2 DESCRIPTIVE ANATOMY. 



respectively nearer to or farther from the median plane. Sagittal indicates a dorso- 

 ventral direction in or parallel to the median plane, and coronal or frontal a direction 

 perpendicular to the foregoing in a transverse vertical plane. The terms superficial 

 and deep, central and peripheral, proximal and distal, are often used, and need 

 no explanation. In many cases precision may be obtained by reference to certain 

 fixed relations of parts, such as the vertebral and sternal ends of the ribs, the radial 

 and ulnar, or tibial and fibular borders, and the flexor and extensor surfaces of 

 the limbs. Preaxial and postaxial, applied, for instance, to parts of the limb, 

 signify, respectively, on the primitive cephalic or caudal aspect of the axis of 

 the member. 



