Pelvic contents

• Peritoneum (female)

  The parietal peritoneum that lies the abdominal cavity continues into the pelvis and covers the pelvic organs. In females this creates two pouches either side of the uterus. Between the uterus and the bladder is the vesicouterine pouch; and between the uterus and the rectum is the rectouterine pouch. This pouch is often called the “pouch of Douglas’. The peritoneum forms the broad ligament as it passes over the uterus.
• Peritoneum (female)

  The parietal peritoneum that lies the abdominal cavity continues into the pelvis and covers the pelvic organs.

  In females this creates two pouches either side of the uterus.

  Between the uterus and the bladder is the vesicouterine pouch; and between the uterus and the rectum is the rectouterine pouch.

  This pouch is often called the “pouch of Douglas’. The peritoneum forms the broad ligament as it passes over the uterus.

  
• Peritoneum (male)

  In males, the peritoneum passes between the rectum and the bladder to create the vesicorectal pouch.

  
• Bladder

  •Partial covering of peritoneum, ‘stuck’ against pubic bones

  •Transitional epithelium and rugae

  •As the bladder fills it rises into the suprapubic region

  •Apex posterior to pubic symphysis – urachus

  
• Bladder

  Just as the stomach wall was folded into rugae, so is the internal surface of the bladder

  As the bladder fills it rises above the pubic bones

  The relation of the apex of the bladder to the pubic bones is maintained by a small piece of connective tissue called the urachus – an embryological remnant of a structure that drained the foetal bladder and joined the umbilical cord.

  
• Trigone

  •Base of bladder is triangular – trigone internal area of smooth mucous membrane

  •Urethra exit, ureters enter at trigone

  •Muscular coat of smooth muscle = detrusor and at neck circular sphincter vesicae

  •Sphincter vesicae not complete

  •Neck held in place by puboprostatic (male) or pubovesical (female) ligaments

  
• Trigone

  At the base of the bladder there is a small smooth area called the trigone. This is where the two ureters enter the bladder and the urethra exits the bladder. The muscular wall of the bladder is called the detrusor muscle and it forms an incomplete sphincter at the neck of the bladder. This is the sphincter vesicae and as it is composed of smooth muscle is under ANS. There is an external voluntary sphincter of micturition (urination) in the urogenital diaphragm.

  The base of the bladder is supported by ligaments that pass from the pubic bones in males and females.

  
• A sagittal hemisection is often used to show the relationship between the pubic bones, bladder and uterus/rectum

  
• Bladder

  •Arterial = superior (x2) and  inferior vesical from each side (internal iliac, black arrows)

  •Inferior vesical artery in males usually corresponds to the vaginal artery in females

  •Veins = vesical plexus (drain to internal iliac)

  •Nerves = ANS inferior hypogastric plexus

  
• Bladder

  The bladder is supplied from above by superior vesical arteries from the umbilical branch of the anterior division of the internal iliac artery. It is supplied deeper within the pelvis by the inferior vesical artery In females this is usually the vaginal artery, which is also a branch of the anterior division of the internal iliac artery. Venous drainage of the bladder is to the vesical plexus and then into the internal iliac veins. The bladder is an internal organ and is therefore supplied by the ANS via the inferior hypogastric plexus

  
• Lymphatic drainage - bladder

  The main lymphatic drainage of the bladder and urethra is to the internal iliac nodes clustered around the internal iliac arteries. Some drainage can pass to other local nodes – for example those situated close to the sacrum.

  
• If there is an issue releasing urine from the bladder, the urine may sit in the bladder and the salts present in the urine can accrete to form urinary stones or caliculi.

  
• Rectum

  •Upper 1/3rd covered by visceral peritoneum, middle 1/3rd peritoneum on anterior surface, lower 1/3rd infraperitoneal

  •3rd sacral vertebra to tip of coccyx

  
• Rectum

  The other pelvic organ common to males and females is the rectum. It is an extension of the sigmoid colon as it crosses the 3rd (fused) sacral vertebra. It then passes towards the tip of the coccyx where it pierces the pelvis floor as the anal canal.

  
• Rectum

  The internal surface of the rectum is thrown into three transverse folds, with an enlarged area called the rectal ampulla between them. This shape helps to facilitate storage of faeces before it is excreted from the body via the anal canal

  a sling of muscle called puborectalis that passes around the rectum and when it contracts it bends the wall of the rectum. This makes it more difficult to pass faeces from the rectum to the anal canal and therefore helps to maintain continence.

  
• Rectum

  •Superior rectal artery (inf mesenteric)

  •Middle rectal artery (internal iliac)

  •Inferior rectal (internal pudendal)

  •Veins = superior (portal), middle (int iliac), inferior (internal pudendal)

  •Lymph = pararectal to inferior mesenteric and internal iliac

  •Nerve = inferior hypogastric plexus

  
• Rectum

  There is only one main superior rectal artery as it is a branch from the inferior mesenteric artery but the middle rectal and internal pudendal arteries (giving the inferior rectal arteries) are bilateral structures as they are branches of the internal iliac arteries.

  The rectum is a site of portal systemic anastomosis as the blood from the superior part of the rectum passes into the portal system via the inferior mesenteric vein but the inferior parts of the rectum drain to local veins that drain into the internal iliac veins that are part of the systemic system.

  
• Rectum

  Lymph drainage is also split with lymph passing from superior parts of the rectum into pre-aortic nodes at L3 clustered around the inferior mesenteric artery and lymph from lower parts of the rectum passing to local pararectal nodes and then nodes around the internal iliac arteries.

  
• Lymphatic drainage - rectum

  
• Uterus

  The uterus is a hollow, muscular organ that sits in the middle of the pelvic cavity covered by the broad ligament.

  The uterus and ovaries are usually much smaller because they shrink after menopause

  Other common features are pathologies such as tumours, or as seen on the Thiel embalmed uterus, fibroids

  
• Uterus – broad ligament

  The broad ligament is a fold of peritoneum that overlies the uterus and uterine tubes. It provides a small degree of support to the uterus (the main support is from ligaments at the cervix) and carries the neurovascular structures of the uterus. It is divided into three areas. The mesovarium holds the ovaries to the posterior surface of the broad ligament, the mesosalpinx supports the uterine tubes and the mesometrium is the main part of the broad ligament associated with the body of the uterus.

  
• Uterus - features

  The most superior part of the uterus is the fundus which rises above the entrance of the uterine tubes. The main part is called the body which narrows to form the cervix inferiorly. The cervix opens into a muscular tube called the vagina. The walls of the uterus are muscular (myometrium) but it is lined by the endometrium which is increased and then shed during each menstrual cycle.

  
• The internal walls of the uterus form a small narrowed area called the internal os superior to the cervix and an external os at the cervix. As the cervix bulges into the vagina there are small spaces each side of the cervix called the lateral fornices (singular is fornix).

  The uterus is supplied by uterine arteries from the anterior division of the internal iliac artery. The uterine artery anastomoses with the ovarian artery which supplied the ovaries, fundus of the uterus and the uterine tubes.

  
• Uterine tube (Fallopian tube)

  The uterine tubes pass from the area above the ovary to open into the uterus. They have a narrowed section called the isthmus as they pierce the wall of the uterus, then an expanded area called the ampulla which ends at a wide infundibulum. The most distal part of the tube is divided into finger-like fimbrae which help to gather the ovum released by the ovary and direct it into the uterine tube. There is no direct contact between the fimbrae and the ovary, so immediately after release the ovum is briefly suspended in the peritoneal cavity.

  
• Ligaments

  The main support to the uterus lies at the cervix – this allows the uterus to expand and rise into the abdomen during pregnancy but still maintain its relationship with the vagina and pelvic floor.

  The slide shows the ligaments associated with the cervix – the transverse cervical ligaments are also called the cardinal ligaments

  
• The uterus lies between the bladder and the rectum and usually bends over the bladder in a position described as anteverted and anteflexed. This standard position allows the uterus to flop forwards over an empty bladder for support.

  The pelvic floor muscles also support the uterus to prevent prolapse through the pelvic floor. Pubococcygeus forms a sling around the vagina – called pubovaginalis in an equivalent way that puboprostaticus supports the prostate gland.

  
• Ovaries

  •Ova and hormone production

  •Attached to back of broad ligament by mesovarium

  •Arterial supply from abdominal aorta (ovarian artery@L2)

  •Venous drainage - ovarian vein to IVC on R and left renal vein on L

  •Nerve = aortic plexus

  
• Ovaries

  The ovaries are small bean-shaped structures that sit attached by the mesovarium to the posterior surface of the broad ligament. They release ova each month from puberty until menopause. The right and left ovaries are both supplied by direct branches of the abdominal aorta but the veins drain into the inferior vena cava directly on the right and the left renal vein on the left.

  
• Ligaments

  The ovaries are also supported by folds of connective tissue. The ligament of the ovary passes between the uterus and the ovary; the suspensory ligament of the ovary carries the ovarian artery and vein.

  
• Arterial supply

  The ovarian and uterine arteries supply the ovaries, uterine tubes and uterus. The vaginal artery supplies the distal uterus and vagina; it can be a branch of either the uterine artery or a direct branch of the anterior division of the internal iliac artery. The internal pudendal artery supplies the distal vagina and perineum.

  The diagram on the right demonstrates the ‘bridge over water’ relationship between the uterine artery and the ureter near the base of the broad ligament.

  
• Lymphatic drainage

  Broad and round ligaments act as conduits to carry lymph away from the uterus, in addition to the more standard ‘lymph following arterial supply’ pattern seen in other areas.