Esophagus

Definition

The anterior, narrow section of the foregut in arthropods that conveys food from the pharynx or mouthparts to the crop or midgut, often distinguished by muscular walls that drive peristaltic transport. In insects, the esophagus typically lies dorsal to the nerve cord and may expand into a crop for temporary food storage before passing contents through the proventriculus or directly into the ventriculus.

Etymology

From Ancient Greek οἰσοφάγος (oisophágos), 'that which carries or eats food,' from οἴσω (oísō), future of φέρω ('to carry') + ἔφαγον ('to eat')

Example

In a grasshopper, the esophagus extends posteriorly from the pharynx, passes through the nerve ring, and widens into the crop, where chewed plant material is held before enzymatic digestion begins in the midgut.

Synonyms

• oesophagus

Related Terms

• Foregut
• pharynx
• crop
• Proventriculus
• Midgut
• peristalsis
• Ventriculus
• Stomodeum

Usage Notes

In arthropod anatomy, 'esophagus' and 'oesophagus' are interchangeable spellings, with the former more common in American usage. The structure is sometimes less distinctly demarcated from the crop than in vertebrates, and some authors use 'esophagus' broadly to include the crop. In spiders and other arachnids, the esophagus is typically short and muscular, reflecting the liquid-feeding habit and the need to pump food into the gut. Contrast with intestine (midgut/hindgut region) and diverticula (blind outpocketings of the gut).