DIRECTIONAL TERMS
Dorsal structures (or positions) lie toward the back (dorsum) of the trunk or by extension, toward the corresponding surface of the head or tail.
Ventral structures lie toward the belly (venter) or the corresponding surface of the head or tail.
Cranial structures lie toward the head (cranium, skull), caudal ones toward the tail (cauda).
Within the head, structures toward the muzzle (rostrum) are said to be rostral; caudal remains appropriate.
Medial structures lie toward the median plane (medianus, in the middle) that divides the body into symmetrical right and left “halves”.
Lateral structures lie toward the side (latus, flank) of the animal.
Different conventions apply within the limbs. Structures that lie toward the junction with the body are
proximal (proximus, near), whereas those at a greater distance are distal (distantia, distance).
Within the proximal part of the limb, structures that lie toward the “front” are said to be cranial, those that lie toward the “rear” caudal.
Within the remaining distal part of the limb, structures toward the “front” are dorsal (dorsum, back of the hand) and those toward the “rear” are palmar (palma, palm of the hand) in the forelimb or plantar (planta, sole of the foot) in the hind limb.
PLANES
The median plane divides the body into symmetrical right and left halves.
Any plane parallel to this is a sagittal plane and those close to the median are sometimes termed paramedian planes.
A dorsal plane sections the trunk or other part parallel to the dorsal surface.
A transverse plane transects the trunk, head, limb or other appendage perpendicular to its own long axis.
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