B22 - The hindgut of the horse and ruminants, blood supply and innervation

Question 1

Define hindgut

Answer 1

• The caudal portion the the embryonic gut which develops into the colon and the rectum​
• Begins at the cecum
• Ends at the anus

Question 2

Give the portions of the hindgut

Answer 2

1. Cecum (​Right side of the abdominal cavity, except from in pig)
2. Colon
3. Rectum (Partly inside, partly outside the abdomen)

Question 3

Caecum

Answer 3

• Basis caeci (Dorsal dilation of cecum, eq)
• Corpus caeci
• Apex caeci
• Curvatura caeci major
• Curvatura caeci minor
• Teniae caeci (eq, su) (Bands of cecum)
  
  • Tenia dorsalis (Ø su)
  • Tenia ventralis
  • Tenia medialis
  • Tenia lateralis
• Haustra caeci (eq, su) (Sacculations of the cecum between the teniae and between the plica semilunares)
• Ostium caecocolicum (Opening between cecum → colon)
• Valva caecocolica (eq)
• M. sphincter caeci (ca, bo, su)
• Plica iliocolica (Attaches to tenia dorsalis)
• Plica caecocolica (C**olon ventrale dextrum → tenia lateralis of the caecum)
• Location in horse:
  
  • Right dorsal part of the abdominal cavity
  • Most dorsal part: basis caeci​
  • Basis caeci extends from pelvic inlet to rib 14/15
  • Dorsally: attaches to fascies ventralis of right kidney and right lobe of the pancreas
  • Left surface of basis caci is attached to the root of the mesentery
• Location in ruminants:
  
  • Right dorsal part of the abdominal cavit
  • Rounded blind tip is directed caudally
• Haustra/tenia:
  
  • Eq: 4
  • Ru: 0
• Eq: can hold 30-50 liter

Question 4

Caecum

Give the interspecies differences

Answer 4

• Tenia caeci (eq, sus)
  
  • Tenia dorsalis (ø sus)
  • Tenia ventralis
  • Tenia medialis
  • Tenia lateralis
• Haustra caeci (eq, sus)
• Valva caecolica (eq)
• M. sphincter caeci (ø eq)

Question 5

Colon

Horse

Answer 5

• Colon ascendens [Colon crassum] (Loop fromed by the colon ventrale and colon dorsale, which bends aronud to the left side)
  
  • Colon ventrale dextrum (Cecum → flexura sternalis, 4 tenia and haustra)
  • Flexura sternalis [=flexura diaphragmatica ventralis]
  • Colon ventrale sinistrum (Flexura sternalis → flexura pelvina, 4 tenia and haustra)
  • Flexura pelvina
  • Colon dorsale sinistrum (Flexura pelvina → flexura diaphragmatica
  • Flexura diaphragmatica [=flexura dorsalis]
  • Colon dorsale dextrum (Terminal part of colon crassum, joins colon transversum, 3 tenia)
  • Ampulla coli (Dilatation of colon dorsale dextrum)​
• Colon transversum
• Colon descendens [Colon tenue] (Flexura coli sinistra → rectum)
• Teniae coli
• Haustra coli
• Everything is attached to the right side
• Only tenia and haustra on the ventral portion
• Can hold 120 liter

Question 6

Colon

Ruminant

Answer 6

• Colon ascendens
  
  • Ansa proximalis coli (Continued by ansa spiralis)
  • Ansa spiralis coli (Coiled on the left side of the mesentery)
    
    • Gyri centripetales (Coils in which the ingesta move toward the flexura centralis)
    • Flexura centralis (The last in-going coil is continuous with the first out-going coil
    • Gyri centrifugales (Coils in which the ingesta move away from the flexura centralis towards the ansa distalis)
  • Ansa distalis coli
• Colon transversum (Passes from right to left cranial to the cranial mesentery artery, joining the right and left colic flexures)
• Colon descendens
• Colon sigmoideum (bo) (S-shaped curve just cranial to the rectum)

Question 7

Rectum

Answer 7

• Ampulla recti (enlargement of terminal part)
• Follows colon into the pelvic cavity, terminates at canalis analis
• Pelvic part of large intestines
• Most is covered with peritoneum
• Horse:
  
  • Peritoneal cover is last → retroperitoneal tissue
  • No more sacculation
  • Amulla coli = canalis analis
  • M. retrococcygeus deep from long muscle layer of the rectum
• Ruminants:
  
  • Peritoneal is here
  • Retroperitoneal is short
  • Thin muscular layer
  • M. retrococcygeus:
    
    • ​Origin: long rectal musculature
    • Insertoon: ventral surface of 1^st coccygeal

Question 8

Blood supply of the large intestines

Horse

Answer 8

• Cecum:
  
  • A. ileocolica → a. caecalis medialis et lateralis
• Colon ascendens:
  
  • Colon ventrale: a. ileocolica → r. colicus
  • Colon dorsale: a. mesenterica cranialis → a. colica dextra
• Colon transversus:
  
  • A. mesenterica cranialis → a. colica media
• Colon descendens:
  
  • A. mesenterica caudalis → a. colica sinistra
• Rectum:
  
  • A. mesenterica caudalis → a. rectalis cranialis

Question 9

Blood supply of the large intestines

Ruminants

Answer 9

• Cecum:
  
  • A. mesenterica cranialis → a. ileocolica → a. caecalis
• Colon ascendens
  
  • Gyri centripetalis: a. ileocolica → r. colici
  • Gyri centrifugalis: a. ileocolica → a. colica dextrae
• Colon transversus:
  
  • A. mesenterica cranialis → a. colica media
• Colon descendens:
  
  • A. mesenterica caudalis → a. colica sinistra
• Colon sigmoideum:
  
  • A. mesenterica caudalis → aa. sigmoideae
• Rectum:
  
  • A. mesenterica caudalis → a. rectalis cranialis

Question 10

Innervation

Answer 10

• Sympathetic
  
  • Decreased activity
  • Ggl. & plexus mesentericus cranialis
  • Ggl. & plexus mesentericus caudalis
• Parasympathetic:
  
  • Increased activity
  • Vagal nerves: supply intestines to the junction between colon transversus and colon descendens
  • Pelvic nerves: supply colon descendens and rectum