HUMAN ANATOMY. 



Anatomy is that subdivision of morphology — the science of form as contrasted 

 with that of function or physiology — which pertains to the form and the structure of 

 organized beings, vegetal or animal. Phytotoiny and Zootomy, the technical names 

 for vegetal and animal anatomy respectively, both imply etymologically the dissocia- 

 tion, or the cutting apart, necessary for the investigation of plants and animals. 



The study of organized bodies may be approached, evidently, from several stand- 

 points. When the details of the structure of their various tissues and organs par- 

 ticularly is investigated, such study constitutes GeJieral Anato^ny or Histology, fre- 

 quently also called Microscopical Anatomy, from the fact that the magnifying lens is 

 used to assist in these examinations. The advantages of comparing the organization 

 of various animals, representing widely different types as well as those closely related, 

 are so manifest in arriving at a true estimate of the importance and significance of 

 structural details, that Comparative Anatomy constitutes a department of biological 

 science of far-reaching interest, not merely for the morphologist, but likewise for 

 the student of human anatomy, since we are indebted to comparative anatomy for 

 an intelligent conception of many details encountered in the human body. Devel- 

 opmental Anatomy, or Embryology, also has been of great service in advancing our 

 understanding of numerous problems connected with the adult organism by tracing 

 the connection between the complex relations of the completed structures and their 

 primitive condition, as shown by the sequence of the phases of development. These 

 three departments of anatomical study — general, comparative, and developmental 

 anatomy — represent the broader aspects of anatomical study -in which the features 

 of the human body are only incidents in the more extended contemplation of 

 organized beings. 



The exceptional importance of an accurate knowledge of the body of man has 

 directed to human anatomy, or anthropotomy , so much attention from various points 

 of view that certain subdivisions of the subject are conveniently recognized ; thus, 

 the systematic account of the human body is termed Descriptive Anatomy, while 

 when the mutual relations and peculiarities of situation of the organs located in par- 

 ticular parts of the body especially claim attention, such study is spoken of as Topo- 

 graphical or Regional A7iato7ny. Consideration of the important group of anatomi- 

 cal facts directly applicable to the diagnosis and the treatment of disease constitutes 

 Applied Anatomy. 



General Plan of Construction. — Vertebrate animals, of which man rep- 

 resents the most conspicuous development of the highest class, — fishes, amphibians, 

 reptiles, birds, and mammals being the recognized subdivisions of the vertebrata, — 

 possess certain characteristics in common which suffice to distinguish the numerous 

 and varied members of the extended group. 



The fundamental anatomical feature of these animals is the possession of an 

 axial column, or spine, which extends from the anterior or cephalic to the poste- 

 rior or caudal pole and establishes an axis around which the various parts of the 

 elongated body are grouped with more or less symmetry. While this body-axis is 

 usually marked by a series of well-defined osseous segments constituting the ver- 

 tebral column of the higher animals, among certain of the lower fishes, as the sharks 

 or sturgeons, the axial rod is represented by cartilaginous pieces alone ; in fact, the 

 tendency towards the production of a body-axis is so pronounced that the formation 



