Transition Zones Flashcards
What is/are the characteristic(s) of occipitalization of C1?
the atlas may be partially or completely fused to the occiput
What is another way of implying occipitalization of C1?
atlas assimilation
What is the incidence of occipitalization of C1?
.1% to .8%
When do the centers of ossification for the odontoid process first appear?
during the last trimester in utero
What joint is formed between the odontoid process ossification centers and the centrum of C2?
the subdental synchondrosis
What is the classification of the joint formed between the C2 odontoid process and centrum?
amphiarthrosis synchondrosis
Ossification between the odontoid process and centrum joint of C2 first appears at what age?
4 years old
A joint between the odontoid process and centrum of C2 is last identified at what age?
7 years old
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?
os odontoideum
What is the name given to the joint between the odontoid process and centrum of C2 which is still evident beyond age 7?
persistant subdental synchondrosis
What is the name given to the joint formed between the tip ofthe dens and odontoid process centers of ossification?
tip of the dens of synchondrosis
What is the classification of the joint formed between the tip of the dens and odontoid process centers of ossification?
amphiarthrosis synchondrosis
At what age will the tip of the dens center of ossification appear?
sometime in early adolescence
Based on the age of appearance, how is the tip of the dens center of ossification classified?
secondary center of ossification
At what age will the tip of the dens fuse with the odontoid process?
before age 12
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?
terminal ossicle
What is a basilar impression?
persistence of the nonunion of the basilar and condylar parts of the chondocranium such that the cartilage deforms due to the weight of the brain
What is a basilar invagination?
the upper cervical spine appears to the invaginated into the skull on x-ray analysis
What is the incidence of rib-related changes following dorsalization of C7?
from one-half to two and one-half percent of the population
Do patients typically present with symptoms specific for dorsalization of C7?
no, they are typically asymptomatic
What is the gender bias suggested in dorslaization of C7?
female
What alteration in C7 facet orientation may accompany dorsalization?
the superior articular facet of C7 may change from back, upward, and medial to that ofa typical thoracic facet…back, upward, and lateral; the inferior articular facet is unchanged
What alteration in C6 facet orientation may accompany dorsalization?
C6 demonstrates a change in inferior articular facet orientation from forward, lateral, and downward to forward, medial, and downward; the superior articular facet unchanged
What percent of the population may demonstrate thoracic-like feature at C7?
up to 46%
What rib related chnages may accompany cervicalization of T1?
the first rib may decrease in mean relative length or become absent
What is the incidence of cervicalization of T1 in the population?
up to 28% of the population
What is the incidence of lumbar ribs in the population?
over 7% of the population demonstrates lumbar ribs
What T12 facet orientation changes may accompany dorsalization?
the inferior articular facet may change from convex, forward, lateral,and downward to flat, forward, medial, and downward; the superior articular facet is unchanged
What is the gender bias associated with dorslaization of L1?
males are two to three times more affected
What rib related changes may accompany lumbarization of T12?
a significant shortening of the mean relative length of 113mm of the twelfth rib or it become absent
What T12 facet orientation changes may accompany lumbarization?
the superior articular facet may change from flat, back, upward, and lateral to concave, back, upward, and medial; the inferior artiucular facet is unchanged
What T11 facet orientation changes may accompany lumbarization?
the inferior articular facet may change from flat, forward, medial, and downward to convex, forward, lateral, and downward; the superior articular facet is unchanged
What is the usual way of idnetifying the number of cervicals, thoracics, and lumbar vertebrae during imaging studies?
identify the vertebrae with ribs- they will be thoracics; those higher are cervicals, those lower are lumbars
What is the charactistic of lumbarization of S1?
the failure of synostosis between S1 and S2, squaring of the vertebral body of S1 and flaring of the sacral ala
What is the incidence of sacralization of L5 in the population?
41% to 85%
Which segment demonstrates the greatest morphological variation along the spine?
L5
What articular facet changes accompany sacralization of L5?
none
What is the incidence of variation within the sacrococcygeal region in the population?
up to 14%
What is the characteristics of sacralization of Co1?
the premature fusion of Co1 to the sacrum
What is the characteristic of coccygealization of S5?
the seperation of S5 from sacrum and it’s premature fusion to Co1
When do the bilateral ossification centers for the odontoid process fuse?
at or shortly after birth
