Search results
Results from the WOW.Com Content Network
The atlas is the topmost vertebra and the axis (the vertebra below it) forms the joint connecting the skull and spine. The atlas and axis are specialized to allow a greater range of motion than normal vertebrae. They are responsible for the nodding and rotation movements of the head.
In anatomy, the axis (from Latin axis, "axle") is the second cervical vertebra (C2) of the spine, immediately inferior to the atlas, upon which the head rests. The spinal cord passes through the axis. The defining feature of the axis is its strong bony protrusion known as the dens, which rises from the superior aspect of the bone.
The atlas (C1) and axis (C2) are the two topmost vertebrae. The atlas (C1) is the topmost vertebra, and along with the axis forms the joint connecting the skull and spine. It lacks a vertebral body, spinous process, and discs either superior or inferior to it. It is ring-like and consists of an anterior arch, posterior arch, and two lateral masses.
The atlanto-axial joint is a joint between the atlas bone and the axis bone, which are the first and second cervical vertebrae.It is a pivot joint that provides 40 to 70% of axial rotation of the head.
A typical cervical vertebra. There are seven cervical vertebrae (but eight cervical spinal nerves), designated C1 through C7. These bones are, in general, small and delicate. Their spinous processes are short (with the exception of C2 and C7, which have palpable spinous processes). C1 is also called the atlas, and C2 is also called the axis.
The number of those in the cervical region, however, is only rarely changed. [4] The vertebrae of the cervical, thoracic, and lumbar spines are independent bones and generally quite similar. The vertebrae of the sacrum and coccyx are usually fused and unable to move independently. Two special vertebrae are the atlas and axis, on which the head ...
There is one disc between each pair of vertebrae, except for the first cervical segment, the atlas. The atlas is a ring around the roughly cone-shaped extension of the axis (second cervical segment). The axis acts as a post around which the atlas can rotate, allowing the neck to swivel.
It also will miss vertical or posterior displacement of the cervical spine. [5] Other measurements include occiput-atlas distance, angle between anterior arch of atlas and axis, vertical distance between posterior arch of atlas and spinous process of axis, vertical atlanto-dens interval, and joint space between C1 and C2. [6]