Sacrum The number of sacral vertebrae varies slightly. For instance, the S1S5 vertebrae of a horse will fuse, the S1S3 of a dog will fuse, and four pelvic vertebrae of a rat will fuse between the lumbar and the caudal vertebrae of its tail. The "Stegosaurus" dinosaur had a greatly enlarged neural canal in the sacrum, characterized as a "posterior brain case”. The sacrum is a complex structure providing support for the spine and accommodation for the spinal nerves. It also articulates with the hip bones. The sacrum has a base, an apex, and three surfaces – a pelvic, dorsal and
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