ANUS, THE, AND ITS DISEASES. The term anus is applied by anatomists to the lower or (in the case of animals) the posterior aperture of the intestinal canal; the rectum terminating externally in the anus. With regard to its anatomy, it is sufficient to state that it is kept firmly closed on ordinary occasions by the external and internal sphincter muscles, the former of which contracts the integument around the opening, and, by its attachment to the coccyx behind, and to a tendinous center in front, helps the legator ani muscle in supporting the aperture during the expulsive efforts that are made in the passage of the faces or intestinal evacuations; while the latter or internal sphincter, is an aggregation of the circular muscular fibres of the lowest part of the rectum, and acts in contracting the extremity of the tube. The main function of the legator ant muscle is expressed in its name, it being the antagonist of the diaphragm and other muscles which act in the expulsion of the fines. The integument around the anus lies in radiating plaits, which allow of its stretching without pain during the passage of the finces; and the margin is provided with a number of sebaceous glands, which, in some of the lower animals, secrete strongly odorous matters. See ANAL GLANDS. Infants are occasionally born with an imperforate anus, or congenital closure of the rectum. In the simplest form of this affection, the anus is merely closed by thin skin, which soon becomes dis tended with the meconium (q.v.). More complicated cases are those (1) in which the gut terminates some distance above the seat of the anus in a blind sac or pouch, (2) where the rectum terminates in the bladder, etc. Fortunately, the closure by a layer of skin is far the most common form of imperforate anus, and the little patient is at once relieved by a very simple surgical operation. If, however, no treatment be adopted, which is too often the case, in consequence of a popular delusion that the affection is incurable, the abdomen becomes distended and bard. vomiting comes on, the vomited matters soon assume a faecal smell, and the infant dies in a few days, either from exhaustion or rupture of the intestines.
Spasm of the sphincter ani is by no means a rare affection; it is characterized violent pain of the anus, with difficulty in passing the fieces. On attempting an exami nation, the muscle feels hard, and resists the introduction of the finzer. It usually occurs in sudden paroxysms, which soon go off: but sometimes it is of a more persistent character. Its causes are not clearly known, and although most surgeons regard it as a special affection, some consider that the spasm is not a disease in itself, but merely a symptom of some slight excoriation or ulceration. Suppositories containing opium or belladonna introduced during the period of relaxation, are sometimes of use; and if there are ulcers, they must be specially treated. Ulceration occurring as a breach of surface at one or more points around the anus, but not extending within the orifice, is by no means uncommon in persons who are not attentive to cleanliness, and especially in women with vaginal discharges. Strict attention to cleanliness, the patient being directed to apply warm water to the parts at least twice daily with a sponge (which after each operation should be carefully rinsed out), and one or two applications of the solid nitrate of silver, followed by black-wash, will effect a speedy cure. If the ulcer is seated
partly without the anus and partly within the rectum, the distress is much more severe, and the treatment often requires the use of the knife. Fissure of the anus is a term applied to an affection consisting in one or more cracks, excoriations, or superficial ulcerations, situated between the folds of the skin and mucous membrane at the verge of the anus, and only slightly the rectum. They give rise to intense pain during the passage of the evacuations, and for some hours afterwards to great discomfort, smart ing, and itching. The treatment to be adopted is to endeavor to procure regular and somewhat soft evacuations, and to sponge with warm water immediately afterwards, the parts being dried with a soft cloth. One or two applications of solid nitrate of silver will sometimes cure the disease; and an ointment of oxide of zinc, or one containing chloroform, will sometimes serve to allay the irritation and heal the parts.—Pruritus ant, which simply means intense itching and irritation of this part, is perhaps rather to be regarded as a symptom of certain morbid changes rather than as a special disorder; but as it is a very common affection, and is productive of much suffering, it must not be passed over. It is often associated with an unhealthy state of the intestinal secretions, or with simple constipation; with a congested state of the mucous membrane; with a disordered condition of the womb; with the presence of thread-worms in the rectum, etc.; and it is peculiarly common in persons whose occupations are sedentary. The affection is often much aggravated by the patient's being unable to refrain from scratch ing the parts, which leads to excoriations, ulcerations, thickening of the skin, etc. The symptoms are usually most severe when the sufferer begins to get warm in bed. If the affection arise from worms, or a loaded state of the large intestines, enemata and purgatives will give immediate relief. If unhealthy excretions exist, attention must be paid to the diet, and the occasional administration of spill containing a grain of calomel and four grains of watery extract of aloes, together with the local application of soap' and water to the parts, will often stop the itching. If there are any cracks or ulcers, nitrate of silver must be applied until they heal. To prevent the reappearance of these sores, the patient should bathe the parts night and morning with a strong solution of alum. An ointment composed of a drachm of calomel and an ounce of lard is strongly recommended by Mr. Smith of King's College hospital, when other means have failed; who also states that the daily introduction of a well-oiled bougie, made of black wax, will sometimes succeed in very obstinate cases. The other principal affections of the anus are fistula, piles, and prolapsus, which are discussed in special articles.
an iron block, with a smooth, flat, steel face, on which malleable metals are hammered and shaped. A.'s are of all sizes, from the tiny articles used by watchmakers to the immense masses for trip-hammer work in great iron foundries. The common A. of blacksmiths has a cone or horn at one end, and a socket for a chisel in the other. The best A. are made of cast iron, faced with steel, the steel being placed at the bottom of the mold and the iron poured upon it.