Lecture Notes: Pelvic Wall and Pelvic Cavity

Introduction

• Lecturer: Dr. Adel Bondok
• Subject: Anatomy and Neuroscience
• Institution: Mansoor University, Egypt
• Focus: Pelvic wall and pelvic cavity

Pelvic Wall

Components

• Bones:
  • Two hip bones
  • Sacrum
  • Coccyx
• Joints:
  • Pubic symphysis
  • Lumbosacral joint
  • Sacro-coccygeal joint
  • Sacroiliac joint
• Ligaments:
  • Sacro-tuberous ligament
  • Sacrospinous ligament
• Membranes:
  • Obturator membrane (closes obturator foramen)
  • Perineal membrane (closes subpubic space)
• Muscles:
  • Lateral pelvic wall: Piriformis, Obturator internus
  • Pelvic floor: Levator ani, Coccygeus (collectively called the pelvic diaphragm)

Anatomical Position

• Anterior superior iliac spine and pubic symphysis on the same vertical plane
• Upper border of pubic symphysis and tip of coccyx on the same horizontal plane

Sacrum

Structure

• Formed of five fused pieces
• Features:
  • Anterior and posterior sacral foramina
  • Promontory (more prominent in males)
  • Lateral mass called ala of the sacrum
• Articulation:
  • Lumbosacral joint (secondary cartilaginous) with L5
  • Sacro-coccygeal joint with coccyx
  • Sacroiliac joint (plain synovial joint) with ilium

Relations

• Muscles: Iliacus, Piriformis, Coccygeus
• Arteries: Median sacral artery, lateral sacral arteries, iliolumbar artery
• Nerves: Sympathetic chain, ventral rami of upper four sacral nerves, lumbosacral trunk, obturator nerve
• Viscera: Rectum

Sacral Canal and Hiatus

• Contents: Phylum terminale, cauda equina, dura and arachnoid mater, branches of lateral sacral arteries, venous plexus, and fat
• Clinical significance: Used for caudal anesthesia

Differences Between Male and Female Sacrum

• Female: Shorter, wider, less prominent promontory, sharply curved at S3
• Male: Longer, narrower, more prominent promontory

Pelvic Cavity

Structure

• Inlet (Pelvic brim):
  • Bounded by upper border of pubic symphysis, promontory, and ala of the sacrum
  • Iliopectineal line
• Outlet:
  • Bounded by lower border of pubic symphysis, tip of coccyx, pubic arch, and sacrotuberous ligament
• Cavity divided by inlet into:
  • False pelvis (part of abdominal cavity)
  • True pelvis (contains pelvic organs)

Organs

• Female Pelvic Organs:
  • Rectum (posterior)
  • Urinary bladder (anterior)
  • Uterus, ovaries, uterine tubes, vagina (middle)
• Male Pelvic Organs:
  • Rectum (posterior)
  • Urinary bladder (anterior)
  • Seminal vesicle, vas deferens (middle)
  • Prostate gland (below urinary bladder)

End of Lecture

Note: Additional information on pelvic diaphragm details and coronal sections are to be discussed in another presentation.