Intestine

• Parts of the intestine

  • Duodenum
  • Jejunum
  • Ileum
  • Cecum
  • Colon
  • Rectum
  • Anal canal

  
• Cecocolic junction


  Junction of the cecum and colon
• Mesentery


  Membrane that suspends the intestines from the abdominal wall
• Nonglandular


  Lacking glands
• Hepatoduodenal ligament


  Ligament that attaches the duodenum to the liver
• Ampula recti

  Enlarged terminal portion of the rectum
• Identifying and recognizing the different parts of the intestine in domestic animals

  1. Know the structures and function of different parts of intestine

  2. Identify and recognize the different parts of intestine of domestic animals

  3. Describe the structures of each part of intestine and differentiate between intestine of domestic animals

  
• Small intestine


  • Small lumen of proximal part
  • Duodenum, jejunum & ileum

  
• Large intestine


  • Wider distal part
  • Cecum, colon & rectum
  • Anal canal - short end portion

  
• Length of intestine varies among species
• Small intestine

  • Mucous membrane bears villi, not in large intestine

  
• Duodenum

  • Cranial part closely related to liver & pancreas, forms a sigmoid loop in horse, ruminants & pigs
  • Attached to liver by hepatoduodenal ligament
  • Receives bile duct & pancreatic ducts

  
• Jejunum


  • Longest part
  • Usually empty
  • Mesentery is long & allows great range, esp in carnivores and horse
  • In carnivores - occupies ventral part of abdominal cavity, covered by greater omentum, lies against lateral and ventral abdominal wall
  • In ruminants - intestines entirely to the right

  
• Ileum


  • Short terminal part connect to large intestine
  • Suspended by caudal part of mesentery (mesoileum)
  • Attached to cecum by ileocecal fold
  • Terminates at cecocolic junction forming ileal orifice

  
• Cecum


  • Initial blind part of large intestine, joined to colon at ileal orifice
  • Shortest in cat, increasingly longer in dog, pig, ruminants, Horse - large, elongated pouch
  • In carnivores, ruminants & horse - cecum lies on right side of abdominal cavity, In pig - on the left
  • Base of cecum usually found high in right flank (exc. in pig)

  
• Colon


  • Continues from the descending colon into pelvic cavity
  • Before ending at the short anal canal, it becomes enlarged, forming ampula recti
  • Very prominent in horse, absent in cat, sheep and goat
• Anal canal


  • Short terminal portion, the orifice it surrounds is anus
  • Mucous membrane - stratified squamus epithelium
  • External and internal sphincters surround the anus
  • Internal anal sphincter - continuation of circular smooth muscle of rectum
  • External anal sphincter (striated) - from the caudal vertebrae, lies superficial to internal sphincter
• Blood supply to the intestine

  • Small intestine - cranial mesenteric artery, Prox. duodenum - celiac artery, Large intestine - cranial and caudal mesenteric arteries, Rectum - internal iliac arteries
  • Veins of entire intestinal tract go to portal vein, Blood from rectum returned to the caudal vena cava
• Nerve supply to the intestine

  • Sympathetic - retarded, Parasympathetic - accelerates
  • Parasympathetic fibres - originate in both cranial and sacral regions