Spinal Nerves ( 12 Pairs Of Thoracic Spinal Nerves ) :- • Intercostal Nerves is the name given to the anterior primary rami of the upper 11 thoracic spinal nerves ( T1 - T11 ) as they use the route through the intercostal spaces. • The abdominal wall below the 12th rib is where the anterior primary ramus of the 12th thoracic nerve runs and this is why it is termed as subcostal nerve. ~ The intercostal nerves are classified into the following 2 groups :- • Typical intercostal nerves ( 3rd, 4th, 5th, and 6th ) . • Atypical intercostal nerves ( 1st, 2nd, 7th, 8th, 9th, 10th, and 11th ) . √ The normal intercostal nerves are those which stay confined to their very own intercostal spaces. √ The atypical spinal nerves go past the thoracic wall and partially or completely supply the other regions.