Pelvic anatomy

ANATOMICAL AND LAPAROSCOPIC BY DR PRITHEESH

1. ANATOMY OF PELVIS PRESENTER - DR. PRITHEESH RAJAN MODERATOR - PROF. VISHAL GUPTA

2. INTRODUCTION Anterior – Bladder and urethra Middle – Uterus, cervix and vagina Posterior – Rectum, anus and anal sphincter Salvador et al. Insights into Imaging (2019) 10:4 Milana Flusberg et al Springer Nature 2019

3. Connecting these compartments there are three structures responsible for the pelvic support: ( craniocaudally ) Endopelvic fascia Pelvic diaphragm Urogenital diaphragm Restricted to Anterior and Middle García del Salto et al r adiographics.rsna.org September-October 2014

4. The integrity of the support of the pelvic organs is dependent upon the following complex of structural features : Extraperitoneal smooth muscle and associated visceral ligaments passing from the pelvic sidewalls to the viscera Musculature, aponeurotic tissues, and fasciae of the pelvic diaphragm Muscles, cavernous tissues, and fasciae of the urogenital triangle, including the perineal membrane Salvador et al. Insights into Imaging (2019) 10:4

5. G ives support to all pelvic organs, covering superiorly the levator ani muscle . Anterior compartment , it gives rise to: the pubocervical ligaments; the three groups of ligaments that support the urethra : periurethral , paraurethral , and pubourethral and the pubovesical ligaments . Middle compartment it relates to the parametrium and paracolpium,where the cardinal ligaments and uterosacral ligaments are located. Salvador et al. Insights into Imaging (2019) 10:4 Endopelvic Fascia

6. Posterior compartment I ts midline condensation originates the perineal body in the anovaginal septum, serving as an anchor of support for multiple muscles and ligaments and preventing the expansion of the urogenital hiatus . It continues as the rectovaginal fascia, between the posterior wall of the vagina and the anterior wall of the rectum. Lateral condensations represent the tendinous arch, providing passive pelvic support and serving as a point of attachment of the levator ani muscle

7. On MR images , only the urethral ligaments, the perineal body and sometimes the uterosacral ligaments can be identified. Others can be inferred only from anatomic defects that usually result in pelvic prolapses. Salvador et al. Insights into Imaging (2019) 10:4

8. Pelvic Diaphragm Consists of four muscles: I schiococcygeus , I liococcygeus , P ubococcygeus , and P uborectalis (the three forming the levator ani muscle). Skandalakis ' Surgical Anatomy 2e

9. Levator Ani Levator ani composed of three muscles: Puborectalis Pubococcygeus iliococcygeus . ( Shafik considers the puborectalis to be part of the external sphincter and not a part of the levator ani ) Skandalakis ' Surgical Anatomy 2e

10. Skandalakis ' Surgical Anatomy 2e

11. Puborectalis The puborectalis forms the so-called anorectal ring with the superficial and deep parts of the external sphincter and the proximal part of the internal sphincter . Skandalakis ' Surgical Anatomy 2e

12. These muscles, at rest , are tonically and simultaneously contracted, in order to provide pelvic floor tone, support the pelvic organs, and maintain continence. The two most important and easily identified on MR images are the iliococcygeus and puborectalis muscles. Midline openings : urogenital hiatus and the rectal hiatus. Salvador et al. Insights into Imaging (2019) 10:4

13. Iliococcygeus fans out laterally from the external anal sphincter and inserts in the posterior part of the tendinous arch ( seen on corona l planes) The P uborectalis muscle has a U-shape sling-like appearance, inserting in the parasymphiseal area and going around the posterior wall of the rectum (seen on axia l planes ), defining the anorectal junction

14. Levator Plate The striated musculature between the coccyx and the rectum, including the iliococcygeus and the posterior part of the pubococcygeus , forms the " levator plate ." The strength of the levator plate and its degree of angulation with the horizontal plane from the coccyx to the rectum are both of importance in maintaining fecal continence. The normal levator plate ascends to meet the organs, impinging upon them and preventing their prolapse.

15. Observations Regarding the Pelvic Floor The pelvic diaphragm prevents evisceration and never prolapses. Together with the anal sphincters, the anococcygeal ligament, and the perineal body, it supports the rectum and anal canal In both male and female, the puborectalis is the most important sling . The passive stretching and active contraction of the iliococcygeus participates in the mechanisms of defecation, micturition, and parturition. The obturator nerve supplies the adductor muscles of the thigh. It is the most important nerve to protect in the superolateral wall of the true pelvis

16. The pudendal nerve and internal pudendal artery and vein provide neural and vascular supply for the perineum and, in part, for the pelvic floor. The internal iliac vessels, the hypogastric nerve, and the pelvic splanchnic nerves provide the blood supply and innervation to the rectum and urinary bladder . The endopelvic fascial lining of the muscles ( pelvic surface ) is essentially continuous with the transversalis fascial layer of the abdominal cavity. Skandalakis ' Surgical Anatomy 2e

17. Boat in Dock Analogy Boat – Pelvic Organs Water – Pelvic Floor Muscles Ropes – Ligaments that support pelvic organ Problem is with the Water or Ropes or both Result is sinking of the Boat Really the boat itself is fine Pelvic Floor Anatomy and Pathology J.O.L. DeLancey

18. Pubococcygeal Line A straight line connecting the inferior border of the pubic symphysis to the last coccygeal joint . This represents the plane of attachment of the pelvic floor muscles , used as reference for measuring organ prolapses and drawn in the midline sagittal plane. In healthy asymptomatic patients, the movement of pelvic organs in any phase of the MR defecography is minimum and never more than 1 cm below this line Salvador et al. Insights into Imaging (2019) 10:4

19. The next important mark is the posterior wall of the rectum at the anorectal junction. This is the point where the puborectalis muscle slings around the rectum . To this anatomical point converge two important lines : H and M lines.

20. It is easily individualized in the axial plane, when searching for the puborectalis muscle. Midline sagittal plane, it is defined as the point of taper and angulation of the distal part of the rectum as it meets the anal canal .

21. HMO Classification system A - the inferior margin of the symphysis pubis. B - the posterior aspect of the puborectalis muscle sling. C - the junction between the first and second coccygeal elements PCL  A to C H line  A to B M Line shortest distance between B & PCL XHinaArif -Tiwari et al Current Problems in Diagnostic Radiology 2018

22. Both these lines are dynamic , shrinking or elongating depending on the degree of contraction or relaxation of the pelvic floor muscles, respectively . Normal distances are considered not to exceed 5 cm and 2 cm, for the H and M line respectively. These two lines are important to grade the severity of pelvic floor relaxation.

23. The posterior wall of the anorectal junction serves also as the apex of the anorectal angle, between the posterior border of the distal part of the rectum and the central axis of the anal canal . Normal measures obtained at rest are considered between 108° and 127° As the levator ani muscle contracts, the anorectal angle is decreased to about 15° to 20°. The anorectal angle is important to access the pelvic diaphragm basal tonus and the ability to normally contract and relax. Salvador et al. Insights into Imaging (2019) 10:4

24. Rest Squeeze Evacuation

25. Perineal Body ( Center ) and Perineal Hernia The perineal body, located under the pelvic floor, is formed by the attachments of several muscles. These include the following: Superficial transverse perineus Bulbospongiosus Sphincter urethrae in the male Sphincter urethrovaginalis and deep transverse perineus muscles in the female Superficial part of the external anal sphincter Levator prostatae and pubovaginalis of the levator ani Skandalakis ' Surgical Anatomy 2e

26. The perineal body is a midline landmark between the anterior and posterior triangles of the perineum. It gives some support to the levator ani muscle and thus to the pelvic organs . A perineal hernia is the protrusion of a viscus through the floor of the pelvis (pelvic diaphragm) into the perineum. A hernial sac is present. Skandalakis ' Surgical Anatomy 2e

27. Perineum Skandalakis ' Surgical Anatomy 2e

28. Boundaries of the Perineum The perineum is a diamond-shaped region. The arcuate pubic ligament, the tip of the coccyx, and the ischial tuberosities form its angles Anterior : pubic symphysis Anterolateral: ischiopubic rami Inferolateral : ischial tuberosities Posterolateral: sacrotuberous ligaments and gluteus maximus Posterior: coccyx

29. Perineum Complex Membranous fascial layer of Colles and superficial perineal cleft below Superficial perineal pouch (superficial compartment) Deep perineal pouch (urogenital diaphragm) Ischioanal (formerly ischiorectal ) fossae Various fasciae of the perineum Perineal center (perineal body) Pelvic diaphragm

30. Laparoscopic Anatomy Laparoscopic Pelvic Anatomy in Females Shailesh Puntambekar Sambit M. Nanda

31. At the level of Sacral Promontory str The common iliac divides into internal and external artery. The ureter crosses the common iliac artery from the lateral to the medial side and continues to remain as the most medial tubular structure . 3 ) The superior hypogastric plexus lies at that level and the hypogastric nerves then travel on the posterolateralside of the organs .. These nerves lie at a deeper plane than the ureter. Remaining at the level of ureter will prevent damage to the nerves

32. From the sacral promontory to the pelvic diaphragm there is Waldeyer’s fascia which covers the presacral veins . During the surgical dissections this fascia should not be violated as there can be torrential bleeding. The risk of damaging the fascia is when one takes suture to fix the mesh at the sacral promontory 4

33. Fascial Anatomy

34. This fascia helps separate the bladder from the uterus . Fat belongs to bladder is the dictum to be followed here . Forceful encroachment into the fascia leads to haemorrhage.

35. The avascular fascia behind the rectum

36. Under the Waldeyer’s fascia lie the important ( vital) presacral veins which tend to bleed torrentially when injured. Hence it is important to always remain anterior and above the Waldeyer’s fascia. Fat belongs to rectum . Thus here in this fascia own goal is to remain below the fat as the rectum is above. The avascular plane of dissection lies below the fat always.

37. The presacral veins comprise the medial and the lateral presacral veins. While the medial sacral vein drains directly into the inferior vena cava or the left common iliac vein, the lateral sacral vein drains into their ipsilateral internal iliac veins . Presacral veins drain intercommunicated with the intervertebral veins which flow independently . Thus in case of presacral vein injury bleeding is torrential and not controlled easily

38. T wo layered and the desired plane of dissection lies between the two layers of the fascia . The first step of the Denonvilliers ’ fascia dissection is the posterior U-cut. Fat belongs to rectum . Always dissect above the level of fat so that the fat falls down as a part of the rectum

39. Ian Lindsey et al DCR Sep 2004

40. M ale specimens as three fascial layers originating from the perineal body, seminal vesicles and posterior bladderneck . The first layer merged posterolaterally and fused with the rectosacral fascia ( Waldeyer’s fascia). The neurovascular bundle in male specimens was observed piercing the second and third layers, while the first layer acted as a protective cover . Dissection of female specimens demonstrated only one layer in the prerectal space .

41. Yabuki’s space The right-angled triangular space between the uterus surface, bladder surface and anterior cervicovesical ligament is called as the Yabuki space. The hypotenuse is composed of the anterior cervicovesical ligament . It contains the ureter and the pelvic splanchnic nerves which supply the bladder. The pyramidal space with its tip pointing inwards to the medial midline side.

42. The sympathetic superior hypogastric plexus condenses into two strong hypogastric nerves that travel laterally to merge with the parasympathetic splanchnic ( erigent ) nerves(S2–S4 ) within the inferior pelvic plexus. Mixed nerve fibres branch to the bladder and prostate (bundle of Walsh)

43. P reparation of the splanchnic nerves at the mid-posterior sidewall, T he hypogastric nerves at the upper sidewall The urogenital nerve branches (Walsh) at the caudal-anterior sidewall The dissection of the lateral ligament is strictly performed as the last step

44. S planchnic ( erigent ) nerves travel on piriformis muscle covered by a frail fascial sheath

45. Dissection (“sliding down”) of the left hypogastric nerve from the promontory (blue arrow) until the lateral ligament is reached ( green arrow )

46. Lateral ligament on the left sidewall (T-junction) (4) with the mesorectum (3) retracted to the right. (1) left hypogastric nerve; (2) neurovascular bundle Walsh; (5) levator ani

47. An international consensus definition for the rectum is the point of the sigmoid take-off as visualized on imaging. The sigmoid take-off can be identified as the mesocolon elongates as the ventral and horizontal course of the sigmoid on axial and sagittal views respectively on cross-sectional imaging. Routine application of this landmark during multidisciplinary team discussion for all patients will enable greater consistency in tumour localization.

48. SHACKELFORD’S SURGERY OF THE ALIMENTARY TRACT, EIGHTH EDITION