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Equine Alimentary System - Anatomy & Physiology (view source)
Revision as of 14:01, 12 July 2008
, 14:01, 12 July 2008→Ascending colon
===Ascending colon===
===Ascending colon===
*The ascending colon is very large and takes up most of the ventral abdomen.
*The ascending colon is very large and takes up most of the ventral abdomen.
*It is the shape of a double "U", where one U is on top of the other.
*It is the shape of a double "U", where one "U" is on top of the other.
*There are four limbs that lie parallel to each other, and three flexures that change the direction of the limbs.
*There are four limbs that lie parallel to each other, and three flexures that change these direction of the limbs.
*Sequence of the limbs and flexures of the ascending colon:
*Sequence of the limbs and flexures of the ascending colon:
**Right Ventral Colon ''(for those with an RVC bias remember, "the RVC comes first!")''
**Right Ventral Colon ''(for those with an RVC bias remember, "the RVC comes first!")''
**Sternal Flexure
***Passes out of the caecocolic orifice on the right side of the abdomen and continues cranially to the xiphoid region.
**''Sternal Flexure''
***Passes across the midline from right to left.
**Left Ventral Colon
**Left Ventral Colon
**Pelvic Flexure
***Runs caudally on the left ventral abdominal floor.
**''Pelvic Flexure''
***Turns dorsally just cranial to the pelvic inlet and then runs cranially to the diaphragm.
**Left Dorsal Colon
**Left Dorsal Colon
**Diaphragmatic Flexure
***Runs cranially, parallel and dorsal to the left ventral colon.
**''Diaphragmatic Flexure''
***Turns caudally at the diaphragm.
**Right Dorsal Colon
**Right Dorsal Colon
***The right ventral colon passes out of the caecocolic orifice and continues cranially to the xiphoid region.
***Continues caudally on the right. It is the shortest limb of the ascending colon.
*The '''transverse colon''' continues on from the right dorsal colon as the right dorsal colon turns medially.
*The right dorsal colon is attached by a mesentry to the dorsal abdominal wall, the base of the caecum, the root of the mesentry and the pancreas.
**This anatomical arrangement of mesentry allows the left ascending colon to twist and is a common cause of colic (colonic torsion).
*The ventral parts of the ascending colon are attached to the dorsal parts by a short mesocolon.
***At the diaphragm it turns caudally as the diaphragmatic flexure.
**The mesocolon houses the blood vessels, nerves and lymphatics.
*The transverse colon continues as the right dorsal colon turns medially.
*In the ventral colon many important digestive and absorptive functions take place, whilst the dorsal colon is mainly responsible for transportation of ingesta.
*In the ventral colon many important digestive and absorptive functions take place, whilst the dorsal colon is mainly responsible for transportation of ingesta.
*Taenia are present.
*Taenia are present.
**Different parts of the colon can be distinguished by the number of taenia present:
**Different parts of the colon can be distinguished by the number of taenia present:
***The left dorsal colon and pelvic flexure have '''one''' taenia.
***The left dorsal colon and pelvic flexure have '''one''' taenia.
***The right dorsal colon and diaphragmatic flexure have '''three''' taenia.
***The right dorsal colon and diaphragmatic flexure have '''three''' taenia.
***The descending colon has '''two''' taenia.
===Transverse Colon===
*Short
*Passes from across the midline from right to left. It passes cranial to the root of the mesentry
*The transverse colon has '''two''' taenia.
*Turns caudally to become the descending colon at the level of the left kidney.
===Descending Colon===
*Between 2-4m long.
*Suspended by a long mesentry; ''mesocolon descendens''.
*The descending colon has '''two''' taenia.
**Between the two taenia are distinct sacculations that house the faecal balls.
==Rectal Palpation==
==Rectal Palpation==