splenial

from The Century Dictionary.

• In zoology and anatomy: Acting like a splint or clasp; having the character of a splenial: noting one of the pieces of the compound ramus of the lower jaw of many vertebrates below mammals.
• Of or pertaining to the splenium of the brain: as, the splenial border of the corpus callosum. See splenium.
• Of or pertaining to a splenius: as, the splenial muscles of the neck.
• noun The splenial element of the compound mandible of a vertebrate below a mammal.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Anat.) The splenial bone.
• adjective Designating the splenial bone.
• adjective Of or pertaining to the splenial bone or splenius muscle.
• adjective (Anat.) a thin splintlike bone on the inner side of the proximal portion of the mandible of many vertebrates.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective Relating to the splenium, especially describing the pair of muscles, at the back of the neck, that move the head and neck
• noun splenial bone