Pelvis Concepts

You can understand a great deal about the basic structure and function of the pelvis and perineum if you learn some important concepts. Some of them may seem obvious, but if you keep them in mind it will save you some memorization.

  1. The false pelvis is part of the abdominal cavity.
  2. Muscles in this region have multiple function; muscles of the pelvis act primarily on the hip joint; other muscles are supportive (e.g., pelvic diaphragm) or function as sphincters.
  3. The pelvic diaphragm separates pelvis from perineum. Structures leave the pelvis and enter the perineum via the greater and lesser ischiadic foramina, respectivley.
  4. Visceral ligaments are formed by both peritoneum (e.g., broad ligament) and condensations of subserous fascia (e.g., cardinal ligament).
  5. The deep fascia (parietal pelvic fascia, superior fascia of the pelvic diaphragm, etc.) are continuations of the transversalis fascia of the abdomen.
  6. Male structures have female homologues and vice versa.
  7. The innervation can be functionally divided into: somatic efferents and afferents to the abdominal wall and lower limb; pudendal nerve to the perineum; and autonomics to viscera.
  8. Parasympathetics have a sacral outflow (pelvic splanchnics); sympathetics reach this region via the hypogastric plexus.
  9. The rectum and anal canal have rich vascular anastomoses. Venous drainage is into both caval and portal systems.
  10. Lymphatic drainage is to both superficial (inguinal) and deep nodes along the pelvic wall, iliac vessels and aorta. Remember that the lymphatic drainage of a structure tends to follow the venous drainage (e.g., testes).
  11. The superficial and deep perineal pouches are delinated by both superficial (e.g., Colle's) and deep (e.g., perineal membrane) fascia. Blood or urine in the superficial perineal pouch can enter the scrotum and ascend the anterior abdominal wall.
    John A. McNulty, Ph.D.
    Last Updated: July 11, 2005
    Created: 1 March 1996