The importance of the perianal connective tissue in the surgical anatomy and function of the anus.
The anatomy of the perianal connective tissue has been reviewed. The most important element is the conjoined longitudinal coat, the axis of the connective-tissue system. Fibers of the longitudinal coat penetrate the internal and external sphincter, interlacing with each other as well as the perimysium and endomysium and forming a fibroelastic network. The fibers and bundles of the internal and external sphincters lie in the meshes of this network with innumerable attachments to it. The fibroelastic network continues through the perianal fat to the pelvic wall and is connected to the lower levator fascia and the perianal skin, insuring the firm anchoring of the anus. During sphincter contraction the fibroelastic network moves together with the sphincters. Thus, the sphincter function is the integration of the contraction of the muscle fibers attached to the web. The elastic elements of the network pull the anal canal slightly apart, but the muscle tone overcomes this and keeps the anus closed. Surmounting the elasticity of the web causes the muscle function to be elastic as well. Surgical procedures such as stretching, transecting the sphincters, whether sharply or gradually, can lead to scar formation with loss of elasticity or mobility in that part of the sphincter and secondary impairment of function.
D001003:Anal Canal / Q000033:anatomy & histology* / Q000601:surgery; D003238:Connective Tissue / Q000033:anatomy & histology* / Q000601:surgery; D006801:Humans; D009130:Muscle, Smooth / Q000033:anatomy & histology; D010388:Pelvis / Q000033:anatomy & histology; D012867:Skin / Q000033:anatomy & histology