Linea alba
The linea alba is the tough fibrous seam running down the middle of the front abdominal wall, from the sternum's xiphoid process to the pubis.
At a glance
- English
- Linea alba
- Latin (TA2)
- Linea alba
- System
- Connective tissue
- Region
- Trunk
- Side
- Single, on the midline
About the linea alba
In the abdominal midline the aponeuroses of the flat abdominal muscles meet and interweave to form a single strong cord of connective tissue: the linea alba. The Latin name means white line, and the colour comes about because it consists almost entirely of collagen fibres, with very little muscle, fat or blood supply. It divides the left rectus abdominis from the right, and in a lean, muscular person it shows on the surface as the vertical groove between the two halves of a six-pack.
Above, it is fixed to the xiphoid process at the lower end of the sternum; below, it reaches the pubic symphysis and the pubic crest. It is formed where the sheaths of the external oblique, internal oblique and transversus abdominis from each side cross the midline, their fibres decussating so that each side is anchored to the other. Above the umbilicus it is fairly broad, up to about a centimetre or more; below the umbilicus it narrows to a thin line because the two recti lie almost side by side there. Near the pubis it is strengthened behind by a triangular extension, the adminiculum lineae albae. The umbilicus itself is a scar in the linea alba, ringed by the umbilical ring.
Because the muscles of both sides attach to it, the linea alba acts as a central tendon, letting the two halves of the wall pull against each other and keeping the abdominal wall stable when the trunk moves or abdominal pressure rises. Pyramidalis, when present, tightens its lower part.
The line is a favourite surgical route into the abdomen: a midline incision through it opens the cavity quickly, bleeds little and avoids cutting muscle or major nerves. Its poor blood supply, though, means it heals slowly, and incisional hernias may follow. Small defects above the umbilicus allow fat to push through as epigastric hernias, and widening of the gap between the two recti, known as divarication, makes the midline bulge on straining.
Function and supply
- Begins at
- Xiphoid process of the sternum.
- Ends at
- Pubic symphysis and pubic crest.
- Function
- Acts as a central tendon for the flat abdominal muscles, anchoring each side to the other and stabilising the anterior abdominal wall.
Anthromica
See the linea alba where it really sits, with every layer of the body around it.
- Every layer, one body. Peel from muscle to bone, nerve, vessel and organ, and turn it any way.
- English and Latin. Every structure named the way your exam names it.
- Quiz until it sticks. Short drills on the structures you keep missing.
Free to start. No card.
