The distribution of the internal carotid circulation in the brain of the macaque monkey (Macaca mulatta)

The distribution of the internal carotid circulation of the macaque brain was studied by using a method of intracarotid dye injections which produced no appreciable disturbance of the dynamics of the cerebral circulation. The areas in cortical and diencephalic structures supplied by the carotid circulation are described and displayed semidiagrammatically in a set of figures. The carotid artery supplies most of the lateral and mesial surfaces of the cerebral hemisphere, whereas the hemispherical portion supplied by the posterior cerebral artery is confined to the occipital and inferior temporal region. Left and right internal carotid territories overlap widely across the midline in cortical areas due to the existence of a single pericallosal arterial trunk formed by the junction of both anterior cerebral arteries. In the diencephalon the segregation of the territories of the left and right internal carotid arteries is sharp, except in its anterior‐most portion. The pattern of internal carotid supply to the thalamus is somewhat variable, the most lateral structures are most consistently supplied by this vessel, whereas the more medial structures, even those lying far rostral within the thalamus, are supplied by the posterior cerebral artery. The territories of the two vessels overlap considerably within the thalamus. In a certain number of animals, the posterior cerebral artery is part of the internal carotid, rather than of the vertebral‐basilar system.