High-Yield Points:
• Three parts: Duodenum, Jejunum, Ileum. Total length in ox ~ 40 m.
• Duodenum: short, fixed; receives bile + pancreatic ducts. S-shaped sigmoid flexure cranially.
• Jejunum: longest, most coiled, suspended by long mesentery — fills the right flank in ox arranged around the supraomental recess.
• Ileum: terminal short part; ends at ileocecal orifice.
• Lies almost entirely on the RIGHT side of abdomen in ox (rumen occupies left).
• Surgical access in cattle = right paralumbar fossa laparotomy.
• Blood supply: cranial mesenteric artery. Drained via portal vein → liver.

Bovine Small Intestine

The bovine small intestine averages 40 metres long with a small diameter (~5 cm). It lies almost entirely in the right half of the abdominal cavity because the massive rumen occupies the left.

Duodenum (~1 m): Begins at the pylorus on the right side, runs cranially, makes the sigmoid (cranial) flexure, then turns caudally as the descending duodenum along the right flank, crosses behind the root of the mesentery (caudal flexure), and returns cranially as the ascending duodenum to become the jejunum. The major duodenal papilla (bile duct opening) is in the proximal duodenum; the minor duodenal papilla (accessory pancreatic duct) opens further distally.

Jejunum: The longest part, hanging in coils from a long mesentery. In cattle most jejunal coils occupy the supraomental recess on the right, an arrangement relevant to a right-flank surgical approach.

Ileum: The short terminal segment that runs cranio-dorsally and opens into the cecum at the ileocecal orifice; the ileocecal fold (a peritoneal band from ileum to cecum) is the surgeon's landmark to identify the ileum during laparotomy.

Vasculature: Most of the small intestine is supplied by the cranial mesenteric artery, while the proximal duodenum also receives celiac-derived cranial pancreaticoduodenal supply. Venous blood drains to the portal system; lymphatic drainage follows regional intestinal nodes.