The colon and rectum | Canadian Cancer Society

Diagram of the digestive system

The large intestine is made up of the cecum, colon, rectum and anus. The colon and rectum are held in the abdomen by folds of tissue called mesenteries.

The cecum is a pouch-like passage that connects the colon to the ileum (the last part of the small intestine). If cancer develops in the cecum, it is treated like colon cancer.

The colon is the longest part of the large intestine. It receives almost completely digested food from the cecum, absorbs water and nutrients, and passes waste (stool or feces) to the rectum. The colon is divided into 4 parts:

• The ascending colon is the start of the colon. It is on the right side of the abdomen. It continues upward to a bend in the colon called the hepatic flexure.
• The transverse colon follows the ascending colon and hepatic flexure. It lies across the upper part of the abdomen. It ends with a bend in the colon called the splenic flexure.
• The descending colon follows the transverse colon and splenic flexure. It is on the left side of the abdomen.
• The sigmoid colon is the last part of the colon and connects to the rectum.

The proximal colon is the ascending colon and the transverse colon together. The distal colon is the descending colon and the sigmoid colon together.

The rectum is the lower part of the large intestine that connects to the sigmoid colon. It is about 15 cm (6 in) long. It receives waste from the colon and stores it until it passes out of the body through the anus.

Diagram of the large intestine

Mesentery is made of fatty connective tissue that contains blood vessels, nerves, lymph nodes and lymph vessels. The mesocolon is a mesentery that attaches the colon to the wall of the abdomen. The rectum is surrounded by a mesentery called the mesorectum.

When part of the colon or rectum is removed to treat cancer, nearby mesentery is also removed. The lymph nodes within the mesentery are examined to see if they contain cancer cells.

The colon and rectum are made up of the following layers of tissues.

The mucosa is the inner lining of the colon and rectum. It is made up of:

• a thin layer of epithelial cells (called the epithelium)
• a layer of connective tissue (called the lamina propria)
• a thin layer of muscle (called the muscularis mucosa)

The submucosa is a layer of connective tissue that surrounds the mucosa. It contains mucous glands, blood vessels, lymph vessels and nerves.

The muscularis propria lies outside the submucosa. It is a thick layer of muscle. It has an inner ring of circular muscle fibres and an outer ring of long muscle fibres that surround the wall of the colon and rectum.

Diagram of the layers of the colon and rectum

The colon and rectum:

• absorb water and some nutrients from what we eat and drink
• form and store stool
• move waste out of the body

Partly broken down or digested food moves from the small intestine into the colon. Sections of the colon tighten and relax to move the food through the colon and rectum. This movement is called peristalsis.

In the colon, bacteria break down food into smaller pieces. The inner layer of the mucosa (called the epithelium) absorbs, or takes up, water and some nutrients. The liquid waste remaining in the colon is formed into semi-solid stool.

The mucosa also makes mucus that helps stool move easily through the colon and rectum. As stool moves through the colon, more water is absorbed from it and it becomes more solid.

Stool leaves the colon and moves into the rectum. The rectum is a holding area for the stool. When the rectum is full, it pushes the stool out of the body through the anus.

• American Cancer Society. Colorectal Cancer. 2018: https://www.cancer.org/cancer/colon-rectal-cancer.html.

• Martini FH, Timmons MJ, Tallitsch RB. Human Anatomy. 7th ed. San Francisco: Pearson Benjamin Cummings; 2012.

• National Cancer Institute. Colon Cancer Treatment (PDQ®) Patient Version. 2018: https://www.cancer.gov/types/colorectal/patient/colon-treatment-pdq#section/all.

• National Cancer Institute. Rectal Cancer Treatment (PDQ®) Patient Version. 2018: https://www.cancer.gov/types/colorectal/patient/rectal-treatment-pdq#section/all.

Types of bowel cancer | Cancer Research UK

Bowel cancer can start in the large bowel (colon) or the back passage (rectum). It is also known as colorectal cancer.

Bowel cancer is divided into different types depending on where it starts in the bowel, and the type of cell that it starts in. Knowing this helps your doctor decide which treatment you need. 

Grades

The grade of a cancer tells you how much the cancer cells look like normal cells. This gives your doctor an idea of how your cancer might behave and what treatment you need.

The grades of bowel cancer cells are from 1 to 4:

Low grade – slow growing

•   grade 1-  well differentiated, the cells look most like normal cells
•   grade 2 – moderately differentiated – the cells look a bit like normal cells

High grade – fast growing

•   grade 3 – poorly differentiated, the cells look very abnormal
•   grade 4 – undifferentiated, the cells look completely different from normal cells

The bowel

The bowel makes up a part of the digestive system. It’s split into the small and large bowel:

• cancer of the small bowel is called small bowel cancer
• cancer of the large bowel is called colon cancer
• cancer of the back passage is called rectal cancer
• cancer of the bowel opening is called anal cancer

This section is about colon and rectal cancer. We have separate sections about anal cancer and small bowel cancer.

Types of bowel cancer

Your type of cancer depends on what type of cell it starts in.

Adenocarcinoma 

Adenocarcinomas start in the gland cells in the lining of the bowel wall. The gland cells normally produce mucus. This is a slimy substance that makes it easier for the poo (also called faeces or stool) to pass through the bowel. Adenocarcinoma is the most common type of bowel cancer. 

There are 2 rare types of adenocarcinoma:

• mucinous tumours 
• signet ring tumours 

They are treated in the same way as the most common types of adenocarcinoma of the bowel.

Rare types of bowel cancer

Squamous cell tumours 

Squamous cells are the skin cells that make up the bowel lining, together with the gland cells. They are treated in the same way as cancer of the anus.

Carcinoid tumours 

Carcinoid is a type of slow growing tumour called a neuroendocrine tumour. They grow in hormone producing tissue, usually in the digestive system. 

Carcinoid is treated differently to the most common types of bowel cancer. 

Sarcomas 

Sarcomas are cancers of the supporting cells of the body, such as bone or muscle. Most sarcomas in the bowel are called leiomyosarcomas. This means they are sarcomas that started in smooth muscle. 

Sarcomas are treated differently to adenocarcinomas of the bowel. 

Lymphomas 

Lymphomas are cancers of the lymphatic system. They are treated very differently to other bowel cancers. 

Melanoma 

Melanoma is a type of skin cancer. Melanoma can begin in the back passage (rectum). 

• Cancer principles and practice of oncology (11th edition)
  VT De Vita, TS Lawrence and SA Rosenberg
  Wolters Kluwer Health, 2019

• Textbook of Uncommon Cancer (5th Edition)
  D Raghavan and others
  Wiley Blackwell, 2012.  

• Cancer and its management (7th edition)
  J. Tobias and D. Hochhauser
  Wiley Blackwell, 2015

Last reviewed: 

11 Jan 2022

Next review due: 

11 Jan 2025

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“Gramota.ru” – reference and information Internet portal “Russian language”

Punctuation

Colon

07

1. If the listing is preceded by a generic word (and often, in addition, the words , for example, * , somehow * 90 014, namely ), for example:

Cossacks rose from everywhere: from Chigirin, from Pereyaslav, from Baturin, from Glukhov, from the lower side of the Dnieper and from all its upper reaches and islands.

Gogol

were familiar details: deer horns, shelves with books, mirror, a stove with an obstetric, a paternal sofa, a large table, an open book, a broken fever, an Aurial his handwriting.

L. Tolstoy

Large fish, such as pike, catfish, asps, zander*, fight with a sharp edge.

S. Aksakov

some more attractive knots and boxes.

L. Tolstoy

§ 160. A colon is placed before an enumeration in the middle of a sentence if the enumeration is preceded by a generalizing word or words somehow 05 , for example * , namely , for example:

And all this: the river, and the twigs of the verbose, and this boy – reminded me of the distant days of childhood.

Perventsev

I visited the largest cities of the USSR, namely: Moscow, Leningrad, Baku, Kyiv – and returned to the Urals.

For a dash after an enumeration in the middle of a sentence after a colon, see § 174, paragraph 3, note.

§ 161. A colon is placed after a sentence followed by one or more sentences not connected to the first by conjunctions and containing:

a) an explanation or disclosure of the content of what is said in the first sentence, for example:

I was not mistaken: the old man did not refuse the offered glass.

Pushkin

Moreover, the worries of a large family constantly tormented her: now the feeding of the baby did not go, then the nanny left, then, as now, one of the children fell ill.

L. Tolstoy

Here a rather entertaining picture opened up: a wide hut, whose roof rested on two finished pillars, was full of people.

Lermontov

b) the basis, the reason for what is said in the first sentence, for example:

Do not overtake you with a crazy trio: the horses are full, and strong, and lively.

Nekrasov

It was not for nothing that the Greek gods recognized the irresistible power of fate over themselves: fate was that dark boundary beyond which the consciousness of the ancients did not cross.

Belinsky

§ 162. A colon is placed between two sentences not connected by conjunctions, if in the first sentence such verbs as see, look, hear, know, feel , etc., a warning is given that further exposition will follow some fact or some description, for example:

And then the buoy-keeper and the Kirghiz assistant see: two boats are floating on the river.

A. N. Tolstoy

I crawled along the thick grass along the ravine, I see: the forest is over, several Cossacks are leaving it for a clearing, and now my Karagyoz jumps right towards them …

Lermontov

0034 Here we are at last climbed the Gud-mountain, stopped and looked back: a gray cloud hung on it, and its cold breath threatened a coming storm… .

Pushkin

Pavel feels: someone’s fingers are touching his arm above the elbow.

N. Ostrovsky

But (without a shade of warning):

I hear the earth tremble.

Nekrasov

§ 163. A colon is placed after a sentence introducing direct speech, in particular a direct question or exclamation, for example: gin came up and said: “You they wrote to me, don’t deny it.”

Pushkin

At the end of the work, Peter asked Ibragim: “Do you like the girl with whom you danced the minuet at the last assembly?”

Pushkin

And I thought: “What a heavy and lazy fellow!”

Chekhov

A group of sentences that include direct speech should be distinguished from complex sentences with a subordinate clause: as usual, a comma is placed before the subordinate clause, and at the end of it is a sign required by the nature of the entire complex sentence, for example:

I was thinking about how heavy and lazy this guy is.

I tried to remember where I was that day exactly one year ago.

Will he again remind you of what happened a year ago?

How hard it is to remember what happened on that terrible day!

* Portal editorial comment

Somehow . The hyphenated spelling of the compound union like or (meaning ‘namely’) should be considered obsolete. In the code “Rules of Russian spelling and punctuation. Complete academic reference book “(under the editorship of V.V. Lopatin. M., 2006 and subsequent editions) in § 142 union like is included in the list of function words that are written separately.

Even in the “Dictionary of the Russian language” by S. I. Ozhegov, in the article HOW it was indicated: “Somehow – the same as namely. All enterprises, such as construction, textile, printing, are working normally .

The separate spelling of the compound union as t o makes it possible to distinguish it in writing from the pronominal adverb to and to something .

Example . For other cases of word punctuation, see §§ 154, 155.

punctuation – Two colons in a sentence: is it permissible or not?

The offer is:

I also saw space the way it can only be seen in a vacuum: complete absence of chiaroscuro, everything is very contrasting: black and white.

Can there be two colons in a sentence and is it correct? Or in this case, it was necessary to put a dash before “black and white”?

• punctuation
• colon

In such sentences, the second colon is suggested to replace the dash, contrary to the rule. A colon shows the boundary between parts of a complex sentence, a dash highlights the clarifying “black and white”. So the proposal is better perceived by readers. Such a replacement is presented as possible. See Lopatin

2

Take a look at the question 177700

“Tell me, please, can there be two colons in a sentence? The Federal Constitutional Court has recognized only one exception to this rule: the principle of the priority of European law does not apply when it comes to the basic structural principles of the Constitution, namely : the principles of federalism, democracy and respect for the inalienable rights and freedoms of the individual.
Maria

Answer of the Russian language reference service

The use of two colons in one sentence is correct.”

rule (in both cases the rules provide for a colon), it is possible to replace one of the colons with a dash to convey different shades of meaning.0277
§161. Interaction of punctuation marks in complex constructions

In your sentence, two colons are provided for by the rules – you can leave it as it is. But for a better perception of the construction with the “explanation of the explanation” it is better to put a dash.

I also saw the cosmos the way it can only be seen in a vacuum: the complete absence of chiaroscuro, everything is very contrasting – black and white.

A similar offer was found.
And here is the postman. She knew his car well: small, squat, painted in bright colors – red, white and blue.
John Ball. Five Jade Shards

Acceptable, but undesirable.

Question No.