Identify the external and internal intercostal muscles. (G 3.18;N 186;Gl 7.10)

1. Locate the 3 ^rd intercostal space (the 2 ^nd rib is at the level of the sternal angle). Identify the external intercostal muscle in this space.
2. Identify the internal intercostal muscle in the 4 ^th intercostal space.
3. Identify the internal thoracic artery and vein. Attempt to identify an anterior intercostal artery and vein branching from (or draining into) the internal thoracic artery and vein. (G 3.21;N 186;Gl 7.17)