The linea alba (white line) is a long band of tendinous connective tissue which runs vertically along the midline of the abdomen anterior aspect. It stretches from the xiphoid process of sternum to the pubic symphysis. It is about 2 cm wide in the upper part of the abdominal wall and it narrows as it descends towards the pubic region, measuring 33 cm in length in a medium height adult. Although it is narrower in the lower portion, it gets thicker there as it is reinforced by a connective tissue structure.
The linea alba is formed by the interlacing fibers of the aponeuroses of the three pairs of abdominal muscles (rectus abdominis, transversus adbominis, and abdominal internal oblique muscle). In the upper part, where it is thinner and wider, there are slits between the interlacing fibers, through which sometimes herniation may occur. Approximately on the middle line of the linea alba is the umbilical ring, which is filled by loose cicatricial tissue called the navel. In the intrauterine developmental period, in place of the navel, there is a round opening through which the umbilical vein and arteries go. Hernia also often may occur here, at this point of the linea alba.
Function
The linea alba stabilizes the muscles of the abdominal wall, keeping them together and working as an anchorage line of support for their contractile forces.
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| Schematic and anatomical image showing the linea alba and the abdominal muscles. |
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