Peritoneal umbilical folds
The peritoneum lining the anterior abdominal wall from the abdominal cavity side is elevated above the cords and vessels running beneath it. As a result, folds converging toward the umbilicus are formed. In addition, in the upper part of the relief, the obliterated umbilical vein (v. umbilicalis) and functioning paraumbilical veins (vv. paraumbilicales) are distinguished.
In the lower half of the abdomen, the peritoneum forms five folds:
- Median umbilical fold (plica umbilicalis mediana). This is the only unpaired structure. It extends strictly along the midline from the apex of the urinary bladder to the umbilicus. The obliterated urachus is located here under the peritoneal layer.
- Medial umbilical fold (plica umbilicalis medialis). This is a paired formation. It originates from the lateral surfaces of the urinary bladder and runs toward the umbilicus. The contents of this elevation are the obliterated umbilical artery (a. umbilicalis).
- Lateral umbilical fold (plica umbilicalis lateralis). This is also a paired structure. It is located lateral to the preceding ones and contains the inferior epigastric artery and vein (a. et v. epigastricae inferiores).
Peritoneal recesses (fossae) as weak spots
Between the peritoneal folds described above, peculiar recesses, or fossae, are formed. These anatomical zones lack robust muscular-aponeurotic coverage, making them act as "weak spots" of the anterior abdominal wall.
Three types of peritoneal fossae are distinguished:
- Supravesical fossa (fossa supravesicalis). Located directly above the urinary bladder. Its medial border is the unpaired median umbilical fold (plica umbilicalis mediana), and its lateral boundary is the paired medial umbilical fold (plica umbilicalis medialis).
- Medial inguinal fossa (fossa inguinalis medialis). A paired recess localized between the medial and lateral umbilical folds (plica umbilicalis medialis and plica umbilicalis lateralis). From the standpoint of topographical anatomy, this fossa has a direct projection onto the superficial inguinal ring.
- Lateral inguinal fossa (fossa inguinalis lateralis). A paired structure located lateral to the lateral umbilical fold (plica umbilicalis lateralis). This zone strictly projects onto the deep inguinal ring.
Topography of folds and fossae
For quick memorization of the correspondence between fossae and folds, all relief elements can be represented as a table:
| Recess (fossa) | Boundaries (peritoneal folds) | Projection onto the inguinal canal |
|---|---|---|
| Supravesical (fossa supravesicalis) | Between the median and medial | Located above the urinary bladder |
| Medial inguinal (fossa inguinalis medialis) | Between the medial and lateral | Superficial inguinal ring |
| Lateral inguinal (fossa inguinalis lateralis) | Lateral to the lateral | Deep inguinal ring |
Briefly: answers to topical questions
Which hernias emerge through the medial inguinal fossa?
The medial inguinal fossa is the exit point for direct inguinal hernias. Features of this type of hernia:
- Pathway of protrusion — the hernia sac stretches the posterior wall of the inguinal canal (transversalis fascia) and emerges directly through the superficial inguinal ring without passing through the entire canal.
- Relation to the cord — located outside the spermatic cord (the cord is located lateral to the sac).
- Descent — does not descend into the scrotum.
Which hernias emerge through the lateral inguinal fossa?
The indirect inguinal hernia emerges through the lateral inguinal fossa. Characteristic features of this type of hernia:
- Pathway of protrusion — the hernia sac enters through the deep inguinal ring, passes through the entire inguinal canal, and emerges through the superficial ring.
- Relation to the cord — located inside the spermatic cord (beneath the internal spermatic fascia).
- Descent — may descend into the scrotum in men or into the labium majus in women.
Median (Mediana) — single, conceals the urachus. Medial (Medialis) — paired, contains the artery. Lateral (Lateralis) — the most lateral, conceals the inferior epigastric vessels.
Class and exam questions
Which structures form the lateral umbilical fold?
The lateral umbilical fold (plica umbilicalis lateralis) is formed by the inferior epigastric artery and vein (a. et v. epigastricae inferiores) covered by the parietal peritoneum.
What anatomical structure does the medial inguinal fossa project onto?
The medial inguinal fossa (fossa inguinalis medialis) projects onto the superficial inguinal ring.
What is located inside the unpaired median umbilical fold?
Inside the plica umbilicalis mediana is the obliterated urachus, which runs from the apex of the urinary bladder to the umbilicus.
Which fossa projects onto the deep inguinal ring?
The lateral inguinal fossa (fossa inguinalis lateralis), located lateral to the lateral umbilical fold, projects onto the deep inguinal ring.
What else to study on this topic
- Topographical anatomy of the superficial and deep inguinal rings.
- Surgical anatomy of inguinal hernias (how they relate to peritoneal fossae).
- Weak spots of the anterior abdominal wall.
- Blood supply to the anterior abdominal wall (epigastric artery system).
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Other topics in the section "Topographic Anatomy of the Abdomen"
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