The dorsal surface of sacrum presents the dorsal sacral foramina (openings for the exit of the dorsal branches of the sacral nerves) and different crests:
The median sacral crest, formed by the totally fused spinous processes, in ox, and sometimes in other ruminants (ov. and cap.). In carnivores and horses, the based of spinous processes are fused but the free end remain separate, so there is no median sacral crest. In pigs, it is an indistinct crest.
The intermediate sacral crest is formed by the fused articular processes, in ruminants,
The lateral sacral crest is formed by the fused transverse processes.