The linea semilunaris (also semilunar line or Spigelian line) is a curved

tendinous intersection The rectus abdominis muscle is crossed by three fibrous bands called the tendinous intersections or tendinous inscriptions. One is usually situated at the level of the umbilicus, one at the extremity of the xiphoid process, and the third about mid ...

found on either side of the

rectus abdominis muscle The rectus abdominis muscle, ( la, straight abdominal) also known as the "abdominal muscle" or simply the "abs", is a paired straight muscle. It is a paired muscle, separated by a midline band of connective tissue called the linea alba. It exte ...

Structure

The linea semilunaris corresponds with the lateral border of the

. It extends from the

cartilage Cartilage is a resilient and smooth type of connective tissue. In tetrapods, it covers and protects the ends of long bones at the joints as articular cartilage, and is a structural component of many body parts including the rib cage, the neck an ...

of the ninth

rib In vertebrate anatomy, ribs ( la, costae) are the long curved bones which form the rib cage, part of the axial skeleton. In most tetrapods, ribs surround the chest, enabling the lungs to expand and thus facilitate breathing by expanding the ches ...

to the

pubic tubercle The pubic tubercle is a prominent tubercle on the superior ramus of the pubis bone of the pelvis. Structure The pubic tubercle is a prominent forward-projecting tubercle on the upper border of the medial portion of the superior ramus of th ...

. It is formed by the

aponeurosis An aponeurosis (; plural: ''aponeuroses'') is a type or a variant of the deep fascia, in the form of a sheet of pearly-white fibrous tissue that attaches sheet-like muscles needing a wide area of attachment. Their primary function is to join musc ...

of the

internal oblique The abdominal internal oblique muscle, also internal oblique muscle or interior oblique, is an abdominal muscle in the abdominal wall that lies below the external oblique muscle and just above the transverse abdominal muscle. Structure Its fibers ...

at its line of division to enclose the rectus. This is reinforced anteriorly by the

external oblique The abdominal external oblique muscle (also external oblique muscle, or exterior oblique) is the largest and outermost of the three flat abdominal muscles of the lateral anterior abdomen. Structure The external oblique is situated on the lateral ...

, and posteriorly by the

transversus abdominis The transverse abdominal muscle (TVA), also known as the transverse abdominis, transversalis muscle and transversus abdominis muscle, is a muscle layer of the anterior and lateral (front and side) abdominal wall which is deep to (layered below) th ...

above the arcuate line.

Clinical significance

A hernia through the linea semilunaris is called a

Spigelian hernia A Spigelian is the type of ventral hernia where aponeurotic fascia pushes through a hole in the junction of the linea semilunaris and the arcuate line creating a bulge. It appears in the abdomen lower quadrant between an area of dense fibrous tiss ...

. This usually occurs at the meeting point of the linea semilunaris with the arcuate line and the lateral border of the

Reference

External links

* - "The Linea Alba and Linea Semilunaris" * - "Insertions of Rectus Abdominis, Anterior View" {{DEFAULTSORT:Linea Semilunaris Abdomen