Inside the bottom jaw and below the 3 molar teeth (1,2,3 in in Fig.1) lies a big tube (canal: C).  The molar #3 is the wisdom tooth.  Its root tips (particularly the one with *) are the closest to the canal among the 3 molar teeth.

Why Severe Bleeding after Extraction

Xin Wei, DDS, PhD, MS 1st edition 01/08/2015, last revision 01/09/2015