Transition Zones Flashcards
What is/are the characteristics 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?
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
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 odontium
What is the name given to the joint between the odontoid process and 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 odontoid process centers of ossification?
tip of the dens synchondrosis
What is the classification of the joint formed between the tip of the dens and the odonotoid process center 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 chondrocranium such that the cartilage deforms due to the weight of the brain
What is the 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 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 for 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 (BUM) to that of a typical thoracic facet…back, upward, and lateral (BUL); 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 (FoLD) to forward, medial and downward (ForMeD); the superior articular facet is unchanged
