Veterinary Splanchnology and Applied Anotomy

SMALL INTESTINE (OX)

• The small intestine measures about 21.5 m. in the adult (Indian ox) and has a diameter of about 5 to 6 cm
• It begins at the pylorus and terminates at the caecum. It is divisible into a fixed part and a mesenteric part
• The fixed part is duodenum and mesenteric part is arbitrarily divided into jejunum and ileum

• The duodenum is about 1m long. It begins at the pylorus at the ventral end of the 10th rib
• The first part passes upwards to the visceral surface of the liver. Here it forms a ‘S’ shaped curve
• The second part runs backwards to the tuber coxae where it turns forward forming the iliac flexure. 
• The third part extends forward in contact with the terminal part of the colon and joins the mesenteric part
• It is attached to the liver by the lesser omentum, to the remainder of its extent by the mesoduodenum -a narrow fold derived from the right layer of the mesentery
• The bile duct opens into the convexity of the ventral part of the ‘S’ shaped curve
• The pancreatic duct opens about 30 cm further back
• The remaining part of the small intestine, the jejunum is arranged in numerous very close coils, which form a festoon at the edge of the mesentery
• It lies chiefly in the space bounded medially by the right face of the rumen, laterally and-below the large intestine and in front the terminal part leaves the edge of the mesentery runs forwards between the caecum
• The last 120 cm constitutes the ileum
• In the interior, lymphoid tissue occurs in the form of distinct nodules, which are either scattered - Solitary glands or in groups - Payer's patches
• The Payer’s patches are large and are about 18 to 40 in number; in calves 35 to 50. Usually there is a very long patch close to the ileo-caecal valve