The ischioanal fossa is a wedge-shaped, fat-filled space located lateral to the anal canal below the pelvic diaphragm. It has boundaries formed by fascia covering nearby muscles. Within the fossa are the perianal space and ischioanal space, separated by the perianal fascia. The ischioanal space contains large fat deposits and structures like the pudendal canal, which contains the pudendal nerve and vessels. Infection of the fat deposits can lead to a painful ischioanal abscess.

1. JULIT MATHEW
ROLL NO. 86

2. oIschioanal fossa
oWedge-shaped, fat-filled space
o Lateral to the anal canal below the pelvic
diaphragm
oThe two fossae communicate behind the
anal canal.

3. o Base-skin over the anal region of the
perineum
o Apex-directed upward and laterally.
o Measurements-
5cm-5cm-5cm

5. oLateral: Fascia covering the
obturator internus muscle and
ischial tuberosity.
oMedial: Fascia covering the
levator ani muscle and
external anal sphincter.
oPosterior: Sacrotuberous
ligament, on the posterior
surface of which is gluteus
maximus.

7. o Anterior: Posterior border
of the perineal membrane.
oFloor: Perineal skin.
oRoof: Meeting point of the
fascia covering obturator
internus and inferior
fascia of the pelvic
diaphragm.

8. Anterior Recess :Anteriorly
above Urogenital Diaphragm
Posterior Recess :Posteriorly
deep to Sacrotuberous ligament
Horseshoe-shaped Recess :
Connects the two fossa behind
the anal canal

10. Perianal space
o Subcutaneous space on either sides of Anal orifice
o Bounded above-Perianal fascia , below-Perianal skin
PERIANAL FASCIA
o Fibrous septum
o Extends from White line of Hilton (medially) to Pudendal Canal (laterally)
o Perianal space is divided into compartments by fibroelastic septa.
o The fat in here is tightly arranged in small loculi.
o Infection – perianal abscess-painful

12.  Ischioanal space
 Large and deep
 Fat here is arranged in large loculi,formed by incomplete
delicate septa
LUNATE FASCIA
 Arches over Ischioanal fat
 Begins laterally at the pudendal canal ,merges medially
with fascia covering deep part of External anal sphincter.
Fascia divides the space into :
Suprategmental space and Tegmental space

13. o Pudendal canal(Alcock’s canal)
 Fascial canal present in the lateral wall of the ischiorectal fossa about 1
inch (2.5 cm) above the ischial tuberosity
 Extends from the lesser sciatic foramen to the posterior limit of the deep
perineal pouch
 The pudendal canal is formed either by the splitting of the obturator
fascia or by separation between the fascia lunata and the obturator
fascia.
CONTENTS
 1. Pudendal nerve which divides within the canal into the dorsal nerve
of penis and the perineal nerve.
 2. Internal pudendal vessels

14.  Ischioanal pad of fat
 Inferior rectal nerve and vessels- pass through the fossa from lateral to
medial side. They arch upwards above the fat to supply mucous
membrane, External sphincter, skin around the anus.
 Pudendal canal with its contents. The canal lies along the lateral wall of
the fossa.
 Posterior scrotal(males) or posterior labial(females) nerves and vessels.
They cross the Anterolateral part of the fossa and enter the urogenital
triangle.
 Perineal branch of S4 nerve. It enters the posterior angle of the fossa and
runs over the levator ani to the external anal sphincter.
 Perforating cutaneous branches of nerves S2,S3.They appear at the lower
border of the gluteus maximus, in the posterior part of the fossa

16. ISCHIORECTAL ABSCESS

17.  HIATUS OF SCHWALBE

18. THANK YOU