Digestive anatomy: Small & Large Intestine

Digestive System Overview

• Covers the digestive system of domestic animals and poultry
• Focuses on the small and large intestines, liver, and pancreas

Small and Large Intestine

• Also known as the Intestinum tenue et crassum
• Longer than body length, varying by species like: ca x5, su x15, eq x10, and Ru x25
• Mesenterium: serosal folds suspending the intestinal tract from the abdominal cavity roof
• Radix mesenterii: the root of mesentery, dorsally attached

Small Intestine: Intestinum tenue

• First part is the duodenum
• Duodenum extends from the pylorus to the beginning of the jejunum
• Gll. duodenales submucosae are present
• Duodenum length varies:
  • bo: 90-120 cm
  • eq: 1-1.50 m
  • su: 40-95 c
  • ca: 20-60 cm
  • fe: 10 cm
• Mesoduodenum: suspends most of the duodenum except in dogs (wide suspension)
• Lig. hepatoduodenale: attaches the cranial part to the liver
• Plica duodenocolica: attaches at the duodenojejunal flexure to the descending colon via the duodenocolic fold

Duodenum Details

• Pars cranialis: cranial part
• Flexura duodeni cranialis: cranial flexure (1)
• Ansa sigmoidea - sigmoid loop (s-shaped flexure in Ru, eq, su)
• Pars descendens: descending duodenum (2)
• Pars transversa: (3)
• Flexura duodeni caudalis: caudal flexure ( present in eq)
• Pars ascendens - ascending duodenum (4)
• Flexura duodenojejunalis: duodenojejunal flexure (5)

Jejunum Highlights

• The longest part of the small intestine, between the duodenum and ileum
• Characterized by loops (ansa)
• Length varies by species:
  • Ru/ bo: up to 40 m
  • ov/cap: ~30 m;
  • eq: 14-22 (28) m
  • su: 15 m
  • ca: 1 m
• Mesojejunum is long
• Jejunum is most mobile, free part of the alimentary canal

Ileum Characteristics

• The short terminal part of the small intestine
• Ostium ileale (7): ileal orifice at the cecum and ascending colon junction
• Plica ileocecalis fold (18) attaches to the antimesenterial surface of the ileum to the cecum
• Suspended by the Mesoileum [17]

Large Intestine: Intestinum Crassum

• Includes the cecum, colon, and rectum
• Lacks villi intestinales
• Contains pll. intestinales
• Parts of the wall in eq and su contain bands (teniae [taeniae]) [t] and sacculations (haustrae) [h]

Cecum Overview

• Functionally a blind sac
• Length varies by species: shortest in cats, increasing through ca, su, Ru to eq (largest)
• Located in the abdominal cavity
• Right side in Car, Ru, eq
• Pig exception: located on the on the left
• Composed of the body (Corpus ceci (caeci) and apex (Apex ceci (caeci)) directed toward the pelvic inlet (excluding eq)

Cecum Orifice and Fixation

• Opens freely into the colon at the cecocolicum orifice
• Fixation via the Plica ileocecalis and Mesocecum

Cecum of Carnivores

• Irregularly twisted or S-shaped blind tube about 20 cm long
• Comma-shaped
• Only 204 cm long
• Located medially the the right plane; VL 2-4
• Related to: right kidney (dorsally), ileum/jejunum (ventrally), descending duodenum /right pancreas lobe (laterally).
• Connects to the ileum and ascending colon via short peritoneal folds

Cecum of Ruminants

• Occupies dorsal third,right abdomen starting ventrally to VL 3-4.
• Apex ceci points toward the inlet
• Shaped cylindrically
• Length is 30-70 cm in cattle and 25-42 cm in capra

Cecum in Horse and Pig

• Characterized by longitudinal muscular layer concentrated into bands (TENIAE ceci (caeci)) and sacculations (HAUSTRA ceci (caeci)).

Cecum of Pigs

• Situated on abdominal cavity's left side, starts at the caudal left kidney
• Has Apex ceci directed caudoventrally
• 25-30cm long
• Volume is 1,5-2,2
• Features 3 Teniae ceci + 3 rows of Haustra ceci.

Cecum of Horses

• Situated mostly right of the median plane
• Stretches from right side of the iliac and sublumbar regions to the xiphoid cartilage
• Length is ~80-130 cm
• Volume is 30 L
• Plica cecocolica facilitates its attachemnt
• Plica ileocecalis and the Mesocolon.

Cecum: eq

• Contains 4 Teniae ceci +4 rows of Haustra ceci
• Comma shaped
• Basis ceci lies in fossa paralumbalis dextr.,
• Corpus ceci adjoins the abdomnal's right wall
• Apex ceci goes to the Xiphid Cartilage

Colon Portions

• Begins at the cecocolic orifice, ends at the rectum and the inlet
• Three parts:
  • Colon ascendens:
    • In horses, this is the Colon crassum (ascending) aka great colon
  • Colon transversum
  • Colon descendens:
    • In horses, this is the Colon Tenue (descending. aka small colon

Mesocolon

• Has Mesocolon descendens (attaches here) and transversum (attaches here and to the Colon Ascendens)

Colon of Dogs

• Begins at the cecum and right root side of the root of the mesentery
• Transversely, left to cranial root
• Descending: joins at flexure, goes to inlet then the rectum

Colon of Ruminants

• The Colon ascendens is Ansa Proximalis (disc shaped coil)
  • The Ansa Spiralis has:
    • Turns to Gyri centripetales in ingoing coils
      • Flexura centralis (flexure)
    • Turns out as (Gyri centrifugales centrifugal)
  • Ansa distalis is also part of the Colon
• Colon transversum as well
• Descendens with Colon Sigmoideum in bovine

Colon of Pigs

Colon Ascendens

• Features: The "cone shape coil"
• The "spiral loop" includes - wider turns to The Gyri centripetales - 2 bands of Teniae and 2 sacculated rows - Flexura Centralis and turns to The Gyri centrifugales Colon Transversum faces right: Colon Descendens is also present

Colon of the Horse

• Large colon (Colon crassum)
• Transverse colon (Colon transversum)
• Small colon (Colon tenue)

Equine Large Colon

• Shaped to a double "u", resembling a shoe
• The long section runs 3-4 meters
• 80 is the Volume (Liters)
• Has Colic flexure

Ileum (anatomical)

Horse lleum Info

• Includes Flexura Sternalis and Pelvina
• Colon dorsale sinistrum, Colon dorsale dextrum

Transverse

• Colon 2,5 to4 m 2 rows with sacculations

Rectum Overview

• Straight section of the end of the anal at the inlet, it is preceded by the end Includes • Ampulla recti (enlarged with transverse Rectal folds) • Anal's terminal, brief canal with muscular internus and externus

Anal canal Details

• The anus' canal has no intestinal glands,
• contains an orifice inside itself plus M. sphincter ani and externus.
• 3 membranous zones around the anus' canal with columnar
  • Intermedia, junction/ cutaneous, and sinus

Accessory Digestive Glands

• Focuses two glands associated with the alimentary: liver and Pancreas

Liver Definition

• Medically can be labeled Hepar,
• a hepatic or hepatic from the Greek word for liver, hēpar, largest body's glands Is caudal to the diaphragm+ cranial in theabdominal cavity mass Reddish brown (shade) Size relies on breed/ species

Liver Features

• Has both faces with the visceral one being concave
• borders being right left, ventral and dorsal sharp (thin)
• ventral border has incisions dividing various liver segments

Ligaments

• Connects to diagphram, (hepatis foramen)
• Left Triangulare (dextrum+sinistrum) conjoin in (lobes)
• connects with falciform + free edge
• Hepatorenale

Additional Ligaments

• Hepatogastricum (connects to the liver)

Ruminant Livers

4 lobes ( sinistra, dextra,quadratus, and processes with large caudatus/small papillaris) Interlobares is shallow

• It is right of intercostal VII (space), with a last right rib and 3.4 to 10kg mass with shallow lobes and 3.4
• The gall bladder location is e.

Bovine Livers

• Has Face types :The "Diaphragmatica and visceralis" has a 3.4 to 10g mass
• In this case: Quadrate is The Lobus hepatis and bilairis are the ( fellea + vesica)

The Liver (horse)

• Located on diagphram+ closer/ right abdomen (5kg)
• No bladder but bile exists

Equine (Continued)

Hepar is

• Diagphramatic close by the right with 5 lobe surfaces (0 -4)
• gall is not in the duct
• Ductus hepaticus(2) (communis)

Liver carnivores (carnivores) with parts like

Hepatics

General

• On diaphragm's right side (hepar and cartoid has 3-4kg/ m4.5 sinister (a) lateralis), medialis/quadratics/caudatus

In pigs versus cats (same, ca)

Gland (Bile)

Fellea on face Between the quadrate/ right liver pears shape and united Has parts/ body/ duct

Bile (Duct)

• "Hepaticus Dexter
• sinister hepaticus (communis/cystic" and bile (duct and major
• Is absent and hepatic with cm and

Pancreas

• Soft glad (red/grey)
• It's body is notched and has sinister /dexter sides

The Pancreas: Surfaces and Features

• Contains pancreatic and borders (dorsalis)
• Conducts the pancreatic
• To open major is where the (accessory releases and duodenum

Explore the digestive system's small and large intestines (Intestinum tenue et crassum) in domestic animals and poultry. Covers the duodenum, its length variations across species, and its attachments to the liver and colon.