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Linea alba

The linea alba is a fibrous midline raphe of the anterior abdominal wall, extending from the xiphoid process of the sternum superiorly to the pubic symphysis inferiorly. It is formed by the interlacing aponeurotic fibers of the external oblique, internal oblique, and transversus abdominis muscles.

The linea alba separates the rectus abdominis muscles on either side and serves as a central tendinous structure of the abdominal wall. It is relatively avascular, which makes it a preferred site for surgical incisions such as midline laparotomy. However, its lack of vascularity also contributes to slower healing and a higher risk of incisional hernias.

Its width varies: narrow in the epigastric region, widening below the umbilicus. At the umbilicus, fibers encircle and insert into the umbilical scar. Clinically, defects or weaknesses in the linea alba contribute to conditions such as diastasis recti and epigastric hernias.

Synonyms

  • Abdominal midline raphe

  • White line of the abdomen

Function

  • Provides central tendonous support to the anterior abdominal wall

  • Maintains structural integrity between rectus abdominis muscles

  • Serves as a line of force transmission for abdominal musculature

  • Acts as a surgical access point for midline abdominal incisions

MRI Appearance

T1-weighted images:

  • Linea alba appears as a low-signal intensity band between rectus abdominis muscles

  • Best seen in axial and sagittal planes

T2-weighted images:

  • Also appears as a low-signal fibrous structure

  • Separation or thinning may be visualized in diastasis recti or hernia

STIR:

  • Linea alba itself remains dark (hypointense)

  • Associated edema, trauma, or inflammatory changes appear hyperintense

T1 Fat-Saturated (Pre-contrast):

  • The linea alba appears as an intermediate signal structure

  • Stands out against the suppressed fat signal of the surrounding mesenteric and subcutaneous tissue

T1 Fat-Saturated Post-Contrast (Gadolinium):

  • Normal linea alba shows no significant enhancement

  • Pathology (inflammation, tumor infiltration) may show enhancing signal along or within the structure

MRI Non-Contrast 3D Imaging:

  • Provides 3D reconstructions of linea alba and abdominal wall

  • Useful in mapping diastasis recti and hernia defects for surgery

CT Appearance

CT Pre-Contrast:

  • Appears as a thin, linear soft-tissue density separating rectus abdominis muscles

  • Useful in detecting hernias or diastasis

CT Post-Contrast:

  • Linea alba itself does not enhance

  • Pathology such as inflammatory infiltration, tumor invasion, or hernia sac contents enhances adjacent to the linea alba

  • 3D reconstructions useful in abdominal wall reconstruction planning

MRI image

Linea alba MRI axial anatomy image-img-00000-00000

MRI image

Linea alba MRI CORONAL anatomy image-img-00000-00000

CT image

Linea alba axial image 1

CT image

Linea alba CT SAG image