OESOPHAGUS (Ox, Sheep, Goat, Horse, Pig, Dog, Rabbit, Fowl )

 

OESOPHAGUS (Ox, Sheep, Goat, Horse, Pig, Dog, Rabbit, Fowl )

Ox

• It is a musculo-membranous tube, which extends from the pharynx to the stomach. It is divided into cervical and thoracic parts
• The cervical part begins at median line above the cranial border of the cricoid cartilage of larynx
• At the level of the fourth cervical vertebra, it passes to the left of the trachea and continues this relation on the left side of the neck and enters the thoracic cavity
• The thoracic part begins at the level of the first rib. At the level of third thoracic vertebra it gains the dorsal face of the trachea passes backwards and crosses the right side of aortic arch
• It continues its course through the mediastinum between the lungs backwards and slightly upwards inclines to the left, reaches the hiatus oesophagi of the diaphragm
• It passes through it and immediately terminates on the dome-like rumino-reticular wall -the atrium ventriculi
• Directions : At first downward and backward till the thoracic inlet; upward to the dorsal face of trachea backwards and upwards between the lungs
• Relation at the origin : Dorsally, the ventral straight muscles of the head. Ventrally cricoid cartilage. Laterally, carotid arteries
• About the middle of the neck : Dorsally, left longus colli. Medially, trachea. Laterally, Left carotid artery, vagus and sympathetic nerves and recurrent laryngeal nerve
• In the thoracic cavity In the cranial mediastinum: dorsally longus colli. Ventrally, trachea. Left side, Aorta, right side right vagus
• In the caudal mediastinum: Oesophageal trunks of vagus lie above and below it

Species difference

Sheep and Goat

• The lumen is about an inch when moderately distended
• Otherwise it resembles that of ox

Horse

• It is longer, being about 125 to 150 cm. It has a small abdominal part. At its origin it is related to the guttural pouches
• It is narrower and less dilatable
• The muscle is striped till the level of the base of the heart and plain thereafter. There is a short abdominal part of oesophagus, about 2 to 3 cm

Pig

• Short and nearly straight
• The potential caliber is wide
• Except the terminal part the muscular coat is striated
• It has a small abdominal part
• There are numerous tubulo-alveolar glands are present in the cranial part of the tube

Dog

• Wide and relatively more dilatable except at the origin where there is a constriction
• Muscular tissue is striated

 

Rabbit

• The tube is 8 cm long and thin walled
• The cervical part is longer than the thoracic part
• It has a considerable length of abdominal part, which is little more than 1cm

Fowl

• It extends from the pharynx to the proventriculus
• It is greatly dilatable
• It is at first dorsal to the trachea, then inclines to the right and presents at the thoracic inlet a ventral dilatation called the crop. Both inlet and outlet are on the internal face of the crop
• It joins the cranial extremity of the proventriculus