ArticleAnatomical science international2026
Why is the umbilicus concave? A histological and three-dimensional anatomical study revealing the "umbilical sheath".
Article in Anatomical science international, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
0 citing papers in PubMed.
No citing paper in PubMed yet.
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
7 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
The umbilicus is a distinct anatomical feature of the anterior abdominal wall, characterized by persistent postnatal depression. Despite its clinical and surgical relevance, the histological and spatial structures underlying the umbilical concavity remain unclear. Herein, we investigated the fibrous connective tissue underlying the umbilical concavity. Five formalin-fixed cadaveric specimens (mean age: 77.4 years) were used. Two were used for macroscopic dissection, two for histological examination, and one for quasi-continuous serial sectioning with three-dimensional reconstruction. Macroscopic dissection revealed a vertically cylindrical fibrous structure extending from the umbilical fossa to the anterior rectus sheath. Histological analysis confirmed that this structure enclosed a small fat compartment distinct from subcutaneous fat, representing an extraperitoneal fat protrusion in contact with the underside of the umbilical skin. Serial sections and three-dimensional reconstruction identified a tunnel-like fibrous structure, termed "umbilical sheath," enveloping the protruded fat and bridging the umbilical ring and dermis. This sheath connected the invaginated skin to the linea alba and rectus sheath. We identified a previously undescribed fibrous structure, the umbilical sheath, enclosing a localized protrusion of extraperitoneal fat, maintaining umbilical concavity. Recognition of this structure may guide optimal port placement and promote abdominal wall closure techniques that preserve anatomical support, potentially reducing incisional hernia risk.
Indexed as
Identifiers
42313266What OpenQuestion holds
Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.