Understanding anatomy of the pelvis and perineum

1. Pelvis + Perineum
Dr
Shittu,LAJ

2. Pelvic Cavity
 Enclosed by bony, ligamentous and
muscular wall
 Contains the urinary bladder, ureters,
pelvic genital organs, rectum, blood
vessels, lymphatics and nerves
 Pelvic inlet (superior pelvic aperture)
 Pelvic outlet (inferior pelvic aperture)

3. Superior Apeture

4. Inferior Pelvic Border

5. Bony Pelvis
 Innominate bone (Ilium, ischium and
pubis)
 Sacrum
 Coccyx
 Joined anteriorly by pubic symphysis
 Posteriorly by sacro-iliac joint

6. Bony Pelvis

7. Female Pelvis

8. Male Pelvis

9. Pelvis

10. Greater Pelvis (pelvis major)
 Location of some abdominal viscera (ileum
and sigmoid colon)
 Bounded by abdominal
 wall anteriorly,
 the iliac fossa posteriolaterally and
 L5 S1 vertebrae posteriorly
 a.K.a False Pelvis

11. Lesser Pelvis ( pelvis minor)
 Location of pelvic viscera – the urinary
bladder and reproductive organs such as
the uterus and ovaries
 Bounded by the pelvic surfaces of the
hip bones, sacrum, and coccyx
 Limited inferiorly by the musculofascial
pelvic diaphragm
 AKA True Pelvis

12. Pelvic Walls and Floors
 Anterior pelvic wall – is formed
primarily by the bodies and rami of the
pubic bones and the pubic symphysis
 Lateral pelvic walls – formed by the hip
bones and the obturator internus
muscles (O: proximal surface of the ilium
and ischium; obturator membrane I:
greater trochanter of the femur)

13. Anterior Pelvic Wall

14. Pelvic Walls and Floor
 Posterior Pelvic Wall – formed by the sacrum
and coccyx,
 adjacent parts of the ilia, and the S-I joints;
 piriformis muscle covers the area (O: pelvic
surface of 2nd
and 4th
sacral segments, superior
margin of the greater sciatic notch and
sacrotuberous ligament, I: greator trochanter
of femur)

15. Posterior Pelvic Wall

16. Posterior Pelvic Wall

17. Pelvic Floor
 Formed by the funnel shaped pelvic
diaphragm – consists of the levator ani and
coccygeus muscles and their fascia
 Stretches between the pubis anteriorly and the
coccyx posteriorly and from one lateral pelvic
wall to the other

18. Nerves of Pelvis
 Sacral plexus (to pelvic mm., viscera and perineum)
 Posterior pelvic wall on anterior surface of piriformis m.
 Anterior rami of L4-L5 and S1-S4
 L4-L5 form lumbosacral trunk
 Pudendal n. (S2-S4) leaves via greater sciatic foramen
within Alcock’s canal,
 inferior to piriformis and passes into the lesser sciatic
foramen
 -Alcock’s canal is important for a pudendal nerve block.
 Inferior rectal n.
 Dorsal n. of penis or clitoris
 Perineal n.
 Nerves to piriformis m.
 Perforating cutaneous n.

19. Sacral plexus
 Sacral plexus leaves the pelvis through greater
sciatic foramen (N468)
 Sciatic n. (L4-5, S1-3)
 Superior gluteal n. (L4-5, S1)
 Inferior gluteal n. (L5, S1-2)
 Nerve to obturator internus m. (L5, S1-2)
 Nerve to quadratus femoris m. (L5, S1)
 Posterior cutaneous n. of thigh (S1-3)

20. nerve
 The branches of the pudendal nerve supply most of the
perineal structures. This nerve arises from the 2nd
, 3rd
, and 4th
sacral segments of the spinal cord.
 a. The superficial branches supply: Labia major + External
genital structures
 b. The deep branches supply: Muscles, vestibular bulb,
and the clitoris
 Additional nerves include:
 a. Ilioinguinal- anterior labial nerves
 b. Genital branch of the genitofemeral nerves
 c. Perineal branch of the femoral cutaneous nerve of the
thigh
 d. Perineal nerve- posterior labial nerves

21.  Gluteal nerves:
 A. Superior gluteal vessels:
 a. Innervate and supply the gluteus minimus and gluteus
medius
 b. Superior gluteal nerve arises from the posteror divisions
of the anterior rami of L4 through S1

 B. Inferior gluteal vessels: Innervate and supply the gluteus
maximus.
 a. Innervate and supply the gluteus maximus
 b. Inferior gluteal nerve arises from the posterior divisions
of the anterior rami of L5 through S2


22. The nerve supply to the perineum originates
from three main sources:
 The Genito-femoral Nerve (L1,L2).
 The pudendal nerve
 The perineal branch of the posterior
femoral nerve

23. Pelvic Diaphragm

24. Pelvic Floor - Male

25. Pelvic Floor - Female

26. Pelvic Floor- Lateral Inferior

27. Female – Medial View

28. Levator Ani
 Consists of three parts – the pubococcygeus, the puborectalis
and the iliococcygeus.
 Collectively they run from the body of the pubis, the tendinous
arch of the obturator fascia and the ischial spine TO the perineal
body, the coccyx, the anococcygeal ligament, the walls of the
prostate or vagina, the rectum and the anal canal
 Innervated by the nerve to levator ani from S4 and the inferior
anal (rectal) nerve (from S2-S4) and the coccygeal plexus
 Help to support the pelvic viscera; acting together they raise the
pelvic floor and assist the abdominal muscles in forced expiration
activities

29. Perineal Body

30. Coccygeus Muscle
 O: ischial spine, I: inferior end of the
sacrum, I: branches of S4 and S5
 Forms a small part of the pelvic
diaphragm that supports the pelvic
viscera, flexes the coccyx

31. Viscera
 Urinary organs in the pelvis
 Ureters – muscular (smooth) tubes
running from kidneys to bladder 25 to 30
cm long
 Bladder – a hollow container surrounded
by a strong smooth muscular wall
 Temporary reservoir for urine
 Apex, Body, Fundus, Neck, Uvula

32. Ureters

33. Bladder

34. Bladder

35. Bladder

36. Pelvic Viscera - Female

37. M v. F Bladder

38. Viscera
 Bladder Continued
 Detrussor muscle – smooth muscles
surrounds bladder
 Internal sphincter muscle
 Innervation – Parasympathetic to
detrussor (S2-S4)); Sympathetic to
internal sphincter (T12-L1/L2)

39. Viscera
 Ureter
 Urinary urethral orifice in bladder to
external urethral orifice
 External sphincter – somatic nerves from
S2-S4)
 Prostate

40. Female Urethra

41. Female Urethra

42. Male Urethra

43. Male Urethra

44. Uterus

45. Rectum
 Alimentary canal (GI Tract) connects
sigmoid colon with anus
 Follows the curve of the sacrum and
coccyx
 Innervated by sympathetic (T12/L1)and
parasympathetic nerves (S2-S4)

46. Rectum

47. Rectum and Anal Canal

48. Perineum
 Lies inferior to the pelvic outlet and is
separated from the pelvic cavity by the
pelvic diaphragm (Levator ani and
coccygeus muscles)
 Bounded by Pubic symphysis anteriorly;
inferior pubic rami and ischial rami
anterolaterally; ischial tuberosity laterally;
sacrotuberous ligament posterolaterally;
inferiorly by sacrum and coccyx

49. Perineum
 Two Triangles
• Anal triangle (posterior) contains the anus
• Urogenital triangle (anterior) contains the root of the
scrotum and penis in males or the external genitalia in
females
 The perineal membrane stretches between the two
sides of the pubic arch and covers the anterior part of
the outlet
 The perineal body is an irregular fibromuscular mass
located between the anal canal and the perineal
membrane

50. Triangles

51. Perineal Body

52. Perineal Membrane

53. Perineum-Female

54. Perineum - Male

55. Perineum
 Muscles
 Bulbospongiosus – F O: central tendon of
perineum, M O: central tendon of perineum
and bulb of penis; F I: dorsum of clitoris,
urogenital diaphragm, M I: root of penis; A:
compress vagina orifice or compress urethra,
N: perineal nerve, pudenal nerve
 Ischiocavernosus – O: ramus of ischium, I:
near pubic symphysis, maintains erection of
penis or clitoris

56. Muscles - Female

57. Muscles - Female

58. Muscles – Male

59. Muscles - Male

60. Perineum
 Muscles
 External anal sphincter (skeletal muscle)
– O: skin an fascia surrounding anus and
coccyx, I: perineal body, A: closes anal
canal, N: Inferior Anal Nerve (Somatic
nerve from S2-S4) – inhibits voiding
 Internal Anal Sphincter – smooth muscle
innervated by sympathetic NS
(S2,S3,S4) – inhibits voiding

61. External/Internal Anal Sphincter

62. Superficial Transverse Perineal
 O: Ischial tuberosity
 I: Perineal body
 A: Support perineal body
 N: Pudenal nerve

63. External Urethral Sphincter
 O: Ischial tuberosity
 I: surround urethra
 A: compress urethra to maintain urine
continence
 N: Pudenal (S2-S4)

64. Superficial Transverse Perineal
F

65. Superficial Transverse Perineal
F

66. Superficial Transverse Perineal
M

67. Deep Transverse Perineal
 O: Medial Aspect of Ischial Ramus
 I: Pineal Body
 A: Stabilizes position of the perineal
body
 N: Pudenal N (S2-S4)

68. Deep Transverse Perineal - F

69. Deep Transverse Perineal -M

70. Deep Transverse Perineal - M

71. Deep Transverse Perineal M

72. Superficial Perineum Female

73. Superficial Perineum Female

74. Superficial Perineum Male

75. Superficial Perineum Male

76. Peritoneum
 Continuous with peritoneum of abdomen
 Drapes over pelvic viscera in the midline
to form:
 Pouches
 Folds between viscera and pelvic walls
 Pouches protect viscera from rectum

77. Female Peritoneum

78. Female Peritoneum

79. Male Peritoneum

80. Male Peritoneum

81. Major Blood Supply