Intervertebral Disc: Annulus Fibrosus

Question 1

What is unusual about the cervical annulus fibrosus?

Answer 1

it lacks any lamellar or layered organization

Question 2

What is the appearance of the cervical annulus fibrosus?

Answer 2

• a horse-shoe with the anterior margin thick and the lateral margin tapering to the uncinate processes
• the posterior margin is thin

Question 3

What compensates for the thinness of the posterior part of the cervical annulus fibrosus?

Answer 3

posterior longitudinal ligament

Question 4

What is the organization of the lumbar annulus fibrosus?

Answer 4

it has 12-14 concentric cylindrical lamellae

Question 5

What is the reason the anterior margin of the lumbar intervertebral disc is less susceptible to rupture, herniation, prolapse, or protrusion?

Answer 5

the anterior margin of each lamellus is thick and the anterior longitudinal ligament is also better developed than the posterior lamellae or posterior longitudinal ligament

Question 6

Why is the posterior part of the lumbar annulus fibrosus more susceptible to rupture, herniation, prolapse, or protrusion?

Answer 6

the posterior margin of the lamellus is thin and the posterior longitudinal ligament is also less developed

Question 7

What is the mechanism for growth of the lumbar annulus fibrosus?

Answer 7

the outside of the lumbar annulus fibrosus adds new lamellae by appositional growth

Question 8

What is the water concentration in the lumbar annulus fibrosus at birth and after 30?

Answer 8

• birth: 78%

- after 30: 70%

Question 9

What is the organizational pattern for glycosaminoglycans in the lumbar annulus fibrosus?

Answer 9

they typically have a binding site for hyaluronic acid and are thus aggregated

Question 10

What is the consequence of aggregated glycosaminoglycans in the lumbar annulus fibrosus?

Answer 10

the annulus fibrosus will retain water under deformation conditions

Question 11

Which type of collagen is dominant in the annulus fibrosus?

Answer 11

collagen type I

Question 12

What is the organizational pattern for collagen fibers in the annulus fibrosus?

Answer 12

they are parallel with one another in a single lamellus and angled

Question 13

What is the organization of collagen fibers between lamellae?

Answer 13

collagen fibers will be angled in the opposite direction such that a spiral-counterspiral organization is observed

Question 14

What is the angle of collagen fibers within the annulus fibrosus?

Answer 14

they average 50 to 60 degrees

Question 15

What is the difference in the angle of collagen fibers within the inner lamellae and outer lamellae of the annulus fibrosus?

Answer 15

• the outer lamellae collagen fibers are more vertical

- the inner lamellae collage fibers are more horizontal

Question 16

What is the attachment site for collagen fibers within the annulus fibrosus?

Answer 16

• collagen fibers of the outer lamellae will become Sharpey’s fibers and penetrate the epiphyseal rims
• collagen fibers of the inner lamellae will attach to the cartilaginous end plate

Question 17

What is the origin for the cells of the annulus fibrosus?

Answer 17

sclerotomites

Question 18

What cell type is associated with the annulus fibrosus?

Answer 18

fibroblast and fibrocyte