Transition Zones Flashcards
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 characteristic(s) of occipitalization of C1?
The atlas may be partially or completely fused to the occiput
What is an other way of implying occipitalization of C1?
Atlas assimilation
What is the incidence of occipitalization of C1?
0.1% to 0.8%
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
What is an os odontoideum?
A persistence beyond age 7 of the joint formed between the centrum and odontoid process centers of ossification
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 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 invagination?
The upper cervical spine appears to be invaginated into the skull on x-ray analysis
What is/are the characteristic(s) of dorsalization of C7?
The addition of a rib and changes in superior articular facet orientation are typical
What is the incidence of rib-related changes following dorsalization of C7?
From one-half to two and one-half percent of the population
What is the gender 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, ad medial to that of a typical thoracic facet…back, upward, and later; the inferior articular facet is unchanged
What percent of the population may demonstrate thoracic-like features at C7?
Up to 46%
What rib-related changed may accompany cervicalization of T1?
The first rib may decrease in mean relative length or become absent
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 lumbar ribs in the population?
Over 7% of the population demonstrates lumbar ribs
What is 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 the incidence of sacralization of L5 in the population?
41% to 85%
Which segment demonstrates the greatest morphological variation along the spine?
L5
What is the incidence of variation within the sacrococcygeal region in the population?
Up to 14%
