Collagen fibers in linea alba and rectus sheaths. I. General scheme and morphological aspects.

BACKGROUND: The anatomy of the anterior abdominal wall plays a most significant role in surgery. Thus the three-dimensional architecture of the collagen fibers in linea alba and rectus sheaths was investigated in 12 human cadavers.
MATERIAL AND METHODS: The linea alba was divided into 14 different anatomical segments in the craniocaudal direction. Two-hundred-micrometer-thick, eosin-stained sections from these segments were analyzed by confocal laser scanning microscopy. In this way the direction of the collagen fibers was estimated in the midline of the linea alba and in the medial parts of the rectus sheaths. Width and thickness of the linea alba and thickness of the rectus sheaths were measured.
RESULTS: In the ventral rectus sheath essentially oblique fibril bundles intermingle with each other, while the dorsal rectus sheath consists chiefly of transverse fibril bundles. In the linea alba three different zones of fiber orientation follow each other from ventral to dorsal: The lamina fibrae obliquae consists of intermingling oblique fibers. The lamina fibrae transversae contains mainly transverse fibril bundles, while an inconstant, small lamina fibrae irregularium is composed of oblique fibers. Different regions can be distinguished in the craniocaudal course of the linea alba: supraumbilical part, umbilical part, transition zone, and infraarcuate part.
CONCLUSIONS: A new model of fiber architecture of the linea alba was developed that describes the fiber architecture as a three-dimensional, highly structured meshwork of collagen fibers. In contrast to former models, no separate lines of decussation of the fibers could be found. Copyright 2001 Academic Press.