Fig. 5. Type 3 angulation in A3. Note a near right angle bend at A3. Also notice that increase in acuty of A3 results in increase in vertical segment of C-ICA (i.e., between A3 and A4). The black bands demarcate different parts of ICA. ICA, internal carotid artery; P-ICA, petrous part of ICA; C-ICA, cavernous part of ICA; A1, first angle of petrous segment; A2, second angle of petrous segment; A3, first angle of cavernous segment; A4, second angle of cavernous segment.