Directional Terms Used in Describing Anatomy
Anterior: The portion of the insect body toward the head. Opposite the posterior portion.
Apical: The adjectival form of apex, which is the tip of a structure. The apical portion of a lepidopteran wing is the tip that is most anterior and farthest from the base (where the wing attaches to the body; see basal, below).
Axis: The imaginary line drawn from the tip of the head to the tip of the abdomen. Essentially equivalent to midline.
Basal: The adjectival form of base. The basal portion of a lepidopteran wing is the region closest to the point of attachment to the body.
Distal: Farther from the axis of the body; opposite of proximal.
Dorsal: The side of the insect that is opposite the side with the legs and mouth parts. The upper surface when the animal is sitting at rest, opposite the ventral surface.
Inferior: In a lower position, relative to some other structure or region. Opposite of superior.
Lateral: On the side of a structure or body.
Medial: The adjectival form of median, referring to the middle of the body or structure. If referring to the body, the medial line is equivalent to the midline. If referring to a wing, the middle of the wing.
Midline: A line drawn down the middle of the body, from anterior to posterior. Essentially equivalent to axis.
Porrect: stretched out or extending horizontally.
Posterior: The portion of the insect body toward the abdomen and genital opening. Opposite the anterior portion.
Proximal: Closer to the axis of the body; opposite of distal.
Superior: In a higher position, relative to some other structure or region. Opposite of inferior.
Terminal: Opposite to basal; the terminal portion of a lepidopteran wing is the region farthest from the point of attachment to the body (also called the outer margin).
Transverse: Running across a structure or body. On segments of a caterpillar, a line running across a body segment from dorsal to ventral.
Ventral: The side of the insect that includes the legs and mouth parts. The underside of the animal when it is sitting at rest, opposite the dorsal side.