Sacrum a lateral surface. The base of the sacrum, which is broad and expanded, is directed upward and forward. On either side of the base is a large projection known as an ala of sacrum and these alae (wings) articulate with the sacroiliac joints. The alae support the psoas major muscles and the lumbosacral trunk which connects the lumbar plexus with the sacral plexus. In the articulated pelvis the alae are continuous with the iliac fossa. Each ala is slightly concave from side to side, and convex from the back and gives attachment to a few of the fibers of the
The White Bone the novel are mostly from the "She-S" family, into which Mud, a young cow who is pregnant with her first calf, has been adopted. Mud is blessed with visionary powers and can occasionally see into the future. Thrown into a drought, with human poachers becoming increasingly common, Mud and her family must find the legendary "Safe Place" where drought and poachers do not come. The "White Bone," a rib of a newborn elephant, is rumored to be lying somewhere in the savannah and is said to point in the direction of the Safe Place. After a slaughter which leaves most