular eminence.

Front 43

Question:
What is the capsule of the TMJ composed of?

Back 43

Answer:
This is composed of dense fibrous CT.

Front 44

Question:
Describe the attachments of the TMJ capsule.

Back 44

Answer:
1. the upper half forms a loose envelope with a posterior attachment at the squamotympatic fissure
2. an anterior attachment at the articular eminence
3. a lateral attachment at the glenoid fossa
4. attached medially, laterally, and posteriorly at the articular disk
5. firmly attached to the neck of the mandibular condyle

Front 45

Question:
What is the function of the articular disk of the TMJ?

Back 45

Answer:
This structure functions as an articular surface and divides the TMJ into 2 distinct compartments.

Front 46

Question:
Describe the composition, innervation, and vascularization of the TMJ articular disk.

Back 46

Answer:
This structure is:
1. composed of fibrous connective tissue
2. it is avascular and aneural centrally
3. it is vascular and innervated at its periphery

Front 47

Question:
What can be said about the attachment of the bioconcavity structure in the TMJ articular disk?

Back 47

Answer:
This structure is attached to the medial and lateral poles of the condyle.

Front 48

Question:
Describe the upper lamella of the TMJ anterior articular disk.

Back 48

Answer:
This region runs forward and fuses with the capsule and periosteum of the anterio slope of the articular eminence.

Front 49

Question:
Describe the lower lamella of the TMJ anterior articular disk.

Back 49

Answer:
This region is attached to the anterior surface of the condylar neck.

Front 50

Question:
What inserts between the lamellae of the TMJ articular disk?

Back 50

Answer:
The superior head of the lateral ptyerygoid is found here.

Front 51

Question:
Describe the upper lamella of the TMJ posterior articular disk.

Back 51

Answer:
This region is composed of fibrous and elastic CT and inserts into the squamotympatic fissure (as part of the capsule)

Front 52

Question:
Describe the lower lamella of the TMJ posterior articular disk.

Back 52

Answer:
This region merges with the periosteum of the condylar neck

Front 53

Question:
What 2 things are found in the zone between the posterior lamallae?

Back 53

Answer:
1. retrodiscal tissue
2. comprised of loose vascular CT

Front 54

Question:
Name and describe the lateral portion of the TMJ capsule.

Back 54

Answer:
This portion is thickened and fanshaped and is known as the temporomandibular ligament.

Front 55

Question:
Describe how the temporomadibular ligament is placed within the TMJ.

Back 55

Answer:
This structure runs in an oblique course posteriorly and inferiorly from the later aspect of the articular eminence to the posterior part of the condylar neck.

Front 56

Question:
Identify the muscle of the TMJ.

Back 56

Answer:
The muscle of this structure is called the lateral pterygoid.

Front 57

A - mandibular condyle
B - glenoid fossa
D/C - articular disc
E - articular eminence
H - region of squamotympanic fissure

*** There's more! Check your notes! ***

Back 57

Image Question:
Can you name all the structures in the TMJ?