The perineum is the region between the thighs and behind the genitals. It is divided into an anterior urogenital triangle and a posterior anal triangle by an imaginary line between the ischial tuberosities. The pelvic outlet forms the inferior boundary and consists of the pubic arch anteriorly and sciatic notches posteriorly. The perineum contains the anus, ischiorectal fossae in the anal region, and male or female genitals in the urogenital region. It has three spaces - subcutaneous, superficial, and deep perineal pouches. The urethral sphincter mechanism surrounds the membranous urethra in males and middle/lower u

1. Perineum

2. Abdominopelvic Cavity
2

3. Superficial and Deep
boundaries of Perineum
� An arbitrary line joining the ischial tuberosities (the
interischial line) divides the perineum into an
anterior urogenital triangle and a posterior anal
triangle.

4. � The deep limit of the perineum is the inferior surface of
the pelvic diaphragm and its superficial limit is the skin
which is continuous with that over the medial aspect
of the thighs and the lower abdominal wall.

6. Pelvic outlet (inferior pelvic aperture)
� Its perimeter consists of three wide
arcs.
� Anteriorly is the pubic arch, between
the converging ischiopubic rami.
� Posteriorly and laterally on both sides
are the sciatic notches between the
sacrum and ischial tuberosities.
� These are divided by the
sacrotuberous and sacrospinous
ligaments into greater and lesser
sciatic foramina.
� The outlet is thus not rigid in its
posterior half, being limited by
ligaments and the coccyx, all slightly
yielding.

7. � Two planes at an
angle.
� Ischiopubic part has
a plane which is
inclined down and
back to a transverse
line between the
lower limits of the
ischial tuberosities
� Posterior half has a
plane
approximating to
the sacrotuberous
ligaments, sloping
down and forwards
to the same line.

8. Divisions of Perineum

9. Anal Region: Contains Anus
and Ischiorectal Fossae

10. Urogenital region: Female

11. Urogenital Region Male

14. Perineal Membrane
� previously the inferior fascia of the urogenital diaphragm
� triangular membrane attached laterally to the periosteum of the
ischiopubic rami and its apex is attached to the arcuate ligament
of the pubis.

15. Perineal Spaces/ Pouches

16. Perineal Spaces
�Subcutaneous perineal pouch
�Superficial perineal pouch
�Deep perineal pouch

17. Subcutaneous perineal space
� lies between the deep
perineal fascia and the
superficial perineal fascia.
� Normally flaccid but is
capable of expansion in
cases of fluid collection.
� The fluid in this space can
spread throughout the
triangle including the scrotum
or labia majora, but cannot
pass posteriorly into the anal
triangle or laterally into the
medial thigh due to the firm
tethering of the posterior
attachments of the
subcutaneous fascia.

21. Male Urogenital Region

28. Deep Perineal Space

29. Urogenital Diaphragm in
Males

31. Structures piercing the
perineal membrane in male

33. Female Urogenital Region

35. Labia Major, Minora and
Vestibule

38. Cutaneous Innervation

39. Superficial Fascia

40. Superficial and Deep
perineal pouches

42. Urogenital Diaphragm in
females

44. Structures piercing the
perineal membrane

46. � Urethral sphincter mechanism
� The urethral sphincter mechanism consists of the
intrinsic striated and smooth muscle of the urethra and
the puboperinealis (pubourethralis) component of
levator ani which surrounds the urethra at the point of
maximum concentration of those muscles

47. � It surrounds the membranous urethra in the male and
the middle and lower thirds of the urethra in the
female.
� In the male, fibres also reach up to the lowest part of
the neck of the bladder and, between the two, lie on
the surface of the prostate.
� The bulk of the fibres surround the membranous
urethra and some fibres are attached to the inner
surface of the ischiopubic ramus.
� In the female, the sphincter mechanism surrounds
more than the middle third of the urethra. It blends
above with the smooth muscle of the bladder neck
and below with the smooth muscle of the lower urethra
and vagina.

48. Compressor Urethrae

49. 49
4 cm above the lower limit of
Ischial Tuberosity
Pudendal Canal

50. 50

51. 51

52. 52

53. 53

54. In Conclusion…

55. 55