The median umbilical fold is an anatomical feature found on the inner surface of the anterior abdominal wall. It is one of several folds created by the peritoneum, the membrane that lines the abdominal cavity and covers most of the abdominal organs.
Location
The median umbilical fold is located on the inner side of the lower anterior abdominal wall. It runs in the midline from the apex of the urinary bladder to the umbilicus (navel). This fold is positioned in the center, between the two medial umbilical folds, which are remnants of the obliterated umbilical arteries.
Structure
The median umbilical fold is formed by the peritoneum as it reflects over an underlying cord-like structure called the urachus, a remnant of the embryonic allantois. During fetal development, the allantois connects the bladder to the yolk sac, playing a role in waste removal. After birth, the allantois becomes obliterated and turns into the urachus, which later becomes a fibrous cord extending from the bladder to the umbilicus.
In detail, the structure of the median umbilical fold comprises:
- Peritoneal Covering: The outermost layer is the peritoneum that forms the visible fold.
- Fibrous Core: Inside the fold is the urachus, now a fibrous band after its obliteration post-birth.
- Location Relation: It is centrally located and is flanked on either side by the medial umbilical folds, with the lateral umbilical folds situated further out, covering the inferior epigastric vessels.
The appearance of the median umbilical fold can vary depending on factors such as the individual’s age, body composition, and the presence of any pathological conditions. In most cases, it is not visible externally but can be observed during surgical procedures or on imaging studies of the abdomen.
Location
The median umbilical fold is located on the interior surface of the lower anterior abdominal wall. It extends from the apex of the urinary bladder to the umbilicus (navel), lying directly in the midline of the body.
Function
In adults, the median umbilical fold does not have an active physiological function because it primarily consists of the urachus remnant, a structure that was only active during fetal development. In the fetus, the urachus is part of the allantois, connecting the fetal bladder to the yolk sac and allowing urine to pass from the fetus to the amniotic fluid.
However, while the median umbilical fold does not serve a significant physiological function in postnatal life, it has clinical and surgical relevance:
- Anatomical Landmark: It serves as an important anatomical landmark during surgical procedures, particularly in laparoscopic surgeries and procedures involving the lower abdomen. Surgeons and radiologists use it to orient themselves when navigating the abdominal cavity.
- Pathological Indicator: Although the median umbilical fold itself does not perform active functions, the presence of abnormalities associated with it, such as a urachal cyst, sinus, or fistula, can indicate developmental anomalies. These conditions might require medical intervention if they lead to infections or other complications.
Clinical Significance
While the median umbilical fold itself typically does not perform any function after birth, its underlying structure, the urachus, can be involved in various clinical conditions:
- Urachal Anomalies: These are conditions where the urachus does not fully obliterate, leading to issues such as urachal cysts, sinus, or fistula. These can result in infections or communication between the bladder and the umbilicus.
- Surgical Reference: During abdominal surgeries, particularly laparoscopic procedures, the median umbilical fold serves as an important anatomical landmark, helping surgeons navigate the region and avoid damaging underlying structures.
- Diagnostic Importance: In imaging studies, recognition of the median umbilical fold can help in diagnosing urachal anomalies and other pathologies of the lower anterior abdominal wall.
