L4
L IV
Definition
The lumbar vertebrae are different from thoracic vertebrae:
- longer size than thoracic vertebrae
 - more uniform shape to their bodies
 - no costal facet
 - shorter spinous process that is craniodorsally oriented
 - long and flattened transverse processes sometimes termed costal processes
 - flat articular surfaces on their cranial and caudal extremities
 
References
Text by Antoine Micheau, MD - Copyright IMAIOS Veterinary Anatomy of Domestic Mammals: Textbook and Colour Atlas, Sixth Edition - Horst Erich König, Hans-Georg Liebich - Schattauer - ISBN-13: 978-3794528332