The splenial bone, also known as the splenial plate or simply the splenial, is a small, thin, and flat bone found in the lower part of the jaw of many animals, including reptiles, birds, and some mammals. It is usually located on the inner side of the mandible, running along the midline of the lower jaw.
The splenial bone plays a crucial role in providing structural support and stability to the lower jaw, aiding in the proper functioning of the jaw during feeding and movement. It serves as a connection point for various muscles involved in jaw movement, including the muscles responsible for biting, grinding, and chewing.
In reptiles, the splenial bone is particularly notable as it participates in the formation of some reptilian jaw joints, known as the cranial kinesis. This phenomenon allows reptiles, such as snakes and lizards, to have remarkable flexibility in their jaws, enabling them to swallow relatively large prey.
The size, shape, and presence of the splenial bone can vary across different species. In some animals, the splenial bone may be absent altogether, fused with other bones, or exist in a reduced form. Nonetheless, its function remains consistent, providing structural support to the lower jaw and facilitating proper jaw movement.
Understanding the anatomy and function of the splenial bone is essential for comparative anatomists, evolutionary biologists, and veterinarians, as it helps shed light on the diversity and adaptations present in the lower jaw among different animal species.
