Posterior arch
Encyclopedia
In a cervical vertebra, the posterior arch forms about two-fifths of the circumference of the ring: it ends behind in the posterior tubercle, which is the rudiment of a spinous process
and gives origin to the Recti capitis posteriores minores.
Spinous process
The spinous process of a vertebra is directed backward and downward from the junction of the laminae , and serves for the attachment of muscles and ligaments. In animals without an erect stance, the process points upward and may slant forward or backward...
and gives origin to the Recti capitis posteriores minores.