Splanchnology is that branch of anatomy devoted to the study of the viscera. The internal body structure of vertebrates, including that of humans, is divided by anatomists into two cavities, the dorsal cavity (containing only the brain and spinal cord) and the ventral cavity. The ventral cavity is further subdivided by the diaphragm muscle into the thoracic (chest) cavity and abdominopelvic cavity. The organs contained by the dorsal and ventral body cavities--that is, in the chest and abdomen--are the viscera.

The term splanchnology is at the same level of medical generality as osteology (study of the bones), syndesmology (study of the joints), or neurology (study of the nervous system). However, since the viscera include the heart, digestive system, respiratory system, and urogenital organs, splanchnology is too broad to be an actual field of study. Textbooks are not written about splanchnology as such. It is, rather, a term of convenience--a quick way of indicating the study of all that part of the body that does not include the skin, skeleton, nervous system, and other non-visceral parts.

Some definitions of the visceral organs studied by splanchnology, such as that used by the classic Gray's Anatomy of the Human Body, exclude the heart.