splanchnocranium

The splanchnocranium, also known as the visceral cranium or viscerocranium, is the portion of the skull derived from the pharyngeal (branchial) arches. It comprises the skeletal elements that support the pharyngeal apparatus and, in many vertebrates, forms the jaw and gill arch structures.

In jawed vertebrates, the splanchnocranium includes the cartilages and bones formed by the pharyngeal arches, particularly the first (mandibular) and second (hyoid) arches. The first arch gives rise to the jaw apparatus (such as Meckel’s cartilage in early development and its skeletal derivatives), while the second arch contributes to the hyoid apparatus and associated elements. In fishes, these arches provide the complete jaws and gill supports. In tetrapods, this skeletal portion is largely integrated into the facial skeleton and hyoid apparatus, and, in mammals, includes the auditory ossicles (malleus and incus from the first arch; stapes from the second arch).

Developmentally, the splanchnocranium is primarily neural crest–derived and can ossify or persist as cartilage depending on lineage. It is contrasted with the neurocranium, which forms the braincase, and the dermatocranium, which contributes to the external skull bones. In humans, the viscerocranium encompasses the bones of the face and certain base-skull elements, as well as the auditory ossicles and the hyoid bone, reflecting its pharyngeal arch origins.