Lateral abdominal cutaneous branch of intercostal nerve

About the middle of their cours, the lower intercostal nerve (7 to 12) give off lateral cutaneous branches called lateral abdominal cutaneous branches. 

These pierce the Intercostales externi and the Obliquus externus abdominis, in the same line as the lateral cutaneous branches of the upper thoracic nerves, and divide into anterior and posterior branches, which are distributed to the skin of the abdomen and back; the anterior branches supply the digitations of the Obliquus externus abdominis, and extend downward and forward nearly as far as the margin of the Rectus abdominis; the posterior branches pass backward to supply the skin over the Latissimus dorsi.