The paired, usually multiple jointed, sensory organs articulating on the procephalic region of the head capsule; its highly versatile sensory structures are capable to detect the various environmental stimuli. In the context of Drosophila refers to they are the most anterior segmented sensory appendage of the head.
anterior thoracic air sac
appendage girdle complex +
appendage musculature +
appendage vasculature +
aryepiglottic fold
arytenoid cartilage +
ascidian ampulla +
atlanto-occipital joint +
beak +
branch of Y-shaped fibrocartilage skeleton of ventral pouch