In cases of trifurcation, the orbitofrontal and operculofrontal arise from the anterior trunk; the central, parietal, and gyrus angular arteries arise from the middle trunk; the temporal branches arise from the posterior trunk.
He divided MCA into four groups: Group I: absence of a main division (that is, a single-trunk type of MCA) (in 6% of cases); Group II: bifurcation (64%); Group III: trifurcation (29%); and Group IV: quadrifurcation (1%).
In the study reported by Gibo et al, (1) 78% of the MCAs divided into a bifurcation, 12% divided into a trifurcation, and 10% divided into multiple trunks.
Cases Division Bilateral division Total thyroidectomy 100 43 (43) * 11 Inferior laryngeal nerve 200 54 (27) Trifurcation
4 (2) Sex (Female/male) 77/23 33/10 Division at right side Total thyroidectomy 8 Inferior laryngeal nerve 19 (19) Trifurcation
2 (2) Sex (Female/male) 15/4 Division at left side Total thyroidectomy 24 Inferior laryngeal nerve 35 (35) Trifurcation
2 (2) Sex (Female/male) 27/8 * Numbers in parentheses are percentages.