Ischiorectal fossa

P.S. Measurements-total breadth of both the fossae= 5cm

1. ISCHIORECTAL FOSSA JULIT MATHEW ROLL NO. 86

2. Ischioanal fossa Wedge-shaped, fat-filled space Lateral to the anal canal below the pelvic diaphragm The two fossae communicate behind the anal canal.

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

4. boundaries Lateral : Fascia covering the obturator internus muscle and ischial tuberosity. Medial : Fascia covering the levator ani muscle and external anal sphincter. Posterior : Sacrotuberous ligament, on the posterior surface of which is gluteus maximus .

5. boundaries Anterior : Posterior border of the perineal membrane. Floor : Perineal skin. Roof : Meeting point of the fascia covering obturator internus and inferior fascia of the pelvic diaphragm.

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

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

8. 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

9. 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

10. CONTENTS OF ISCHIORECTAL FOSSA 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

11. Clinical correlation ISCHIORECTAL ABSCESS

12. HIATUS OF SCHWALBE

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