The accessory processes on all vertebrae are jutting out the sides of the vertebrae, horizontally planed and parallel to the animal's back. They are in similar position to the transverse processes but are smaller (hence the name accessory) and have a slightly different angle (pointing more upwards than downwards). See below for examples.


lumbar_vertebrae.jpg (labeled as C here)

thoracic_vertebrae.jpg While the accessory process is not labeled here, it is the smaller jut you see pointing up on the sides of the vertebrae just above the transverse process