Anatomy of the Pelvis and Perineum

Overview

• The pelvis is a complex anatomical structure.
• The perineum is located at the bottom of the pelvis.
  • It is the space between the thighs encompassing the anus and genitals.

Perineum Structure

• Borders of the Perineum:
  • The corners of the perineum's diamond shape are defined by:
    • Coccyx
    • Pubic symphysis
    • Ischial tuberosities
• Ceiling of the Perineum:
  • Formed by the pelvic floor muscles (levator ani).
  • These muscles are bowl-shaped, creating a partly convex ceiling.

Pelvic Outlet Boundaries

• Main Ligaments:
  • Pubic Remo
  • Sacrotuberous ligament
• Triangle Divisions:
  • Anterior half: Urogenital triangle
  • Posterior half: Anal triangle

Orientation

• In a standing position:
  • Urogenital triangle is roughly horizontal.
  • Anal triangle is tilted upward at about 30 degrees.

Detailed Anatomy

• Femur's Approximation:
  • Provides perspective on the coronal plane.
• Inferior View of the Pelvis:
  • Perineal Membrane:
    • A fibrous sheet within the urogenital triangle.
    • Has upturned anterior and posterior edges.
    • Contains a space known as the deep perineal pouch.
  • Deep Perineal Pouch:
    • Shallow space within the perineal membrane.
    • Contains muscles including the external urethral sphincter.
    • In females, includes openings for the vagina and urethra.
    • Urogenital hiatus: U-shaped space allowing passage through levator ani muscles.

Superficial Structures

• Collie's Fascia:
  • A membranous layer of superficial fascia just beneath the skin.
• Superficial Perineal Pouch:
  • Located between the perineal membrane and Collie's fascia.
  • Contains muscles like bulbospongiosus, ischiocavernosus, and superficial transverse perineal muscles.
  • Includes erectile tissues of the penis and clitoris.

Key Anatomical Points

• Perineal Membrane:
  • Free posterior border.
  • Center features the perineal body, a fibromuscular meeting point.
• Anal Sphincter Muscles:
  • Located posterior and superior to the perineal body within the anal triangle.

Summary

• The perineum is a 3D space, with the pelvic floor muscles as its ceiling.
• It is divided into two triangles: urogenital (anterior) and anal (posterior).
• Consists of two perineal pouches: superficial and deep, separated by the perineal membrane.

This concludes the overview of the pelvis and perineum. Subscribe for more content and updates.