“…It has been reported that the traumatic or non-traumatic lesions of terminal motor branches of the PIN end up as isolated drop thumb deformity (Suematsu and Hirayama, 1988;Hirachi et al, 1998;Hirayama and Takemitsu, 1998), isolated drop fingers (Cravens and Kline, 1990;Hirachi et al, 1998) , and the sign of horns (Spinner et al, 1998;Leechvavengvongs et al, 2001). Detailed anatomic knowledge of the terminal motor branches of the PIN is required for a correct diagnosis and surgery and most of the studies did not look into the correlation between the anatomy and the clinical outcome with the exception of a few (Spinner et al, 1998).…”