Esophagus Flashcards
What is a gullet?
Another name for esophagus
What is the function of the esophagus?
To conduct food from the mouth to the stomach
What is the structure ?
Simple muscular tube that runs from the pharynx to the stomach in 3 segments:
1) cervical
2) thoracic
3) Abdominal
Runs from pharynx -> thoracic inlet
- surrounded by the 1st rib, 1st sternebra, 1st thoracic vertebra
- follows trachea down neck, initially leaning to the left = returns medial
Begins at the dorsal cricoid cartilage of larynx
The Cervical Segment
Runs within mediastinum in thorax
Passes over base of heart
Penetratrates oesophageal hiatus of diaphragm
Thoracic segment
What is formed from serous membranes that separate the thorax into two pleural cavities and surround unpaired structures such as the heart and esophagus?
The mediastinum
Which segment is very short, especially in ruminants?
And what does it pass over?
The Abdominal segment
- passes over the dorsal border of liver (indenting it) to join the stomach dorsally at the cardia
Prominent longitudinal folds
Stratified squamous epithelium
Lamina propria
Mucosa layer: muscular mucosa
- sometimes keratinized depends on species (usually K. In horses, ruminants and pigs but not carnivores)
- lamina rich in collagen
- muscularis mucosae: thin layer of smooth muscle in mucosa at caudal end
Loose connective tissue
Rich in glands
Submucosa layer:
- glands for secreting mucus for lubricaiton
- glands cranial in most species = full length in dogs
Main functional layer
Usually thickest layer of muscle
Two layers of muscle usually difficult to define at cranial end but not caudal
Muscularis Externa layer
What type of muscle is found in the muscularis externa layer?
starts as skeletal muscle in cranial end - turns into smooth muscle near caudal end
- dogs and ruminants have skeletal throughout the entire length though
What is the outermost layer of esophagus?
The Adventitia/Serosa
Avendtitia
Where the esophagus lived OUTSIDE the thorax and abdomen; connective tissues are covered by epithlial layer
RETROPERITONEAL ORGANS
Serosa
Where the esophagus lies WITHIN the thorax or abdomen; connective tissues covered by epithlial layer
INTRAPERITONEAL ORGANS
Where are some possible sites of obstruction when swallowing?
Cranial and caudal ends of the esophagus
Entrance to the thoracic cavity = thoracic inlet
Over the base of the heart ( thoracic segment)
Immediately anterior to diaphragmatic hiatus
