Understanding Pelvic Floor Anatomy and Function

Lecture Notes: Overview of the Pelvic Floor

Summary of Pelvic Floor Anatomy

The tutorial provides a detailed examination of the pelvic floor, which separates the pelvic cavity above from the perineum below. Key structures include the pelvic diaphragm, perineal membrane, and deep perineal pouch. Focus is given to the muscles forming the pelvic diaphragm - primarily the levator ani muscles and the coccygeus muscles - and their roles in supporting pelvic organs and functions related to the urogenital structures and fecal continence.

Detailed Anatomy and Function of Pelvic Floor Components

Pelvic Diaphragm

• General Structure: Dome-shaped comprised mainly of levator ani and coccygeus muscles.

• Levator Ani Muscles:

  • Made up of pubococcygeus, iliococcygeus, and puborectalis muscles.
  • Forms a bowl shape; does not extend as high as it appears in some visualizations.
  • Functions:
    • Supports pelvic viscera.
    • Maintains the angle of the anorectal junction crucial for continence.
    • Sphincteric control over rectum and urogenital structures.
    • Resists intra-pelvic pressure increases during activities like coughing.

  Specific Muscles of Levator Ani

  • Pubococcygeus: Extends from pubis to coccyx, with fibers looping around the prostate in males and vagina in females.
  • Iliococcygeus: Posterior fibers supporting the more dorsal aspects of the pelvic floor.
  • Puborectalis: Forms a sling around the anorectal junction, maintaining the crucial anorectal angle for fecal continence.

• Coccygeus (Ischiococcygeus) Muscle:

  • Located posteriorly in the pelvic diaphragm.
  • Originates from the ischial spine and inserts on the sacrum and coccyx.
  • Provides pelvic floor support and has a role in stabilizing the coccyx.

Other Pelvic Structures

• Obturator Internus: Forms part of the lateral walls of the pelvis, aids in thigh lateral rotation.
• Piriformis: Also contributes to the lateral pelvic wall and thigh external rotation.

Perineal Membrane and Deep Peroneal Pouch

• Detailed discussions not covered in the transcript, but identified as integral parts of the pelvic floor structure supporting in-depth segmental function.

Key Muscular Attachments and Innovations

• Origination and Insertion:

  • Attachment points include pubis, coccyx, and fascia of the obturator internus.
  • Tendinous arch of the pelvic fascia crucial for origin of levator ani muscles, especially along the line from the pubis to the ischial spine.

• Innervation:

  • Levator Ani: Primarily by branches of the pudendal nerve (S2-S4), essential for pelvic floor functionality.
  • Coccygeus: Innovated by branches from the anterior rami of S4 and S5.
  • Mnemonic: "S2, S3, S4 keep the floor" reflects the innervation and functional roles of these muscles.

Functionality and Clinical Significance

• Support and Tension: Muscles work synergistically to support pelvic organs, maintain continence, and respond to increases in intra-pelvic pressure.
• Defecation and Urogenital Functions: The arrangement of muscles around the anorectal and urogenital areas facilitates controlled passage during defecation and maintains the positions and operations of urogenital organs.

This session enhances the understanding of pelvic floor anatomy, with specific focus on muscular configurations, their attachments, roles in supporting viscera, and implications for clinical health and biomechanical functionality.