=Anatomy= is the branch of biological science which deals with the form
and structure of organisms, both animal and vegetal. It is therefore in
close correlation with physiology, which treats of the functions of the
body.
Etymologically the word “anatomy” signifies the cutting apart or
disassociating of parts of the body. In the earlier phases of its
development anatomy was necessarily a purely descriptive science, based
on such observations as were possible with the unaided eye and simple
dissecting instruments—the scalpel, forceps, and the like. At this time,
therefore, the term adequately expressed the nature of the subject. But
as the scope of the science extended and the body of anatomical
knowledge grew, subdivisions became necessary and new terms were
introduced to designate special fields and methods of work. With the
introduction of the microscope and its accessories it became possible to
study the finer details of structure and minute organisms hitherto
unknown, and this field of inquiry rapidly developed into the science of
=microscopic anatomy= or =histology= as conventionally distinguished
from =gross= or =macroscopic anatomy=. In the same way the study of the
changes which organisms undergo during their development soon attained
sufficient importance to be regarded on practical grounds as a separate
branch known as =embryology=.
This term is usually limited in its application to the earlier phases
of development during which the tissues and organs are formed. The
term =ontogeny= is used to designate the entire development of the
individual. The ancestral history or =phylogeny= of the species is
constituted by the evolutionary changes which it has undergone as
disclosed by the geological record.
=Comparative anatomy= is the description and comparison of the structure
of animals, and forms the basis for their classification. By this
means—including extinct forms in the scope of inquiry—it has been
possible to show the genetic relationship of various groups of animals
and to elucidate the significance of many facts of structure which are
otherwise quite obscure. The deductions concerning the general laws of
form and structure derived from comparative anatomical studies
constitute the science of =morphology= or =philosophical anatomy=. The
morphologist, however, deals only with such anatomical details as are
necessary to form a basis for his generalizations. The anatomical
knowledge required in the practice of medicine and surgery is evidently
of a different character and must include many details which are of no
particular interest to the morphologist.
=Special anatomy= is the description of the structure of a single type
or species, _e. g._, anthropotomy, hippotomy.
=Veterinary anatomy= is the branch which deals with the form and
structure of the principal domesticated animals. It is usually pursued
with regard to professional requirements, and is therefore largely
descriptive in character. As a matter of convenience the horse is
generally selected as the type to be studied in detail and to form a
basis for comparison of the more essential differential characters in
the other animals.
Two chief methods of study are employed—the =systematic= and the
=topographic=. In the former the body is regarded as consisting of
systems of organs or apparatus which are similar in origin and structure
and are associated in the performance of certain functions. The
divisions of =systematic anatomy= are: