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
Cuboid bone Cuboid bone In the human body, the cuboid bone is one of the seven tarsal bones of the foot. The cuboid bone is the most lateral of the bones in the distal row of the tarsus. It is roughly cubical in shape, and presents a prominence in its inferior (or plantar) surface, the tuberosity of the cuboid. The bone provides a groove where the tendon of the peroneus longus muscle passes to reach its insertion in the first metatarsal and medial cuneiform bones. The dorsal surface, directed upward and lateralward, is rough, for the attachment of ligaments. The plantar surface