Difference between revisions of "Colon - Anatomy & Physiology"
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− | + | <big><center>[[Alimentary - Anatomy & Physiology|'''BACK TO ALIMENTARY - ANATOMY & PHYSIOLOGY''']]</center></big> | |
− | + | <big><center>[[Large Intestine - Anatomy & Physiology|'''BACK TO LARGE INTESTINE - ANATOMY & PHYSIOLOGY''']]</center></big> | |
− | + | ==Introduction== | |
+ | |||
+ | The colon can be divided into the following portions: | ||
+ | |||
+ | *Ascending | ||
+ | *Transverse | ||
+ | *Descending | ||
==Structure== | ==Structure== | ||
− | |||
− | The following | + | The following anatomocial arrangement is found only in cats and dogs, see species differences. |
− | The '''ascending colon''' continues from the | + | *The '''ascending colon''' continues from the iluem at the ileocolic junction. |
+ | **It runs to the right of the cranial mesenteric artery in a caudal to cranial direction. | ||
+ | **At the cranial border of the mesentry it turns medially to become the '''transverse colon'''. | ||
+ | *The transverse colon runs from the right side of the abdomen to the left side of the abdomen. | ||
+ | **Cranial to the transverse colon is the stomach, and caudal to it is the [[Small Intestine - Anatomy & Physiology|small intestine]] and cranial mesenteric artery. | ||
+ | *The '''descending colon''' continues on from the transverse colon running caudally on the left from the level of (???). | ||
+ | **It then passes more medially as it enters the pelvic cavity | ||
+ | **Upon entering the pelvic cavity it is continued as the [[Rectum - Anatomy & Physiology|rectum]]. | ||
==Function== | ==Function== | ||
− | |||
− | |||
− | == | + | ==Vasculature== |
− | + | ||
− | + | ||
− | + | ==Innervation== | |
− | + | ||
− | === | + | ==Lymphatics== |
− | |||
− | |||
− | |||
− | |||
==Histology== | ==Histology== | ||
− | + | *Mucosa has a columnar epithelium. | |
− | + | **Mucosa is thick. | |
+ | **Mucosa has long glands. | ||
+ | *Submucosa has large lymphatic nodules which may interrupt the lamina muscularis. | ||
+ | *Lamina muscularis is incomplete. | ||
− | == | + | ==Species Differences== |
− | ''' | + | ===Ruminant=== |
+ | *The '''ascending colon''' is the longest part of the colon and is composed of three parts: | ||
+ | **'''Ansa proximalis''' | ||
+ | ***Has a sigmoid flexure that passes around the caudal border of the mesentry to the left side of the root of the mesentry. | ||
+ | **'''Ansa spiralis''' | ||
+ | ***Consists of two centripetal turns and two centrifugal turns in the ox. | ||
+ | ****There are three turns in the sheep and four in the goat. | ||
+ | ****In the ox, the ansa spiralis is a flat disc, whilst in the small ruminants it takes the form of a cone. | ||
+ | **'''Ansa distalis''' | ||
+ | ***Goes back around the caudal border of the mesentry, to the right side of the root of mesentry. | ||
+ | ***It then passes cranially adjacent to the mesentry until it reaches the cranial border of the mesentry. | ||
+ | *The '''transverse colon''' crosses the midline of the abdomen, from right to left at the cranial border of the mesentry. | ||
+ | *The '''descending colon''' continues caudally to the rectum and anus. | ||
+ | **It has a sigmoid flexure before it enters the pelvic cavity. | ||
+ | *'''Development''' | ||
+ | **The ox's ascending colon expands '''caudally''' around the root of the mesentry on the left side of the mesentry (compare to horse, where it expands cranially). | ||
− | + | ===[[Hindgut Fermenters - Horse - Anatomy & Physiology|Horse]]=== | |
− | |||
− | |||
− | |||
− | |||
− | |||
− | == | + | ===Pig=== |
− | + | *The arrangement of the transverse and descending colon is similar to that of the dog and cat, but the ascending colon is different. | |
+ | **The ascending colon is elongated and coiled to form a cone-shaped organ. | ||
+ | **The base of the cone is attached to the dorsal abdominal wall and the apex points ventrally. | ||
+ | **The position of the ascending colon varies with filling of the stomach. | ||
+ | **From the caecum, there are clockwise centripetal turns to the apex of the cone. | ||
+ | **Then the centrifugal turns run anti-clockwise on the inside of the cone. | ||
+ | ***Centripetal turns have two taenia, whilst centrifugal turns have none. | ||
− | + | ==Links== | |
− |
Revision as of 08:46, 14 July 2008
Introduction
The colon can be divided into the following portions:
- Ascending
- Transverse
- Descending
Structure
The following anatomocial arrangement is found only in cats and dogs, see species differences.
- The ascending colon continues from the iluem at the ileocolic junction.
- It runs to the right of the cranial mesenteric artery in a caudal to cranial direction.
- At the cranial border of the mesentry it turns medially to become the transverse colon.
- The transverse colon runs from the right side of the abdomen to the left side of the abdomen.
- Cranial to the transverse colon is the stomach, and caudal to it is the small intestine and cranial mesenteric artery.
- The descending colon continues on from the transverse colon running caudally on the left from the level of (???).
- It then passes more medially as it enters the pelvic cavity
- Upon entering the pelvic cavity it is continued as the rectum.
Function
Vasculature
Innervation
Lymphatics
Histology
- Mucosa has a columnar epithelium.
- Mucosa is thick.
- Mucosa has long glands.
- Submucosa has large lymphatic nodules which may interrupt the lamina muscularis.
- Lamina muscularis is incomplete.
Species Differences
Ruminant
- The ascending colon is the longest part of the colon and is composed of three parts:
- Ansa proximalis
- Has a sigmoid flexure that passes around the caudal border of the mesentry to the left side of the root of the mesentry.
- Ansa spiralis
- Consists of two centripetal turns and two centrifugal turns in the ox.
- There are three turns in the sheep and four in the goat.
- In the ox, the ansa spiralis is a flat disc, whilst in the small ruminants it takes the form of a cone.
- Consists of two centripetal turns and two centrifugal turns in the ox.
- Ansa distalis
- Goes back around the caudal border of the mesentry, to the right side of the root of mesentry.
- It then passes cranially adjacent to the mesentry until it reaches the cranial border of the mesentry.
- Ansa proximalis
- The transverse colon crosses the midline of the abdomen, from right to left at the cranial border of the mesentry.
- The descending colon continues caudally to the rectum and anus.
- It has a sigmoid flexure before it enters the pelvic cavity.
- Development
- The ox's ascending colon expands caudally around the root of the mesentry on the left side of the mesentry (compare to horse, where it expands cranially).
Horse
Pig
- The arrangement of the transverse and descending colon is similar to that of the dog and cat, but the ascending colon is different.
- The ascending colon is elongated and coiled to form a cone-shaped organ.
- The base of the cone is attached to the dorsal abdominal wall and the apex points ventrally.
- The position of the ascending colon varies with filling of the stomach.
- From the caecum, there are clockwise centripetal turns to the apex of the cone.
- Then the centrifugal turns run anti-clockwise on the inside of the cone.
- Centripetal turns have two taenia, whilst centrifugal turns have none.