Cecum

CECUM (caecum, s.typhlon). Development. The development of the c., like the entire intestine, is derived from the embryonic endoderm. As early as the third month of intrauterine life, the c. can be clearly distinguished on the large intestine, initially located under the liver, and then gradually moving downward. By the seventh month of intrauterine life, it lies below the right kidney, and by the eighth month - already below the crista ilii. Simultaneously with this, the c. increases in length and shows uneven development: the terminal part turns into the proper c., while the initial part becomes the vermiform appendix. Initially, in the embryo, the c. has a long mobile mesentery - common to the entire intestine (mesenterium commune), but by the end of embryonic life, the ligamentous apparatus of the c. fuses with the posterior abdominal wall and the intestine becomes immobile. Anatomy. The c. is conventionally called that small section of the large intestine which, in the form of a blind pouch, protrudes below the point of entry of the ileum terminalis. Its length averages 6-8 cm, varying with age and under the influence of a number of factors. In the elderly, the c. is dilated and has thin walls; in the young, on the contrary, its dimensions are smaller, and the walls are thicker. Like the entire large intestine, the c. has taenia and haustra. The latter also show age-related changes: in the young they are more pronounced than in the elderly (Shevkunenko, Lisitsyn). The shape of the c. is most often sac-like, less frequently conical. The c. is located in the right iliac region on the fascia iliaca and in the young lies high, but with age it descends. On the anterior abdominal wall, the point of entry of the ileum terminalis into the c. is projected at a point located midway between the spina ilii ant. superior and the navel (McBurney's point). Histology. Histologically, the wall of the c. does not differ from the wall of the large intestine (see Intestine). The mucous membrane of the c. is gathered in places into small folds - plicae semi-lunares (usually weakly expressed in the c.): two valve-like folds (valvula Bauhini; see Bauhin's valve) (Fig. 1), which also contain muscle fibers, and one single fold (valvula appendicularis, Gerlach's valve). The mucous membrane contains Lieberkühn's glands (glandulae intestinales) and goblet cells. Under the mucous membrane is the tunica submucosa. The latter consists of loose connective tissue containing fat cells and smooth muscle fibers - lamina muscularis mucosae, by means of which it is delimited from the strongly developed lamina propria located between the individual Lieberkühn's glands. In the thickness of the mucous membrane there are also solitary lymphatic nodules (noduli lymphatici solitarii).

Figure 1. Internal structure of the cecum. The slit between the upper and lower folds of Bauhin's valve. From the latter, the tentorium extends to the sides. Somewhat below is visible the valve of the vermiform appendix. 755 The arteries of the c. belong to the system of the a. mesentericae sup. (a. ileo-caeco-colo-appendicularis) (see Mesentericae arteriae, venae). The veins belong to the system of the v. portae and flow through the v. ileo-colic into the superior mesenteric. The lymphatic vessels of the c. run perivascularly and flow into lymphatic nodes located partly retrocecal, partly in the ileocecal angle. Through small anastomoses, the lymphatic pathways of the c. are connected with the lymphatic vessels of the right kidney, gallbladder, and stomach. Nerves approach the ileocecal angle in the form of the n. ileo-caecalis.

Figure 2. Types of cecum position. (According to Lisitsyn.)

which contains fibers of the sympathetic, vagus, and partially spinal nerves. - From the described position and shape of the cecum, there are deviations: funnel-shaped form, its low position (in the small pelvis), high position (under the liver). High position is more often observed in the brachymorphic type, low position in the dolichomorphic type (fig. 2). Examination of the cecum is performed by means of palpation, percussion, and X-ray. Palpation makes it possible to determine the boundaries of the cecum in pathological changes of its walls and when its lumen is filled with dense fecal masses (in normal conditions, the cecum is difficult to palpate), splashing sound in case of dilation and atony, mobility of the cecum, and rumbling. Percussion determines the accumulation of gases in the cecum (tympanitis), the presence of an abscess in the vicinity of the cecum (dull sound), etc. X-ray examination (using a barley 'porridge' introduced per os, or a contrast enema) makes it possible to determine the function of the Bauhinian and appendicular valves (throwing of intestinal contents in the reverse direction in case of insufficiency of these valves), narrowing of the cecum's lumen, its position, etc. Diseases of the cecum 1. Dilatation of the cecum (dilatatio caeci) develops in the presence of membranous formations in the region of the ascending part of the colon and in the region of the hepatic flexure, which hinder the peristalsis of the large intestine. As a result of the stagnation of fecal masses, the walls of the cecum become stretched. On the basis of atony, pains, meteorism, and a feeling of heaviness in the right half of the abdomen subsequently develop. On palpation, a splashing sound in the right ileocecal region and rumbling are determined. A cecum filled with fecal masses can usually be palpated. Treatment of dilatation of the cecum in the initial stages can be therapeutic (appropriate diet, enemas, laxatives). In far-advanced cases, as well as in those where good results are not obtained from internal treatment, surgical intervention is indicated. The latter consists in suturing the walls of the cecum - caecoplicatio. The operation is reduced to suturing with nodular sutures or continuous taenia longitudinalis ant. with taenia lateralis. Ileo- transverso- or sigmoi-deostomia have also been used. However, these operations usually do not give good results, since atony of the cecum is usually only a partial manifestation of atony of the entire large intestine. 2. Abnormal mobility of the cecum (caecum mobile) is often encountered simultaneously with its dilatation and atony. On opening the abdominal cavity, a long mesentery of the cecum (mesocaecum) is usually found. In the latter case, a volvulus of the ileocecal angle can form. The clinical symptoms of caecum mobile are expressed in abdominal bloating, occurring 6-7 hours after eating, and sometimes the picture of the disease at the moment of pain attacks resembles ileus. With the passage of gases, pains and meteorism pass. On palpation, slight mobility of the cecum and rumbling are determined. Surgical treatment is indicated: fixation of the cecum according to Wilms or, in the presence of dilatation of the cecum - caecoplicatio according to ten-Horn. To fix the cecum, the parietal peritoneum is incised horizontally behind the cecum and the blind pouch is bluntly dissected, into which the cecum is placed after preliminary removal of the appendix. The anterior part of the retroperitoneal pouch is fixed to the parietal peritoneum at the edge of the laparotomy incision. Unfortunately, the described operation does not always achieve its purpose, and painful phenomena in many cases persist even after the operation. With prolonged existence of mobility of the cecum, inflammatory phenomena develop around it, which lead to the formation of adhesions. As a result, the cecum changes its original position and becomes fixed in the region of the liver, gallbladder, duodenum, etc. (caecum mobile fixatum). Then the clinical picture of the disease may resemble liver stones, cholecystitis, duodenal ulcer, etc. 3. Inflammation of the cecum (see Typhlitis). 4. Tuberculosis of the cecum begins either from the mucous membrane or from the peritoneal covering in the form of tuberculous seeding. Infection occurs either parenterally or hematogenously, with the mesenteric glands being primarily affected. Subsequently, ulcers form on the mucous membrane, tumor-like inflammatory infiltration of the intestinal wall, scar narrowing of the cecum's lumen, enlargement of nearby lymph glands (most often those located along vasa iliaca and v. ileo-colica), spread of the process to adjacent parts of the colon, etc. Sometimes an extensive, so-called ileocecal tumor forms, simulating a malignant neoplasm and actually being a proliferation of tuberculous and non-specific granulations." The disease of the cecum with tuberculosis manifests itself as pains in the right ileocecal region, phenomena of chronic obstruction and constipation, alternating with diarrhea of a mucous nature, sometimes with blood. In cecum accompanied by diarrhea, rapid emaciation of patients usually occurs. In cases where a stricture of the cecum has formed on the basis of tbc, a splashing sound is observed on palpation in the right ileocecal region (dilated ileum terminale!). If the tumor of the cecum of tuberculous nature is not operated on, then a cold abscess may form later, infection from the intestine may join, or, which is very rare, spontaneous healing may occur. A cold abscess is opened either under Poupart's ligament on the thigh (more often) or into one of the nearby organs (intestine, bladder, etc.). In this case, fistulas with purulent discharge are formed, which sometimes take on the character of fecal fistulas. Treatment of tbc of the cecum should be surgical (one- or two-moment resection of the ileocecal angle) followed by climatic, dietetic, and physiotherapy. If the patient is weak and there are signs of stricture of the cecum, an enteroanastomosis is indicated. 5. Tumors of the cecum are benign and malignant. The former are rare (lipomas, myomas, enterocysts, adenomas). Among malignant tumors, cancer (usually adenocarcinoma) is most common, less often sarcoma, especially lymphosarcoma. The diagnosis is based on the presence of a dense, nodular, uneven, and not sharply demarcated from surrounding tissues tumor in the right iliac region, painful on palpation and immobile. In addition, there are usually colicky pains in the right ileocecal region, signs of partial obstruction, and in malignant tumors - cachexia. In the initial stages, malignant tumors, in particular cancer, give few characteristic clinical symptoms. If inflammatory phenomena are added to the tumor, the picture of the disease can simulate acute or chronic appendicitis. The prognosis for malignant tumors of the cecum is poor, but with early surgical intervention (resection of the affected part of the intestine), up to 60% recoveries can be achieved. In inoperable cases with stricture of the cecum, ileo-transversostomia or ileo-sigmoideostomia is indicated. 6. Actinomycosis of the cecum more often affects men aged 20 to 40 years. The disease more often occurs on the basis of parenteral infection and quickly spreads from the cecum to the retroperitoneal tissue and the anterior abdominal wall in the form of a dense wide infiltrate, which subsequently softens. Subsequently, fistulas with a narrow course and crumbly pus form. Signs of obstruction in actinomycosis are rarely observed. The prognosis in most cases is unfavorable. Patients die from exhaustion, metastases, and generalization of the process. In the initial stages, surgery (resection of the ileocecal angle) is indicated for patients. 7) Intussusception of the cecum (see Intussusception) gives the same clinical picture as intussusception of other parts of the large intestine, but only pains are usually localized on the right side. Intussusception of the cecum occurs due to the invagination of the terminal ileum into the lumen of the cecum. Treatment is surgical (reduction of the intestine, resection). Among ulcerative processes in the cecum, balantidiasis and amebiasis deserve mention. Pathological pigmentation of the cecum - see Intestine.