Posterior

Definition

Situated at or toward the rear or hind end of a body or structure; the opposite of anterior. In bilaterally symmetrical organisms, posterior denotes the caudal or tailward direction along the primary body axis. In arthropods, this typically corresponds to the abdominal or pygidial end, away from the head and mouthparts.

Etymology

Latin posterior, comparative of posterus meaning "coming after, following"

Example

In a grasshopper, the posterior tibiae are enlarged for jumping, while the posterior abdominal segments house the reproductive structures.

Synonyms

• caudal
• hind
• rear
• distal (when relative to a medial point)

Related Terms

• Anterior
• Dorsal
• Ventral
• Proximal
• Distal
• cephalic
• abdominal
• terminal

Usage Notes

Posterior is an absolute directional term in standard anatomical position, not relative to observer perspective. In appendages, it may contrast with anterior (front/back) rather than proximal/distal (near/far from body). In some contexts, 'caudal' is preferred for the tail end specifically, though posterior remains more general. When describing segments or tagmata, specialists often use 'posterior' to mean toward the last-formed or terminal segments (e.g., posterior margin of the pronotum, posterior spiracles of dipteran larvae). Do not confuse with 'dorsal' (upper surface) or 'ventral' (lower surface). In rotated or flexed specimens, posterior maintains its anatomical meaning regardless of actual spatial orientation.