Transition Zones Flashcards

1
Q

What is the name given to segments that lie in the transition zones of the vertebral column?

A

transition vertebrae

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2
Q

What are the transition zones of the vertebral column?

A
  • occipitocervical
  • cervicothoracic
  • thoracolumbar
  • lumbosacral
  • sacrococcygeal
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3
Q

How are specific segments within a transition zone identified?

A
  • by adjacent region of the segment
  • process of transition
  • specific segment (occipitalization of C1)
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4
Q

What does the suffix “ization” refer to?

A

in the process of becoming like

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5
Q

What are the possible transition zone-segmental combinations?

A
  • cervicalization of occiput, occipitalization of C1
  • dorsalization of C7, cervicalization of T1
  • lumbarization of T12, dorsalization of L1
  • sacralization of L5, lumbarization of S1
  • coccygealization of S5, sacralization of Co1
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6
Q

What are the characteristics of cervicalization of occiput?

A
  • an increase in occipital bone size

- formation of new or larger lines on the occipital bone

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7
Q

What is the characteristic of occipitalization of C1?

A

the atlas may be partially or completely fused to the occiput

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8
Q

What is another way of implying occipitalization of C1?

A

atlas assimilation

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9
Q

What is the incidence of occipitalization of C1?

A

0.1-0.8%

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10
Q

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

A

during the last trimester in utero

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11
Q

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

A

at or shortly after birth

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12
Q

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

A

the subdental synchondrosis

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13
Q

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

A

amphiarthrosis synchondrosis

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14
Q

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

A

4 years old

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15
Q

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

A

7 years old

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16
Q

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?

A

os odontoideum

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17
Q

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

A

persistent subdental synchondrosis

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18
Q

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

A

tip of the dens synchondrosis

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19
Q

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

A

amphiarthrosis synchondrosis

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20
Q

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

A

sometime in early adolescence

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21
Q

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

A

secondary center of ossification

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22
Q

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

A

before age 12

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23
Q

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?

A

terminal ossicle

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24
Q

What is a basilar impression?

A

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

25
Q

What is a basilar invagination?

A

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

26
Q

What are the charactersistics of dorsalization of C7?

A
  • addition of a rib

- changes in superior articular facet orientation

27
Q

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

A

0.5-2.5% of the population

28
Q

What genetic patterns are suggested in dorsalization of C7?

A
  • chromosome karyotypes are abnormal
  • family inheritance patterns are common
  • it is associated with a dominant inheritance pattern
29
Q

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

A

no, they are typically asymptomatic

30
Q

What is the gender bias suggested in dorsalization of C7?

A

female

31
Q

What is the alteration in C7 facet orientation that may accompany dorsalization?

A
  • the superior articular facet of C7 may change from back, upward, and medial (BUM) to that of a typical thoracic facet, back, upward, and lateral (BUL)
  • the inferior articular facet is unchanged
32
Q

What alteration in C6 facet orientation may accompany dorsalization?

A
  • C6 demonstrates a change in inferior articular facet orientation from forward, lateral, and downward (FoLD) to forward, medial, and downward (ForMeD)
  • the superior articular facet is unchanged
33
Q

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

A

up to 46%

34
Q

What rib-related changes may accompany cervicalization of T1?

A

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

35
Q

What will result from fusion of a short rib to the T1 transverse process?

A

the transverse foramen

36
Q

What T1 facet orientation changes may accompany cervicalization?

A
  • the superior articular facet may change from back, upward, and lateral (BUL) to back, upward, and medial (BUM)
  • the inferior articular facet is unchanged
37
Q

What C7 facet orientation changes may accompany cervicalization?

A
  • the inferior articular facet may change from forward, medial, and downward (ForMeD) to forward, lateral, and downward (FoLD)
  • the superior articular facet is unchanged
38
Q

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

A

up to 28% of the population

39
Q

What rib-related changes may accompany dorsalization of L1?

A

elongated bones shaped like ribs may appear

40
Q

What is the incidence of lumbar ribs in the population?

A

over 7% of the population demonstrates lumbar ribs

41
Q

What L1 facet orientation changes may accompany dorsalization?

A
  • the superior articular facet may change from convex, forward, lateral, and downward (FoLD) to flat, forward, medial, and downward (ForMeD)
  • the inferior articular facet is unchanged
42
Q

What T12 facet orientation changes may accompany dorsalization?

A
  • the inferior articular facet may change from convex, forward, lateral, and downward (FoLD) to flat, forward, medial, and downward (ForMeD)
  • the superior articular facet is unchanged
43
Q

What is the gender bias associated with dorsalization of L1?

A

males are two to three times more affected

44
Q

What rib-related changes may accompany lumbarization of T12?

A

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

45
Q

What T12 facet orientation changes may accompany lumbarization?

A
  • the superior articular facet may change from flat, back, upward, and lateral (BUL) to concave, back, upward, and medial (BUM)
  • the inferior articular facet is unchanged
46
Q

What T11 facet orientation changes may accompany lumbarization?

A
  • the inferior articular facet may change from flat, forward, medial, and downward (ForMeD) to convex, forward, lateral, and downward (FoLD)
  • the superior articular facet is unchanged
47
Q

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

A

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

48
Q

What is characteristic of lumbarization of S1?

A
  • the failure of synostosis between S1 and S2
  • squaring of the vertebral body of S1
  • flaring of the sacral ala
49
Q

What is failure of synostosis between S1 and S2?

A

the segments do not completely fuse together

50
Q

What is squaring of the vertebral body of S1?

A

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

51
Q

What is flaring of the sacral ala?

A

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

52
Q

What articular facet changes accompany the lumbarization of S1?

A

none

53
Q

What is characteristic of sacralization of L5?

A

L5 may be partially or completely fused to the sacrum

54
Q

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

A

41-85%

55
Q

Which segment demonstrates the greatest morphological variation along the spine?

A

L5

56
Q

What articular facet changes accompany sacralization of L5?

A

none

57
Q

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

A

up to 14%

58
Q

What is characteristic of sacralization of Co1?

A

the premature fusion of Co1 to the sacrum

59
Q

What is characteristic of coccygealization of S5?

A

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