Urogenital Triangle

What are the boundaries of Urogenital region?

The urogenital  region is a triangular area is the anterior part of the perineum. Its boundaries are

• Anteriorly: pubic symphysis.
• Posteriorly: imaginary line joining anterior ends of ischial tuberosities.
• Laterally: ischiopubic rami.

What are the contents of Urogenital region?

Contents of urogenital triangle

• External genitalia.
• Lower part of urethra & vagina (in females).
• Urogenital diaphragm
• Superficial and deep perineal pouches containing
  Muscles
  Nerves and
  Blood vessels

 Describe the fascial layers and pouches of urogenital triangle.

The urogenital triangle consists of two pouches/spaces (superficial and deep) bounded by three fascial layers. In erect position of body the three fascial layers and the pouches present from below to above are:

• Inferiormost layer is the Membranous layer of superficial fascia of perineum (Colles Fascia).
• Above this is Superficial perineal pouch.
• Superior  to this lies the Inferior layer of  Urogenital diaphragm/Perineal membrane.
• Above this is the Deep perineal pouch.
• Superiormost is the Superior layer of Urogenital diaphargm.

• The inferior and superior layers of Urogenital diaphragm are fused anteriorly as well as posteriorly and  enclose Deep perineal pouch.
• The membranous layer of superficial fascia of perineum (Colles Fascia) fuss es with the two layers of urogenital diaphragm only posteriorly .  Therefore, the deep perineal pouch is a closed space  whereas, the superficial perineal pouch is open anteriorly  and continuous with  scrotum, penis and the space  between the membranous layer of superficial fascia (Scarpa’s fascia) and external oblique muscle in the lower part of anterior abdominal wall.

* The superficial perineal fascia has two layers viz. superficial fatty                      layer and deep membranous layer . 

• Superficial fatty  layer –  Is continuous with Camper’s fascia of the anterior abdominal wall and  the superficial fascia of the thighs. In males in scrotum it is replaced with smooth dartos muscle.
• Deep  membranous layer (Colles’ fascia) –  Is continuous with Scarpa’s fascia of the anterior abdominal wall. On each side it is attached to the margins of pubic arch and to the deep fascia i.e. fascia lata of the of the thigh  along   and imaginary line extending laterally (8cm) from  the pubic tubercle ( Holden’s line).

 What are the boundaries of superficial perineal pouch?

Boundaries of Superficial Perineal Pouch

• Inferiorly: Membranous layer of superficial fascia of perineum (Colles fascia)
• Superiorly: Inferior layer of urogenital diaphragm/Perineal membrane.
• Laterally: Ischiopubic rami.
• Posteriorly: Fused layers of superficial fascia of perineum and Inferior layer of urogenital diaphragm.
• Anteriorly: It is open and continous with the scrotum, penis and anterior abdominal wall.

What are the contents of superficial perineal pouch?

Contents of Superficial Perineal Pouch

 What are the boundaries of deep perineal pouch?

Boundaries of Deep Perineal Pouch

• Inferiorly: Inferior layer of urogenital diaphragm/Perineal membrane.
• Superiorly: Superior layer of urogenital diaphragm/Perineal membrane.
• Laterally: Ischiopubic rami.
• Posteriorly: Fused  superior and Inferior layer of urogenital diaphragm and perineal body in the midline.
• Anteriorly: Fused  superior and Inferior layer of urogenital diaphragm  forming transverse perineal ligament.

 What are the contents of deep perineal pouch?

Contents of Deep Perineal Pouch

Name the structures that pierce perineal membrane in males and females. Illustrate the answer with labelled diagram.

The following structures pierce perineal membrane in males and females:

Describe briefly perineal body.

Perineal body: It is an irregular shaped fibromuscular structure  of  variable size, located at midpoint of the line joining the ischial tuberosities. It lies in the subcutaneous tissue, posterior to vestibule and anterior to the anus.  It forms the central point of the perineum & blends anteriorly with the perineal membrane. It is larger in the female than in the male and  provide support to the posterior wall of the vagina. Its functions are: to 

• Gives attachment to perineal muscles
• Plays an important role in visceral support especially in female.

Muscles attached to the perineal body are 

• Sphincter ani externus
•  Two Levator ani
•  Two superficial transverse muscle of perineum
•  Two deep transverse muscles of perineum
•  Two bulbospongiosus
• Sphincter of urethra (male) or urethrovaginal sphincter (female)

 Enumerate the branches of pudendal nerve.

Following are the branches of pudendal nerve( root value: S2,S3,S4):

•  Inferior rectal nerve: sulies sphincter ani externus and skin around the anus.
•  Perineal nerve: divides into:
  • Posterior scrotal/labial nerves (medial & lateral) : supply skin of the posterior part of the scrotum/labium majus.
  • Muscular benches to the muscles of superficial and deep erineal pouches.
• Dorsal nerve of the penis/clitoris : supplies penis/clitoris.

Enumerate the branches of Internal pudendal artery.

Following are the branches of internal pudendal artery:

•  Inferior rectal artery
•  Perineal artery– gives following branches:
  • Transverse perineal branch
  • Medial and lateral scrotal/labial arteries
• Deep artery of the penis/clitoris

Applied Aspects