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Descending colon

The descending colon is the third segment of the large intestine, a key component of the human digestive system, located on the left side of the abdomen and extending downward from the splenic flexure—where it connects to the transverse colon—to the sigmoid colon at approximately the level of the third sacral vertebra.^[1] Approximately 25 cm (10 inches) in length, it is a retroperitoneal structure fixed to the posterior abdominal wall without a mesentery, positioned adjacent to the left paracolic gutter and facilitating the final stages of waste processing before excretion.^[1]^[2]^[3] Anatomically, the descending colon features a wall composed of four layers typical of the gastrointestinal tract: mucosa, submucosa, muscularis externa (with taeniae coli longitudinal muscle bands), and serosa, enabling its absorptive and propulsive functions.^[1] Its blood supply primarily arises from the left colic artery, a branch of the inferior mesenteric artery, which ensures oxygenation and nutrient delivery, while venous drainage occurs via corresponding colic veins into the inferior mesenteric vein.^[1] Innervation is provided by the inferior mesenteric plexus, incorporating parasympathetic fibers from the pelvic splanchnic nerves (S2-S4) for motility and glandular secretion, sympathetic fibers from the lumbar splanchnic nerves for vasoconstriction, and sensory fibers for pain and distension detection.^[1] In terms of function, the descending colon receives semi-liquid chyme from the transverse colon and continues the absorption of water, sodium, and chloride ions while secreting potassium and bicarbonate, thereby compacting the contents into formed feces and storing them temporarily until propulsion into the sigmoid colon.^[1] This segment's role is essential for maintaining fluid and electrolyte balance, preventing dehydration, and preparing waste for elimination, with its muscular contractions aiding in peristaltic movement.^[2]^[3] Clinically, the descending colon is susceptible to conditions such as diverticulitis, colorectal cancer, and ischemic colitis due to its vascular supply and position, making it a frequent site for diagnostic procedures like colonoscopy.^[1]

Anatomy

Location and dimensions

The descending colon is the third segment of the large intestine, following the ascending and transverse colon. It originates at the splenic flexure in the left upper quadrant of the abdomen, at the level of ribs 9 through 11 near the spleen, and descends inferiorly to the pelvic brim, where it continues as the sigmoid colon. The structure occupies the left paracolic gutter, a peritoneal recess along the posterolateral abdominal wall. Its superior aspect is anchored to the left hemidiaphragm by the phrenicocolic ligament, contributing to its stability in this position. In adults, the descending colon measures approximately 25 to 30 cm in length and has a diameter of about 6 to 7 cm, reflecting its role as a relatively fixed, retroperitoneal portion of the colon. These dimensions provide it with a consistent vertical course through the left flank and lumbar regions into the left iliac fossa.^[4] Congenital variations in the descending colon can include relative shortness or elongation, potentially altering its positioning and leading to increased mobility or atypical fixation to the posterior abdominal wall. Such anomalies arise from incomplete retroperitoneal fusion during embryonic development and occur in a minority of individuals.

Anatomical relations

The descending colon is fixed in a retroperitoneal position along the posterior abdominal wall in the left iliac fossa, distinguishing it from more mobile segments such as the transverse colon.^[5]^[1] Anteriorly, the descending colon relates to loops of the small intestine, the greater omentum, and the anterior abdominal wall.^[5]^[6] Posteriorly, it overlies the left kidney and ureter, while being adjacent to the psoas major, quadratus lumborum, and iliacus muscles.^[5]^[6]^[4] Laterally, the descending colon lies against the left abdominal wall within the left paracolic gutter, a peritoneal recess that separates it from the lateral peritoneum.^[1]^[6] Medially, it contacts loops of jejunum and descending genitourinary structures, including the ureter.^[5]^[6] These fixed anatomical relations contribute to the potential for mechanical compression of the descending colon or its involvement in abdominal wall hernias, particularly in the left iliac region.^[5]^[6]

Blood supply and venous drainage

The descending colon, as part of the hindgut, receives its primary arterial blood supply from the left colic artery, the first major branch of the inferior mesenteric artery (IMA), which arises from the abdominal aorta at the L3 vertebral level.^[1] The left colic artery courses superiorly within the mesentery, bifurcating into ascending and descending branches that form arcades along the mesenteric border of the colon, ultimately giving off vasa recta to directly perfuse the colonic wall.^[7] These arcades ensure a distributed supply, with the descending branch primarily nourishing the descending colon and the ascending branch extending toward the splenic flexure.^[6] Venous drainage parallels the arterial supply, with blood from the descending colon collected by the left colic vein, which drains into the inferior mesenteric vein (IMV) along the IMA.^[1] The IMV ascends to join the splenic vein behind the pancreas, ultimately contributing to the portal vein for hepatic circulation.^[6] Critical anastomotic networks provide collateral flow to the descending colon. The marginal artery of Drummond, a continuous arcade located 2–3 cm from the colonic wall, interconnects the terminal branches of the middle colic artery (from the superior mesenteric artery) with the left colic and sigmoid arteries (from the IMA), facilitating potential bypass in cases of occlusion.^[7] This anastomosis is generally more robust in the left colon, while it can be inconsistent or poorly developed in the right colon in 25–75% of patients, depending on anatomical variation.^[7] The arc of Riolan, when present, offers an additional direct collateral pathway between the proximal middle colic and distal left colic arteries.^[6] The splenic flexure serves as a key watershed area for the descending colon, marking the junction between midgut (superior mesenteric artery) and hindgut (IMA) territories, where perfusion relies on tenuous anastomoses and is thus prone to ischemia during hypoperfusion states.^[8] Specifically, Griffith's point at the splenic flexure represents a potential site of marginal artery discontinuity in 5–7% of cases, heightening vulnerability to compromised blood flow.^[7]

Lymphatic drainage and innervation

The lymphatic drainage of the descending colon follows a hierarchical pathway that parallels the arterial supply, beginning with epicolic lymph nodes situated directly on the serosal surface of the colonic wall.^[9] These nodes collect initial lymph fluid, which then drains into paracolic nodes located along the marginal arteries adjacent to the colon.^[9] From there, lymph progresses to intermediate nodes positioned along the branches of the left colic vessels.^[9] The principal nodes are found at the origin of the inferior mesenteric artery, where lymph from the descending colon converges before ascending to paraaortic nodes and ultimately entering the cisterna chyli.^[9] This drainage pattern is clinically significant for assessing metastasis risk in colonic malignancies, as it directs potential spread along the left colic vascular axis.^[1] Innervation of the descending colon involves both extrinsic autonomic inputs and an intrinsic enteric nervous system. Sympathetic fibers originate from the lumbar splanchnic nerves (T10-L2) and travel via the intermesenteric plexus to the inferior mesenteric plexus, providing inhibitory control over colonic motility and vascular tone.^[1] Parasympathetic innervation arises from the sacral outflow (S2-S4) through the pelvic splanchnic nerves (nervi erigentes), which join the inferior hypogastric plexuses to promote peristalsis and secretion in the hindgut.^[1] The enteric nervous system, embedded within the colonic wall, consists of the myenteric (Auerbach's) plexus between the longitudinal and circular muscle layers for motor coordination and the submucosal (Meissner's) plexus for secretory and vascular regulation, enabling local reflex arcs independent of central input.^[1] Visceral sensory afferents, carried alongside sympathetic and parasympathetic pathways, convey sensations of distension and ischemia, often referring pain to the left lower abdominal quadrant due to shared dermatomal innervation.^[1]

Physiology

Absorption and secretion

The descending colon plays a crucial role in the final stages of fluid and electrolyte reabsorption from the chyme entering from the proximal colon, where the small intestine has already absorbed approximately 90% of ingested water. Here, the epithelium facilitates the uptake of up to 90% of the remaining fluid volume—typically 1.5 to 2 liters daily—primarily through osmosis driven by active sodium transport. Sodium reabsorption occurs via electrogenic pathways involving epithelial sodium channels (ENaC) on the apical membrane and electroneutral mechanisms via sodium-hydrogen exchangers (NHE3), with basolateral extrusion powered by the sodium-potassium ATPase pump; chloride follows paracellularly or through anion exchangers like the down-regulated in adenoma (DRA) transporter, exchanging for bicarbonate.^[10]^[11] In addition to reabsorption, the descending colon secretes bicarbonate ions via chloride-bicarbonate exchangers (e.g., SLC26A3/DRA) to neutralize acidic contents from bacterial fermentation and maintains luminal lubrication through mucus production by goblet cells. Short-chain fatty acids (SCFAs), such as butyrate generated by microbial fermentation of undigested carbohydrates, are absorbed primarily via proton-coupled monocarboxylate transporter 1 (MCT1/SLC16A1), providing 60-70% of the energy needs for colonocytes and further supporting sodium-coupled water uptake. These processes convert the liquid chyme into semi-solid feces, with the descending colon's extended residence time enabling maximal extraction efficiency.^[10]^[12] Regulation of these functions is modulated by hormones, particularly aldosterone, which enhances sodium reabsorption during states of dehydration or volume depletion by upregulating ENaC expression and activity in the distal colon epithelium, thereby promoting water retention to maintain homeostasis. This mineralocorticoid-sensitive mechanism predominates in the descending colon, distinguishing it from more proximal segments with greater reliance on NHE-mediated transport.^[10]^[11]

Motility and transit

The motility of the descending colon involves coordinated contractions that mix and propel luminal contents toward the rectum, primarily through two distinct mechanisms: haustral contractions and mass movements. Haustral contractions are slow, segmental movements that occur within the sac-like haustra formed by the taeniae coli, facilitating thorough mixing of chyme to promote water absorption and prevent rapid transit. These contractions happen approximately every 30 minutes and last about 1 minute, triggered by distension of the haustral walls. In contrast, mass movements are powerful, propagating contractions that drive the aboral propulsion of fecal material, typically occurring 1 to 3 times daily and often aligned with circadian rhythms or postprandial periods. These are mediated by high-amplitude propagating contractions (HAPCs) with pressures exceeding 50 mmHg, lasting 20 to 30 seconds each.^[13]^[14] Transit through the descending colon generally takes about 5-6 hours (range 1-10 hours) in healthy adults, allowing for gradual fecal storage and dehydration before reaching the sigmoid colon. This duration is modulated by the autonomic nervous system, where parasympathetic stimulation via the pelvic splanchnic nerves enhances propulsive activity and segmentation, while sympathetic input from the lumbar splanchnic nerves inhibits motility to maintain storage. The net effect supports efficient progression without excessive haste, with slowed transit contributing to enhanced water and electrolyte absorption in the descending colon.^[15]^[16]^[17]^[18] Neural and hormonal factors tightly regulate these processes to synchronize with digestive cycles. The gastrocolic reflex, activated by gastric distension following a meal, triggers increased colonic contractions, particularly mass movements in the descending and sigmoid regions, to clear space for incoming chyme. Hormonally, motilin promotes overall gastrointestinal propulsion, including colonic segmentation, by acting on smooth muscle receptors to initiate migrating motor complexes that extend into the colon. Serotonin, released from enterochromaffin cells in response to luminal stimuli, further enhances segmentation and peristalsis via 5-HT3 and 5-HT4 receptors on enteric neurons and smooth muscle, amplifying haustral mixing.^[13]^[19]^[20] Defecation coordination involves signals from the distal descending colon and rectum that integrate with sphincter control for efficient evacuation. Distension in the descending or sigmoid colon propagates HAPCs to the rectum, activating stretch receptors that signal via the myenteric plexus and parasympathetic pathways to the spinal defecation center. This elicits reflex relaxation of the internal anal sphincter—a smooth muscle structure under involuntary control—facilitating passage of feces while maintaining continence through external sphincter tone.^[21]

Development and histology

Embryological origin

The descending colon originates from the hindgut, the caudal portion of the embryonic gut tube that forms during the fourth week of gestation as the embryo folds and the endodermal lining of the yolk sac incorporates into the primitive gastrointestinal tract.^[22] During weeks 5 to 10, the hindgut elongates rapidly in conjunction with the overall intestinal growth, contributing to the formation of the distal one-third of the transverse colon, the descending colon, the sigmoid colon, and the superior portion of the rectum.^[23] This development is regulated by key molecular factors, including the Cdx2 transcription factor, which drives hindgut differentiation and regional specification.^[22] A critical event in positioning the descending colon is the counterclockwise rotation of the midgut loop, which occurs in two phases: an initial 90-degree rotation around the superior mesenteric artery by week 6, followed by an additional 180 degrees as the intestines return from their herniated position in the umbilical cord by week 10.^[24] This rotation repositions the hindgut-derived descending colon to the left side of the abdominal cavity, with its final leftward orientation resulting from the completion of these movements. By week 12, the descending colon undergoes fixation to the posterior abdominal wall through the fusion of its mesentery with the parietal peritoneum, establishing its retroperitoneal position in the adult.^[25] Concurrently, the inferior mesenteric artery develops from the vitelline arterial system during weeks 5 to 8, providing the primary arterial supply to the elongating hindgut structures, including the descending colon, while venous and lymphatic drainage systems form in parallel.^[23] Disruptions in these processes can lead to congenital anomalies specific to the descending colon. Incomplete midgut rotation, known as intestinal malrotation, occurs in approximately 1 in 500 live births and may result in abnormal fixation of the descending colon, predisposing to volvulus or obstruction.^[25] Left-sided colonic atresia, accounting for about 10% of all intestinal atresias, arises from vascular insults or failures in hindgut elongation and recanalization during weeks 6 to 12, leading to luminal discontinuity in the descending colon region.^[22]

Microscopic structure

The microscopic structure of the descending colon follows the general organization of the large intestinal wall, consisting of four primary layers: mucosa, submucosa, muscularis externa, and serosa (partially replaced by adventitia due to its retroperitoneal position). The mucosa is lined by a simple columnar epithelium composed predominantly of absorptive enterocytes and goblet cells, which increase in number distally to facilitate mucus production for lubrication and protection. This epithelium forms straight, tubular crypts of Lieberkühn that extend through the lamina propria to the muscularis mucosae, lacking the villi seen in the small intestine. The lamina propria beneath the epithelium is a loose connective tissue layer rich in immune cells, including plasma cells, macrophages, and eosinophils, supporting mucosal defense. The thin muscularis mucosae, formed by interlacing smooth muscle fibers, separates the mucosa from the underlying submucosa.^[26]^[27]^[28] The crypts of Lieberkühn in the descending colon are densely packed, parallel, and non-branching, resembling test tubes that reach the base near the muscularis mucosae. At the crypt base, intestinal stem cells reside and differentiate into various epithelial lineages, including goblet cells for mucus secretion and scattered enteroendocrine cells with eosinophilic granules that regulate local functions. Paneth cells, characterized by their apical refractile granules, are absent or minimally present in the descending colon, unlike their prominence in the small intestine and proximal colon where they contribute to antimicrobial defense.^[26]^[29]^[27] The submucosa is a layer of fibroelastic connective tissue containing blood vessels, lymphatic channels, and nerves forming Meissner's plexus for mucosal regulation. It also features solitary lymphoid follicles, composed primarily of B lymphocytes, which serve as part of the gut-associated lymphoid tissue to monitor luminal antigens.^[26]^[29]^[28] The muscularis externa comprises an inner thick circular smooth muscle layer and an outer longitudinal layer concentrated into three distinct taeniae coli, providing structural support and facilitating haustral contractions. This layer is notably thicker in the descending colon compared to proximal segments, aiding in fecal storage and propulsion. It houses the myenteric (Auerbach's) plexus for coordinating motility.^[26]^[28]^[27] The outer serosa covers the anterior and lateral aspects of the descending colon, consisting of mesothelium over subserosal fibroadipose tissue, while the posterior surface is adhered to the retroperitoneum by adventitia, lacking a complete peritoneal covering. At the epithelial-mucosal interface, a stratified mucus layer produced by goblet cells forms a protective barrier: an inner adherent layer remains largely sterile, while the outer loose layer hosts a dense biofilm of microbiota, preventing direct bacterial contact with the epithelium and maintaining homeostasis. This organization reflects the descending colon's role in water absorption and microbial containment, with its histological features derived from midgut and hindgut endodermal patterning during embryogenesis.^[1]^[29]^[30]

Clinical aspects

Inflammatory bowel diseases

Inflammatory bowel diseases (IBD) encompass chronic conditions such as ulcerative colitis and Crohn's disease that can significantly involve the descending colon, leading to mucosal damage, altered function, and systemic symptoms. These disorders arise from dysregulated immune responses in genetically susceptible individuals, resulting in persistent inflammation that may extend to or prominently affect the left-sided colon, including the descending segment.^[31] Ulcerative colitis (UC) is characterized by continuous inflammation confined to the mucosal layer of the colon, typically originating in the rectum and extending proximally to involve the descending colon in left-sided disease, which accounts for 16% to 45% of cases at presentation.^[32] This inflammation manifests as diffuse friability, superficial erosions, and crypt abscesses—collections of neutrophils within dilated crypts—contributing to the disease's hallmark pathology.^[32]^[33] Common symptoms include bloody diarrhea often mixed with mucus or pus, abdominal cramping, rectal urgency, and tenesmus, reflecting the descending colon's role in water absorption and stool formation.^[34]^[31] In contrast, Crohn's disease (CD) features transmural inflammation that can produce discontinuous skip lesions anywhere in the gastrointestinal tract, including the descending colon as part of isolated colonic involvement seen in approximately 20% of cases.^[35]^[36] These lesions often lead to complications such as fistulas—abnormal connections between bowel segments or to adjacent organs—and strictures due to fibrotic narrowing, arising from the deep penetration of granulomatous inflammation characterized by noncaseating granulomas in up to 33% of resected specimens.^[37]^[35] Symptoms in descending colon involvement may include crampy pain, diarrhea, and weight loss, with the transmural nature increasing risks of penetration and obstruction.^[35] Epidemiologically, both UC and CD show higher involvement of the descending and sigmoid colon in colonic presentations, with left-sided UC being a common initial extent and colonic CD frequently affecting these segments in skip patterns.^[32]^[36] Genetic factors, particularly NOD2/CARD15 mutations, confer increased susceptibility to CD, influencing disease phenotype and severity across colonic sites including the descending colon.^[35] Inflammation in these conditions can disrupt normal colonic motility, leading to delayed transit and heightened spasm in the descending segment.^[31] Diagnosis of IBD affecting the descending colon relies on endoscopy, which reveals mucosal friability and continuous involvement in UC versus patchy, aphthous ulcers or cobblestoning in CD.^[32]^[35] Biopsy confirmation shows crypt abscesses in UC and granulomas in CD, while noninvasive biomarkers like fecal calprotectin levels help detect and monitor intestinal inflammation, with elevated values correlating to active descending colon disease.^[33]^[35]^[38]

Neoplastic conditions

The descending colon is a common site for colorectal adenocarcinoma, which accounts for approximately 95% of all colorectal malignancies and arises from the glandular epithelial cells lining the colonic mucosa. These tumors in the left-sided colon, including the descending segment, frequently present with symptoms related to partial or complete bowel obstruction due to the narrower lumen, such as abdominal pain, constipation, and distension, alongside rectal bleeding or changes in bowel habits. Anemia may also occur secondary to chronic blood loss, though it is more prevalent in right-sided lesions. The TNM staging system is used to classify these cancers, where T describes tumor invasion depth (T1 limited to submucosa; T4 involving adjacent organs), N indicates regional lymph node involvement (N0 none; N2b seven or more nodes), and M denotes distant metastasis (M0 absent; M1c peritoneal spread).^[39]^[40]^[41]^[40] The primary risk factors for adenocarcinoma in the descending colon involve the adenoma-carcinoma sequence, a multistep progression from benign adenomatous polyps to invasive carcinoma driven by accumulated genetic alterations. This sequence typically begins with mutations in the APC gene, a tumor suppressor that regulates Wnt signaling and is inactivated in 60-80% of sporadic colorectal cancers, leading to uncontrolled cell proliferation and polyp formation. Environmental factors such as age over 65, high-fat/low-fiber diet, and family history further elevate risk, with adenomatous polyps serving as precancerous precursors that can be identified and removed to interrupt this pathway.^[42]^[40]^[43] Screening plays a crucial role in early detection of descending colon lesions, with colonoscopy offering high sensitivity of approximately 95% for identifying adenomas and cancers in the distal colon through direct visualization and biopsy. Fecal immunochemical tests (FIT) provide a non-invasive alternative by detecting occult blood, with follow-up colonoscopy recommended for positive results to confirm neoplastic changes. Lymphatic spread from descending colon tumors typically follows inferior mesenteric nodes, influencing staging and surgical planning.^[40] Treatment for descending colon adenocarcinoma centers on surgical resection via left hemicolectomy, which removes the tumor-bearing segment along with adequate margins (at least 5 cm) and regional lymph nodes (at least 12 for accurate staging). For stage III disease, where regional lymph node metastasis is present, adjuvant chemotherapy with regimens like FOLFOX (folinic acid, fluorouracil, and oxaliplatin) is standard, typically administered for 3-6 months postoperatively to reduce recurrence risk by up to 30%. Neoadjuvant therapy may be considered in select cases with advanced local invasion.^[44]^[45]^[40]

Diverticular disease and other disorders

Diverticular disease of the descending colon involves the formation of pseudodiverticula, which are outpouchings of the mucosa and submucosa through the muscular wall, primarily occurring at the sigmoid-descending junction due to elevated intraluminal pressure from low-fiber diets and increased colonic segmentation.^[46] These pseudodiverticula develop in areas of relative weakness in the colonic wall, with approximately 33% of cases affecting the descending colon alongside predominant sigmoid involvement.^[47] Complications arise when these outpouchings become inflamed, leading to diverticulitis, which can progress to perforation, abscess formation, or fistula development, often presenting with left lower quadrant pain, fever, and leukocytosis.^[48]^[49] Ischemic colitis in the descending colon typically affects the watershed area at the splenic flexure, where the superior and inferior mesenteric artery territories meet, making it vulnerable to hypoperfusion during low-flow states such as hypotension, dehydration, or cardiovascular events.^[50]^[51] This ischemia leads to mucosal injury and sloughing, resulting in bloody diarrhea, abdominal pain, and potential ulceration or stricture formation if unresolved.^[52] The condition is more common in older adults and often resolves with supportive care, though severe cases may require intervention for gangrene or perforation.^[53] Other disorders affecting the descending colon include rare instances of volvulus, which is uncommon in this segment compared to the sigmoid or cecum, accounting for less than 5% of colonic volvulus cases due to the fixed retroperitoneal attachment of the descending colon.^[54] In females, endometriosis can involve the descending colon, where ectopic endometrial tissue infiltrates the bowel wall, potentially causing cyclic pain, obstruction, or bleeding, though it more frequently affects the sigmoid and rectum.^[55] Management of diverticular disease emphasizes prevention through a high-fiber diet, which reduces intraluminal pressure and the risk of complications by promoting softer stools and decreased colonic motility strain.^[56]^[57] For acute episodes of diverticulitis, antibiotics are used to treat bacterial overgrowth and inflammation, often alongside bowel rest and hydration, while ischemic colitis management focuses on addressing underlying hypoperfusion and supportive measures like fluids and monitoring.^[58]^[52]

References

[1]
Anatomy, Abdomen and Pelvis: Large Intestine - StatPearls - NCBI
Apr 6, 2025 · The descending colon, a retroperitoneal structure, is positioned adjacent to the paracolic gutters. This segment terminates at the sigmoid ...Missing: reliable | Show results with:reliable
[2]
Large Intestine & Colon: Function, Anatomy & Location
It carries food waste to your descending colon. Descending colon: Your descending colon is about 6 inches (15 cm) long. It sits on the left side of your body.Missing: reliable sources
[3]
Colonoscopy | Johns Hopkins Medicine
Descending colon: extends from the transverse colon downward on your left side; Sigmoid colon: extends from the descending colon to your rectum. The rectum ...Anatomy Of The Colon · Why Might I Need A... · How Do I Get Ready For A...Missing: reliable | Show results with:reliable<|control11|><|separator|>
[4]
The Colon - Ascending - Transverse - Descending - Sigmoid - TeachMeAnatomy
### Summary of Descending Colon Details
[5]
Colon Anatomy - Medscape Reference
Mar 7, 2025 · The descending colon is narrower and more deeply placed than the ascending colon. Omental appendices are more common in this part of the colon.
[6]
Descending colon: Anatomy and function - Kenhub
In adults, the descending colon measures about 25–30 cm. It is a retroperitoneal organ, with its anterolateral surface covered by parietal peritoneum that ...Missing: diameter | Show results with:diameter
[7]
[PDF] Applied vascular anatomy of the colon and rectum
marginal artery in this region may compromise the blood supply to the splenic flexure or descending colon from the middle colic artery if the IMA is ligated ( ...<|control11|><|separator|>
[8]
Ischemic colitis - Colon - Pathology Outlines
Mar 4, 2021 · Watershed areas most commonly affected (splenic flexure and rectosigmoid colon); the right colon is involved in 20 - 25% of cases.
[9]
Surgical Anatomy - Holland-Frei Cancer Medicine - NCBI Bookshelf
The most proximal lymph nodes to the bowel wall are the epicolic nodes. Paracolic lymph nodes are located along the marginal vessels. Intermediate nodes are ...
[10]
Physiology of Intestinal Absorption and Secretion - PMC - NIH
Electrogenic Na+ absorption – predominant in the descending colon, sigmoid and rectum – is most commonly attributed to the activity of mineralocorticoid ...
[11]
Salt and water absorption in the human colon: a modern appraisal
Proposed cellular model of electrogenic Na + absorption in human colon. This process is located predominantly in surface colonocytes.
[12]
A review on the food digestion in the digestive tract and the used in ...
Each day about 1.5–2 L of chyme passes through the ileocecal valve. The chyme volume becomes about 150 ml after the water absorption in the colon (Fig. 1b).
[13]
Physiology, Large Intestine - StatPearls - NCBI Bookshelf - NIH
The descending colon stores feces that will eventually be emptied into the rectum. The sigmoid colon contracts to increase the pressure inside the colon, ...Missing: reliable sources
[14]
[PDF] GI Physiology Series GI Motility Created by - naspghan
Haustral contractions are slow contractions that occur about every 30 minutes and last approximately 1 minute. They are stimulated by stretch when food remnants ...
[15]
First translational consensus on terminology and definitions ... - Nature
Jul 11, 2019 · This motor pattern consists of powerful propagating contractions that are associated with the mass movement of colonic content and with ...
[16]
https://pmc.ncbi.nlm.nih.gov/articles/PMC4858318/
[17]
Central Nervous System Control of Gastrointestinal Motility and ...
The parasympathetic neural innervation to the colon plays a significant role in regulating propulsive colonic motility, particular prior to defecation. Damage ...
[18]
Physiology, Gastrointestinal Nervous Control - StatPearls - NCBI - NIH
The parasympathetic system exerts its effects primarily via the vagus (innervates the esophagus, stomach, pancreas, upper large intestine) and pelvic nerves ( ...
[19]
Physiology, Motilin - StatPearls - NCBI Bookshelf
Sep 26, 2022 · Motilin stimulates gastric and small intestine motility, causing undigested food in these regions to move into the large intestine. This ...
[20]
Serotonin and Colonic Motility - PMC - PubMed Central - NIH
Serotonin promotes colonic motility via activation of multiple receptor subtypes. The relative roles of mucosal and neuronal serotonin in different motility ...
[21]
Physiology, Defecation - StatPearls - NCBI Bookshelf
Nov 13, 2023 · Defecation is involuntary from the colon to the internal anal sphincter, where smooth muscles push feces out. However, it is under conscious ...
[22]
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7255481/
[23]
Gastrointestinal Tract Development - UNSW Embryology
Aug 27, 2020 · Hindgut. The final embryonic division of gastrointestinal tract consisting initially of the cloaca snd extending to the cloacal membrane.
[24]
Embryology, Bowel - StatPearls - NCBI Bookshelf
This article will focus on the development of the midgut and hindgut and explore developmental abnormalities that may occur during this process.Introduction · Development · Cellular · Molecular Level
[25]
[PDF] Embryology and Anatomy of the Gastrointestinal Tract - naspghan
The superior 2/3 of the anal canal originates from hindgut and the inferior 1/3 is derived from proctodeum. The pectinate line is the junction of proctodeum ...
[26]
Anatomy & histology - Colon - Pathology Outlines
Jun 8, 2022 · Muscularis mucosa consists of thin strands of smooth muscle fibers separating the mucosa and submucosa; Presence of muscularis mucosae in ...
[27]
Colon - Histology at SIU - Southern Illinois University
The mucosa of the colon has a simple columnar epithelium shaped into straight tubular crypts. There are no villi. The mucosa in appendix and rectum is similar ...
[28]
Colon: Anatomy, histology, composition, function - Kenhub
The colon has the typical histological structure as the digestive tube: mucosa, submucosa, muscularis and serosa/adventitia. The mucosa is lined by simple ...Anatomy · Morphological Features · Histology
[29]
Large Intestine (Colon) - PMC - PubMed Central - NIH
The descending colon begins at the splenic flexure, becomes retroperitoneal, and extends for 20 cm to 25 cm. At the distal portion of the descending colon, the ...<|control11|><|separator|>
[30]
how the intestinal mucus layer manages the gut microbiota - NIH
Feb 13, 2019 · Thus, the intestinal epithelium is covered with a dense layer of mucus to prevent translocation of the gut microbiota into underlying tissues.Missing: biofilm descending
[31]
Inflammatory Bowel Disease - StatPearls - NCBI Bookshelf
Ulcerative colitis most commonly presents as bloody diarrhea with or without mucus. Patients commonly describe tenesmus, a sensation of incomplete evacuation, ...Missing: descending | Show results with:descending
[32]
Ulcerative Colitis - StatPearls - NCBI Bookshelf - NIH
Ulcerative colitis is an idiopathic inflammatory condition of the colon that results in diffuse friability and superficial erosions on the colonic wall ...Missing: descending | Show results with:descending
[33]
Crypt abscess-associated microbiota in inflammatory bowel disease ...
Crypt abscesses are early lesions observed in IBD, particularly in UC[11], consisting of dilated crypts containing polymorphonuclear cells. They can also occur ...
[34]
Ulcerative colitis - Symptoms and causes - Mayo Clinic
Symptoms · Diarrhea, often with blood, mucus or pus. · Blood in the stool. · Belly pain and cramping. · Rectal pain. · Urgency to pass stool. · Not being able to pass ...Missing: pathology | Show results with:pathology
[35]
Crohn Disease - StatPearls - NCBI Bookshelf - NIH
Feb 24, 2024 · Crohn disease's characteristic transmural inflammation can occur in the entire gastrointestinal tract from the mouth to the perianal area. ...
[36]
Small bowel involvement in Crohn's disease: a prospective ... - NIH
Large reviews state that approximately two thirds of patients have ileocaecal disease, 20% colonic involvement, and 10–30% small bowel involvement.
[37]
Crohn's Disease: A Surgeon's Perspective - PMC - NIH
The inflammation is transmural and can result in strictures, microperforations, and fistulae. The inflammation is non-contiguous and can thus produce skip ...
[38]
Inflammatory bowel disease (IBD) - Diagnosis and treatment
Dec 18, 2024 · Sometimes looking for stool markers of inflammation, such as calprotectin, can be helpful. Endoscopic procedures. Colonoscopy exam Enlarge image.Missing: descending | Show results with:descending
[39]
Your Colon or Rectal Pathology Report: Invasive Adenocarcinoma
Jul 7, 2023 · Adenocarcinoma is a type of cancer that starts in the gland cells that make mucus to lubricate and protect the inside of the colon and rectum.
[40]
Colon Cancer - StatPearls - NCBI Bookshelf - NIH
Feb 27, 2025 · Colon cancer is often sporadic and related to risk factors such as age, race, diet, and the presence of inflammatory bowel disease.
[41]
Left-Sided Colon Cancer and Right-Sided Colon Cancer - NIH
Apr 14, 2023 · For left-sided colon cancers, symptoms of bowel obstruction were the most common, followed by rectal bleeding. For right-sided colon tumors, ...
[42]
MOLECULAR BASIS OF HEREDITARY COLORECTAL CANCER
APC gene mutation is also seen in 60–80% of sporadic CRC. In FAP, a germline allelic mutation is usually followed by loss of heterozygosity. There is a mutation ...Adenoma-Carcinoma Pathway · Familial Adenomatous... · Stem Cells In Crc
[43]
The APC gene in colorectal cancer - PubMed
Colorectal tumours are known to arise through a gradual series of histological changes, the so-called 'adenoma-carcinoma' sequence, each accompanied by a ...
[44]
Surgical Management of Colorectal Cancer - NCBI - NIH
Descending and upper sigmoid colon cancers can be treated with left hemicolectomy ... It is in stage III colon cancer patients that adjuvant therapy has proven to ...
[45]
Treatment of Colon Cancer, by Stage - American Cancer Society
Dec 27, 2024 · Recent research has shown that 3 months of adjuvant chemo for some stage III colon cancers may be just as effective and is acceptable. For some ...
[46]
Colonic diverticular disease - PMC - NIH
Colonic diverticula are outpouchings of the intestinal wall and are common anatomical alterations detected in the human colon. Diverticulosis (the presence ...
[47]
The Burden of Diverticular Disease and Its Complications - NIH
In a retrospective cohort of patients in the United States with acute diverticulitis, 72% had the disease in the sigmoid colon, 33% in the descending colon, 3% ...
[48]
Diverticulitis - Symptoms and causes - Mayo Clinic
Oct 22, 2024 · This common colon disease develops when small pouches form in the colon wall and become inflamed, causing pain, fever and abnormal stool ...
[49]
Diverticulosis - StatPearls - NCBI Bookshelf - NIH
Diverticulosis is a clinical condition in which multiple sac-like protrusions (diverticula) develop along the gastrointestinal tract.Diverticulosis · Epidemiology · PathophysiologyMissing: descending | Show results with:descending
[50]
Ischemic colitis - Symptoms and causes - Mayo Clinic
Nov 7, 2024 · Ischemic colitis happens when blood flow to part of the large intestine, called the colon, is temporarily reduced.Missing: watershed | Show results with:watershed
[51]
Ischemic Colitis - PMC - NIH
Injury to the colon is believed to typically occur in the “watershed” areas of the splenic flexure (Grifith point) and sigmoid colon (Sudeck point). The ...
[52]
Ischemic Colitis - PMC - NIH
Ischemic colitis also known as colon ischemia (CI) is a common disorder of the large bowel in older persons and is the most common form of intestinal ischemic ...Ischemic Colitis · Clinical Features And... · Segmental Ulcerating Colitis
[53]
Management of Ischemic Colitis - PMC - NIH
Areas of the colon most sensitive to decreased blood flow and more likely to suffer from ischemia are the splenic flexure (Griffiths point) and sigmoid colon ( ...
[54]
Management of Colonic Volvulus - PMC - NIH
In a study of 546 cases of colonic volvulus, it is most often found in the sigmoid (60.9%), followed by the cecum (34.5%), the transverse colon (3.6%), and ...
[55]
Bowel endometriosis: Colorectal surgeon's perspective in a ... - NIH
Colorectal involvement results in alterations of bowel habits such as constipation, diarrhea, tenesmus, dyschezia, and, rarely, rectal bleeding.
[56]
Definition & Facts for Diverticular Disease - NIDDK
Diverticulosis is a condition that occurs when small pouches, or sacs, form and push outward through weak spots in the wall of your colon.
[57]
Diverticulitis – An Update from the Age Old Paradigm - PMC
The role of diet in preventing diverticular disease has long been debated. A high fiber diet appears to decrease the likelihood of symptomatic diverticulitis.
[58]
AGA Clinical Practice Update on Medical Management of Colonic ...
Antibiotic treatment can be used selectively, rather than routinely, in immunocompetent patients with mild acute uncomplicated diverticulitis. Antibiotic ...