Axial surface
Facies axialis
Definition
Axial means 'that is located or directed towards the axis'
Abaxial means 'that is located or directed away from the axis'.
In perissodactyle species (that have an odd number of fingers), the axis of the hand or of the foot usually passes through the middle of the third finger.
In Men and Dogs, for example, the lateral surfaces of the fingers I, II and III are abaxial surfaces, while the ones of the fingers IV and V are axial surfaces, because they are directed towards the axis of the hand that passes. *
In the artiodactyle species, the axis of the hand usually passes between the fingers III and IV.
*In Horses, the two surfaces of the third finger could be termed abaxial, therefore they are simply called the medial and lateral surface.
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