What is semi lunar line?

The semi-lunar line is a curved line on the human abdomen that separates the lower lateral muscles from the upper lateral muscles. It is also known as the linea semilunaris or Spigelian line. The line starts from the ninth costal cartilage, or the lower part of the costal margins in the mid-clavicular line of the abdomen, and curves towards the pubic tubercle.

The semi-lunar line is formed by the aponeuroses of the internal oblique and transverse abdominis muscles, and it represents the lateral border of the rectus abdominis muscle. The line can vary in thickness and prominence depending on a person's age, gender, and physical activity level. It is used as a reference point for abdominal surgeries and diagnostic procedures.