A midline cervical incision was made to expose the spinous processes, laminae, and the lateral masses
from C2 to C7 level.
The caudal half of first cervical sclerotome gives rise to the lateral masses
and the anterior and posterior arches of atlas vertebra.
2) A combined lateral displacement of the C1 lateral masses
The CT scan in coronal sections shows asymmetry of the lateral masses
relation to the odontoid.
It has no spinous process or body and consists of 2 lateral masses connected by anterior and posterior arches.
The rule states that on an open-mouth odontoid projection, the displacement of the lateral masses to a certain degree implies a ruptured ligament.
In the AP view, vertical alignment of the spinous processes, smooth undulating borders created by the lateral masses, and uniformity among the disc spaces are indicative of a normal spine (Fig 2) (Holliman, Mayer, Cook, & Smith, 1991).
Malalignment of the lateral masses at the atlantoaxial junction indicates a Jefferson fracture.
Once reduction is achieved we maintain the neutral position of the head and lateral masses
are prepared for screw placement.
This is the site of fracture in traumatic spondylolisthesis, not the pedicles or lateral masses
, as is commonly stated.
The atlas consists of two bulky lateral masses
, connected to each other in front by a short anterior arch, and behind by a long curved posterior arch it thus forms a ring of bone.
The lateral masses
articulate with the occipital condyles to form ellipsoid type of synovial joints.