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==Introduction==
==Introduction==
The oesophageal groove is present in newborn ruminants. It is a channel taking milk from the oesophagues into the rumen, omasum and then abomasum, bypassing the reticulum.
The oesophageal groove is present in newborn ruminants. It is a channel taking milk from the [[Oesophagus - Anatomy & Physiology|oesophagus]] into the [[Abomasum - Anatomy & Physiology|abomasum]], bypassing the [[Rumen - Anatomy & Physiology|rumen]], [[Reticulum - Anatomy & Physiology|reticulum]] and [[Omasum - Anatomy & Physiology|omasum]].
[[Image:Calf Suckling.jpg|thumb|right|250px|''Calf suckling'' <Br> David Monniaux 2005, WikiMedia Commons]]
==Formation of the Groove==
==Formation of the Groove==
The groove is formed by posture of the animal lifting its head to suckle. Calcium ions are obtained from the milk. A teat or teat-shaped experience aids the formation. The formation of the groove can be overridden, e.g. bucket feeding calves.
==Groove Closure==
==Groove Closure==
It is an unconditioned reflex when the animal is eager for milk. Water consumption does not usually initiate groove closure. The age when the [[Rumen - Anatomy & Physiology|rumen]] becomes fully functional and the oseophageal groove closes differs between ruminants; In calves 20 weeks, in lambs 8 weeks, in deer 16 weeks and in goats 12 weeks. It closes by reflex stimulation of the cranial laryngeal branch of the '''vagus nerve''' ([[Cranial Nerves - Anatomy & Physiology|CN X]]) (takes 2-5 seconds). With time it becomes a conditioned reflex. The closure consists of two movements, the lips of the groove become firmly opposed and shorten and the lips become inverted and twisted around the axis of the right lip of the groove, drawing the reticular mucosa over the right lip.
==Function in the Adult Ruminant==
The groove is stimulated in adult ruminants by ADH. The groove can also be closed in adult ruminants by the administration of drugs, e.g copper sulphate, which is of use to prevent drugs becoming diluted in the forechambers. Instead, it directs the drugs directly to the [[Abomasum - Anatomy & Physiology|abomasum]].
==Histology==
The floor of the groove is smooth and pale lined with stratified squamous epithelium.
{{Template:Learning
|flashcards = [[Oesophageal Groove Flashcards]]
|OVAM = [http://www.onlineveterinaryanatomy.net/content/goat-gastric-groove Image - Goat Oesophageal Groove]
}}
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[[Category:Stomach - Anatomy & Physiology]]
[[Category:A&P Done]]
[[Category:Alimentary Anatomy - Cattle]]