For the above discussion emerges a view which conceptualizes the PICA as a branch of the lateral spinal artery - as distinct from AICA and SCA, which are branches of the Anterior Spinal Artery. Now we are in a better position to do justice to the PICA. smaller basilar perforators are but transverse channels which may capture some small segment of anterior cerebellar surface that is not taken by adjacent AICAs or SCAs. Dominant AICAs and PICAs and SCAs are simply variations in extent of cerebellar surface capture by one vessel, with corresponding dominance or hypoplasia of the others. For example, duplicated SCAs and AICAs are just two adjacent perforators, which persisted in co-dominance of cerebellar supply. This simple concept explains ALL variations seen in the area. Others stay relatively small and are thus “limited” to brainstem supply.
As the cerebellum develops, some of these transverse channels enlarge to capture the cortical territory of the cerebellum - thus becoming AICAs and SCAs. As explained above, one can think of the basilar as a longitudinal channel, with multiple trasverse channels. Understanding the embryology of vertebrobasilar circulation helps explain many variations seen in this pattern. Radiculomedullopial arteries are those which happen to supply both anterior and posterior spinal systems simultaneously, sometimes via a coronary artery, and at other times via separate connections to the posterior spinal system. For a more complete discussion of spinal vasculature, see Spinal Vascular Anatomy section, particularly Spinal Arterial Anatomy.Ĭlassical dispostion depicts AICA and SCA arising from the basilar artery, in addition to multiple short basilar perforators whose supply is limited to the brainstem. Radiculopial arteries are those which supply the posterior spinal system. In practice, as you know, the radiculomedullary and radiculopial arteries are fewer, and may arise from longitudinal vessels other than the vert. The entire spinal cord system is supplied via segmental radiculomedullary arteries, which connect the vertebral artery to the anterior spinal artery. A number of perforating arteries into the substance of the cord exist when arising from the anterior spinal artery and penetrating through the ventral cord sulcus, they are named “sulco-comissural” arteries. The anterior and posterior spinal systems are connected by anastomoses running along the circumference of the cord, although known as “coronary” arteries, are conceptually quite clear. The image on the LEFT represents cervical spinal cord arterial supply, which consists of the anterior spinal artery and a paired, loose network of posterolateral vessels known as the posterior spinal arteries, and which are conceptually represented here as contiguous vessels (which is at least mostly true in the cervical spine).
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