Anatomy and physiology of the rectum and anus

Abstract

An understanding of the physiology and structure of rectum and anus, their related structures within the pelvis, and their embryological origins, is important when considering rectal cancer surgery in terms of precise dissection in anatomical planes, oncological clearance and functional impact for the patient. This includes sphincter preservation with restoration of gastrointestinal continuity, as well as preservation of urinary and sexual function. It is by a deeper understanding of pelvic anatomy and embryology that due to the proximity of pelvic structures damage and potential for functional compromise may be avoided when planning and carrying out rectal cancer treatment strategies. This chapter gives an overview of pelvic anatomy and physiology with specific reference to the operative technical considerations but also underpins the principles by which pre-operative staging assessment and adjuvant treatment are conducted in the overall management of rectal cancer.