BeakA chicken picks up its feed with its beak. It has no teeth and cannot chew; the tongue pushes the feed back to be swallowed.
EsophagusA flexible tube. It carries feed down from mouth to crop. From the crop it carries feed on to the proventriculus.
CropAn out-pocketing of the esophagus at the base of the neck. Feed and water are stored here; very little digestion takes place in it.
ProventriculusThe glandular stomach, also called the true stomach. Acid and digestive enzymes are added to the feed here, before it is ground.
GizzardThe muscular stomach, also called the ventriculus. Two sets of strong muscles grind the feed, doing the work of teeth, and a thick lining protects them.
LiverIn two lobes, which lie partly round the gizzard. It makes bile, which helps digest fats.
GallbladderA small sac on the liver's right lobe that stores bile. The bile reaches the duodenum through a duct.
Duodenal loopThe first part of the small intestine, also called the duodenum. A long loop that leaves the gizzard, runs back and returns.
PancreasA long, thin gland between the two limbs of the duodenal loop. Its digestive juices pass into the duodenum.
Small intestineThe duodenal loop is its first part. The rest, the jejunum and ileum, is where most of the nutrients are absorbed.
CecaTwo long blind pouches leaving at the join of small and large intestine. Coarse material left in the feed ferments in them.
Large intestineShort and nearly straight, despite its name. The last of the water is taken back here.
CloacaThe chamber at the end of the tract. Digestive waste mixes here with the waste of the kidneys, and both leave together.
Inside the gizzard 3
Gizzard musclesTwo sets of strong, thick muscles. They squeeze and grind the feed, doing the work of teeth.
Koilin liningA tough layer that lines the gizzard. It protects the gizzard's muscles from the grinding. Older books call it the horny lining.
GritSmall stones the bird has swallowed. The gizzard's muscles work the feed against them, and they stay until they are ground small enough to pass on.
How this list was compiled: Every name checked on 2026-09-30 in two sources. poultry.extension.org, Avian Digestive System, by Dr. Jacquie Jacob of the University of Kentucky: every part of the chicken's tract and what it does, https://poultry.extension.org/articles/poultry-anatomy/avian-digestive-system/. O. C. Bradley, The Structure of the Fowl (1915, public domain): crop, glandular stomach, gizzard, the duodenal loop with the pancreas, liver and gall-bladder, the two caeca, large intestine and cloaca, https://archive.org/details/structureoffowl00brad. Wikipedia, Bird anatomy, Gizzard, Crop, Proventriculus and Cloaca, https://en.wikipedia.org/wiki/Bird_anatomy. Licence: own work
The drawing: Drawn for this site on 2026-09-30 from plain geometry; nothing traced. Licence: own work
How it works
The digestive system of a bird with no label on any part: a hen seen from her left side with the tract drawn inside her, and below it the stomach enlarged and cut open. Sixteen parts wait for a name.
Read the full guide
The word list
Thirteen names go on the hen: beak, esophagus, crop, proventriculus, gizzard, liver, gallbladder, duodenal loop, pancreas, small intestine, ceca, large intestine and cloaca. Three go on the cut stomach: gizzard muscles, koilin lining and grit.
Shapes that look alike
The hen faces left, so feed moves from left to right. The pouch at the base of the neck is the crop, and the short thick part just before the large round organ is the proventriculus. The U-shaped tube leaving that organ is the duodenal loop, and the thin strip inside the U is the pancreas.
Four parts are big enough to write on and have no line: the gizzard, the liver, the coiled small intestine and the gizzard muscles.
In the lower drawing the dotted organ on the left is the proventriculus again. Its line is on the hen, so leave it blank here.
A British textbook prints oesophagus, caeca and gall-bladder. They are the same three parts.
Questions and answers
What are the parts of a bird's digestive system to label?
Sixteen on this sheet: thirteen along the tract in the hen, from the beak to the cloaca, and three inside the gizzard. The comb, the wattle, the eye and the legs are drawn but take no name.
Where is the gallbladder on a bird digestive system diagram?
On the liver. It is the small oval at the lower edge of the two liver lobes, and its line runs down and to the left. The liver itself has no line.
How do you tell the ceca from the large intestine?
The ceca are a pair of long tubes with closed ends, leaving where the small and large intestines join. The large intestine is the single short tube after them, which ends in the round cloaca under the tail.
What is inside a bird's gizzard?
Working inward on the lower drawing: two thick bands of muscle above and below, then the koilin lining as a ring round the hollow, then the grit, the small stones lying in the hollow.