Transition Zones Flashcards
What are the transition zones of the vertebral column?
Occipitocervical, cervicothoracic, thoracolumbar, lumbosacral, and sacrococcygeal zones
What are the possible transition zone - segment combinations?
Cervicalization of the 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
What is/are the characteristic(s) of cervicalization of occiput?
An increase in occipital bone size, formation of new or larger lines, on the occipital bone
What is/are the characteristics(s) of occipitalization or 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?
0.1-0.8%
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 forms between the odontoid process ossification centers and the centrum of C2?
The sub dental 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 IDed 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?
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 dens synchondrosis
At what age will the tip of the dens center of ossification appear?
Sometime in early adolescence
Based on the age to 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
What is a terminal ossicle?
A persistence beyond age 12 of the joint formed between the tip of the dens and odontoid process centers of ossification
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 wight of the brain
What is basilar invagination?
The upper cervical spine appears to be invaginated into the skull on X-Ray analysis