Vascularization of the uncus - Anatomical study and clinical implications

Abstract

Background: The objective of this paper was to describe the arterial supply of the uncus and quantify the branches directed to the anteromedial aspect of the human temporal cortex.

Methods: We studied 150 human cerebral hemispheres identifying main afferent arteries supplying the anteromedial temporal cortex with particular attention to the uncus, determining the territory supplied by each artery through either cortical or perforating branches.

Results: The uncus was supplied by 419 branches of the anterior choroidal artery (AChA), 210 branches of the internal carotid artery (ICA), 353 branches of the middle cerebral artery (MCA), and 122 branches of the posterior cerebral artery (PCA). The total of supplying vessels was 1104 among the 150 hemispheres studied, which corresponds to 7.36 arteries per uncus. The average of branches per hemisphere was as follows: 2.79 from AChA, 1.40 from ICA, 2.35 from MCA, and 0.81 from PCA. The relative contribution of each artery for the total of specimens studied was as follows: 38% from AChA, 19% from ICA, 32% from the MCA, and 11% from the PCA. We identified cortical anastomoses mostly between the MCA and PCA (27 cases).

Conclusion: We described and quantified the uncus' vascularization, including anatomical variations. This updated, detailed description of the mesial temporal vascularization is paramount to improve the treatment of neurosurgical conditions.

Keywords: Neuroanatomy; Temporal lobe; Uncus; Vascularization.

Figure 1:

The uncus and its major supplying arteries. The uncus is the most medial an anterior part of the parahippocampal gyrus. It harbors many difficult mesial temporal lobe pathologies, such as arteriovenous malformations and tumors. The internal carotid, anterior choroidal, middle cerebral, and posterior cerebral arteries are the main trunks that provide blood supply to the uncus. In this medial view, we can identify these arteries and their syntopy. White arrow: Internal carotid artery; yellow arrow: Anterior choroidal artery; green arrow: Middle cerebral artery; black arrow: Posterior cerebral artery.

Figure 2:

Cortical branch from the posterior cerebral artery (PCA) to the uncus. The PCA is a previously underrecognized supplier of the uncus. With an average 0.8 branches per hemisphere, it corresponded to 11% of all branches in our study. 1: PCA; 2: Cortical branch.

Figure 3:

Branches from the anterior choroidal artery (AChA), internal carotid artery (ICA), and middle cerebral artery (MCA) to the uncus. The majority of the arterial inflow to the uncus comes from the anterior circulation. The AChA is the main supplier, with an average 2.8 branches per hemisphere, accounting for 38% of all branches that rich the uncus. 1: AChA branches; 2: ICA branches; 3: MCA branches.

Figure 4:

Duplicated anterior choroidal artery (AChA) in an embryonic circle of Willis. The AChA is the main source of arterial blood to the uncal region. A duplicated AChA is shown in a specimen presenting an embryonic circle of Willis. Recognition of such variations is key to perform safer surgeries in this region. 1: Middle cerebral artery; 2: Posterior cerebral artery; 3: Duplicated AChA.

Figure 5:

Cortical anastomosis between branches of the middle and posterior cerebral arteries. Cortical anastomoses play an important role in the arterial supply of the uncus. The solid black arrow points do an anastomosis between branches of the middle and posterior cerebral arteries, evidence of a mixed vascularization from both the anterior and posterior circulations. This network could be important in protecting the structures in the case of thrombotic or ischemic events.

Figure 6:

Schematic drawing of the major suppliers to the uncus. Schematic drawing summarizing the major uncal suppliers. 1: Internal carotid artery; 2 Posterior communicating artery (removed for better visualization); 3: Anterior cerebral artery; 4: Middle cerebral artery; 5: Anterior choroidal artery; 6: Temporal polar artery; 7: Posterior cerebral artery; 8: Uncus.