Transition Zones

Question 1

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

Answer 1

An increase in occipital bone size, formation of new or larger lines, on the occipital bone

Question 2

What is/are the characteristic(s) of occipitalization of C1?

Answer 2

The atlas may be partially or completely fused to the occiput

Question 3

What is an other way of implying occipitalization of C1?

Answer 3

Atlas assimilation

Question 4

What is the incidence of occipitalization of C1?

Answer 4

0.1% to 0.8%

Question 5

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

Answer 5

The subdental synchondrosis

Question 6

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

Answer 6

4 years old

Question 7

What is an os odontoideum?

Answer 7

A persistence beyond age 7 of the joint formed between the centrum and odontoid process centers of ossification

Question 8

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

Answer 8

Tip of the dens synchondrosis

Question 9

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

Answer 9

Before age 12

Question 10

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 10

Terminal ossicle

Question 11

What is a basilar invagination?

Answer 11

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

Question 12

What is/are the characteristic(s) of dorsalization of C7?

Answer 12

The addition of a rib and changes in superior articular facet orientation are typical

Question 13

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

Answer 13

From one-half to two and one-half percent of the population

Question 14

What is the gender bias suggested in dorsalization of C7?

Answer 14

Female

Question 15

What alteration in C7 facet orientation may accompany dorsalization?

Answer 15

The superior articular facet of C7 may change from back, upward, ad medial to that of a typical thoracic facet…back, upward, and later; the inferior articular facet is unchanged

Question 16

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

Answer 16

Up to 46%

Question 17

What rib-related changed may accompany cervicalization of T1?

Answer 17

The first rib may decrease in mean relative length or become absent

Question 18

What T1 facet orientation changes may accompany cervicalization?

Answer 18

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

Question 19

What is the incidence of lumbar ribs in the population?

Answer 19

Over 7% of the population demonstrates lumbar ribs

Question 20

What is characteristic of lumbarization of S1?

Answer 20

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

Question 21

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

Answer 21

41% to 85%

Question 22

Which segment demonstrates the greatest morphological variation along the spine?

Answer 22

L5

Question 23

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

Answer 23

Up to 14%