This document summarizes the anatomy of the ischio-rectal fossa. It describes the boundaries and contents of the ischio-rectal fossa, including the termination of the anal canal, perineal body, ischioanal fossa, and anococygeal ligament. It also outlines the structures that make up its boundaries, including muscles, ligaments, and fascia. Furthermore, it lists the neurovascular structures that pass through the ischio-rectal fossa and discusses some clinical applications such as ischio-rectal abscesses and pudendal nerve blocks.

1. SRINIVASAN
Ischio-rectal fossa

2.  Faces posteroinferiorly
 Boundaries
 Laterally- sarcotuberous
ligament
 Anteriorly – Horizontal
line between two ischial
tuberosities.
 Posteriorly – Coccyx.

3. Perineal
body

4.  Contains
 Termination of anal canal with external
anal sphincter
 Perineal body
 Ischioanal fossa
 Anococygeal ligament

5. Wedged shaped gutter filled with
fat on either sides of anal canal

6.  Wedged
shape
 Apex
directed
upwards
 Base
Downwards

7.  Lateral
 Medial
 Apex
 Base

8.  Laterally- Obturator internus, Obturator fascia,
Ischial tuberosity
 Medially – Levator ani covered by anal fascia
 In front – Transverse perinei muscles separated
by perineal membrane
 Behind – sacrotuberous ligament covered by
fibres of gluteus maximus
 Apex- fusion of anal fascia & obturator fascia
 Base – Skin & superficial fascia

9.  Anterior
 Perineal membrane
 Posterior
Gluteus maximus
Sacrotuberous lig.

10.  Along
the
pubic
arch &
above
the deep
perineal
pouch.
UD

13.  Between
sacrotuberous
&
sacrospinous
ligaments.
GLUTEUS MAXIMUS

15. Lunate
Fascia

16.  Supra-
tegmental
space
 Ischioanal
space
 Perianal
space

18.  Ischioanal Pad of fat
 Pudendal canal with its contents
 Inferior rectal vessels and nerve
 Posterior scrotal Vessels & nerve
 Perineal branch of 4th sacral nerve
 Perforating cutaneous branches of S2 &
S3

19.  Fascial tunnel in lateral wall of ischiorectal
fossa

20. Lesser Sciatic notch to deep perineal pouch

23. 1. Pudendal nerve (PN)
2. Inferior rectal N (IRN)
3. Posterior scrotal N
4. Perineal branch of 4th
sacral nerve
5. Perforating cutaneous
branches of S2 & S3

24. 1. Internal Pudendal
Vessels
2. Inferior rectal
Vessels
3. Posterior scrotal
(Labial) Vessels
IPA
IRA
PLA

25. Applied anatomy
Allows distention of rectum & anal canal during
defecation
Ischiorectal fat acts as a cushion for rectum &
anal canal
Debilitating diseases like diarrhoea - Loss of fat –
Prolapse of rectum
Perianal & Ischiorectal fossa – Common site of
abscesses
Poor blood supply
Coarse lobulated fat

27. Ischirectal abscess
While performing I & D
– Avoid injury to
Inferior rectal nerve –
To prevent paralysis
of external anal
sphincter
Fournier's Gangrene –
uncommon, lethal
complication of
ischiorectal abscess

28. Pudendal Nerve block
The pudendal nerve is
infiltrated with local
anaesthetic solution
where it crosses the
ischial spine.
The ischial spine is
palpated through the
vagina / rectum and the
needle is inserted
through the perineum,
medial to the ischial
tuberosity to
anaesthetize the
perineum.

29.  Hiatus of
Schwalbe
 Due to defective
origin of Levator
ani muscle from
Obturator Fascia