Transition Zones Flashcards
What is/are the characteristics of occipitalization of C1?
the atlas may be completely or partially fused to occiput
What is another way of implying occipitalization of C1?
atlas assimilation
What is the incidence of occipitalization of C1?
0.1% to 0.8%
When do the centers of ossification for the odontoid process first appear?
during the last trimester in utero
When do the bilateral ossification centers for the odontoid process fuse?
at or shortly after birth
What joint is formed between the odontoid process ossification centers and the centrum of C2?
the subdental 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 the centrum of C2 persists beyond age 7?
os odontoideum
What is the name given to the joint between the odontoid process and the centrum of C2 which is still evident beyond age 7?
persistent subdental synchondrosis
What is the name given to the joint formed between the tip of the dens and the odontoid process centers of ossification?
tip of the dens synchondrosis
At what age will the tip of dens center of ossification appear?
sometime in early adolescence
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 the odontoid process centers of ossification persist beyond age 12, what is this condition called?
terminal ossicle
What is a basilar impression?
persistence of the nonunion of the basilar and condylar parts of chondrocranium such that the cartilage deforms due to the weight of the brain
What is a basilar invagination?
the upper cervical spine appears to be invaginated into the skull on x-ray analysis
What is the incidence of rib related changes following dorsalization of C7?
from 0.5% to 2.5% of the population
Do patients typically present with symptoms specific for dorsalization of C7?
no, they are typically asymptomatic
What is thegender bias suggested in dorsalization 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 of the typical thoracic fact…back, upward and lateral; the inferior articular facet is unchanged
What percent of the population may demonstrate thoracic-like features at C7?
up to 46%
What T1 facet orientation changes may accompany cervicalization?
the superior articular facet may change from back, upward and lateral to back, upward and medial; the inferior articular facet is unchanged
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 demonstrate lumbar ribs
What L1 facet orientation changes may accompany dorsalization?
the superior articular facet may change from concave, back, upward and medial to flat, back, upward and lateral; the inferior articular facet is unchanged
What is the gender bias associated with dorsalization of L1?
males and two to three times more affected
What T12 facet orientation changes may accompany lumarization?
the superior articular facet may change from flat, back, upward and lateral to concave, back, upward and medial; the inferior articular 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 remains unchanged
What is the usual way of identifying the number of cervicals, thoracics, and lumbar vertebrae during imaging studies?
identify the verterbrae with the ribs - they will be thoracics; those higher are cervicals, those lower are lumbars
What is the characteristic 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 failure of synostosis between S1 and S2?
the segments do not completely fuse together
What is squaring of the vertebral body of S1?
the S1 vertebral body has similar anterior and posterior heights, hence a lack of wedging
What is flaring of the sacral ala?
the transverse process of the ala appears to elevate as though separating from the rest of the sacral ala
What articular facet changes accompany lumbarization of S1?
none
What is characteristic of sacralization of L5?
L5 may be partially or completely fused to sacrum
What is the incidence of sacralization of L5 in the population?
41% to 85%
What segement demonstartes 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 characteristic 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 its’ premature fusion to Co1
