THORAX ABDOMEN AND PELVIS

Detailed explanation-1: -The thoracic part of the spinal cord gives rise to twelve pairs of thoracic spinal nerves. The anterior/ventral rami of the first eleven thoracic spinal nerves give rise to eleven intercostal nerves. The twelfth nerve is located inferior to the last rib and is thus called the subcostal nerve.

Detailed explanation-2: -Seventh-to-eleventh intercostal nerves They supply the rectus abdominis muscle and terminate as anterior cutaneous branches of the abdomen supplying the cutaneous sensation to the anterior abdominal wall. The lower intercostal nerves also supply the intercostal muscles and anterior abdominal wall musculature.

Detailed explanation-3: -At the T1 through T11 levels, the ventral ramus eventually becomes an intercostal nerve that travels along the same path as the ribs (specifically between the innermost and internal intercostal muscles that connect adjacent ribs). At T12, the ventral ramus becomes a subcostal nerve that travels beneath the twelfth rib.