The temporal branches of the MCA (M2 and M3 temporal branches) supply the lateral surface of the temporal lobe from the superior temporal gyrus (Wernicke area in the dominant hemisphere) through the middle and inferior temporal gyri. The anterior temporal branch supplies the temporal pole and superior temporal sulcus; the posterior temporal branch supplies the posterior STG, MTG, and the planum temporale — Wernicke's area.
The posterior temporal MCA branch is the critical vessel for language: its occlusion in the dominant hemisphere produces Wernicke aphasia (fluent paraphasic speech with severely impaired comprehension). The temporal branches are the primary vessels at risk during temporal lobe resection for epilepsy (temporal lobectomy): preserving the branches supplying the dominant superior temporal gyrus while sacrificing those to the middle and inferior temporal gyri maintains language function during resection. The temporal MCA branches are mapped by pre-operative functional MRI and intraoperative cortical stimulation.
Embolism to the posterior temporal MCA branch in the dominant hemisphere produces Wernicke aphasia — fluent speech with phonemic and semantic paraphasias, severely impaired auditory comprehension, and inability to repeat — from infarction of the posterior superior temporal gyrus and planum temporale; the deficits tend to improve partially with language therapy over months.
