34 DESCRIPTIVE AND APPLIED ANATOMY 



replete with serious imperfections and inconsistencies. Thus while one of the 

 branches of the radial nerve is called the N. cutaneus brachii posterior, the nominal 

 suffix of two other branches of the same nerve is dorsalis. It cannot be said 

 that the BNA has as yet completely displaced some of the designations in 

 common use to that degree which its enthusiastic advocates would wish. The 

 ambiguous, confusing, and vague terms will .gradually fall into disuse as time 

 shows their inutility and better expressions achieve universal adoption. 



For descriptive purposes the human body is supposed to be in th? erect position, 

 the arms hanging by the sides and the palms of the hands directed forward. 

 The body, as a whole, as with most vertebrates, consists of two general divisions, 

 axial and appendicular; the former is the body proper (soma), the latter comprises 

 the limbs (membra). The middle plane of the body is called the meson, from the 

 Greek TO juteaov, the middle; while mesal and mesad (ad being the Latin equiva- 

 lent of the English -ward) are adjectival and adverbial inflections. The mesal 

 plane is also the dorsoventral plane which passes approximately through the 

 sagittal suture of the skull, and hence any plane parallel to it is termed a sagittal 

 plane. A vertical plane at right angles to the mesal plane passes, roughly speaking, 

 through the central part of the coronal suture or through a line parallel to it; 

 such a plane is therefore called a coronal plane or frontal plane. A plane at right 

 angles to both the mesal and coronal planes is termed a transverse plane. The 

 terms anterior and posterior have been employed to indicate the relation of parts 

 to the front or back of the body, and the terms superior and inferior to signify the 

 relative levels of different structures ; but the growing use of data derived from com- 

 parative anatomy and embryology in the elucidation of the human structure makes 

 it desirable that terms should be employed which may without ambiguity indicate 

 relative position in both man and animals. Thus, ventral and dorsal, cephalic and 

 caudal (together with their adverbial derivatives ending in -ad], are preferable and 

 are thus sometimes used in this edition. Lateral and laterad are general terms per- 

 taining to the sides of the body, while dextral and sinistral are specific terms for 

 right and left respectively. The terms central (centrad) and peripheral (periph- 

 erad) are in general use, though specially applicable to the bloodvessels and the 

 nerve system. The common terms "inner" and "outer," "deep" and "superfi- 

 cial," "beneath," "under," and so on, are too frequently ambiguous. The use of 

 the words ental and ectal, derived respectively from ^vroc (inward) and IXTO^ 

 (outward), and their inflections entad and ectad often serve to avoid such ambi- 

 guity. Wherever a series of organs embraces several similar parts, bearing like 

 names, the general terms are combined \vith distinctive prefixes, as, for instance, 

 swpraspinatus and m/raspinatus. The terms proximal and distal refer to the 

 attached and free ends of the limbs and their parts, being preferable to the less 

 precise and sometimes confusing designations of upper and lower. The other 

 aspects (borders or sides) of each limb are variously designated by the terms 

 ulnar, radial, anconal, and thenar; tibial, fibular, patellar, and popliteal. It is 

 often convenient to speak of the flexor and extensor aspects of the limb divisions 

 and their bones. The designation of parts in the limbs by anterior and posterior is 

 still largely employed, though the demands of consistency and logic will probably 

 compel the adoption of substitutes more in accord with the nomenclature of com- 

 parative anatomy. The classification which is used in the present work is as follows : 



Osteology, or description of the bones. 



Syndesmology, or description of the ligaments. 



Myology, or description of the muscles and fasciae. 



Angiology, or description of the heart and the bloodvessels and lymph vessels. 



Neurology, or description of the nerve system and organs of special sense. 



Splanchnology, or description of the viscera, comprising the organs of respira- 

 tion and phonation, digestion, reproduction, excretion, and internal secretion. 



