Читать книгу Ridley's The Vulva - Группа авторов - Страница 75

The anal triangle is the triangular area bounded by the ischial tuberosities and the coccyx. The anal canal lies within this area. The ischiorectal fossae lie laterally to the anal canal (Figure 2.14). These are pyramid‐shaped areas bounded by ischium and obturator internus laterally, levator ani medially, and the perianal skin inferiorly. The fossae contain fat and connective tissue, and the nerves to the anus, perineum, and external genitalia traverse this space. The anal canal is the terminal 2.5–3.5 cm of the large intestine and passes through the levator ani. It has an internal involuntary sphincter derived from the smooth muscle of the rectum around its upper two‐thirds and an external voluntary sphincter muscle around the lower two‐thirds. This sphincter muscle blends with the puborectalis muscle.