ELEMENTS OF ANATOMY. 



INTRODUCTION. 



ANATOMY, in its mosfc extended sense, is the science which deals with the 

 structure of organized bodies. It is divided into departments according to its 

 subjects ; such as Human Anatomy ; Comparative Anatomy, or the study of the 

 structure of different animals ; and Vegetable Anatomy, comprehending the 

 structure of plants. 



On examining the structure of an organized body, we find that it is made up of 

 members or organs, by means of which its functions are executed, such as the root 

 stem and leaves of a plant, and the heart, brain, stomach and limbs of an animal ; 

 and farther, that these organs are themselves made up of certain constituent 

 materials named tissues or textures, such as the cellular, woody, and vascular tissues 

 of the vegetable, or the osseous, muscular, connective, vascular, nervous, and other 

 tissues, which form the animal organs. 



Most of the tissues occur in more than one organ, and some of them indeed, as 

 the connective and vascular, in nearly all, so that a multitude of organs, and these 

 greatly diversified, are constructed out of a small number of constituent tissues ; 

 and parts of the body, differing widely in form, construction, and uses, may agree in 

 the nature of their component materials. Again, as the same tissue possesses the 

 same essential characters in whatever organ or region it is found, it is obvious that 

 the structure and properties of each tissue may be made the subject of investigation 

 apart from the organs into whose formation it enters. 



The foregoing considerations have led to the subdivision of anatomy into two 

 branches, the one of which, under the name "General Anatomy," or "Histology," 

 treats of the minute structure of the component tissues -of the body ; the other, 

 named " Special or Descriptive Anatomy," treats of its several organs, members, and 

 regions, describing the outward form and internal structure of the parts, their 

 relative situation and mutual connection, and the successive conditions which they 

 present in the progress of their formation or development. 



To the description of the origin and formation of organs in the embryo, a special 

 chapter is devoted in this work, under the name Embryology. 



The study of anatomy may be viewed in two different aspects ; viz., the physio- 

 logical and the morphological. In the former, anatomy supplies the materials 

 relating to structure from which an explanation is sought of the uses or functions 

 of organs by the physiologist ; and for this purpose the study of histology is of 

 particular service. In its morphological aspect, anatomy investigates and combines 

 the facts relating to the structure and relations of organs, from which may be 

 deduced general principles as to the construction of the human body or that of 



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