Transition Zones

Question 1

What is/are the characteristic of occipitalization of C1?

Answer 1

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% to 0.8%

Question 4

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

Answer 4

During last trimester in utero

Question 5

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

Answer 5

At or shortly before birth

Question 6

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

Answer 6

Subdental synchondrosis

Question 7

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

Answer 7

Amphiarthrosis synchondrosis

Question 8

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

Answer 8

4 years old

Question 9

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

Answer 9

7 years old

Question 10

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 10

Os odontoideum

Question 11

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

Answer 11

Persistent subdental synchondrosis

Question 12

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

Answer 12

Tip of dens synchondrosis

Question 13

What is the classification of the joint formed between the tip of the dens and odontoid process centers of ossification?

Answer 13

Amphiarthrosis synchondrosis

Question 14

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

Answer 14

Sometime in early adolescence

Question 15

Based on the age of appearance, how is the tip of the dens center of ossification classified?

Answer 15

Secondary center of ossification

Question 16

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

Answer 16

Before age 12

Question 17

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 17

Terminal ossicle

Question 18

What is a basilar impression?

Answer 18

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 19

What is a basilar invagination?

Answer 19

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

Question 20

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

Answer 20

From 0.5% - 2.5% of the population

Question 21

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

Answer 21

No, they are typically asymptomatic

Question 22

What is the gender bias suggested in dorsalization of C7?

Answer 22

Female

Question 23

What alteration in C7 facet orientation may accompany dorsalization?

Answer 23

Superior articular facet of C7 may change from BUM to a typical thoracic of BUL
Inferior articular facet is unchanged

Question 24

What alteration in C6 facet orientation may accompany dorsalization?

Answer 24

C6 demonstrates a change in inferior articular facet orientation from FoLD to ForMeD
Superior articular facet is unchanged

Question 25

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

Answer 25

Up to 46%

Question 26

What rib-related changes may accompany cervicalization of T1?

Answer 26

First rib may decrease in mean relative length or become absent

Question 27

What is the incidence of cervicalization of T1 in the population?

Answer 27

Up to 28% of the population

Question 28

What is the incidence of lumbar ribs in the population?

Answer 28

Over 7% of the population demonstrates lumbar ribs

Question 29

What T12 facet orientation changes may accompany dorsalization?

Answer 29

Inferior articular facet may change from convex FoLD to flat ForMeD
Superior articular facet is unchanged

Question 30

What is the gender bias associated with dorsalization of L1?

Answer 30

Males are two to three times more affected

Question 31

What rib-related changes may accompany lumbarization of T12?

Answer 31

Significant shortening of the mean relative length of 113mm of the twelfth rib or it becomes absent

Question 32

What T11 facet orientation changes may accompany lumbarization?

Answer 32

Inferior articular facet may change from flat ForMeD to convex FoLD
Superior articular facet is unchanged

Question 33

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

Answer 33

Identify the vertebrae with ribs - they will be thoracics; those higher are cervical, those lower are lumbars

Question 34

What is characteristic of lumbarization of S1?

Answer 34

The failure of synostosis between S1 and S2
Squaring of the vertebral body of S1
Flaring of the sacral ala

Question 35

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

Answer 35

41%-85%

Question 36

Which segment demonstrates the greatest morphological variation along the spine?

Answer 36

L5

Question 37

What articular facet changes accompany sacralization of L5?

Answer 37

None

Question 38

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

Answer 38

Up to 14%

Question 39

What is characteristic of sacralization of Co1?

Answer 39

Premature fusion of Co1 to the sacrum

Question 40

What is characteristic of coccygealization of S5?

Answer 40

Separation of S5 from sacrum and its premature fusion to Co1