Areas - Perineum

Question 1

What is the perineum?

Location?

Contents?

Answer 1

The most inferior aspect of the pelvic outlet. The perineum is separated from the pelvic cavity with the pelvic floor.

Contains structures that support the urogenital and GI systems for micturition, defecation, sexual intercourse, and childbirth.

Question 2

What are the boundaries of the perineum?

Answer 2

Anteriorly - pubic symphysis

Posteriorly - tip of the coccyx

Laterally - inferior pubic rami and sacrotuberous ligament

Roof - pelvic floor

Base - skin and fascia

The perineum is shaped like a diamond and can be divided in two between the ischial tuberosities, to form two triangles - anal triangle and urogenital triangle.

Question 3

What are the surface borders of the perineum?

Answer 3

Anteriorly - mons pubis

Laterally - medial surfaces of thighs

Posteriorly - intergluteal cleft

Question 4

Contents of the anal triangle?

Answer 4

Located posteriorly.

Contains:
1) Anal aperture

2) External anal sphincter muscle
3) Ischioanal fossae - contains fat and connective tissue - allows for expansion during defecation.
4) Pudendal nerve - supplies perineum with somatic fibres

Question 5

Layers of the urogenital triangle?

Answer 5

Note that the anal triangle does not have a deep fascia.

From deep to superficial:

1) Deep perineal pouch - between the deep fascia of the pelvic floor and the perineal membrane - contains urethra, external urethral sphincter, and vagina.
2) Perineal membrane - a layer of tough fascia - perforated by the urethra and the vagina. Provides attachement for muscles of the external genitalia.
3) Superficial perineal pouch - a space between the perineal membrane and the superficial perineal fascia - contains erectile tissue of the penis and clitoris. It contains three muscles: ischiocavernosous, bulbospongiosus and superficial transverse perineal muscles. It also contains vestibular glands (Bartholin’s glands).
4) Superficial perineal fascia - a continuity of the abdominal fascia that has two components:
i) Deep fascia - covers the superficial perineal muscles and protruding structures
ii) Superficial fascia - composed of two layers of fascia
1) Superficial fascia - continuous with Camper’s fascia
2) Deep fascia (Colle’s fascia) - continuous with Scarpa’s fascia

Question 6

Perineal body

Attachments?

Answer 6

This is an irregular fibromuscular mass located between the triangles.

It acts as a site of attachment of muscles:

1) Levator ani
2) Bulbospongiosus
3) Superficial and deep transverse perineal muscles
4) External anal sphincter muscles
5) External urethral sphincter muscles fibres

In women, it acts as a tear resistant body between the vagina and external anal sphincter.

Question 7

Neurovascular supply?

Answer 7

Pudendal nerve (S2, S3, S4)

Internal pudendal artery

These structures travel along the inner surface of the ischial tuberosity though a canal formed by a thickening of the obturator fascia (Alcock’s canal). The pudendal neurovascular bundle travels through each ischioanal fossa, giving off branches to the anal and genitourinary triangle.

Question 8

Clinical relevance: perineal body

Question 9

Clinical relevance: Bartholin’s gland cysts