Foramina on the tail bones of whales

[animaltoyforum]

Does anybody know why the openings (nutrient foramina) on the lower surface of cetacean tail bones are so pronounced - the are presumably channels for the supply of blood and/or nerves but does anyone have any details? I'd appreciate if anyone can point me to any articles/papers discussing the function of such nutrient foramina in vertebrae in general, or in whale vertebrae in particular. Here's a picture showing the nutrient foramina in a sperm whale: