40 ANATOMY OF THE RABBIT 



line as possible and the limbs are extended as nearly at right 

 angles to the axial skeleton as possible with the radial and 

 tibial sides mediad. Thus only four topographic terms, 

 cranial, caudal, medial, and lateral, are essential and the 

 confusing terms, dorsal and ventral need be applied only to 

 the trunk, head, and tail. However, it is easier, although not 

 necessary, to refer to the back of the hand or foot as the dorsal 

 side than as the cranial side, but the dorsal side of the humerus 

 would be the caudal side while the dorsal side of the femur 

 would actually be the cranial side if these terms are applied to 

 the limbs. The anatomical position employed in studying 

 human anatomy is that in which the human cadaver is laid on 

 its back with the arms straight along the sides and the palms 

 of the hands turned up (supinated) and with the heels resting 

 on the table. 



Although the following rules on the use of the various forms 

 of the different terms are often violated by good anatomists 

 their validity remains unshaken. The -al ending denotes 

 the adjectival use of the term, e.g., caudal appendage, caudal 

 region; the -ad ending denotes the adverbial use of the term, 

 usually as an adverb of direction or of location (cf. Reighard 

 and Jennings, p. viii), as one structure or region is caudad to 

 another, e.g., the pelvis is caudad to the sternum. Both forms 

 of this term are derived from the Latin noun cauda, the tail. 

 The other three terms are derived from the Latin nouns cranium, 

 the bony case surrounding the brain; ventrum, the external 

 surface of the thorax and abdomen and dorsum, the region of 

 the back. These terms are often compounded with each 

 other and with other terms such as medial or mesial (middle) 

 and lateral (side) to indicate a position or plane. Just as the 

 cardinal directions. North, South, East, and West are com- 

 pounded into Northeast, Northwest, etc. to designate the 

 direction of points between, so also in anatomy topographical 

 terms are compounded to designate intermediate positions. 

 These terms are equally as applicable to the dissected as to the 

 entire animal. As an example, the kidneys are later oventr ad 



