Changes

==Introduction==

==Introduction==

The oesophagus (or gullet) is a muscular tube which transports food from the [[Pharynx - Anatomy & Physiology|pharynx]] to the [[Monogastric Stomach - Anatomy & Physiology|stomach]]. A bolus of food is passed down the oesophagus by peristalsis. The oesophagus is divided into cevical, thoracic and abdominal sections.

The oesophagus (or gullet) is a muscular tube which transports food from the [[Pharynx - Anatomy & Physiology|pharynx]] to the [[Monogastric Stomach - Anatomy & Physiology|stomach]]. A bolus of food is passed down the oesophagus by peristalsis. The oesophagus is divided into cervical, thoracic and abdominal sections.

==Structure and Function==

==Structure and Function==

[[Image:Oesophagus anatomy.jpg|thumb|right|250px|Oesophagus Anatomy - Copyright RVC 2008]]

[[Image:Oesophagus anatomy.jpg|thumb|right|250px|Oesophagus Anatomy - Copyright RVC 2008]]

The oesophagus begins dorsal to the '''cricoid cartilage''' of the [[Larynx - Anatomy & Physiology|larynx]]. It follows the trachea down the neck, first on the left and then medially once in thorax in the mediastinum. It passes over the [[Heart - Anatomy & Physiology|heart]] then through the oesophageal hiatus of the diaphragm. It passes over the dorsal border of the [[Liver - Anatomy & Physiology|liver]] then joins the [[Monogastric Stomach - Anatomy & Physiology|stomach]] at the cardia. The cervical section is accompanied by the common carotid artery, the vagosympathetic trunk and the recurrent laryngeal nerves. The thoracic section is accompanied by the right and left vagus nerves ([[Cranial Nerves - Anatomy & Physiology|CN X]]).   

The oesophagus begins dorsal to the '''cricoid cartilage''' of the [[Larynx - Anatomy & Physiology|larynx]]. It follows the trachea down the neck, first on the left and then medially once in thorax in the mediastinum. It passes over the [[Heart - Anatomy & Physiology|heart]] then through the oesophageal hiatus of the diaphragm. It passes over the dorsal border of the [[Liver - Anatomy & Physiology|liver]] then joins the [[Monogastric Stomach - Anatomy & Physiology|stomach]] at the cardia. The cervical section is accompanied by the common carotid artery, the vagosympathetic trunk and the recurrent laryngeal nerves. The thoracic section is accompanied by the right and left vagus nerves ([[Cranial Nerves - Anatomy & Physiology|CN X]]).   

There are different proportions of striated muscle across the species;  

There are different proportions of striated muscle across the species;  

**Dog and ruminant = 100%

:Dog and ruminant = 100%

**Cat              = 80% (rostral)

:Cat              = 80% (rostral)

**Horse            = 65% (rostral)

:Horse            = 65% (rostral)

**Pig              = 33% (rostral)

:Pig              = 33% (rostral)

==Histology==

==Histology==

[[Image:Oesophagus Histology.jpg|thumb|right|250px|Oesophagus Histology (Rat) - Copyright RVC 2008]]

[[Image:Oesophagus Histology.jpg|thumb|right|250px|Oesophagus Histology (Rat) - Copyright RVC 2008]]

The oesophagus has a '''stratified squamous epithelium'''. It has mucosal folds present for distension. The degree of keratinisation of the oesophagus depends on the animal's diet.

The oesophagus has a '''stratified squamous epithelium'''. It has mucosal folds present for distension. The degree of keratinisation of the oesophagus depends on the animal's diet.

==Innervation==

==Innervation==

The oesophagus is innervated by the sympathetic nerves and parasympathetic from the vagus nerve ([[Cranial Nerves - Anatomy & Physiology|CN X]]) and recurrent laryngeal nerves. The myenteric plexus extends the length of the oesophagus.

The oesophagus is innervated by the sympathetic nerves and parasympathetic supply from the vagus nerve ([[Cranial Nerves - Anatomy & Physiology|CN X]]) and recurrent laryngeal nerves. The myenteric plexus extends the length of the oesophagus.

==Species Differences==

==Species Differences==

Mucous glands are present in the horse, cats and ruminants only at the pharyngeal-oesophageal junction. There is a thick and strong sphincter of tunica muscularis in dogs and pigs. Ruminants, horse and pig have stratified squamous epithelium continuing from the oesophagus into the [[Monogastric Stomach - Anatomy & Physiology|stomach]]. Carnivores have an abrupt transition to columnar epithelium.

Mucous glands are present in the horse, cats and ruminants only at the pharyngeal-oesophageal junction. Ruminants, horse and pig have stratified squamous epithelium continuing from the oesophagus into the stomach. Carnivores have an abrupt transition to columnar epithelium.

===Canine===

===Canine===

No keratinisation, the '''lamina muscularis''' is skeletal muscle and is present caudally (spirally aranged). The lamina muscularis is, however, absent cranially. Mucous glands are present throughout but more abundant caudally.  

No keratinisation, the '''lamina muscularis''' is skeletal muscle and is present caudally (spirally aranged). The lamina muscularis is, however, absent cranially. Mucous glands are present throughout but more abundant caudally. There is a thick and strong sphincter of tunica muscularis.

===Equine===

===Equine===

===Porcine===

===Porcine===

The lamina muscularis is present caudally (very thick) and absent cranially. There is some keratinisation. Mucous glands are abundant cranially but absent caudally.

The lamina muscularis is present caudally (very thick) and absent cranially. There is some keratinisation. Mucous glands are abundant cranially but absent caudally. There is a thick and strong sphincter of tunica muscularis.  

===Avian===

===Avian===

See [[Crop - Anatomy and Physiology|the crop]]. '''Ducks''' have an oesophangeal [[Tonsils - Anatomy & Physiology|tonsil]] present in the caudal segment of the oesophagus.

See [[Crop - Anatomy and Physiology|the crop]]. '''Ducks''' have an oesophangeal [[Tonsils - Anatomy & Physiology|tonsil]] present in the caudal segment of the oesophagus.

==Links==

==Links==

[[Category:Alimentary System - Anatomy & Physiology]]

[[Category:Alimentary System - Anatomy & Physiology]]

[[Category:Oesophagus]]

[[Category:Oesophagus]]

[[Category:To Do - Review]]

[[Category:A&P Done]]