Transition Zones

Question 1

What is/are the characteristic(s) of occipitalization of occiput?

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% to 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 years old

Question 8

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

Answer 8

7 years old

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 the 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 the 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 one-half to two and one-half 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 alterations in C7 facet orientation may accompany dorsalization?

Answer 20

the 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 may demonstrate thoracic-like features at C7?

Answer 21

up to 46%

Question 22

What T1 facet orientation changes may accompany cervicalization?

Answer 22

the superior articular facet may change from back, upward, and lateral to back, upward, and medial; the inferior articular facet is unchanged

Question 23

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

Answer 23

up to 28% of the population

Question 24

What is the incidence of lumbar ribs in the population?

Answer 24

over 7% of the population demonstrates lumbar ribs

Question 25

What L1 facet orientation changes may accompany dorsalization?

Answer 25

the superior articular facet may change from concave, back, upward, and medial to flat, back, upward, and lateral; the inferior articular facet is unchanged

Question 26

What is the gender bias associated with dorsalization of L1?

Answer 26

males are two to three times more affected

Question 27

What T12 facet orientation changes may accompany lumbarization?

Answer 27

the superior articular facet may change from flat, back, upward, and lateral to concave, back, upward, and medial; the inferior articular facet is unchanged