1. What is the function of the connective tissue of the anal canal?
The connective tissue of the anal canal includes the joint longitudinal muscle, external sphincter connective tissue, internal sphincter connective tissue, submucosal connective tissue, subcutaneous connective tissue, and connective tissue of the colorectal fossa.
Its functions and clinical significance are as follows.
Defecation and self-control: The joint longitudinal muscle is a direct continuation of the internal rectal longitudinal muscle and a partial continuation of the anal raphe, so the contraction of the anal raphe and rectal longitudinal muscle during defecation will definitely cause the anal canal to contract, the official cavity to expand and the anus to open, and the opposite when defecation is terminated. The joint longitudinal muscles assist the muscles around the anal canal in this process to maintain normal defecation function. Li Guodong, Department of Anorectology, Guang’anmen Hospital, Chinese Academy of Traditional Chinese Medicine
Sphincter function: The connective tissues of the anal canal are reticulated, and these reticulated connective tissues entwine, separate, and unite the anal sphincter. When the sphincter contracts, the connective tissues move together with the muscle fibers to jointly complete the sphincter function. When part of the sphincter is severed during surgery, the twisting effect of the connective tissue network keeps the severed end from separating greatly and facilitates the integrity of the anal sphincter function.
Support role: The connective tissue of the anal canal, with the united longitudinal muscles as the central axis, links the anal canal rectum with the surrounding tissues into a functional whole, which is fixed to the pelvic diaphragm and its fascia, the lateral wall of the pelvis and the perianal skin. Like the steel frame of a building, when coughing and defecation increase abdominal pressure, especially when the fecal mass is propelled by abdominal pressure, there is a strong vertical force acting on the anal canal. In this case, the connective tissue of the anal canal plays an important role in preventing the position of each part of the anal canal from shifting down or mucosal prolapse. If the joint longitudinal muscle is poorly developed, or if the degeneration or atrophy of its mesh structure destroys the stability of the anal canal, anal canal ectropion and rectal prolapse will occur.
2. What are the physiological functions and clinical significance of the internal anal sphincter?
The internal sphincter is a continuation of the rectal circular muscle, which is not a random muscle and has no intramuscular ganglion; even if it is partially or completely cut off, it does not affect the self-control function of the anus. However, external stimuli, such as loose stool, gas in the rectum or contraction of nearby random muscles, can reflexively cause an increase in tension of the internal sphincter.
The internal sphincter, with its unique smooth muscle extensibility, ensures sufficient dilatation of the anal canal when fully relaxed to prepare for defecation. At the termination of defecation, the internal sphincter contracts to empty the anal canal, which generates a strong retrograde peristaltic wave that pushes the remaining stool upward into the rectum.
The internal sphincter has inherent properties of the circular muscle layer of the GI tract and is prone to spasm. Injuries to the anal canal in general expose the internal sphincter very easily, causing inflammation and spasm, resulting in pain. If spasm is prolonged, structural changes in its musculature lead to pathological changes, such as anal fissures and tightness of the anal canal.
In addition to the mechanical closure of the anal canal, the internal sphincter is also involved in random inhibition. During defecation, the external sphincter contracts at will, preventing the internal sphincter from relaxing, and the latter inhibits rectal contraction through neural reflexes, causing fecal matter to be retained in the rectum, thus achieving anal self-control. This process is called random inhibition. If the internal sphincter is destroyed, the contraction of the external sphincter will not cause the above reflex activity, and the rectum will continue to contract, resulting in overflow of feces from the anus when the external sphincter is fatigued. Therefore, the internal sphincter plays a non-negligible role in casual self-control. Therefore, the repair of the internal sphincter should be emphasized in the surgical treatment of anal incontinence.
3. What is the pectineal band? Is the pectineal band a pathological or healthy tissue?
The pectineum refers to the epithelium of the anal canal between the dentate line and the intersphincteric sulcus. This epithelium is a migrating epithelium, thin and dense, light red and smooth. The pectineum and the pectineal zone are two different meanings. the pectineal zone is located subcutaneously in the pectineal area and its main components are fibrous connective tissue and smooth muscle fibers with a thickness of 1.5 to 5.3 mm. it is histologically confirmed to be normal tissue. Because of the anal flap, anal fossa, anal glands and anal ducts on the upper edge of the pectineal area, and because the pectineum itself is very fragile, it is easily damaged and leads to inflammation of the pectineal zone under it. Therefore, when examining patients with anal fissures or chronic inflammation of the anal canal, poorly elastic annular pectineal bands are often found, leading some people to believe that the pectineal bands are pathological tissue. Of course, by loosening or cutting off this tissue during treatment, the anal canal will regain its ability to dilate, and the disease that caused the pectus carinatum to occur will be relieved. In the treatment of anal fissures, it is difficult to cut the pectineal band or the internal sphincter alone, and often the thickened connective tissue, the pectineal band, is cut at the same time. Therefore, the internal sphincterotomy for anal fissure should include cutting both the internal sphincter and the pectineal band.
4. What are the causes of increased discharge from the anal opening?
There are many causes of increased discharge from the anal orifice, which can be physiological or pathological.
The sebaceous glands and sweat glands in the anal area secrete a lot: Because the anus is deeply sunken between the buttocks on both sides, this deep sunken position. For the evaporation of sweat around the anus is quite unfavorable, especially for people with obese body shape, the anal position is deeper, causing humidity around the anus. Some people also have sebaceous glands and sweat glands that secrete a lot, and if they don’t pay attention to hygiene, they also cause symptoms of increased secretions in the anal area.
In elderly or weak people, the anal sphincter is relaxed and weak, resulting in poor anal closure and the flow of intestinal and anal fluids out of the anus, resulting in symptoms of increased secretions.
Severe anal fissures and anal fistulas with the external opening near the anus produce symptoms due to more inflammatory exudation and overflow outside the anus.
In anal fistula and fissure surgery, more external sphincters and all internal sphincters are severed, so that the ability of anal closure decreases and anal fluid and intestinal fluid can flow out of the anus, which is an after-effect of surgery and is clinically called postoperative anal fluid overflow.
Complete rectal prolapse degree III often occurs when the anal sphincter is weak and the whole rectum or mucous membrane prolapses out of the anus when walking or straining, and the fluid on the surface of the rectal mucous membrane will contaminate the perianal skin, resulting in the symptom of a large amount of secretion in the anal opening.
Anal eczema and herpes, anal contact dermatitis, are also factors that cause increased local secretions in the anus.
5. What positions are often chosen for the examination of anal diseases?
When examining and treating anal and rectal diseases, different positions should be selected according to the patient’s physical condition and the specific requirements of the examination, and the following positions are commonly used.
Lateral position: Usually the left lateral position is used, sometimes the right lateral position can be used if required for surgery. The correct side lying position is the hip near the bed, the upper side of the hip and knee flexion of 90 degrees, the lower side of the hip and knee flexion of 45 degrees, this position is suitable for small anorectal surgery or sick, old and frail patients.
Bladder truncated position: the patient lies on his back, both legs are flexed and lifted upward on the left and right side of the leg frame, and the hips are moved to the bedside, or the patient holds the thighs with his own hands. The anus is fully exposed. This position has better exposure of the operative area during surgery and is generally not used as an examination position.
Chest and knee position: the patient lies prone, knees flexed, kneeling on the bed, elbows and chest close to the bed, hips elevated, is a common position for examination, but can not last, sick or old and frail should not be used.
Squatting position: the patient squatting for deep breathing, force to increase abdominal pressure, suitable for the examination of patients with prolapse, rectal polyps and hemorrhoids prolapse.
Bending chair position: the patient bends forward, at least 90 degrees, hands on the chair, exposing the buttocks, this position is suitable for outpatient examination.
Prone position: The patient lies prone on the operating table with the buttocks elevated and the head and both lower extremities lower. (with picture)
6. Why are women more likely to suffer from anorectal diseases than men?
In a 1977 census of 57,292 people in 18 provinces, municipalities and autonomous regions, the incidence of anorectal disease was 59%, 67% for women and 53.9% for men, with women having a 13.1% higher incidence than men.
Why do women suffer more from anorectal disease? This is because women have more chances to have their pelvic organs compressed and blood flow obstructed in the course of life, which constantly causes pelvic organ congestion and bruising and affects the blood circulation of the anus; the rectum is compressed, so that the passage of feces is obstructed and defecation is not smooth. These are all factors that induce the development of anal disease.
Menstruation and pregnancy can increase the burden on the anus. Some women often have prolonged intervals between bowel movements during menstruation or pregnancy, with bowel movements every 2 to 3 days, resulting in difficulty in defecation. In the second trimester of pregnancy, the enlarged fetus presses on the rectum, which not only makes defecation difficult, but also obstructs the venous blood flow back to the rectum and anus, which not only makes hemorrhoids easier to occur, but also further aggravates the existing hemorrhoids.
After delivery, the abdominal cavity is empty and the sense of defecation becomes sluggish, coupled with the reduced activity of the flaccid abdominal wall, the symptoms of weakness and difficulty in defecation increase, and there are often no defecation symptoms for several days. The feces stays in the intestine for too long and is highly hardened, and as a result, strong defecation can damage the anorectum causing anorectal disease.
In addition to the above-mentioned pregnancy and childbirth women, when women reach menopause, most of their muscles become flaccid and weak, and the tissues related to anal function such as sphincter, anal raphe, and puborectal muscle also become weak and anal function decreases. At the same time, endocrine and neurological dysfunctions often occur in women during menopause, making them irritable and feeling like they can’t finish their bowel movements, resulting in frequent trips to the toilet, which is also a trigger for anal disease.