Transition Zones

Question 1

What is/are the characteristics of occipitalization of C1?

Answer 1

The atlas may be partially or completely fused to the occiput

Question 2

What is another way of implying occipitalization of C1?

Answer 2

Atlas Assimilation

Question 3

What is the incidence of occipitalization of C1?

Answer 3

0.1% - 0.8%

Question 4

When do the centers of ossification for the odontoid process first appear?

Answer 4

During the last trimester in utero

Question 5

When do the bilateral ossification centers for the odontoid process fuse?

Answer 5

At or shortly after birth

Question 6

What joint is formed between the odontoid process ossification centers and the centrum of C2?

Answer 6

Subdental Synchondrosis

Question 7

Ossification between the odontoid process and centrum joint of C2 first appears at what age?

Answer 7

4

Question 8

A joint between the odontoid process and centrum joint of C2 is last identified at what age?

Answer 8

7

Question 9

What is the name given to the condition in which the joint formed between the odontoid process and centrum of C2 persists beyond age 7?

Answer 9

Os Odontoideum

Question 10

What is the name given to the joint between the odontoid process and centrum of C2 which is still evident beyond age 7?

Answer 10

Persistent Subdental Synchondrosis

Question 11

What is the name given to the joint formed between the tip of the dens and the odontoid process centers of ossification?

Answer 11

Tip of Dens Synchondrosis

Question 12

At what age will the tip of the dens center of ossification appear?

Answer 12

Sometime in early adolescence

Question 13

At what age will the tip of the dens fuse with the odontoid process?

Answer 13

Before age 12

Question 14

If the joint formed between the tip of the dens and odontoid process centers of ossification persists beyond age 12, what is the condition called?

Answer 14

Terminal Ossicle

Question 15

What is a basilar impression?

Answer 15

Persistence of the nonunion of the basilar and condylar parts of the chondrocranium such that the cartilage deforms due to the weight of the brain

Question 16

What is a basilar invagination?

Answer 16

The upper cervical spine appears to be invaginated into the skull on x-ray analysis

Question 17

What is the incidence of rib-related changes following dorsalization of C7?

Answer 17

From 1/2 to 2 and a 1/2 percent of the population

Question 18

Do patients typically present with symptoms specific for dorsalization of C7?

Answer 18

No. They are typically asymptomatic

Question 19

What is the gender bias suggested in dorsalization of C7?

Answer 19

Female

Question 20

What alteration in C7 facet orientation may accompany dorsalization?

Answer 20

Superior Articular Facet of C7 may change from back, upward, and medial to that of a typical thoracic facet; back, upward and lateral.
The inferior articular facet is unchanged

Question 21

What percent of the population many demonstrate thoracic like features at C7?

Answer 21

up to 46%

Question 22

What T1 facet orientation changes may accompany cervicalization?

Answer 22

Superior articular facet may change from forward, medial and downward to forward, lateral and downward.
The inferior articular facet is unchanged

Question 23

What is the incidence of lumbar ribs in the population?

Answer 23

Over 7% of the population demonstrates lumbar ribs

Question 24

What L1 facet orientation changes may accompany dorsalization?

Answer 24

Superior articular facet may change from concave, back, upward and medial to flat, back upward and lateral
The inferior articular facet is unchanged.

Question 25

What is the gender bias associated with dorsalization of L1?

Answer 25

Males are 2-3 times more affected

Question 26

What T12 facet orientation changes may accompany lumbarization?

Answer 26

Superior articular facet may change from flat, back, upward and lateral to concave, back, upward and medial
The inferior articular facet is unchanged

Question 27

What is the usual way of identifying the number of cervicals, thoracics, and lumbar vertebrae during imaging studies?

Answer 27

Identify the vertebrae with ribs– they will be thoracics

Those higher are cervicals and those lower are lumbars

Question 28

What is the characteristic of lumbarization of S1?

Answer 28

The failure of synostosis between S1 and S2, squaring of the vertebral body of S1 and flaring of the sacral ala

Question 29

What is the failure of synostosis between S1 and S2?

Answer 29

The segments do not completely fuse together

Question 30

What is the squaring of the vertebral body of S1?

Answer 30

The S1 vertebral body has similar anterior and posterior heights, hence a lack of wedging

Question 31

What is the flaring of the sacral ala?

Answer 31

The transverse process of the ala appears to elevate as though separating from the rest of the sacral ala

Question 32

What articular facet changes, accompany lumbarization of S1?

Answer 32

None

Question 33

What is the characteristic of sacralization of L5?

Answer 33

L5 may be partially or completely fused to the sacrum

Question 34

What is the incidence of sacralization of L5 in the population?

Answer 34

41% to 85%

Question 35

Which segment demonstrates the greatest morphological variation along the spine?

Answer 35

L5

Question 36

What articular facet changes accompany sacralization of L5?

Answer 36

None

Question 37

What is the incidence of variation within the sacrococcygeal region in the population?

Answer 37

Up to 14%

Question 38

What is characteristic of sacralization of Co1?

Answer 38

Premature fusion of Co1 to the Sacrum

Question 39

What is the characteristic of coccygealization of S5?

Answer 39

Seperation of S5 from sacrum and it’s premature fusion to Co1