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The intestine extends from the pylorus of the stomach to the anus.
It is divided into:
Small intestine → involved mainly in digestion and absorption.
Large intestine → concerned with water absorption and faeces formation.
Total length: about 6.5–7 metres in adults.
Small intestine: ~6 metres
Large intestine: ~1.5 metres
The small intestine is longer and narrower; the large intestine is wider and sacculated due to taeniae coli.
Parts:
Duodenum – 25 cm
Jejunum – 2.4 metres
Ileum – 3.6 metres
Functions:
Final digestion of food.
Absorption of nutrients and electrolytes.
Secretion of intestinal juice and hormones.
Peritoneal Relations:
Duodenum: mostly retroperitoneal.
Jejunum and ileum: intraperitoneal (mobile with mesentery).
Blood supply:
From superior mesenteric artery (SMA) and its branches.
Venous drainage → superior mesenteric vein → portal vein.
Lymphatics:
Drain into mesenteric lymph nodes, then to cisterna chyli.
Nerve supply:
Sympathetic (T9–T11) → inhibits peristalsis and causes vasoconstriction.
Parasympathetic (vagus) → stimulates peristalsis and secretion.
1. Mucosal folds (valves of Kerckring or plicae circulares):
Permanent circular folds of mucosa and submucosa.
Increase surface area for absorption.
Most prominent in jejunum, fewer in ileum, absent in duodenum and distal ileum.
2. Villi:
Microscopic finger-like projections of mucosa containing blood capillaries and lacteals.
Greatly increase absorptive surface area.
3. Microvilli:
Present on the apical surface of epithelial cells; form the brush border.
Contain digestive enzymes for final carbohydrate and protein breakdown.
4. Peyer’s patches:
Lymphoid aggregates in ileum (antimesenteric border).
Provide immune defense in gut (GALT – gut-associated lymphoid tissue).
5. Brunner’s glands:
Submucosal glands in the duodenum secreting alkaline mucus → neutralises gastric acid.
The small intestine has the largest absorptive surface in the body due to:
Plicae circulares → 3× increase.
Villi → 10× increase.
Microvilli → 20× increase.
→ Combined → approximately 600 times greater surface area than a simple tube.
Functional advantage:
Maximises nutrient absorption despite compact anatomical length.
General Features:
Shortest and widest part of the small intestine (~25 cm).
Begins at pylorus (L1) and ends at the duodenojejunal flexure (L2).
Mostly retroperitoneal except the first 2.5 cm (duodenal cap).
Forms a C-shaped loop around the head of pancreas.
Parts (by position):
First (Superior) part – 5 cm
Second (Descending) part – 7.5 cm
Third (Horizontal) part – 10 cm
Fourth (Ascending) part – 2.5 cm
Locate the pylorus on the right of the midline at the level of L1.
Trace the first part of the duodenum posteriorly from pylorus.
Note its relation to gall bladder, liver, and common bile duct.
Follow the C-shaped loop of duodenum embracing the head of pancreas.
Identify:
Opening of the common bile duct and pancreatic duct on the posteromedial wall of second part → major duodenal papilla.
Accessory pancreatic duct opens at minor duodenal papilla, 2 cm above the major one.
The duodenojejunal flexure lies at the left of L2, held by the suspensory muscle of duodenum (ligament of Treitz).
| Part | Anterior Relations | Posterior Relations |
|---|---|---|
| 1st (superior) | Gall bladder, liver | Portal vein, gastroduodenal artery, bile duct |
| 2nd (descending) | Transverse colon | Hilum of right kidney |
| 3rd (horizontal) | Root of mesentery, SMA & SMV cross anteriorly | IVC, aorta |
| 4th (ascending) | Beginning of jejunum | Left psoas, aorta |
Arterial supply:
1st and 2nd parts: Superior pancreaticoduodenal artery (branch of gastroduodenal).
3rd and 4th parts: Inferior pancreaticoduodenal artery (branch of SMA).
These form an anastomotic arcade between coeliac and SMA territories.
Venous drainage:
Into portal vein via pancreaticoduodenal veins.
Lymphatic drainage:
Pancreaticoduodenal and pyloric nodes → coeliac nodes.
Nerve supply:
Sympathetic (T9–T10) → via coeliac and superior mesenteric plexuses.
Parasympathetic → via vagus nerve.
Duodenal ulcers are most common in the first part (duodenal bulb) due to acid exposure.
Posterior ulcers may erode the gastroduodenal artery, causing severe bleeding.
The ampulla of Vater (in second part) is a common site for gallstone impaction, leading to obstructive jaundice and pancreatitis.
Congenital duodenal atresia → bilious vomiting in neonates (“double bubble” sign on X-ray).
Superior mesenteric artery syndrome → compression of 3rd part between SMA and aorta.
The duodenum is mostly retroperitoneal, except its first 2.5 cm (duodenal cap), which is intraperitoneal and movable.
The remainder (descending, horizontal, ascending parts) is fixed to the posterior abdominal wall and covered by peritoneum anteriorly only.
Detailed relations:
First (Superior) Part:
Anterior surface: covered by peritoneum and in contact with liver and gall bladder.
Posterior surface: bare, related to portal vein, bile duct, and gastroduodenal artery.
Superior border: related to the neck of gall bladder.
Inferior border: continuous with the second part.
Second (Descending) Part:
Anterior: covered by peritoneum and related to transverse colon and jejunum.
Posterior: bare; related to right kidney, hilum, renal vessels, and ureter.
Medial: receives bile duct and pancreatic duct at the major duodenal papilla.
Third (Horizontal) Part:
Anterior: crossed by superior mesenteric vessels and root of mesentery.
Posterior: related to inferior vena cava, aorta, and right psoas major.
Peritoneum covers front only.
Fourth (Ascending) Part:
Anterior: covered by peritoneum and related to the transverse colon and stomach.
Posterior: related to aorta, left psoas, and left sympathetic chain.
Ends at the duodenojejunal flexure (left of L2), suspended by the ligament of Treitz.
A fibromuscular band connecting the duodenojejunal flexure to the right crus of the diaphragm.
Consists of skeletal muscle fibres (from right crus) and smooth muscle fibres (from duodenum and connective tissue).
Attachments:
Upper end: Right crus of diaphragm near the oesophageal opening.
Lower end: Duodenojejunal junction (left of L2).
Function:
Elevates the duodenojejunal flexure, helping movement of chyme from duodenum to jejunum.
Maintains the sharp angle of the flexure, preventing regurgitation from jejunum to duodenum.
Applied anatomy:
Acts as a surgical landmark separating upper and lower GI bleeding sources.
Its location marks the junction between retroperitoneal (duodenum) and intraperitoneal (jejunum) bowel.
Layers of the wall:
Mucosa:
Lined by simple columnar epithelium with villi and microvilli.
Villi → broad and leaf-like.
Contains intestinal glands (crypts of Lieberkühn).
Lamina propria rich in lymphoid cells and capillaries.
Submucosa:
Characteristic feature: Brunner’s glands (unique to duodenum).
Secrete alkaline mucus → neutralises acidic chyme from stomach.
Prevents mucosal damage and provides optimal pH for pancreatic enzyme action.
Muscular layer:
Inner circular and outer longitudinal smooth muscle.
Responsible for peristaltic movement.
Contains Auerbach’s (myenteric) plexus between layers.
Serosa/Adventitia:
Serosa covers the first 2.5 cm; rest has adventitia (retroperitoneal).
Histological identifiers:
Villi → leaf-like.
Brunner’s glands → in submucosa.
No Peyer’s patches (unlike ileum).
1. Duodenal Ulcer:
Commonest site: posterior wall of the first part (duodenal cap).
Complication: erosion of gastroduodenal artery → severe haemorrhage.
Pain referred to epigastrium (T9 dermatome).
2. Perforated Duodenal Ulcer:
Causes peritonitis; air under diaphragm visible in erect X-ray.
May lead to adhesions between duodenum and gall bladder → cholecystoduodenal fistula.
3. Superior Mesenteric Artery (SMA) Syndrome:
Compression of 3rd part of duodenum between SMA and aorta → intestinal obstruction.
Seen in emaciated patients with loss of retroperitoneal fat.
4. Gallstone Ileus:
Large gallstone erodes into duodenum, passes to ileum, causing mechanical obstruction (usually at ileocaecal junction).
5. Duodenal Atresia:
Congenital absence or closure of duodenal lumen (failure of recanalisation).
Clinical feature: Bilious vomiting soon after birth; “double bubble” sign on X-ray (stomach + duodenal bulb distension).
6. Malrotation of Midgut:
Improper rotation may alter duodenal position → volvulus or obstruction.
7. Tumours and Cysts:
Ampullary carcinoma near major duodenal papilla leads to obstructive jaundice and pale stools.
8. Endoscopic Importance:
Second part of duodenum is visualised during upper GI endoscopy to identify ampullary opening and detect ulcers or stones.
The duodenum forms the vascular watershed between coeliac and superior mesenteric artery territories, explaining frequent ischaemic ulcers and surgical importance.
The jejunum and ileum form the mobile, intraperitoneal portion of the small intestine extending from the duodenojejunal flexure (L2) to the ileocaecal junction in the right iliac fossa.
Total length: ~6 m
Jejunum: upper 2/5 (≈ 2.4 m)
Ileum: lower 3/5 (≈ 3.6 m)
Suspension: by a fan-shaped mesentery attached to the posterior abdominal wall from the left side of L2 to the right sacro-iliac joint.
| Feature | Jejunum | Ileum |
|---|---|---|
| Location | Upper left abdomen | Lower right abdomen |
| Wall | Thick and vascular | Thin and pale |
| Lumen | Wider | Narrower |
| Plicae circulares | Large, numerous | Small, sparse; absent distally |
| Vascularity | Rich, red | Poor, pale |
| Arterial arcades | Few (1–2 tiers) | Numerous (3–4 tiers) |
| Vasa recta | Long | Short |
| Fat in mesentery | Less | More (reaching gut wall) |
| Peyer’s patches | Scanty | Abundant along antimesenteric border |
| Function | Major site of absorption | Terminal absorption of bile salts, vit B₁₂ |
Both are completely covered by peritoneum and suspended by the mesentery of the small intestine.
The root of the mesentery crosses obliquely over the following:
3rd part of duodenum,
aorta,
inferior vena cava,
right ureter,
right psoas major.
Between its two layers run:
Superior mesenteric vessels,
branches to intestine,
lymphatics and lacteals,
autonomic nerve plexuses.
Arterial: Jejunal and ileal branches of the superior mesenteric artery (SMA).
They form arterial arcades in mesentery → give vasa recta to gut wall.
Venous: Superior mesenteric vein → joins splenic vein → portal vein.
Lymphatics: Mesenteric nodes → superior mesenteric nodes → cisterna chyli.
Nerves:
Sympathetic (T9–T10) – inhibit peristalsis and act vasoconstrictor.
Parasympathetic (vagus) – promote motility and secretion.
Layers of wall (common to both):
Mucosa:
Epithelium: simple columnar with goblet cells.
Villi: tall, slender (jejunum); short, finger-like (ileum).
Crypts of Lieberkühn: tubular glands between villi.
Lamina propria: rich in capillaries, lacteals, lymphocytes.
Submucosa:
Jejunum: ordinary connective tissue.
Ileum: contains Peyer’s patches — lymphoid follicles forming prominent elevations opposite the mesenteric border.
Muscular coat:
Inner circular and outer longitudinal smooth-muscle layers.
Auerbach’s plexus between them regulates peristalsis.
Serosa:
Entire intestine covered by peritoneum.
Distinctive Features
Jejunum → tall villi, fewer goblet cells.
Ileum → abundant goblet cells, Peyer’s patches, shorter villi.
A congenital remnant of the vitellointestinal (omphalomesenteric) duct.
Represents persistence of its proximal part.
Features:
True diverticulum (contains all gut layers).
Located on antimesenteric border of ileum, about 60 cm (2 ft) proximal to ileocaecal valve.
Length: usually 2–5 cm (≈ 2 inches).
Rule of 2s:
Occurs in 2 % of population.
2 in long.
2 ft from ileocaecal valve.
Common before age 2.
May contain 2 types of ectopic mucosa – gastric or pancreatic.
Complications:
Peptic ulceration (if gastric mucosa present) → bleeding.
Inflammation (Meckel’s diverticulitis) mimics appendicitis.
Intussusception or volvulus if attached by fibrous band to umbilicus.
Expose coils of jejunum and ileum by lifting greater omentum and transverse colon.
Trace the root of mesentery obliquely from the left of L2 to right sacro-iliac joint.
Identify vascular pattern:
Jejunum → long vasa recta, few arcades.
Ileum → many arcades, short vasa recta.
Observe colour difference: jejunum pink and thicker; ileum paler and thinner.
Locate Peyer’s patches on antimesenteric border of ileum.
Follow ileum to ileocaecal junction, identifying the ileocaecal valve.
1. Intestinal Obstruction:
May occur due to adhesions, hernias, volvulus, or intussusception (telescoping of one segment into another).
Presents with colicky pain, distension, vomiting, and constipation.
2. Mesenteric Ischaemia:
Occlusion of SMA or its branches → gangrene of jejunum/ileum.
Severe abdominal pain disproportionate to clinical findings.
3. Meckel’s Diverticulitis:
Inflammation of Meckel’s diverticulum mimics appendicitis, pain in right lower quadrant.
4. Enteric Fever (Typhoid):
Peyer’s patches undergo necrosis and ulceration → intestinal perforation and haemorrhage (usually distal ileum).
5. Malabsorption Syndromes:
Damage to villi or microvilli (celiac disease, tropical sprue) → diarrhoea, weight loss, anaemia.
6. Intussusception:
Invagination of ileum into caecum → “red-currant jelly” stools, common in infants.
7. Crohn’s Disease:
Chronic granulomatous inflammation, mostly involving terminal ileum, leading to fibrosis and obstruction.
8. Surgical Landmark:
The duodenojejunal flexure (left of L2) marks transition from fixed to mobile intestine.
Ligament of Treitz helps locate upper GI versus lower GI bleed.
| Feature | Jejunum | Ileum |
|---|---|---|
| Length ratio | 2/5 | 3/5 |
| Plicae circulares | Large, numerous | Small, sparse |
| Vascularity | High | Low |
| Peyer’s patches | Absent/scanty | Prominent |
| Function | Major absorption | Terminal absorption |
| Common pathology | Ischaemia | Typhoid ulcers, Meckel’s |
Extends from the ileocaecal junction to the anus.
Length: about 1.5 metres.
Function: absorption of water and electrolytes, formation and temporary storage of faeces, and bacterial synthesis of vitamin K and certain B-complex vitamins.
Parts:
Caecum
Appendix
Ascending colon
Transverse colon
Descending colon
Sigmoid colon
Rectum
Anal canal
These features distinguish the large intestine from the small intestine:
| Feature | Description |
|---|---|
| Taeniae coli | Three longitudinal muscle bands: taenia libera, taenia mesocolica, taenia omentalis. |
| Haustra coli | Sacculations of the wall between the taeniae due to shorter outer muscle. |
| Appendices epiploicae | Fat-filled peritoneal pouches along the colon. |
| Wider lumen | About 5–6 cm in diameter. |
| Mucosa | Smooth—no villi, but has straight tubular crypts of Lieberkühn rich in goblet cells. |
Caecum and transverse colon → intraperitoneal and mobile.
Ascending and descending colon → secondarily retroperitoneal (fixed).
Sigmoid colon → intraperitoneal with its own mesocolon.
Arteries:
Caecum to mid-transverse colon → superior mesenteric artery (SMA) branches (ileocolic, right colic, middle colic).
Distal transverse to upper rectum → inferior mesenteric artery (IMA) branches (left colic, sigmoid, superior rectal).
These form a continuous marginal artery of Drummond along the inner border.
Veins:
Correspond to arteries → drain into SMV and IMV → portal vein.
Lymphatics:
Epicolic → paracolic → intermediate → main colic → SMA/IMA nodes → cisterna chyli.
Nerves:
Sympathetic – T10–L2 via superior and inferior mesenteric plexuses → inhibit peristalsis.
Parasympathetic – vagus (up to mid-transverse colon) and pelvic splanchnic (S2–S4) → increase motility.
Mucosa: smooth, numerous straight tubular glands lined by simple columnar epithelium with many goblet cells.
Submucosa: dense connective tissue, blood vessels, nerves.
Muscularis externa: inner circular layer continuous, outer longitudinal condensed into three taeniae coli.
Serosa: peritoneal covering with appendices epiploicae.
Open the abdomen; reflect greater omentum upward to expose the coils of small intestine.
Trace the ileum to its termination at the ileocaecal junction.
Identify the caecum, appendix, and ascending colon in the right iliac fossa.
Note the taeniae coli converging at the base of the appendix.
Follow the colon upward (ascending), across (transverse), and downward (descending).
Observe haustra and appendices epiploicae.
Demonstrate peritoneal folds: mesocolon and paracolic gutters on either side.
1. Diverticulosis
– Outpouchings of mucosa through weak points in muscular wall (commonly sigmoid colon).
– May cause bleeding or diverticulitis.
2. Volvulus
– Twisting of mobile segments (sigmoid or caecum) → intestinal obstruction and gangrene.
3. Intestinal Obstruction
– May occur due to hernia, adhesions, tumours, or volvulus; characterised by pain, distension, vomiting.
4. Colonic Carcinoma
– Common in sigmoid and rectosigmoid regions; spreads via lymphatics to mesenteric nodes and liver (via portal circulation).
5. Hirschsprung’s Disease (Congenital Megacolon)
– Absence of ganglion cells in Auerbach’s and Meissner’s plexuses (usually rectosigmoid) → failure of peristalsis and dilatation proximally.
6. Appendices Epiploicae Torsion
– Inflammation or infarction of these fat tags can mimic appendicitis.
7. Intestinal Ischaemia
– Sudden occlusion of SMA or IMA → segmental gangrene of colon; splenic flexure (Griffith’s point) most vulnerable.
First part of the large intestine, situated in the right iliac fossa below the level of the ileocaecal junction.
Shape: blind pouch with large capacity (6 × 7 cm).
Peritoneal relation: completely covered; free and mobile.
Position:
Adults: mainly in right iliac fossa.
Children: may be higher (subhepatic).
Openings:
Ileocaecal orifice – communicates with ileum; guarded by the ileocaecal valve.
Appendicular orifice – located below and behind the ileocaecal opening; base marked by convergence of the three taeniae coli.
Ileocaecal valve: two semilunar folds projecting into lumen; prevent regurgitation of contents into ileum.
Ileo-caecal orifice: slit-like, bounded by superior and inferior lips.
Frenula: small mucosal folds at each end of the orifice.
Artery: Ileocolic artery (branch of SMA) → anterior and posterior caecal branches.
Vein: correspond → drain into SMV → portal vein.
Lymphatics: to ileocolic and superior mesenteric nodes.
Nerve supply: sympathetic (T10–T12) and parasympathetic (vagus).
Identify the caecum in the right iliac fossa.
Note its three taeniae coli meeting at the base of the appendix.
Observe peritoneal folds: mesoappendix and retrocaecal recess (site where appendix may lie).
Open the caecum anteriorly to display ileocaecal valve and appendicular orifice.
Demonstrate the frenula of the valve and the caecal pouch below it.
1. Caecal Volvulus:
– Twisting of a mobile caecum on its mesentery → intestinal obstruction; presents with distension and pain in right lower abdomen.
2. Caecal Typhlitis:
– Inflammation of the caecum, often secondary to appendicitis or ulceration; common in immunocompromised patients.
3. Subhepatic Caecum (in children):
– Due to delayed descent; appendicitis pain then localises in right upper quadrant, mimicking gall-bladder disease.
4. Ileocaecal Tuberculosis:
– Most common site of intestinal tuberculosis; causes ulceration, fibrosis, and strictures → obstruction.
5. Cancer of Caecum:
– May present with anaemia and right-sided mass; spreads to liver via portal circulation.
6. Pericaecal Recesses:
– Four possible: superior ileocaecal, inferior ileocaecal, retrocaecal, and paracaecal; potential sites for internal hernia or pus collection.
Base of appendix lies at McBurney’s point — one-third the distance from anterior superior iliac spine to umbilicus.
The taeniae coli converge here, a key landmark in surgery.
The vermiform appendix is a narrow, worm-like diverticulum arising from the posteromedial wall of the caecum, about 2 cm below the ileocaecal valve.
Length: 2–20 cm (average 9 cm).
Diameter: about 5 mm.
Position: variable; its base is constant (where three taeniae coli converge).
Function: a lymphoid organ, part of gut-associated lymphoid tissue (GALT).
Common positions of the tip (base remains constant):
| Position | Description | Frequency |
|---|---|---|
| Retrocaecal | Behind caecum (commonest) | ~65% |
| Pelvic | Hanging into pelvis | ~30% |
| Subcaecal | Below caecum | ~2% |
| Pre-ileal | In front of ileum | ~1% |
| Post-ileal | Behind ileum | ~1% |
Clinical correlation: Pain of appendicitis may vary with position — pelvic appendicitis may cause suprapubic pain and urinary irritation.
Appendix is completely covered by peritoneum and connected to the mesentery of the terminal ileum by a small triangular fold — the mesoappendix.
The appendicular artery runs within the mesoappendix.
Artery: Appendicular artery (branch of the posterior caecal artery from ileocolic artery of SMA).
Vein: Appendicular vein → ileocolic vein → SMV.
Lymphatics: to ileocolic and superior mesenteric nodes.
Nerves:
Sympathetic (T10–T12) → pain.
Parasympathetic (vagus) → peristalsis.
Anteriorly: coils of small intestine, sometimes caecum.
Posteriorly: psoas major, external iliac vessels (in pelvic position).
Base: located at McBurney’s point — one-third the distance from the anterior superior iliac spine (ASIS) to the umbilicus.
Lumen opens into the caecum by the appendicular orifice, guarded by a small mucosal fold — the valve of Gerlach (inconstant).
Lumen often obliterated in elderly due to fibrosis.
1. Mucosa:
Lined by simple columnar epithelium with goblet cells.
Contains crypts of Lieberkühn, but no villi.
Lymphoid follicles occupy lamina propria and submucosa — characteristic feature.
2. Submucosa:
Contains large lymphoid nodules, which may merge and almost replace the wall.
3. Muscular coat:
Inner circular and outer longitudinal layers; outer layer continuous with caecal taeniae.
Between them lies Auerbach’s plexus.
4. Serosa:
Complete peritoneal covering forming mesoappendix.
Histological hallmark: dense lymphoid tissue → immune function (produces IgA, protects gut flora balance).
1. Appendicitis
Acute inflammation due to lumen obstruction by fecolith, seeds, or lymphoid hyperplasia.
Sequence of pain:
Initially periumbilical (visceral, T10 dermatome).
Later localised to right iliac fossa (parietal peritoneum involvement).
Tenderness point: McBurney’s point.
Signs: guarding, rebound tenderness, fever, leukocytosis.
2. Retrocaecal Appendicitis
Pain less localised; may cause psoas sign (pain on hip extension).
3. Pelvic Appendicitis
Causes tenesmus, diarrhoea, and urinary frequency due to irritation of bladder or rectum.
4. Ruptured Appendix
Causes generalised peritonitis and septic shock; life-threatening emergency.
5. Chronic Appendicitis
Recurrent mild attacks due to fibrosis or partial obstruction.
6. Referred Pain Explanation
Appendix receives visceral afferents via T10 segment → pain referred to umbilical region.
7. Appendicectomy
Surgical removal; incision at McBurney’s point.
Identify base where taeniae coli converge.
Mesoappendix ligated, artery secured to prevent bleeding.
Extends from caecum to right colic (hepatic) flexure.
Length: ~15 cm.
Lies on right side of posterior abdominal wall, between caecum below and inferior surface of right lobe of liver above.
Peritoneal relation:
Covered by peritoneum anteriorly and laterally, fixed posteriorly (retroperitoneal).
Relations:
Anterior: coils of small intestine.
Posterior: right iliacus, quadratus lumborum, transversus abdominis, and right kidney (via fascia).
Medial: small intestine loops.
Lateral: paracolic gutter (for fluid spread).
Arteries: Right colic and ileocolic arteries (branches of SMA).
Veins: Correspond → SMV.
Lymphatics: Paracolic → right colic → superior mesenteric nodes.
Nerves: Sympathetic (T11–L1) and vagus.
Ascending colon cancer → causes occult bleeding and anaemia.
Paracolic gutter → route for spread of peritoneal pus or fluid to subphrenic space.
Crohn’s disease may extend to involve ascending colon from terminal ileum.
Junction between ascending and transverse colon.
Lies under the inferior surface of right lobe of liver, in contact with gall bladder.
More acute and higher than the splenic flexure.
Attached to diaphragm by hepaticocolic ligament (peritoneal fold).
Clinical note: site where colon may kink → obstruction; frequent site of spread of gall-bladder inflammation.
Longest and most mobile part of large intestine (~45 cm).
Extends from right colic flexure to left colic (splenic) flexure.
Occupies umbilical and upper hypogastric regions.
Peritoneal relations:
Completely covered; suspended by transverse mesocolon, which attaches to anterior border of pancreas.
Greater omentum hangs from its anterior border.
Relations:
Superiorly: liver, gall bladder, stomach.
Inferiorly: coils of small intestine.
Posteriorly: duodenum, pancreas.
Arteries:
Proximal 2/3: Middle colic artery (from SMA).
Distal 1/3: Left colic artery (from IMA).
Marginal artery connects them.
Veins: SMV and IMV → portal vein.
Lymphatics: middle colic → superior mesenteric nodes; distal → inferior mesenteric nodes.
Nerves:
Proximal 2/3: vagus.
Distal 1/3: pelvic splanchnic (S2–S4).
Transverse Colon Volvulus: twisting on its mesocolon → obstruction.
Cancer: common at hepatic and splenic flexures (watershed zones).
Colostomy: transverse colon often used for temporary faecal diversion.
Paracolic gutter spread: right gutter leads infection to subhepatic space; left is shallower due to phrenicocolic ligament.
| Part | Peritoneal Type | Main Artery | Common Pathology |
|---|---|---|---|
| Appendix | Intraperitoneal | Appendicular (SMA) | Appendicitis |
| Ascending colon | Retroperitoneal | Right colic (SMA) | Cancer, abscess |
| Hepatic flexure | Retroperitoneal | Middle colic (SMA) | Kinking, inflammation spread |
| Transverse colon | Intraperitoneal | Middle & left colic | Volvulus, carcinoma |
Junction between transverse colon and descending colon.
Located in the left hypochondrium, opposite the tip of the 9th rib, slightly higher and more acute than the hepatic flexure.
Directed upward, backward, and medially.
Suspended by a peritoneal fold — phrenicocolic ligament — extending from its angle to the diaphragm near the spleen.
Anteriorly: stomach and spleen.
Posteriorly: left kidney.
Superiorly: diaphragm.
Inferiorly: coils of jejunum.
Artery: Left colic artery (branch of IMA).
Vein: Inferior mesenteric vein → splenic vein.
Lymphatics: along left colic vessels → inferior mesenteric nodes.
Nerve supply: sympathetic (L1–L2) and parasympathetic (pelvic splanchnic, S2–S4).
Watershed area: junction of SMA and IMA territories → vulnerable to ischaemia.
Splenic flexure syndrome: pain due to gas distension at the flexure.
In peritonitis, phrenicocolic ligament acts as a barrier to spread of infection upward.
Extends from the splenic flexure to the sigmoid colon.
Length: about 25 cm.
Occupies the left lumbar region.
Covered by peritoneum anteriorly and laterally, fixed posteriorly (retroperitoneal).
Anterior: coils of small intestine.
Posterior: left kidney, quadratus lumborum, transversus abdominis, iliac crest.
Medial: small intestinal loops.
Lateral: left paracolic gutter (shallower than right due to phrenicocolic ligament).
Artery: Left colic artery (from IMA).
Vein: Inferior mesenteric vein → splenic vein.
Lymphatics: to inferior mesenteric nodes.
Nerves: sympathetic (L1–L2), parasympathetic (pelvic splanchnic, S2–S4).
Descending colon carcinoma presents late with obstruction.
Left paracolic gutter limits downward spread of pus from subphrenic abscess.
Pain in left iliac fossa may mimic sigmoid or ureteric pain.
Begins at the end of descending colon in the left iliac fossa and ends at the rectosigmoid junction (S3).
Length: about 40 cm.
Forms an S-shaped loop.
Lies in pelvic cavity, highly mobile due to its sigmoid mesocolon (a V-shaped peritoneal fold).
Anterior: coils of ileum, urinary bladder (in males), uterus (in females).
Posterior: sacrum, rectum.
Completely covered by peritoneum and attached to the posterior pelvic wall by sigmoid mesocolon.
Arteries: Sigmoid branches of IMA.
Veins: IMV → splenic vein → portal vein.
Lymphatics: sigmoid nodes → inferior mesenteric nodes.
Nerves:
Sympathetic: L1–L2.
Parasympathetic: pelvic splanchnic (S2–S4).
Sigmoid volvulus: twisting of the sigmoid loop on its mesentery → obstruction, distension, and gangrene.
Diverticulitis: herniation of mucosa through weak points in muscular wall → inflammation, pain, bleeding.
Carcinoma: common site for left-sided colonic cancer; may lead to ribbon-like stools.
Sigmoid colostomy: preferred site for surgical faecal diversion due to mobility.
Mucosa
Epithelium: simple columnar with numerous goblet cells (for lubrication).
Villi: absent.
Crypts of Lieberkühn: straight, deep, lined by absorptive cells and goblet cells.
Lamina propria: rich in lymphocytes and plasma cells.
Submucosa
Dense connective tissue with blood vessels, lymphatics, and Meissner’s plexus.
Muscularis externa
Inner circular layer continuous.
Outer longitudinal layer condensed into three taeniae coli.
Between them lies Auerbach’s plexus.
Serosa
Peritoneal covering containing appendices epiploicae (fat pouches).
Key features:
Abundant goblet cells → lubrication for faecal passage.
No villi, but well-developed glands.
Taeniae coli and haustra are characteristic gross features.
Derived from midgut and hindgut portions of the primitive gut tube.
Midgut: from distal duodenum to proximal 2/3 of transverse colon.
Hindgut: from distal 1/3 of transverse colon to upper part of anal canal.
Midgut forms a U-shaped loop with the superior mesenteric artery as its axis.
Physiological herniation into umbilical cord occurs during 6th week.
Loop undergoes 270° counterclockwise rotation:
First 90° during herniation.
Remaining 180° during return to abdominal cavity (~10th week).
After rotation:
Jejunum and ileum occupy central abdomen.
Caecum descends to right iliac fossa.
Colon forms its characteristic frame.
Some parts lose their mesentery and become retroperitoneal (duodenum, ascending, and descending colon).
Others remain intraperitoneal (jejunum, ileum, transverse and sigmoid colon).
Gives rise to distal transverse colon, descending colon, sigmoid colon, rectum, and upper anal canal.
Terminal part ends in cloaca, divided by the urorectal septum into:
Rectum and anal canal (posterior).
Urogenital sinus (anterior).
Malrotation: abnormal rotation → volvulus or obstruction.
Omphalocoele: failure of intestinal loops to return → herniation at umbilicus.
Meckel’s diverticulum: persistence of vitelline duct.
Aganglionic megacolon (Hirschsprung’s disease): absence of enteric ganglia in distal colon → obstruction.
Atresia/Stenosis: due to failure of recanalisation.
| Structure | Arterial Supply | Peritoneal Relation | Clinical Notes |
|---|---|---|---|
| Splenic Flexure | Left colic (IMA) | Retroperitoneal | Ischaemia (watershed area) |
| Descending Colon | Left colic (IMA) | Retroperitoneal | Cancer, abscess |
| Sigmoid Colon | Sigmoid branches (IMA) | Intraperitoneal | Volvulus, carcinoma |
| Colon (Histology) | — | — | Goblet-rich mucosa, no villi |
| Development | Midgut & hindgut | — | 270° rotation; malrotation, Hirschsprung’s |
1. Parts of Large Intestine (in order):
Cats Are Too Lazy During Sleep
→ Caecum, Ascending, Transverse, Left/Splenic Flexure, Descending, Sigmoid
2. Features of Large Intestine (3 T’s):
Taeniae coli
Taenia omentalis
Taenia mesocolica
3. Rule of 2 for Appendix:
2 inches long
2 feet from ileocaecal valve
In 2% population
Two types of mucosa (gastric/pancreatic)
4. Rotation of Midgut (Development):
My Intestine Rotates 270°
→ Midgut, Intestine, Rotation = 270° counterclockwise
5. Contents of Sigmoid Mesocolon:
Sigmoid Artery, Vein, Lymphatics, Nerves
→ “SAVL Nerves”
6. Blood Supply (Colic arteries):
Inferior Left Means Superior **Middle Right
→ IMA → Left colic, SMA → Middle & Right colic
The large intestine extends from the ileocaecal junction to the anus, about 1.5 m long.
It is divided into: caecum, colon (ascending, transverse, descending, sigmoid), rectum, and anal canal.
Three taeniae coli run along the colon—taenia libera, taenia mesocolica, and taenia omentalis.
The taeniae are shorter than the intestinal wall, producing haustra (sacculations).
Appendices epiploicae (fat pouches) are numerous on the sigmoid and transverse colon but absent in the appendix and rectum.
The marginal artery of Drummond runs along the inner border of the colon, connecting the SMA and IMA.
The vasa longa and vasa brevia arise from the marginal artery and supply the intestinal wall.
Blood supply:
Midgut derivatives → SMA (up to proximal 2/3 of transverse colon).
Hindgut derivatives → IMA (from distal 1/3 of transverse colon to upper anal canal).
Venous drainage: via superior and inferior mesenteric veins → portal vein.
Nerve supply:
Sympathetic: T11–L2 (via superior and inferior mesenteric plexuses).
Parasympathetic: vagus (midgut) and pelvic splanchnic nerves S2–S4 (hindgut).
Lymphatic drainage: epicolic → paracolic → intermediate → main colic → SMA/IMA nodes → cisterna chyli.
Functions of the colon:
Absorption of water and electrolytes.
Mucus secretion for faecal lubrication.
Vitamin B and K synthesis by colonic flora.
Development:
Midgut forms up to proximal 2/3 of transverse colon.
Hindgut forms distal 1/3 of transverse colon, descending, sigmoid, and rectum.
Midgut loop rotates 270° counterclockwise around SMA.
Fixation: Ascending and descending colon become retroperitoneal; transverse and sigmoid remain intraperitoneal.
Clinical correlation:
Watershed area: splenic flexure (junction of SMA–IMA supply).
Sigmoid volvulus: twisting due to long mesocolon.
Diverticulosis: mucosal herniation through weak muscular points.
Cause: Obstruction of appendicular lumen by fecolith, lymphoid hyperplasia, or worms.
Pain: Initially periumbilical (T10 dermatome) → localises to right iliac fossa (McBurney’s point).
Complication: Perforation → peritonitis → sepsis.
Definition: Inflammation of a colonic diverticulum (mucosal outpouching through weak muscular wall).
Common Site: Sigmoid colon.
Clinical Picture: Left-sided abdominal pain, fever, blood in stool.
Complication: Abscess or perforation leading to peritonitis.
Mechanism: Twisting of the mobile sigmoid loop on its mesentery.
Result: Intestinal obstruction, distension, gangrene.
Radiology: “Coffee-bean sign” on X-ray.
Treatment: Sigmoid colectomy or detorsion.
Right-sided (Ascending colon): Occult bleeding, anaemia, palpable mass.
Left-sided (Descending/Sigmoid): Altered bowel habits, obstruction, ribbon-shaped stools.
Metastasis: Spreads to liver via portal vein.
Cause: Absence of ganglion cells in Auerbach’s and Meissner’s plexuses (distal colon).
Effect: Failure of relaxation → functional obstruction → proximal dilatation.
Site: Usually rectosigmoid region.
Treatment: Surgical resection of aganglionic segment.
Cause: Compromised blood flow in marginal artery (often at splenic flexure — “watershed zone”).
Symptoms: Crampy pain, bloody diarrhoea.
Common in: Elderly with atherosclerosis.
Mechanism: Infection/pus in peritoneal cavity tracks along paracolic gutters.
Right gutter: Communicates with subhepatic and subphrenic spaces.
Left gutter: Limited by phrenicocolic ligament.
Cause: Abnormally mobile caecum twists on its mesentery.
Symptoms: Acute obstruction, distension, pain in right abdomen.
Radiograph: Gas-filled caecum displaced centrally or to the left.
Site: Terminal ileum and caecum.
Findings: Ulceration, fibrosis, and stricture formation → obstruction.
Clinical mimic: Carcinoma or Crohn’s disease.
Cause: Inflammation of a persistent vitellointestinal duct remnant.
Presentation: Mimics appendicitis but located 2 ft proximal to ileocaecal valve.
Complication: Ulceration or bleeding due to ectopic gastric mucosa.
Cause: Incomplete or abnormal 270° rotation during development.
Effect: Abnormal fixation → volvulus, obstruction.
Infants: Bilious vomiting within first few days of life.
Cause: Failure of intestinal loops to return from physiological herniation (6th–10th week).
Appearance: Umbilical sac containing intestinal loops, covered by peritoneum.
Cause: Non-obliteration of vitellointestinal duct.
Result: Fistula between ileum and umbilicus → discharge of intestinal contents from umbilicus.
Cause: Failure of recanalisation of embryonic gut tube.
Effect: Intestinal obstruction (vomiting, distension, failure to pass meconium).
Pathology: Necrosis of Peyer’s patches (ileum) → ulceration, haemorrhage, perforation.
Complication: Peritonitis and fatal bleeding.
Description: Multiple outpouchings in sigmoid colon due to weak muscular wall.
Causes: Low-fibre diet, chronic constipation, increased intraluminal pressure.
Symptoms: Pain, altered bowel habits, rectal bleeding.
Reason for importance: Common site for malignant change due to stasis and chronic irritation.
Clinical Significance: Detected by digital rectal examination; spreads locally and via lymphatics.
Mechanism: Trapped gas at the highest point of colon.
Symptom: Sharp left upper quadrant pain relieved by passing flatus.
Cause: Reduced motility or prolonged water absorption in large intestine.
Effect: Hard stool, faecal impaction, sigmoid distension.
Cause: Spillage of purulent contents into peritoneal cavity.
Effect: Rigid abdomen, severe pain, rebound tenderness.
Spread: Along right paracolic gutter to subhepatic space.
| Condition | Common Site | Pathophysiology |
|---|---|---|
| Diverticulitis | Sigmoid colon | Mucosal herniation |
| Volvulus | Sigmoid or caecum | Twisting of mesocolon |
| Carcinoma | Sigmoid/rectosigmoid | Adenocarcinoma |
| Hirschsprung’s | Rectosigmoid | Aganglionic segment |
| Ischaemia | Splenic flexure | SMA–IMA junction |
| Malrotation | Midgut | Abnormal 270° rotation |
Presence of three taeniae coli.
Sacculations (haustra) due to shorter longitudinal layer.
Appendices epiploicae — fat pouches on the wall.
Wider lumen and absence of villi.
In the rectum, the three taeniae spread out to form a uniform outer longitudinal layer, giving a smooth surface with no sacculations.
Absorption of water and electrolytes.
Formation and temporary storage of faeces.
Bacterial synthesis of vitamins K and B complex.
Secretion of mucus for lubrication of faecal matter.
From SMA: caecum, ascending, and proximal two-thirds of transverse colon.
From IMA: distal one-third of transverse, descending, sigmoid, and upper rectum.
These anastomose to form the marginal artery of Drummond.
A continuous arterial arcade along the inner border of the colon, formed by branches of SMA and IMA, ensuring collateral circulation.
Splenic flexure — a watershed zone between SMA and IMA territories (Griffith’s point).
Ascending and descending colon: secondarily retroperitoneal.
Transverse and sigmoid colon: intraperitoneal with mesocolon.
Small peritoneal fat pouches that reduce friction and serve as fat storage, though sometimes may become inflamed.
Serve as pathways for peritoneal fluid or pus spread.
Right gutter communicates freely with subphrenic space; left is limited by phrenicocolic ligament.
Because it is long, mobile, and has a long mesocolon, allowing it to twist on its mesentery.
They represent condensed outer longitudinal muscle layers that produce haustra and converge at the appendix base, marking it during surgery.
Sacculations of the colon caused by the shorter taeniae coli pulling on the intestinal wall.
Flexures are sites of stasis and angulation, leading to chronic irritation and increased epithelial turnover.
Because its wall contains abundant lymphoid follicles extending into the submucosa, forming part of GALT (gut-associated lymphoid tissue).
Sigmoid branches of the inferior mesenteric artery (IMA), forming sigmoid arterial arcades within the sigmoid mesocolon.
In infants or cases of delayed caecal descent, it remains high under the liver — known as subhepatic caecum.
Derived from:
Midgut: up to proximal two-thirds of transverse colon.
Hindgut: distal one-third of transverse colon, descending colon, sigmoid colon, and rectum.
During the 6th week of development, midgut loops temporarily herniate into the umbilical cord before returning to the abdomen by the 10th week.
The midgut loop rotates 270° counter-clockwise around the axis of the superior mesenteric artery.
Non-rotation: small intestine lies on the right side.
Reversed rotation: colon lies behind the duodenum.
Incomplete rotation: predisposes to volvulus and obstruction.
A true diverticulum from the ileum — a remnant of the vitellointestinal duct.
Common site of bleeding, ulceration, and inflammation mimicking appendicitis.
Supports the spleen from below and limits upward spread of infection along the left paracolic gutter.
| Intraperitoneal | Retroperitoneal |
|---|---|
| Transverse colon | Ascending colon |
| Sigmoid colon | Descending colon |
| Caecum | — |
Sympathetic: lumbar splanchnic (L1–L2).
Parasympathetic: pelvic splanchnic nerves (S2–S4).
These regulate colonic motility and reflex defecation.
Congenital absence of enteric ganglion cells (Auerbach’s and Meissner’s plexuses) in distal colon → failure of peristalsis → megacolon.
Because visceral afferents from sigmoid colon pass through L1–L2 segments, corresponding to that dermatome.
Sigmoid colon (most common).
Caecum (less common).
Due to excessive length and mobility of mesentery.
Prevents regurgitation of colonic contents into ileum, thus avoiding bacterial contamination of small intestine.
Synthesize vitamin K and B-complex vitamins.
Produce short-chain fatty acids.
Protect against pathogenic bacteria.
Twisting obstructs both lumen and blood vessels, leading to closed-loop obstruction, rapid distension, and gangrene.
| Topic | Key Answer |
|---|---|
| Features of colon | Taeniae, haustra, appendices epiploicae |
| Most mobile part | Transverse & sigmoid colon |
| Most fixed parts | Ascending & descending colon |
| Watershed area | Splenic flexure |
| Lymph drainage | Epicolic → paracolic → mesenteric → SMA/IMA nodes |
| Development | Midgut + Hindgut rotation (270°) |
| Common pathology | Diverticulosis, volvulus, carcinoma |
1. The length of the large intestine in an adult is approximately:
a. 2.5 m
b. 1.5 m
c. 3.5 m
d. 0.5 m
➡️ Answer: b. 1.5 m
2. The part of the colon which is completely intraperitoneal is:
a. Ascending colon
b. Descending colon
c. Transverse colon
d. Rectum
➡️ Answer: c. Transverse colon
3. The sigmoid colon receives its blood supply from which artery?
a. Superior mesenteric artery
b. Inferior mesenteric artery
c. Internal iliac artery
d. Middle colic artery
➡️ Answer: b. Inferior mesenteric artery
4. The taeniae coli converge at the base of the:
a. Caecum
b. Appendix
c. Ascending colon
d. Sigmoid colon
➡️ Answer: b. Appendix
5. The marginal artery of Drummond is formed by:
a. Superior and inferior pancreaticoduodenal arteries
b. Internal iliac and median sacral arteries
c. Superior and inferior mesenteric arteries
d. Coeliac and superior mesenteric arteries
➡️ Answer: c. Superior and inferior mesenteric arteries
6. Which of the following features is absent in the rectum?
a. Haustra
b. Taeniae coli
c. Appendices epiploicae
d. All of the above
➡️ Answer: d. All of the above
7. The most common site of diverticulosis is:
a. Ascending colon
b. Caecum
c. Sigmoid colon
d. Rectum
➡️ Answer: c. Sigmoid colon
8. The watershed area between SMA and IMA territories is:
a. Hepatic flexure
b. Splenic flexure
c. Caecum
d. Sigmoid colon
➡️ Answer: b. Splenic flexure
9. The midgut rotates around which artery during development?
a. Coeliac trunk
b. Inferior mesenteric artery
c. Superior mesenteric artery
d. Umbilical artery
➡️ Answer: c. Superior mesenteric artery
10. During development, the midgut rotates through how many degrees?
a. 90° clockwise
b. 90° counterclockwise
c. 180° clockwise
d. 270° counterclockwise
➡️ Answer: d. 270° counterclockwise
11. The distal one-third of the transverse colon develops from the:
a. Midgut
b. Hindgut
c. Foregut
d. None of the above
➡️ Answer: b. Hindgut
12. The commonest site of volvulus in the large intestine is:
a. Caecum
b. Transverse colon
c. Sigmoid colon
d. Rectum
➡️ Answer: c. Sigmoid colon
13. Which ligament supports the spleen from below?
a. Gastrocolic ligament
b. Phrenicocolic ligament
c. Hepatocolic ligament
d. Gastrosplenic ligament
➡️ Answer: b. Phrenicocolic ligament
14. The lymph from the descending colon drains primarily into:
a. Superior mesenteric nodes
b. Inferior mesenteric nodes
c. Coeliac nodes
d. Lumbar nodes
➡️ Answer: b. Inferior mesenteric nodes
15. The caecum is supplied by branches of which artery?
a. Left colic artery
b. Right colic artery
c. Ileocolic artery
d. Middle colic artery
➡️ Answer: c. Ileocolic artery
16. The rectosigmoid junction lies at the level of which vertebra?
a. L5
b. S1
c. S3
d. S5
➡️ Answer: c. S3
17. Failure of descent of the caecum results in:
a. Volvulus
b. Subhepatic caecum
c. Hirschsprung’s disease
d. Megacolon
➡️ Answer: b. Subhepatic caecum
18. The mucosa of the colon differs from that of the small intestine by:
a. Absence of villi
b. Presence of taeniae coli
c. Abundant goblet cells
d. All of the above
➡️ Answer: d. All of the above
19. The congenital absence of enteric ganglion cells in distal colon is known as:
a. Megarectum
b. Megacolon
c. Hirschsprung’s disease
d. Meckel’s diverticulum
➡️ Answer: c. Hirschsprung’s disease
20. The vitellointestinal duct normally obliterates by:
a. 3rd week
b. 5th week
c. 7th week
d. 9th week
➡️ Answer: c. 7th week
| Concept | Key Answer |
|---|---|
| Length of large intestine | 1.5 m |
| Intraperitoneal parts | Transverse & Sigmoid colon |
| Marginal artery | SMA + IMA |
| Taeniae coli converge | At base of appendix |
| Watershed zone | Splenic flexure |
| Common site of volvulus | Sigmoid colon |
| Rotation of midgut | 270° counterclockwise |
| Hindgut derivatives | Distal 1/3 of transverse colon → rectum |
| Caecal artery | Ileocolic |
| Rectosigmoid level | S3 vertebra |
1. What distinguishes the large intestine from the small intestine?
Presence of taeniae coli, haustra, and appendices epiploicae; wider calibre; absence of villi.
2. Where do the taeniae coli meet?
At the base of the appendix.
3. What are haustra?
Sacculations formed because the taeniae coli are shorter than the intestinal wall.
4. Name the parts of the colon that are intraperitoneal.
Transverse and sigmoid colon.
5. Which parts of the colon are retroperitoneal?
Ascending and descending colon.
6. What is the arterial supply of the colon?
SMA supplies midgut derivatives up to two-thirds of transverse colon; IMA supplies the distal one-third and hindgut parts.
7. What is the marginal artery of Drummond?
An anastomotic arcade between SMA and IMA along the inner border of the colon.
8. What is the venous drainage of the colon?
To the portal system via the superior and inferior mesenteric veins.
9. What is the nerve supply of the colon?
Sympathetic—thoracolumbar (T10–L2); parasympathetic—vagus for midgut, pelvic splanchnic (S2–S4) for hindgut.
10. What is the lymphatic drainage of the colon?
Epicolic → paracolic → intermediate → main mesenteric nodes.
11. Why is the splenic flexure called the watershed area?
Because it is the junction of SMA and IMA territories—most prone to ischaemia.
12. What is the function of the large intestine?
Absorption of water & electrolytes, formation of faeces, vitamin K and B-complex synthesis.
13. Why does the rectum have no taeniae coli?
The three taeniae spread out to form a continuous longitudinal coat.
14. What is the function of the ileocaecal valve?
Prevents backflow of colonic contents into the ileum.
15. What is Meckel’s diverticulum?
A true diverticulum of the ileum—persistent vitellointestinal duct, 2 inches long, 2 feet from the ileocaecal valve.
16. Which part of the colon is most mobile?
Sigmoid colon.
17. What is Hirschsprung’s disease?
Congenital absence of enteric ganglia in distal colon leading to functional obstruction and megacolon.
18. What are appendices epiploicae?
Peritoneal fat tags along the colon.
19. What is the developmental rotation of the midgut?
270° counter-clockwise around the SMA axis.
20. Which parts of the gut arise from the hindgut?
Distal ⅓ of transverse colon, descending colon, sigmoid colon, rectum, upper anal canal.
21. What is the ligament of Treitz?
Suspensory muscle of the duodenum marking the duodenojejunal flexure.
22. What are the common sites of volvulus?
Sigmoid colon > caecum.
23. What causes haustra to disappear in pathology?
In ulcerative colitis—loss of muscular tone gives a “lead-pipe” colon on X-ray.
24. What is the average length of the large intestine?
About 1.5 metres.
25. What is the clinical significance of the appendix position?
Helps locate appendicitis; McBurney’s point marks the junction of lateral and middle third of the line from ASIS to umbilicus.
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