Uterus Anatomy: Position, Supports, and Clinical Correlations

Overview

The uterus is a hollow, pear-shaped, thick-walled muscular organ in the female pelvis, located between the bladder (anteriorly) and rectum (posteriorly). It is essential for menstruation, implantation, pregnancy, and labor.

Anatomical Position

• Normal position: Anteverted and anteflexed
  • Anteversion: angle between cervix and vagina (~90°, opening anteriorly)
  • Anteflexion: angle between cervix and body of uterus (~170°)
• Position variations: Retroverted uterus occurs in ~20-30% of women (usually asymptomatic)

Anatomical Regions

• Fundus: Dome-shaped superior portion above the entry of the uterine tubes
• Body (corpus): Main central portion
• Isthmus: Narrowed transition between body and cervix (~1 cm long)
• Cervix: Inferior cylindrical portion projecting into the vagina

Layers of the Uterine Wall

1. Perimetrium: Outer serous layer (peritoneum)
2. Myometrium: Thick smooth muscle layer; the layer that contracts during labor and menstruation
3. Endometrium: Inner mucosal layer that sloughs during menstruation and proliferates during the cycle
   • Functional layer: Sloughs during menstruation
   • Basal layer: Retained, regenerates the functional layer each cycle

Ligamentous Supports

Primary Supports

1. Transverse cervical (cardinal) ligaments: Most important support; contain the uterine vessels; extend from cervix to pelvic side walls
2. Uterosacral ligaments: From cervix to sacrum; resist posterior displacement

Secondary Supports

3. Round ligaments: Maintain anteflexion; pass through the inguinal canal to the labia majora (homologue of gubernaculum testis)
4. Broad ligaments: Double folds of peritoneum extending from uterus to lateral pelvic walls; contain the uterine tubes, ovaries (via mesovarium), round ligaments, and uterine vessels
5. Pubocervical fascia: Supports anteriorly; prevents cystocele