The anatomy of hens is organized around the faculty which have these birds to fly: the bones are light and the digestive system short.
The pulse of hen is definitely higher than that of the mammals: from 240 to 340 beats per minute. Body heat also: 41,6 °C for the chicken.
The number of cervical vertebrae also constitutes a characteristic: the chicken has 14 of them. Those allow the animal to turn its head in all directions, which compensates for the side position of the eyes.
The sight is the dominating sense: the chicken sees up to 50 m.
The poultry, like the birds, does not have an outer ear. A little behind the eyes is an auditory canal protected by small feathers. The hen can hear cries up to 50 m of distance.
The olfactive and gustatory senses of chickens are little developed.
The genitals of a hen are developed only left side. They are composed of:
Lets start by noting absences: lips, teeth, the velum, the pharynx.
After the mouth is the oesophagus with a dilated part called crop where the food soaks in mucus. Further, the gastric juices are secreted in the proventriculus.
Then the bolus arrives in the gizzard. In absence of teeth, the gizzard often contains small stones which contribute to the crushing of food. These stones remain in the gizzard and are thus not evacuated with the food pulp.
In the small intestine, the food is still more broken up. The nutritive substances are absorbed and pass in blood.
The cellulose is broken up in the large intestine.
Dejections of the intestine and urines are then evacuated via the caeca.
As for all birds, it is important that the food and digestion do not weigh down the animal exaggeratedly; this could block the flight. The length of the intestine compared to the length of the body is thus low (1:8) in comparison with an ox for example (1:30) or a pig (1:25).
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