In order to describe the posterior arch of atlas vertebra extensively, we used Hasan's protocol and divided the class I vertebra into two subclasses--with deeper and with shallower groove for the vertebral artery.
Ponticulus posticus on the posterior arch of atlas, prevalence analysis in asymptomatic patients.
A line was drawn across the following two points, one point is the midpoint of the posterior margin of foramen magnum and superior margin of posterior arch of atlas
, the other point is gracile tubercle in medulla oblongata [Figure 1].
The exclusion criteria applied in the two samples were the poor quality of the image and the presence of craneofacial syndromes; for the PP sample, the projection of the mastoid apophysis over the posterior arch of atlas
was included as exclusion criteria.
AT: anterior tubercle of atlas, RIAF: Right inferior articular facet, LIAF: Left inferior articular facet, RTP: Right transverse process, LTP: Left transverse process, PA: Posterior arch of atlas
& FM: Foramen Magnum.
Associated atlanto-axial subluxation, odontoid dysplasia and a short posterior arch of atlas
can exacerbate the CV junction stenosis.
(19,28) Remodelling of the inferior surface of the posterior arch of atlas
is also visualized in this case, and this variation is likely the result of similar longstanding stress due to C2 spinous contact.
Satheesha Nayak B (4) in 2008 reported abnormal foramina on the posterior arch of atlas
. Similarly, C.
In next step, the cadaver is turned prone and the remaining scalp is cleaned, two oblique incisions are given from the cut margin of squamous part of the occipital bone and extend up to posterior arch of atlas
. Posterior nuchal muscles are removed as well as squamous part of occipital bone is nibbled and removed in piece meal.
Basic far lateral approach includes dissection of muscles of back and suboccipial triangle, adequate exposure of C1 transverse process and posterior arch of atlas
, identification of vertebral artery above the posterior arch of atlas
and a suboccipital craniotomy with removal of at least half of posterior arch of atlas
Gardner E1 and Davies F2 suggested that the posterior arch of atlas
vertebra which corresponds to the laminae of other vertebrae, presents a wide groove for the vertebral artery on its upper surface.
Spina bifida posterior of atlas vertebra, means each half of posterior arch of atlas
have not fused with each other and projecting from lateral masses.(fig no.