18 VETERINARY ANATOMY 



apparatus which are similar in origin and structure and are associated in the per- 

 formance of certain functions. The divisions of systematic anatomy are: 



1. Osteology 



2. Arthrology 



3. Myology 



4. Splanchnology 



(1) Digestive System 



(2) Respiratory System 



(3) Urogenital System 



(a) Urinary Organs 



(b) Genital Organs 



5. Angiology 



6. Neurology 



7. ^Esthesiology 



(1) Sense Organs 



(2) Common Integument. 



The term topographic anatomy designates the methods by which the relative 

 positions of the various parts of the body are accurately determined. It presup- 

 poses a fair working knowledge of systematic anatomy. 



Descriptive Terms. — In order to indicate precisely the position and direction 

 of parts of the body, certain descriptive terms are employed, and must be under- 

 stood at the outset. In the explanation of these terms it is assumed here that 

 they apply to a quadruped such as the horse in the orcUnary standing position. 

 The surface directed toward the plane of support (the ground) is termed inferior 

 or ventral, and the opposite surface is superior or dorsal ; the relations of parts in 

 this direction are named accordingly. The longitudinal median plane divides the 

 body into similar halves. A structure or surface which is nearer than another to 

 the median plane is internal or medial to it, and an object or surface which is further 

 than another from the median plane is external or lateral to it. Planes parallel 

 to the median plane are sagittal. Transverse or segmental planes cut the long axis 

 of the body perpendicular to the median plane, or an organ or limb at right angles 

 to its long axis. A frontal plane is perpendicular to the median and transverse 

 planes. The head end of the body is termed anterior, cephalic, or cranial ; and the 

 tail end posterior or caudal ; relations of structures with regard to the longitudinal 

 axis of the body are designated accordingly. Certain terms are used in a special 

 sense as applied to the limbs. Proximal and distal express relative distances of 

 parts from the axis of the body. The anterior face of the thoracic limb from the 

 elbow downward is also termed dorsal, and the opposite face volar. In the corre- 

 sponding part of the pelvic limb the terms are dorsal and plantar respectively. In 

 the same regions radial and ulnar (thoracic limb), tibial and fibular (pelvic limb), 

 may be used to designate that side of the extremity on which the corresponding 

 bone is situated; they are therefore equivalent respectively to internal or medial 

 and external or lateral in the animals with which we are concerned. 



It is evidently advantageous to employ terms which are as far as possible independent of 

 the position of the body in space and capable of general application, e. g., dorsal, ventral, proximal, 

 etc. It is also desirable that the terms internal and external be reserved to indicate relations of 

 depth in ca\aties or organs, and medial and lateral to designate relations to the median plane. 

 Such terms are coming into more extensive use in human and veterinary anatomy, but the older 

 nomenclature is very firmly established and cannot well be discarded at once and entirely. 



