Trunk (thorax, abdomen, back)

Linea Alba (White Line)

Linea alba

Origin

Not a muscle, but a median tendinous band: formed by the merging of the aponeuroses of external oblique, internal oblique and transversus abdominis from both sides, running from the xiphoid process to the symphysis

Insertion

Pubic symphysis

Function

Connects the two rectus sheaths in the midline, distributes pulling forces from the broad abdominal muscles and stabilizes the anterior abdominal wall during abdominal straining, coughing and trunk flexion

Innervation

No motor innervation of its own (connective tissue structure, not contractile tissue); sensory supply via the anterior cutaneous branches of the thoracoabdominal nerves (T7-T12)

Movement & chain

Functions as a central anchor along which force from the left and right abdominal wall is transmitted; during unilateral contraction of the abdominal muscles, the linea alba prevents the navel from shifting to one side

Palpation

Felt as a narrow, slightly indentable groove in the midline between the two bellies of rectus abdominis, clearly visible when tensed ("six-pack line")

Clinical

Weakening or widening (rectus diastasis) is common after pregnancy or with chronically increased abdominal pressure; can lead to an umbilical or epigastric hernia through the linea alba

Segmental innervation

T7–T12 (intercostal nerves)

In clinical practice

The linea alba is the preferred incision site for a midline laparotomy, since hardly any muscle and vascular tissue needs to be cut here.

Region in the model

Trunk (thorax, abdomen, back)