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- Description
-  I    Open (usually from stabbing)
- II    Closed (usually from motorcycle accident)
- IIa  Supraclavicular
          - preganglionic:
               - avulsion of nerve roots, usually from high speed injuries
                   with other injuries and LOC;
               - no proximal stump, no neuroma formation (neg Tinel's)
               - pseudomeningocele, denervation of neck muscles are common
               - horner's sign (ptosis, miosis, anhydrosis)
         - postgangionic:
               - roots remain intact;
               - usually from traction injuries;
               - there are proximal stump and neuroma formation (pos Tinel's)
               - deep dorsal neck muscles are intact, and pseudomeningoceles
                    will not develop;
- Infraclavicular Lesion:
    - usually involves branches from the trunks (supraclavicular);
    - function is affected based on trunk involved;
         - Trunk Injured          Functional Loss
             Upper                   biceps , shoulder muscles
             Middle               Wrist and Finger Extension;
             Lower                Wrist and Finger Flexion;
-  III     Radiation induced
-  IV    Obstetric
-  IVa  Erb's  (upper root) - waiter's tip hand;
-  IVb  Klumpke (lower root)