Expansion
Collateral, lateral cutaneous and anterior cutaneous branches, plus rami communicantes
Expansion
A typical intercostal nerve is the anterior ramus of T1 to T11. Along its course it gives:
- Rami communicantes - to and from the sympathetic trunk
- Collateral branch - runs along the upper border of the rib below
- Lateral cutaneous branch - pierces the wall near the mid-axillary line, dividing into anterior and posterior branches
- Anterior cutaneous branch - the terminal branch, near the sternum
- Muscular branches to the intercostal muscles
Two nerves are atypical and worth naming: T1 contributes largely to the brachial plexus, and T12 is the subcostal nerve. The T7 to T11 nerves leave the intercostal space to continue into the abdominal wall, which is why lower thoracic pathology such as pleurisy or shingles can present as abdominal pain.