CHAPTER 4 Surgical Anatomy of the Pelvis
BONY ANATOMY AND PELVIC SPACES
Which is the thinnest of the pelvic bones?
The pubic bones, which are often fractured in blunt pelvic trauma. Their fragments may injure the bladder, urethra, and vagina.
True/False: The sacroiliac (SI) joint is often fractured in pelvic trauma.
False. The synovial SI joint gains additional strength from anterior and posterior ligaments and fractures rarely involve this joint.
Where is Bogros space, what does it represent, and what are its anatomical limits?
Bogros space is located at the pelvic opening of the spermatic cord. It is lateral and superior to Retzius space. It represents the retroinguinal preperitoneium. Its limits are:
• Medially: Epigastric vessels, spermatic cord, iliac vessels, and space of Retzius.
• Anteriorly: Transversalis muscle.
• Laterally: Psoas muscle and lateral cutaneous nerve.
Where is the border between the true and false pelvis?
The boundary between the 2 is the arcuate line that starts at the superior pubic ramus and extends to the sacral promontory.
How many openings are there in the true bony pelvis? Name them.
Eight. Paired—greater and lesser sciatic foramina, obturator foramina; nonpaired—pelvic inlet and pelvic outlet.
What effect has congenital nonunion or resection of the pubic symphysis on the ambulation of the patient?
It does not have any significant effect owing to the strength of the SI joint.
What are the major osseous ligaments of the pelvis?
Sacroiliac, pubic symphysis, sacrococcygeal, and sacrosciatic.
What passes through the anourogenital hiatus?
Urethra, vagina (females), and rectum.
What are the boundaries of the greater sciatic foramen?
Laterally and superiorly: Greater sciatic notch.
Medially: Sacrotuberous ligament.
What structures are found in Alcock canal and what is another name for Alcock canal?
The pudendal (Alcock) canal runs approximately 4 cm above the lower ridge of ischial tuberosity and contains the pudendal artery, pudendal veins, and the pudendal nerve; all are invested in connective tissue, binding these structures to the perineal surface of the obturator internus fascia.
VASCULAR ANATOMY
True/False: As the dorsal vein of the penis passes within the pelvis under the pubic arch it forms a venous complex and part of this complex runs within the anterior and lateral walls of the striated urinary sphincter.
True. One must be cautious during ligation and division of the dorsal venous complex, as damage to the striated sphincter can occur.
What anatomic reason may account for the relatively higher incidence of axial skeletal and pelvic bone metastases in patients with metastatic prostate cancer, as opposed to lung metastases for example?
There are numerous interconnections between the pelvic venous plexuses and the emissary veins of the pelvic bones and vertebral venous plexuses, which may be routes of dissemination of infection or tumor from the diseased prostate.
What artery has its origin off the inferior epigastric artery and can be identified medial to the femoral vein during pelvic surgery?
The accessory obturator artery arises from the inferior epigastric artery in 25% of patients and continues on through the obturator canal.
Following a radical dissection of inguinal lymph nodes for penile carcinoma, the surgeon decided to cover the area with a rectus myocutaneous flap. Where does the blood supply come from for this flap?
Ipsilateral inferior epigastric artery.
What is the most common origin of the superior vesical artery?
The proximal portion of the obliterated umbilical artery.
What structures besides the rectum does the middle rectal artery supply?
The middle rectal artery anastomoses with the superior and inferior rectal arteries to supply the rectum. It also gives small branches to provide additional arterial supply to the seminal vesicles and prostate.
What accessory vein drains into the inferior surface of the external iliac vein in at least 50% of patients?
The accessory obturator vein. Care must be taken to not tear this vein at the time of pelvic lymph node dissection.
True/False: Intramural longitudinal vessels run the length of the ureter in 75% of patients.
True. These vessels are formed by anastomoses of segmental ureteral vessels. In the other 25% of patients, the intramural ureteral vessels form a fine interconnecting mesh with less collateral flow and render the ureter more prone to ischemic insult. This intramural, interconnecting meshlike vascular pattern is often found in the pelvic ureter, and therefore, this portion of the ureter is less suited for ureteroureterostomy.
What is one of the main reasons that the primary repair of the pelvic ureter is often prone to strictures?
The blood supply of the pelvic ureter is based on longitudinal collaterals that run along it, which are often severed following both the primary injury to the ureter and subsequent mobilization during its repair, thus limiting its blood supply with a high risk for ischemic strictures.
What arteries usually supply the ureter with its largest pelvic branches?
The inferior vesical and uterine arteries.
In a normal adult male, at what anatomic location are the ureters closest to each other?
The ureters are closest and are located within 5 cm of each other as they cross the iliac vessels.
What is the principal arterial supply to prostatic adenomas in benign prostatic hyperplasia and where are the origin and principal branches of the prostatic artery?
The inferior vesical arteries have urethral artery branches that enter the prostate posterolaterally at its junction with the bladder and these branches are the principal arterial supply to the adenomas. There is also a capsular branch. The short segment at the end of the inferior vesical artery after all the branches to the bladder but before the bifurcation between the capsular and urethral branches is called the prostatic artery. It can be embolized in selected cases for treatment of benign prostatic hyperplasia (BPH) or intractable prostatic bleeding.
What structures do the uterine arteries supply?
The proximal vagina, uterus, and medial two-thirds of the fallopian tubes.
When an accessory pudendal artery is present and is supplementing or replacing the penile arterial supply by the common penile artery, what is its origin?
An accessory pudendal artery is present in approximately 4% of patients undergoing a radical retropubic prostatectomy and arises from the inferior vesical artery, superior vesical artery, and obturator artery.
What are the anatomic relations of the internal pudendal artery in the male?
The internal pudendal artery in the male lies anterior to the piriformis muscle, sacral plexus of nerves, and the inferior gluteal artery. As it crosses the ischial spine, it is covered by the gluteus maximus muscle and overlapped by the sacrotuberous ligament. The pudendal nerve is medial to the artery while the nerve to the obturator internus muscle is lateral to the internal pudendal artery.
What is the anatomic course of the accessory pudendal artery in relation to the prostate gland?
It runs anterolateral to or within the prostate to reach the penis.
What is the relation of spermatic cord to the deep external pudendal artery?
The spermatic cord is crossed posteriorly by it.
If the right internal iliac artery was ligated, what principal vessels might contribute to collateral circulation?
The following would possibly allow collateral circulation:
• The ovarian artery from the aorta with the uterine artery.
• The vesical arteries of the contralateral side with the same vessels on the ligated side.
• The middle rectal artery branches of the internal iliac artery with the superior rectal artery from the inferior mesenteric artery.
• The obturator artery with the inferior epigastric artery and the medial femoral circumflex artery, and by means of the pubic branch of the obturator artery, with the same vessels from the contralateral side.
• The circumflex artery with perforating branches of the deep femoral artery and the inferior gluteal artery.
• The superior gluteal artery with the posterior branches of the lateral sacral arteries.
• The iliolumbar artery with the last lumbar artery.
• The lateral sacral artery with the middle sacral artery.
• The iliac circumflex artery with the iliolumbar and the superior gluteal arteries.
Where is the aortic bifurcation relatively to the spine?
The aorta gives rise to 2 common iliac arteries at the level of 4th lumbar vertebra.
What artery arises posteriorly at the level of the aortic bifurcation and what does it supply?
It is the middle sacral artery and it supplies the sacral foramina and the rectum.
Does the blood supply to the pelvic ureter enter laterally or medially?
Laterally. The pelvic peritoneum should be incised only medial to the ureter.
What are the branches of the internal iliac artery?
The posterior trunk gives rise to 3 parietal branches: The superior gluteal, the ascending lumbar, and the lateral sacral branches. The anterior trunk gives rise to 7 branches: The superior vesical, the middle rectal, the inferior vesical, the uterine, the internal pudendal, the obturator, and the inferior gluteal branches.
What are the sources of collateral blood supply to the pelvic organs in the case of bilateral ligation of the internal iliac arteries due to massive hemorrhage?
Aortic branches (middle sacral and lumbar arteries) and inferior mesenteric branches (inferior mesenteric artery).
What are the pelvic organs that do not receive blood supply from the internal iliac artery?
Gonads (testicles and ovaries) and superior part of the rectum.
True/False: In a nerve-sparing cystoprostatectomy, the unilateral internal iliac artery should be ligated and divided to improve hemostasis and facilitate the nerve-sparing procedure, thereby possibly maintaining erectile function.
False. The internal iliac artery should be preserved and the superior vesical artery should be ligated and divided proximally in order to maintain the integrity of the internal pudendal artery and to prevent vasculogenic erectile dysfunction.
Which blood vessels run in Camper fascia?
The superficial circumflex iliac, external pudendal, and superficial inferior epigastric vessels. They are branches of the femoral vessels.
What 2 branches of the external iliac artery are within the pelvis?
The inferior epigastric and the deep circumflex iliac arteries.
At what anatomic site does the internal iliac artery branch into its anterior and posterior trunks?
The greater sciatic foramen.
Where is the origin of the obturator artery?
The obturator artery has a variable origin. It can arise from the anterior trunk of the internal iliac artery, the inferior epigastric artery, or the inferior gluteal artery.
What are the branches of the obturator artery within the pelvis?
The iliac, vesical, and pubic arterial branches. The iliac branches ascend in the iliac fossa and supply the iliacus muscle and ilium, while anastomosing with branches of the iliolumbar artery. The vesical branch courses medially and posteriorly to help supply the bladder. The pubic branch arises from the obturator artery just before it leaves the pelvis and ascends inside the pelvis to communicate with the same vessel on the contralateral side and with the inferior epigastric vessels.
The middle sacral vein is usually a tributary of which vein?
The left common iliac vein.
What are the origins of the arteries that supply the seminal vesicles?
These arteries are derived from the middle vesical, inferior vesical, and middle rectal arteries.
What is the venous drainage of the vagina?
The venous drainage occurs by means of the vaginal plexus of veins along the lateral aspect of the vagina. These are in continuity with the uterine, vesical, and rectal venous plexuses. The vaginal plexuses are drained by 1 or 2 vaginal veins on each side that flow into the internal iliac veins either directly or through the connections with the internal pudendal veins.
During a radical cystectomy (anterior exenteration) and an ileal conduit in a 65-year-old female, the vagina is observed to have very good vascular supply when the anterior wall is resected en bloc with the specimen. What is the main arterial supply to the vagina?
The vaginal arteries, which can be represented by 1, 2, or 3 arterial vessels. These include arterial branches that can arise from the uterine artery, inferior vesical artery, or separate arterial branches directly from the anterior trunk of the internal iliac artery.
In what percentage of patients undergoing radical retropubic prostatectomy does the superficial dorsal vein of the penis appear to be absent?
Approximately 10%.
During a radical cystectomy and pelvic lymph node dissection, care should be taken to avoid dissection below the presacral fascia. Why?
This dissection may disturb the presacral veins and cause unnecessary blood loss.
What is the arterial supply to the rectum?
• Inferior mesenteric artery to superior rectal
• Internal iliac artery to middle rectal
• Internal iliac to internal pudendal to inferior rectal
What 2 tubular structures can be identified near the cervico-uterine junction upon opening the broad ligament between the round ligament and the infundibulopelvic ligament?
Uterine artery and, beneath it, the ureter.
What life-threatening complication can occur while dissecting posterior to the rectum?
Damage to the presacral venous plexus can be massive and very difficult to control.
LYMPH NODES AND DRAINAGE
To what nodal locations do the lymphatics of the vas deferens and seminal vesicles drain?
The external and internal iliac lymph nodes.
True/False: The external iliac lymph nodes can be further separated anatomically and functionally into 3 chains.
True. The external, middle, and internal chains. For example, the external chain does not receive any lymphatic drainage from organs within the pelvis and these lymph nodes are located lateral to the external iliac vessels.
What is the lymph node of Cloquet anatomic location?
The lymph node of Cloquet lies within the femoral canal, medial to the external iliac vein, and beneath the inguinal ligament.
Lymphatics from the pelvis and testes cross the midline at what level?
At the level of the renal hilum.
How many external iliac lymph nodes are usually present in the normal adult and what is their anatomic arrangement?
There are usually 8 to 10 external iliac lymph nodes that lie along the external iliac vessels. They are arranged in 3 groups. One group is on the lateral aspect, another on the medial aspect, and a third group on the anterior aspect of the external iliac vessels. The third group of lymph nodes on the anterior aspect of the vessels is sometimes absent.
What are the primary lymph nodes that drain the uterus?
The external and internal iliac nodes, obturator nodes, para-aortic nodes (accompanying the drainage of ovary), and superficial inguinal nodes (through round ligament).
How does a previous inguinal surgery (ie, orchiopexy) influence the possible distribution of metastatic disease in testicular cancer?
It can alter the lymphatic drainage, hence allowing additional routes for lymphogenic spread, for example to inguinal, iliac, and obturator lymph nodes.
NERVES AND INNERVATION
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