1. THE PELVIS
DR. J.K. GERALD, (MD, MSc.)
DEC. 2014

2. THE PELVIS
The pelvis is the region of the trunk that lies below the abdomen.
The pelvic cavity is continuous with the abdominal cavity.

3. THE OSTEOLOGY OF PELVIS
THE BONY PELVIS
The bony pelvis is formed by 4 bones;
1) 2 Hip / Innominate bones
Each hip bone is formed by fusion of 3 bones – ilium, ischium and pubis.
2) Sacrum
formed by fusion of 5 sacral vertebrae
3) Coccyx
formed by fusion of 4-5 coccygeal vertebrae

4. THE BONY PELVIS
RIGHT HIP BONE
SACRUM
LEFT HIP BONE
COCCYX

5. THE BONY PELVIS: JOINTS
SACROILIAC JOINT
SACROCOCCYGEAL JOINT
PUBIC SYMPHYSIS

6. FUNCTIONS OF BONY PELVIS
1) To protect pelvic viscera
2) To support the weight of the body - transfer the weight of the upper body from the axial to the lower appendicular skeleton
3) Provides attachment for muscles
4) In females, it provide bony support for the birth canal

7. HIP BONE 2 hip bones are joined anteriorly at the pubic symphysis
Hip bones articulate posteriorly with the sacrum at the sacroiliac joints
Ilium, ischium and pubis are fused at the acetabulum

8. Acetabulum

9. HIP BONE
Ilium
Acetabulum
Pubis
Ischium

10. ILIUM PUBIS ISCHIUM Ala of ileum Body of ilIum Iliac crest Iliac fossa
ASIS
AIIS
PSIS
PIIS
PUBIS
Body of pubis
Superior ramus of pubis
Inferior ramus of pubis
Pubic crest
Pubic tubercle
Subpubic angle
ISCHIUM
Body of ischium
Ramus of ischium
Ischial spine
Ischial tuberosity

11. Body
Ramus

12. Pubic tubercle
Body

13. THE SACRUM Is made up of 5 fused sacral vertebrae Triangular in shape
Is divided into central mass and lateral mass
Lateral mass
Central mass
Tranverse ridge

14. SACRUM: ANTERIOR SURFACE
Sacral promontory
Ala
Ala/wing
Ant. sacral foramina
Sacrococcygeal joint
coccyx

15. SACRUM: POSTERIOR SURFACE
Sacral canal
Median crest
Post. sacral foramina
Sacral cornu
Sacral hiatus

16. THE BONY PELVIS: LIGAMENTS

18. CLASSIFICATION OF PELVIS
The pelvis is divided by the pelvic brim into 2 parts:
1) False pelvis (greater/major pelvis)
Lies above the pelvic brim/inlet
Part of abdominal cavity
2) True pelvis (minor/lesser pelvis)
Lies inferior to pelvic brim/inlet
Is the true pelvic cavity

19. TRUE & FALSE PELVIS
False pelvis
Abdominal cavity
True pelvis

21. APERTURES OF TRUE PELVIS
Two apertures:
Pelvic inlet ( = pelvic brim)
also called superior pelvic aperture
2. Pelvic outlet
also called inferior pelvic aperture
closed by the pelvic diaphragm / floor.

22. PELVIC INLET Pelvic inlet/brim is bounded by:
1. Superior margin of pubic symphysis
2. Pubic crest
3. Iliopectineal line
4. Anterior border of ala of sacrum
5. Sacral promontory

23. PELVIC INLET

24. MEASUREMENTS OF PELVIC INLET
Four diameters of pelvic inlets
1) Anteroposterior (true conjugate)
2) Diagonal conjugate – can be measured clinically
3) Obstetric conjugate
4) Transverse diameter

27. DIAMETER OF PELVIC INLET Anterior-posterior ( True conjugate )
Measurement
Extension
Diameter
Anterior-posterior ( True conjugate )
From the sacral promontory  superior margin of pubic symphysis
11.5 cm
Diagonal conjugate
Sacral promontory  inferior margin of the pubic symphysis
12.0 cm
Obstetric conjugate
Sacral promontary  nearest point on posterior surface of pubic symphysis
10.5 cm
Transverse diameter
The widest distance across pelvic brim
13.5 cm

28. MEASUREMENTS OF PELVIC INLET
Obstetric conjugate is clinically important – It is shortest AP diameter through which the head must pass. But cannot be measured clinically.
Diagonal diameter can be measured clinically through vaginal examination (PV Exam.)

29. Vaginal Examination to Determine Diagonal Conjugate

30. PELVIC OUTLET Diamond shaped Is bounded by:
1) Inferior margin of the pubic symphysis
2) Inferior rami of the pubis
3) Ischial tuberosities
3) Sacrotuberous ligaments
4) Tip of coccyx

32. MEASUREMENTS OF PELVIC OUTLET
Three diameters of pelvic outlet are usually described:
1) Anteroposterior
2) Transverse (intertuberous)
- can be estimated
3) Posterior sagittal

33. Pelvic outlet viewed from below
Ischial tuberosity
Pelvic outlet viewed from below

34. sacrococcygeal joint
Pubic symphysis

35. DIAMETER OF PELVIC OUTLET
Measurement
Extension
Diameter
Anteroposterior diameter
From lower margin of pubic symphysis  sacrococcygeal joint
12.5 cm
Transverse diameter (intertuberous)
Between the ischial tuberosities
(Diameter > 8 cm – normal)
11 cm
The largest diameter of pelvic outlet = AP diameter

36. ROTATION OF FETAL HEAD
Widest diameter of pelvic canal changes from transverse diameter at pelvic inlet to AP diameter at pelvic outlet.

37. To obtain best fit of fetal head, the longest diameter of the fetal head passes through the widest diameter of the pelvis. Therefore the head must rotate during labour.
Failure to rotate or unusual presentation of the fetal head will lead to cephalopelvic disproportion (CPD).

38. WALL OF PELVIC CAVITY The wall of the true pelvis is formed by:
Anteriorly: pubic symphasis, body of pubis, pubic rami , rami of ischium and obturator membrane
Laterally by ischial bone & sacrosciatic ligaments
Posteriorly by sacrum & coccyx

39. WALLS OF PELVIC CAVITY 1) Anterior pelvic wall 2) Lateral pelvic wall
3) Posterior wall
4) Pelvic floor

40. PELVIC FLOOR
Pelvic floor is formed by pelvic diaphragm which is composed of :
1) 3 Levator ani m.
Puborectalis
Pubococcygeus
Iliococcygeus
2) Coccygeus m. (Ischiococcygeus)

41. LEVATOR ANI MUSCLES
Contraction of levator ani muscles raises the entire pelvic floor
Functions:
1) Control of urination & defecation
Relaxation of levator ani muscle allow urination & defecation to occur
2) Support for viscera (eg. uterus, bladder)
3) Helps direct fetal head toward birth canal at parturition

42. LEVATOR ANI MUSCLES INJURY
Levator ani muscles often stretch and can be injured during childbirth.
Of these, pubococcygeus muscle is more commonly damaged
These injuries may predispose women to greater risk of pelvic organ prolapse and urinary incontinence.

43. MALE VS FEMALE PELVIS
There are a large number of differences between male and female pelvis. These differences are basically related to 2 factors :
1) In male - the heavier build and stronger muscles in the males accounting for the stronger bone structure and better defined muscle markings.
2) In females - comparatively wider and shallower pelvic cavity in female correlated with its role as bony part of the birth canal.

44. FEMALE MALE Bones are lighter, thinner False pelvis is shallow
Subpubic angle
Bones are lighter, thinner
False pelvis is shallow
Pelvic cavity is wide & shallow
Pelvic inlet round/oval
Pelvic outlet comparatively large
Subpubic angle large
Coccyx more flexible, straighter
Ischial tuberosities more everted
Bones heavier, thicker
False pelvis is deep
Pelvic cavity is narrow & deep
Pelvic inlet heart-shaped + smaller
Pelvic outlet comparatively small
Subpubic angle more acute
Coccyx less flexible, more curved
Ischial tuberosities longer, face more medially

45. VARIATIATION OF PELVIC SHAPE
Female pelvis shapes may be subdivided as follows
1. Normal and its variants
- Gynaecoid – most common type , suited for delivery
- Android – the masculine type of pelvis
- Platypelloid – flat pelvis; short AP diameter & wide transverse diameter
- Anthropoid – resembling that of anthropoid ape, AP diameter is greater than the transverse diameter (pelvic inlet)
2. Symmetrically contracted pelvis
- That of a small women but with a symmetrical shape

46. - This deformity is caused by rickets (due to Vit D deficiency)
3. Rachitic pelvis
- This deformity is caused by rickets (due to Vit D deficiency)
- Sacrum is rotated so that the sacral promontory projects forward and coccyx tips backward
- AP diameter of inlet is therefore narrowed but the outlet is increased
4. Asymmetrical pelvis
- Asymmetry pelvis can be due to variety of causes such as scoliosis, poliomyelitis, pelvic fracture, congenital abnormality due to thalidomide etc
Rachitic pelvis
Asymmetrical pelvis

47. Caldwel and Moloy Classification - based on the diameters of the pelvic inlet: 1. Gynecoid (41%) 2. Android (33%) 3. Anthropoid (24%) 4. Platypelloid (2%)

48. APPLIED ANATOMY 1. Fractures of the Pelvis
APPLIED ANATOMY 1. Fractures of the Pelvis - Usually brought about by direct trauma. - Secondary hemorrhage is common cause of death. - Associated with damage to pelvic viscera. 2. Uterine and Vaginal Prolapse Due to injury to pelvic floor via difficult childbirth.

49. Fractures of Pelvis

51. FEMALE PELVIC VISCERA

52. Female Pelvic viscera:
Ovaries
Fallopian tubes
Uterus
Ureters
Urinary bladder
Urethra
External genital

53. UTERUS Thick, muscular organ Divided into 3 parts:
-fundus, body and cervix.
Composed of 3 layers: endometrium, myometrium, and perimetrium.

54. Uterine cavity
Fundus
Body
Cervical canal
Cervix

56. FALLOPIAN TUBES 10-14 cm in length, <1 cm in diameter
Isthmus - 1 mm in diameter - perfect spot for tubal ligation.
Ampulla - 6mm in diameter - fertilization occurs here as well as most ectopics .

59. LIGAMENTS Round Ligament: Fibrous and muscle tissue
Anterior to the fallopian tubes
They extend laterally, cross the external iliac vessels, and enter the internal inguinal ring, and insert in the labia majora.
Sampson’s artery; a branch of the uterine artery, runs along the length of the round ligament.

60. LIGAMENTS Broad Ligament:
Double reflection of the peritoneum, draped over the round ligaments.
Cardinal Ligament:
Found at the base of the broad ligament.
Provides the main support for the uterus and cervix.
It attaches to the cervix and extends laterally, connecting to the endopelvic fascia.

61. LIGAMENTS Uterosacral Ligaments: Provide minor cervical support.
Originate from the upper posterior cervix, travel around the rectum bilaterally, and fan out to attach to the 1st - 5th sacral vertebrae.

64. Pouch of Douglas / Rectouterine pouch
vesicouterine pouch
Peritoneum
uterus
Pubic symphysis
coccyx

65. Pouch of Douglas:
a.k.a Rectouterine pouch.
An extension of the peritoneal cavity between the rectum and the post. wall of the uterus. In women it is the deepest point of the peritoneal cavity.
As it is the furthest point of the abdominopelvic cavity in women, it is a site where infection and fluids typically collect.

67. OVARIES
They rest in the ovarian fossa, immediately adjacent to the iliac vessels and the ureters.
Supported along the lateral pelvic sidewalls by the:
Ovarian ligaments: attaching to the posterolateral aspect of the uterus,
Mesovarium: anastomotic region of the uterine and ovarian vessels, and
Infundibulo-pelvic ligament (IP Ligament)
a.k.a suspensory ligament of ovary.
Reflections of the broad ligament attaching the ovaries to the lateral pelvis.

68. URETERS
Ureters originate in the renal calyxes and insert into the inferior bladder at the trigone.
Lie deep to peritoneum, closely applied to the posterior abd. wall in the upper part, and to the lateral pelvic part in the lower part.
Dimensions: length – 25cm, diameter – 3mm.
Careful attention to ureters path in the pelvis is essential for dissection in gynecologic surgery.

71. URINARY BLADDER It has 4 parts:
Apex
Base (post. surface)
Superior surface
2 Inferolateral surfaces
The apex is directed towards the top of the pubic symphysis

73. PELVIS: BLOOD SUPPLY
Majority originates from the internal iliac artery (aka: hypogastric artery).
Additional supply comes from the ovarian arteries, the inferior mesenteric artery, and the external iliac artery.

74. BRANCHES OF INTERNAL ILIAC ARTERY

77. Ovarian arteries Ovarian veins:
Originate directly from the aorta, inferior to the renal arteries.
Most frequently identified at the IP ligament.
Ovarian veins:
Left ovarian vein drains into the left renal vein
Right ovarian vein drains directly into the inferior vena cava.

79. Venous drainage of the ovary
Lt. renal vein
Inf. vena cava
Lt. ovarian vein
Rt. Ovarian vein
LCIV
RCIV
Rt. ovary
Lt. ovary
uterus

80. FEMALE EXTERNAL GENITALIA = VULVA

83. Urethral Catheterization in female
Clitoris
Catheter
Urethral opening
Vaginal opening
Anus

84. APPLIED ANATOMY Cervical Cancer Uterine Cancer
Uterine fibroids / myomas
Ovarian Cancer
Urinary bladder cancer
Colorectal cancer
Rectovaginal fistula & vesicovaginal fistula

87. Uterine fibroids

88. Surgical Removal of Uterine fibroids

89. CANCER OF CERVIX

90. CANCER OF OVARY

91. The End