## Anatomy of Umbilical Hernia **Key Point:** Umbilical hernias occur through a defect in the **linea alba at the umbilicus**, specifically at the site of the umbilical ring where the umbilical vessels passed during fetal life. ### Embryological Basis The umbilicus is a natural area of weakness in the linea alba (midline fascia). During fetal development, the umbilical vessels and urachus pass through the umbilical ring. After birth, these structures obliterate, but the fascial defect at this site remains a point of potential weakness. ### Anatomical Location | Feature | Details | |---------|----------| | **Primary defect location** | Linea alba at the umbilicus | | **Defect size** | Usually 1–5 cm (varies) | | **Fascial layers involved** | Anterior rectus sheath and linea alba | | **Contents** | Omentum, small bowel loops | **High-Yield:** The umbilical ring is the natural weak point; hernias do NOT occur lateral to the linea alba or at other fascial intersections in typical umbilical hernia. ### Clinical Presentation - Bulge at the umbilicus, especially when infant cries or strains - Easily reducible in most cases - Risk of incarceration is low (unlike inguinal hernias) ### Distinction from Other Hernias ~~Do not confuse with paraumbilical hernia~~ — paraumbilical hernias occur above or below the umbilicus but still through the linea alba, whereas true umbilical hernias occur at the umbilicus itself.
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