Descending Colon

Descending Colon It is 10inch in length Runs vertically down from the splenic flexure up to iliac crest and then inclines medially iliacus and psoas major and then continues with sigmoid colon Descending colon is narrower than the ascending colon

Relations of descending colon:

Relations of descending colon: Anterior relations: Coils of small intestine Greater omentum Anterior abdominal wall Posterior relations: Lateral border of left kidney Origin of transversus abdominis muscle Quadratus lumborum muscle Iliac crest Iliacus muscle Left psoas muscle Iliohypogastric and Ilioginuinal nerves Lateral cutaneous nerve of thigh Femoral nerve

Sigmoid Colon

Sigmoid Colon Sigmoid colon starts as descending colon passes in front of the pelvic brim. Below, it becomes continuous with the rectum at the level of S3. Completely surrounded by peritoneum. Sigmoid colon is mobile It hangs down into the pelvic cavity in the form of a loop. It is attached to the posterior wall of the pelvis by a fan shaped fold of peritoneum, known as sigmoid mesocolon. 2-transverse mesocolon

3-small bowel mesentery 4-sigmoid mesentery 1-lesser omentum

Relations of sigmoid colon:

Relations of sigmoid colon: Anterior relations: Urinary bladder (in males) Posterior surface of uterus and upper part of vagina (in females) Posterior relations: external iliac vessels left piriformis left sacral plexus of nerves

Arterial supply of colon

Arterial supply of colon

Both rt. & lt. colic artery has ascending and descending branches

Both rt. & lt. colic artery has ascending and descending branches

Arterial supply of colon

Arterial supply of colon From Marginal artery terminal branch arises Divides into vasa longa and vasa brevia Both enter along mesocolic border (mesocolic taenia) Blood supply will be less on the side between two amesocolic taenia…..so, here the longitudinal incisions can be given

Venous supply of colon

Venous supply of colon Venous supply corresponds to the arterial supply

Lymphatic drainage of colon

Lymphatic drainage of colon Lymph of colon is being drained via different level of nodes., Epicolic – lying on wall of gut Paracolic – on medial side Intermediate – on main branches Terminal nodes – on IM, SM Vessles

If Ca spread occurs till intermediate or terminal nodes, for removing nodes corresponding arteries have to be ligated…so, the corresponding bowel has to be resected eventhough the bowel loop doesn’t contain carcinoma

Nerve supply of colon

Nerve supply of colon Lymph of colon is being drained via different Gut level | Corresponding bowel loops | PNS | SNS | PAIN LEVEL | ROUTE OF NERVE SUPPLY | CLINICAL IMPORTANCE MIDGUT | JUNCN. OF D1/D2 TO RT. 2/3RD TRANVERSE COLON | VAGUS (CN 10) | (T11-L1) COELIAC GANGLION AND SUPERIOR MESENTERIC GANGLION | AROUND UMBLICUS

(T11-L1) DERMATOME | VIA SUPERIOR MESENTERIC PLEXUS | SO, IN ANY MIDGUT PROBLEM PAIN AROUND UMBLICUS HINDGUT | LEFT 1/3RD TRANSVERSE COLON TO ANAL CANAL | NERVI ERIGENTIS (S2, S3, S4) | (L1-L2) LUMBAR SYMPATHETIC CHAIN | AROUND PUBIC REGION | VIA INFERIOR MESENTERIC PLEXUS AND SUPERIOR HYPOGASTRIC PLEXUS | SO, IN ANY HINDGUT PROBLEM PAIN AROUND PUBIC REGION