MRCS Part B (OSCE) - Online Resources

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The relations of the uterus are:

• Anterior :      Vesicouterine pouch and bladder.
• Posterior :      Rectouterine pouch (of Douglas) and rectum.
• Lateral :      Broad ligament, transverse cervical ligaments and ureters.

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"Blood supply to the uterus comes primarily from the uterine arteries, arising from the internal iliac arteries. Contribution also comes from the paired ovarian arteries arising from the abdominal aorta, originating just inferior to the renal arteries. "

"The common iliac artery bifurcates into the internal and external iliac arteries at the vertebral level L5-S1 anterior to the sacroiliac joint. It passes into the pelvis medial to the external iliac vein and obturator nerve and lateral to the peritoneum. It frequently terminates into anterior and posterior divisions just superior to the greater sciatic foramen, although anatomical variations are common. "

"The anterior branch or division of the internal iliac artery supplies the pelvic organs, the muscles of the pelvis, muscles of the medial thigh and the perineum. "

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The branches of the posterior division of the internal iliac artery are:

• Iliolumbar artery supplying muscles psoas major, iliacus and quadratus lumborum, and the cauda equina.
• Lateral sacral arteries (posterior and inferior) supplying piriformis, sacral canal, erector spinae and skin.
• Superior gluteal artery supplying piriformis, gluteal muscles and tensor fascia lata.

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"The broad ligament of the uterus is a double layer of peritoneum within which is enfolded the uterine tube, ligament of the ovary and round ligament of the uterus. The broad ligament helps to fix the uterus in its place in the pelvis. The peritoneum which forms the broad ligament passes from the uterus laterally to the side walls and floor of the pelvis. "

"The ovarian artery is a branch of the abdominal aorta, originating inferior to the renal arteries. It descends on the posterior abdominal wall, where it lies anterior to the ureter, and usually gives branches to it. The ovarian artery then crosses the external iliac artery close to its origin and enters the pelvis, where it runs in the suspensory ligament of the ovary and the broad ligament of the uterus, terminating in branches to the ovary and fallopian tube. "

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The relations of the vagina are:

• Anterior :               Cervix, the bladder and urethra.
• Supero-lateral :      Ureter.
• Posterior :              Ampulla of rectum, Pouch of Douglas, perineal body,                                     anal canal.
• Inferiorly :           Anal canal is separated from the vagina by the perineal                                  body.
• Lateral :              Levator ani, uterine artery and urogenital diaphragm.

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"The pelvic floor is formed by the three components of levator ani (pubococcygeus, puborectalis and iliococcygeus) and the coccygeus muscle. "

"Levator ani originates from the posterior of the body of the pubis bone, spine of ischium and the fascia covering obturator internus. "

The levator ani has a broad insertion. The major contribution, pubococcygeus, passes back posteriorly from the pubis and forms a sling around the prostate in the male, or vagina in the female, and inserts into the perineal body. The puborectalis forms a sling around the rectum and anus, with insertions into the anal sphincter. Levator ani inserts into the coccyx as well as the median fibrous raphe between the coccyx and the anorectal junction

The innervation to levator ani and coccygeus arises from S3 and S4 nerve roots. The pudendal nerve supplies the perineal muscles, external urethral sphincter and external anal sphincter. Innervation of the anal canal inferior to the dentate line is from the inferior rectal (anal) nerves that arise from the pudendal nerve.

"The pudendal nerve is formed from the anterior divisions of the ventral rami of S2-S4. "

"The pudendal nerve innervates the perineum, including the perineal muscles and external urethral and anal sphincters, as well as sensation to the genitalia. "