The document provides an overview of pelvic anatomy including: 1) It describes the three compartments of the pelvis (anterior, middle, posterior), pelvic structures like the bladder, uterus and rectum, and three supporting structures (endopelvic fascia, pelvic diaphragm, urogenital diaphragm). 2) It explains the pelvic diaphragm muscles (levator ani, puborectalis), their roles in support and continence, and how they can be identified on MRI. 3) It discusses the endopelvic fascia and its role in supporting pelvic organs, as well as ligaments like the uterosacral lig

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 radiographics.rsna.org
September-October 2014

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

5. Gives 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
• Its 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:
Ischiococcygeus,
• Iliococcygeus, Pubococcygeus, and
Puborectalis (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 coronal planes)
The Puborectalis muscle has a U-shape sling-like
appearance, inserting in the parasymphiseal area and
going around the posterior wall of the rectum (seen
on axial 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
1) The common iliac divides into internal and
external artery.
2) 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 promontory4

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. Two 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. Male 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.

43. 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.

44. • 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)

46. • Preparation of the splanchnic nerves at the mid-posterior sidewall,
• The 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

47. Splanchnic (erigent) nerves travel on
piriformis muscle covered by a frail
fascial sheath

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

49. 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

51. 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.

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