Proctal sphincter

The main function of a proctal sphincter is control of allocation of contents of intestines. It consists of an external and internal part.

External proctal sphincter

External part of a sphincter represents the ring structure consisting of cross-striped muscles, surrounding anal the channel. The external sphincter can be controlled consciousness of the person.

In length it makes 8-10 cm and its thickness – 2,5 cm. Striated muscles of a sphincter pass pubic прямокишечную a muscle.

Muscles of an external part of a sphincter are divided into three layers:

• The hypodermic muscles representing ring muscles;
• Superficial muscle – the elliptic muscle attached to a tailbone;
• The deep muscle which is closely tied with a pubic pryamokishechnoy a muscle.

Muscles of an external part of an anus clasp the lower part of an internal sphincter. In spite of the fact that sphincters closely contact, between them there is a clear boundary.

In muscles of an external proctal sphincter there are stretch receptors. The healthy adult can easily control passing through a sphincter of fecal masses and their consistence. The Rektoanalny reflex consists in compression of muscles of an external sphincter of an anus. Defecation reaction results from sharp increase in intra belly pressure from which intra rectal pressure results and the internal sphincter of an anus relaxes.

Internal proctal sphincter

Internal part of a sphincter represents the smooth muscle ring structure surrounding anal the channel. It begins from an inside circular muscular layer of a rectum, and below connects to anus skin. In the lower part the internal sphincter is clasped with muscles of an external sphincter.

Internal part of a sphincter has thickness about 5 mm, and length – 25-30 mm. The lower bound of a sphincter is located at distance about 5-6 mm from an anus. Its muscle fibers pass under an inclination along an axis of a gut and to the axial line of a rectum.

Unlike external, the internal proctal sphincter is not controlled consciousness of the person. Its relaxations and reductions happen involuntarily. In a usual state the internal sphincter is reduced. Its reflex relaxation results from irritation of a rectum fecal masses. The peristaltics of a large intestine does not influence a condition of a sphincter.

The main function of an internal sphincter is valve, that is it does not allow to happen to passing of liquid fractions a calla and gases.

Valve function of an internal sphincter is carried out thanks to three-level system:

• Intramural level;
• Spinal level;
• The Nadsegmentarny level located in various parts of a brain.

Spinal and intramural levels are carried out parasympathetic and sympathetic by departments of the autonomic nervous system. Sympathetic fibers hold a sphincter in constantly reduced state and brake motor activity of a rectum. Parasympathetic fibers, on the contrary, weaken a sphincter and stimulate motility of a rectum.

Defects of a proctal sphincter

The most widespread defects of a proctal sphincter are:

• Insufficiency of a proctal sphincter;
• Proctal crack.

Insufficiency of a proctal sphincter is called full or partial disturbance of any deduction of fecal masses.

Normal the sphincter is capable to hold gaseous, liquid and firm contents of a rectum not only in different provisions of a body, but also when sneezing, a severe cough, exercise stresses, etc.

Injuries, preferential, postoperative are the most frequent reason of insufficiency. Also insufficiency can result from change of muscular structure or neuroreflex frustration. Most often diseases of the proctal channel or a rectum, such as hemorrhoids, prolapse of the rectum or various inflammatory diseases are the reasons of these disturbances. Malformations of the proctal channel and a rectum become more rare the insufficiency reason.

There are three degrees of insufficiency of a proctal sphincter:

• The first degree when the patient is not capable to hold gases;
• The second degree when the patient cannot hold gases and liquid kcal;
• The third degree – a full incontience.

Proctal crack – traumatizing a mucous membrane of an anus.

The proctal crack meets quite often and among diseases of a large intestine takes the third place (after colitis and hemorrhoids).

There is a proctal crack as a result of various reasons. The most frequent reason – traumatizing a mucous membrane when passing firm fecal masses. The contributing factors to its emergence is existence of colitis, hemorrhoids, a coloenteritis, proctosigmoiditis. Practically at 70% of patients the crack is combined with chronic diseases of upper parts of a digestive tract (stomach ulcer, gastritis, cholecystitis). The same number of patients combine a proctal crack with existence of hemorrhoids.

Three symptoms are characteristic of a proctal crack:

• Weak bleeding during an excrement;
• Sphincterismus;
• Pain in an anus directly in time or after an excrement.

Pain in an anus is characteristic of acute and chronic cracks. As a result of painful feelings patients aim to carry out as seldom as possible the act of defecation that leads to a lock. Besides, pain can cause a sphincterismus which, in turn, only strengthens pain. The sphincterismus is observed approximately at 60% of patients with proctal cracks.

Blood allocations from an anus rather small also appear as a result of traumatizing a crack. More plentiful blood allocations demonstrate existence of hemorrhoids or tumor.