There is an unpaired bone that is located at the base of the skull called a sphenoid bone. This sits in front of the temporal bone and occipital bone. There are seven bones that form the orbit, and the sphenoid is one of these bones. The sphenoid bone appears to look like a butterfly. The pituitary gland is housed in the sphenoid bone in the median section. This is also housed in the sella turcica. There are two greater and lesser areas of the bone. These sections are called wings. Below the sphenoid bone, the pterygoid processes project. Two other bones, the sphenoidal conchae, are located at the anterior and posterior sections of the body. In other animals, the sphenoid bones are often separate; however, in humans they are merged. Generally, mammals have a fused sphenoid bone, but this is not always the case. For example, in a dog, there are eight bones that make up the sphenoid: the basisphenoid, presphenoid, orbitosphenoid, pterygoids, and the alisphenoids.
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In Depth: Sphenoid sinus