PERINEOLOGY: ANATOMICAL-FUNCTIONAL AND CLINICAL ASPECTS. PART 1. ANATOMY AND FUNCTIONS OF THE ANAL REGION MUSCLES
Perineology is a complex branch of science that studies the development, structure and functions of the perineum in the norm and under various pathological conditions - congenital and acquired. In Russian and English literature, the complex of soft tissues covering the lower aperture of the pelvis is designated by two terms - «perineum» and «pelvic floor». Using these terms the authors describe the cutaneous-muscular-fascial formations, that are different in structure and function. Our work gave grounds to call the complex of soft tissues occupying the space of exit from the small pelvis the «pelvic floor», and the cutaneous-muscular-fascial plate between the posterior wall of the labia major or the base of the scrotum and the tip of the coccyx - the «perineum». The results of the study will be presented in four articles, in which anatomy of the anal and urogenital areas of the pelvic floor will be described in detail. In this article, we present the data on the muscles of the anal region obtained on the purposeful preparation of the corresponding area on the bodies of deceased people, on the preparation of museum specimens of the pelvic floor muscles, on analyzing literature data of the relevant content. The description of individual anatomy of the anal part muscles of the pelvic floor has been provided in every particular. The priority is given to anatomy of the muscle that lifts the anus and the structural features of its three parts. The anterior part of this muscle (the pubic-rectal muscle) is anatomically fused with the external sphincter of the anus, with the muscular covering of the rectum, which allows to consider it as the main functional unit responsible for all phases of defecation. Anatomy of the anus sphincters and their participation together with the pubic-rectal muscle in the rectum closure system are also described.