atlanto-occipital assimilation

Atlanto-occipital assimilation is the fusion of the atlas (C1) to the occiput and is one of the transitional vertebrae.


Atlanto-occipital assimilation occurs in approximately 0.5% (range 0.08-3%) of the population . It is thought to affect males and females equally.

Clinical presentation

It is typically asymptomatic but symptoms from nerve or vascular compression can occur.

Gross anatomy

Fusion of C1 to the occiput can be either :

  • complete: C1 not identifiable
  • incomplete: C1 partially identifiable

It can also be classified as

  • posterior arch assimilation
  • anterior arch assimilation or
  • assimilation of both the anterior and posterior arches

Atlanto-occipital assimilation is associated with :

Siehe auch: