LARGE INTESTINE

LARGE INTESTINE

1. INTRODUCTION :-

                         Large intestine is a “ARCH” like structure in the Digestive system .

2. SITUATION :-

                        It is situated beginning at the caecum in the right iliac fossa and terminating at the rectum and anal canal  deep in the pelvis. 

3. MEASURMENTS:-

                                    Length – 1.5 meters long.

                                    Lumen is about 6.5 cm in diameter.

4. PARTS:-

The colon is divided into

v   THE CAECUM:

v  ASCENDING COLON,

v  TRANSVERSE COLON,

v  DESCENDING COLON,

v   SIGMOID COLON ,

v  RECTUM AND ANAL CANAL.

                      THE CAECUM:- It is the first part of colon . it is a dilated parts and connecting to the ascending colon in superior region.

The vermiform appendix is present in this region ,usually about 8-9cm long and it contains more lymphoid tissue.

ASCENDING COLON,

                   This pass upwards from the caecum to the level of the liver where it curves actually to the left.

  TRANSVERSE COLON,

This is a loop of colon that extends across the abdominal cavitynin front of the duodenum and the stomach to the area of the spleen, curves to downwards.

DESCENDING  COLON :-

This passes down the left side of the Abdominal cavity then curves  the  midline.

After it enters the true pelvis it is known as the SIGMOID COLON.

SIGMOID COLON

It is S shaped curve in the pelvis that contains downwards to become the rectum .

THE RECTUM

It is a slightly dilated section of the colon about 13cm long.

It leads from the sigmoid colon and terminates in the anal canal.

THE ANAL CANAL

v  This is a short passage about 3.8cm long in the adults and leads from the rectum the extesior.

v  2 sphincter muscles control the anus: the internal sphincter consisting of smooth muscle is under the control of the autonomic nervous system.

v  The external sphincter formed by skeletal muscke is under voluntary control.

 

5. STRUCTURE:-

6. BLOOD SUPPLY:-

Arterial supply:

          Superior and Inferior mescentric artery branches of ileocolic artery.

VENOUS DRAINAGE:

   Ileocolic vein joins to portal vein .

7. LYMPH  DRIANAGE:-

Ileocolic group of lymph node.

8. NERVE SUPPLY:-

SYMPHATETIC NERVE SUPPLY:       

                                               

 Preganglionic fibres T10-L1 Segments of sigmoid colon.

PARA SYMPHATETIC NERVE SUPPLY:

                    From vagus nerve.

9. APPLIED ANATOMY:-

v Appendicitis: Inflammation of the vermiform appendix.

v Microbial diseases: Typhoid fever.

v Salmonella infection –Food poisioning,cholera dyscentry.

v Inflammatory diseases- crohns disease –inflammatory condition of the alimentary tract.

v Ulcerative colitis:

Chronic inflammatory disease of the mucosa of the rectum and colon, which  may ulcerate due to infection.

v  TUMOURS:      Rectum and colon.

v  HERNIAS: Protrusion of an organ (or) part of a organ through a weak point.

v  VOLVULOS: This occurs when a loop of bowel twists through 180^ cutting of its blood supply, causing gangrene and obstruction.

v  INTUSSUSCEPTION:  Length of intestine is invaginated into  itself if occurs most common in children.

v  INTESTINAL OBSTRUCTION: Constriction of the Intestine, Stenosis,pressure on the intestine from an outside.

10.             FUNCTIONS:-

1.Storage of matter.

2.Absorption of fluids and solutes.

3. Lubrication of Undigested matter to facilitate its passage.

4.Protection against bacterial invasion due to presence of numerous lymphatic follicles.

5.Synthesis of vitamin B from colonic flora.