Transition Zones

Question 1

What is/are the characteristic(s) 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% 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

the subdental synchondrosis

Question 7

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

Answer 7

amphiarthrosis synchondrosis

Question 8

Ossification between the odontoid process and centrum joint of C2 first appears 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 the 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

Before age 12

Question 13

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 13

terminal ossicle

Question 14

What is a basilar invagination?

Answer 14

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

Question 15

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

Answer 15

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

Question 16

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

Answer 16

no, they are typically asymptomatic

Question 17

What is the gender bias suggested in dorsalization of C7?

Answer 17

female

Question 18

What alteration in C7 facet orientation may accompany dorsalization?

Answer 18

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 19

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

Answer 19

up to 46%

Question 20

What T1 facet orientation changes may accompany cervicalization?

Answer 20

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

Question 21

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

Answer 21

up to 28% of the population

Question 22

What is the incidence of lumbar ribs in the population?

Answer 22

over 7% of the population demonstrate lumbar ribs

Question 23

What L1 facet orientation changes may accompany dorsalization?

Answer 23

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 24

What is the gender bias associated with the dorsalization of L1?

Answer 24

males are two to three times more affected

Question 25

What T12 facet orientation changes may accompany lumbarization?

Answer 25

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

Question 26

What T11 facet orientation changes may accompany lumbarization?

Answer 26

the inferior articular facet may change from flat, forward, medial and downward to convex, forward, lateral, and downward; the superior 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, those lower are lumbars

Question 28

What is 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 sacral ala

Question 29

What is failure of synostosis between S1 and S2?

Answer 29

The segments do not completely fuse together

Question 30

What is 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 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

the premature fusion of Co1 to the sacrum

Question 39

What is characteristic of coccygealization of S5?

Answer 39

the separation of S5 from sacrum and its' premature fusion to Co1