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Distribution of the Occipital Branches of thePosterior Cerebral Artery

Correlation With Occipital Lobe Infarcts

Slobodan V. Marinkovic", MD, Milan M. Milisavljevic", MD,

Vera Lolid-Draganid, MD, and Miroslav S. Kovac'evic', MD

The occipital branches of the posterior cerebral artery were examined in 31 human brains. Theauthors determined the origin, course, and region of supply of each occipital branch: the parieto-occipital, calcarine, posterior temporal, and common temporal arteries, as well as the lingual gyrusartery. These vessels were found in all the brains examined except the lingual gyrus artery, which waspresent in only 8.3%. The occipital branches were noted to supply variable cortical regions. Inaddition, they sometimes took part in irrigation of deep forebrain structures. It was concluded thatocclusion of a certain occipital artery may cause varying clinical signs and symptoms in differentpatients. The neurologic deficits that may occur following the isolated occlusion of individual occipitalbranches of the posterior cerebral artery are discussed. (Stroke 1987;18:728-732)

The occipital lobe is involved in many aspects ofvisual function. '~3 The knowledge of its arteri-al supply is essential in understanding the syn-

dromes occurring in occlusive cerebrovascular dis-ease. Although several authors6"10 have described thecortical (leptomeningeal) branches of the posterior ce-rebral artery (PCA), there is a lack of detailed informa-tion concerning the regions of supply of the individualbranches. The aim of this study was 1) to determine thevariability of the regions supplied by individual occipi-tal branches, and 2) to compare the anatomic data tothe neurologic deficits produced by occlusion of indi-vidual occipital arteries.

Subjects and MethodsThirty-one human brains taken from patients aged

22-63 years were used for the anatomic study. Bothright and left PCAs were perfused with a saline solu-tion, then injected with 10% India ink and gelatin orwith a radiopaque substance (Micropaque), and fixedin 10% formaldehyde solution for 3 weeks or more.We microdissected all the branches of the PCA andexamined the origin, course, and distribution of theirterminal vessels. We drew each specimen and countedthe frequency of the relevant variations. One brain wasused for making a plastic cast of the PCA, according toa previously described injection method."

ResultsThe main cortical branches of the PCA are the pari-

eto-occipital artery, the calcarine artery, and the ante-rior, middle, and posterior temporal arteries (Figure

From the Institute of Anatomy (S. V.M., M.M.M., V.L.-D.) andthe Department of Neurology (M.S.K.), University MedicalSchool, Belgrade, Yugoslavia.

Address for reprints: Dr. Slobodan V. Marinkovid, MD, Instituteof Anatomy, University Medical School, Subotideva 4/n, 11000Belgrade, Yugoslavia.

Received September 12, 1986; accepted February 2, 1987.

1). The temporal vessels often arise from a commontrunk called the common temporal artery. A few of thementioned cortical branches supply the occipital lobe:the parieto-occipital and calcarine arteries, the posteri-or or common temporal artery, and, when present, thelingual gyrus artery.

Parieto-Occipital ArteryThe parieto-occipital artery originated from the

PCA in either the ambient (in 15% of the brains exam-ined) or quadrigeminal cistern (18.3%), or in the cal-carine sulcus (66.7%). The artery was almost alwayssingular (98.3%). It entered the rostral portion of thecalcarine sulcus and then continued along the parieto-occipital sulcus. In 1 of the mentioned sulci, the arterydivided into 2 (Figure 1), 3, or 4 terminal stems, thebranches of which were distributed to the medial andsometimes the lateral surface of the occipital and pari-etal lobes. In addition to the floor and banks of theparieto-occipital sulcus, these branches also supplied10-40% of the precuneus and 10-20% of the cuneus(Figure Id), 50-90% of the precuneus and 10-20% ofthe cuneus (Figure 2b), 10-30% of the precuneus and20-50% of the cuneus (Figure 2c), 40-90% of theprecuneus and 50-80% of the cuneus (Figure Id),40-90% of the precuneus and 80-90% of the cuneus(Figure 2e), 10-20% of the precuneus and 50-80% ofthe cuneus (Figure If), or 10-20% of the precuneusand 80-90% of the cuneus (Figure 2g).

The parieto-occipital artery gave rise to the follow-ing collateral vessels: the calcarine branch (in 20% ofthe brains examined), the anterior (3.3%) or middle(1.7%) or posterior (3.3%) temporal arteries, the hip-pocampal branches (3.3%), the thalamogeniculatebranches (15%), the medial (5%) or lateral (23.3%)posterior choroidal arteries, and the branch to thesplenium of the corpus callosum (48.3%).

In 23.3% of the cases, the parieto-occipital arterysupplied the lateral occipital gyri and the superior pari-

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FIGURE 1. Main cortical branches of the posterior cerebralartery. 1, Anterior temporal arteries; 2, middle temporal ar-tery; 3, posterior temporal artery; 4, parieto-temporal arterydividing into 2 terminal stems (4' and 4"); 5, right posteriorcerebral artery; 6, basilar artery. Plastic cast, dorsal view.

etal lobule. When the artery was large, it also nour-ished the retrosplenial area and the most caudal part ofthe cingulate gyrus (Figure 2, b, d, and e) as well as themost caudal part of the parahippocampal gyrus occa-sionally.

Calcarine ArteryThis artery had the same origin as the parieto-occipi-

tal artery (Figure 1), namely, they both arose from thesame site of the distal segment of the PCA or from thesame terminal stem (called the medial occipital artery)of the PCA. The calcarine artery was singular in 80%of the cases and double in 20%. In the latter group, 1 ofthe 2 vessels always originated from the parieto-oc-cipital artery.

The single calcarine artery, which arose in the ambi-ent or quadrigeminal cistern or in the proximal part ofthe calcarine sulcus, entered the latter and ran along it.In half of the cases the artery divided into 2, and morerarely into 3, terminal stems. One of the 2 terminalstems usually coursed along the floor of the calcarinesulcus, while the other was more superficially located.When 2 calcarine arteries were present, the smallerone, which arose from the parieto-occipital artery,supplied the rostral or superficial part of the calcarinesulcus.

In addition to the floor and the dorsal and ventralbank of the calcarine sulcus, the calcarine artery alsosupplied 80-90% of the cuneus (Figure 3a), 80-90%of the cuneus and most of the lingual gyrus (Figure3b), 50-80% of the cuneus (Figure 3c), 50-80% of thecuneus and most of the lingual gyrus (Figure 3d),20-50% of the cuneus (Figure 3e), 20-50% of thecuneus and most of the lingual gyrus (Figure 3/),10-20% of the cuneus (Figure 3g), or 10-20% of thecuneus and most of the lingual gyrus (Figure 3h).

FIGURE 2. Variation in the areas sup-plied by branching of the terminal stems ofthe parieto-occipital artery in 31 humanbrains. Frequencies in percent.

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730 Stroke Vol 18, No 4, July-August 1987

FIGURE 3. Variation in areas supplied bycalcarine artery in 31 human brains.

The proximal part of the calcarine artery gave offone or more of the following collateral branches: themiddle (in 1.7% of the brains examined) or posterior(5%) temporal arteries, the hippocampal vessels(8.3%), and branches to the medial geniculate body(1.7%), the medial (1.7%) or lateral (1.7%) posteriorchoroidal arteries, and the splenial branch (1.7%).

In 13.3% of the cases, the calcarine artery suppliednot only the medial surface, but also a part of the lateralsurface of the occipital lobe.

Lingual Gyrus ArteryThis artery was present in 8.3% of the brains exam-

ined. It arose from the terminal stem of the PCA, closeto the most rostral part of the calcarine sulcus. Theartery coursed along the lingual gyrus, which it sup-plied entirely (Figure 4a). In 1 case, the lingual gyrusartery gave off a branch to the caudal part of the calca-rine sulcus.

Posterior Temporal ArteryThe posterior temporal artery was present in 60% of

the cases (Figure 1). It was singular and very rarelyduplicated (only 2.8% of the brains examined). Theartery arose in the ambient cistern, either from thePCA (86.1%) or from the parieto-occipital (5.5%) orcalcarine (8.3%) arteries. It coursed caudally and later-ally, along the ventral surface of the hemisphere. Theartery supplied the ventral surface of the occipital andthe ventrocaudal portion of the temporal lobes. Moreprecisely, it nourished the caudal part of the parahippo-campal gyrus, the lingual gyrus (Figure 4c), the caudalhalf or two-thirds of the occipito-temporal (fusiform)gyrus (Figure 4, b and c), and the caudal third or half ofthe inferior temporal gyrus. In 41.6% of the cases, itirrigated a part of the lateral occipital gyrus, includingthe occipital pole, as well. In 3.4% of the brains, theartery gave off a branch to the caudal part of the calca-

rine sulcus. Finally, the proximal portion of the arterygave rise to the hippocampal branches (in 61.1 % of thebrains examined) and to the lateral posterior choroidalartery (2.8%).

Common Temporal ArteryThis common stem of the temporal arteries is also

called the lateral occipital artery or the temporo-occipi-tal artery. It arose as the second terminal stem of thePCA in 40% of the cases. The origin was in the ambi-ent cistern, usually at the level of the lateral geniculatebody. The artery coursed across the parahippocampal

FIGURE 4. Variation in the areas supplied by (a) the lingualartery (no variation), (b, c) the posterior temporal artery, andfd, e) the common temporal artery in 31 human brains.

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gyrus and then distributed its branches to the ventralsurface of the temporal and occipital lobes. The com-mon temporal trunk almost entirely supplied the para-hippocampal, occipito-temporal, and inferior temporalgyri (Figure Ad). In addition, it also supplied the lin-gual gyrus in 28.4% of the hemispheres (Figure Ae).The proximal part of the common temporal artery gaverise to the hippocampal branches (in 55.4% of thebrains examined) and to the lateral posterior choroidalartery (12.5%).

Discussion

Our anatomic results clearly showed that the indi-vidual cortical branches of the PCA have variable re-gions of supply. Thus, the parieto-occipital artery irri-gated almost the entire precuneus and cuneus in certainspecimens (Figure 2, d and e), but in others it suppliedonly a narrow strip along the parieto-occipital sulcus(Figure la). The extent of a region supplied by a corti-cal artery depends mainly on the size and territory ofthe ramifications of that artery as well as on the size ofthe neighboring cortical branches of the posterior,anterior, or middle cerebral arteries. Some corticalregions may have various sources of blood supply. Forexample, the lingual gyrus can be irrigated by thecalcarine, posterior temporal, common temporal, orlingual gyrus arteries (Figures 3 and 4). Certain corti-cal regions are sometimes supplied by several arteries.Thus, the calcarine cortex receives its main blood sup-ply from the calcarine artery. In addition, the parieto-occipital artery gave off a branch to the rostral orsuperficial calcarine cortex in 20% of the cases, and insome other specimens (Figure 2, e and g) it suppliedthe rostrodorsal striate cortex. Finally, the temporalarteries sometimes gave off branches to the caudalportion of the calcarine cortex.

The last anatomic fact of possible clinical signifi-cance is the finding that some of the occipital arteriesalso gave off branches to the thalamus, geniculatebodies, internal capsule, and splenium of the corpuscallosum. This means that occlusion of such an arterymay be followed not only by infarction of certain corti-cal regions, but also of the deep forebrain structures.

In general, our results are in accordance with thedata from the literature.6-10 However, there are somedifferences concerning the anatomic features and re-gions of supply of certain arteries.

According to Zeal and Rhoton,9 the parieto-occipitalartery occasionally supplies the caudal part of the para-central lobule. However, in all the specimens we haveexamined, this part of the paracentral lobule was nour-ished by the paracentral and/or the superior parietalbranch of the anterior cerebral artery.

We found the lingual gyrus artery in 8.3% of thecases studied. This vessel was actually observed bySmith and Richardson,6 but it was incorrectly identi-fied as the posterior temporal artery, or even as thesecond calcarine artery. The lingual gyrus artery, how-ever, has all the features of a separate branch of thePCA.

The vessels that may supply the ventral surface ofthe occipital and temporal lobes are the common tem-poral artery; the posterior, middle, and anterior tempo-ral arteries; and the hippocampal vessels. The commontemporal artery was seen more frequently in our studythan in other reports.89 The posterior temporal artery isone of the largest temporal vessels. It occasionallyoriginated from the parieto-occipital or calcarine arter-ies instead of from the main stem of the PCA. Themiddle temporal artery is the least constant vessel,9

supplying the rostral portions of the parahippocampal,occipito-temporal, and inferior temporal gyri. Theanterior temporal artery may arise as a single trunk oras multiple branches8 and nourishes the rostroventralpart of the temporal lobe. According to Zeal and Rho-ton,9 there are 1 or 2 hippocampal arteries; however,we found as many as 5 arteries in the same specimen(personal observation). They originated from the mainstem of the PCA and/or from the initial portions of thetemporal arteries. The hippocampal vessels suppliedthe uncus and hippocampal formation.

Occlusion of a given occipital or a temporal arteryleads to brain tissue ischemia in its region of supply.The size and extent of the ischemic zone depends on 1)the size of the region supplied by the affected artery, 2)the cause of the occlusion, 3) the efficiency of thearterial anastomoses, and 4) the characteristics of thegeneral and local brain vasculature and blood flow.12-'4

This is the reason for discrepancies between the ex-pected and the real size and shape of the ischemic zonein some patients.

As a result, various neurologic signs and symptomsmay follow the occlusion of these branches of thePCA. Isolated occlusion of the parieto-occipital artery,which often takes part in supplying the most rostral orrostrodorsal part of the striate cortex, may cause anincongruous homonymous hemianopia or inferiorquadrantanopia sparing central fixation.2 Because ofthe damage to the parietal (precuneal) cortex, visualdisorientation and metamorphopsia could also devel-op. 15 In almost half of the patients, the parieto-occipi-tal artery gives off the splenial branch, which nour-ishes the callosal fibers connecting the right visualareas to the left angular gyrus. Hence, occlusion of theleft parieto-occipital artery in some patients can pro-duce impaired color naming or pure alexia.16

Isolated occlusion of the calcarine artery may pro-duce a complete homonymous hemianopia.23 Howev-er, when the most caudal part of the striate cortex issupplied by the temporal branches of the PCA or thetemporo-occipital or angular gyrus arteries," a homon-ymous hemianopia sparing central fixation will devel-op. Because of the additional participation of the par-ieto-occipital artery in irrigation of the rostral orsuperficial striate cortex, an incongruous homony-mous hemianopia is also possible.2 Occlusion of asmall branch of the mentioned arteries may produce asmall central or peripheral scotoma.26

Unilateral occlusion of the posterior temporal or thecommon temporal arteries (which supply, among otherregions, the fusiform and often the lingual gyri) may

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cause pure alexia or hemiachromatopsia and coloranomia.416 In cases with bilateral infarctions in thetemporo-occipital regions, the patients may haveachromatopsia, visual object agnosia, and prosopag-nosia.3'416 Finally, ischemia of the hippocampus (bi-laterally or on the left side only) may cause the impair-ment of memory.1

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3. Damasio AR, Damasio H, Van Hoesen GW: Prosopagnosia:Anatomic basis and behavioral mechanisms. Neurology (NY)1982,32:331-341

4. Damasio AR, Damasio H: Localization of lesions in achroma-topsia and prosopagnosia, in Kertesz A (ed): Localization inNeuropsychology. New York, Academic Press, 1983, pp417-427

5. Bosley TM, Rosenquist AC, Kushner M, Burke A, Stein A,Dann R, et al: Ischemic lesions of the occipital cortex and opticradiations: Positron emission tomography. Neurology 1985;35:470-484

6. Smith CG, Richardson WFG: The course and distribution ofthe arteries supplying the visual (striate) cortex. Am J Ophthal-mol 1966;61:1391-1396

7. Hoyt WF, Newton TH, Margolis MT: The posterior cerebralartery. Section I. Embryology and developmental anomalies.Radiology of the skull and brain, in Newton TH, Potts DG(eds): Angiography, vol 2, book 2. St. Louis, CV Mosby Co,1974, pp 1540-1550

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10. Hayman LA, Berman SA, Hinck VC: Correlation of CT cere-bral vascular territories with function: II. Posterior cerebralartery. AJR 1981; 137:13-19

11. Marinkovid SV, Milisavljevid MM, Kovadevid M, Stevid Z:Perforating branches of the middle cerebral artery. Microanat-omy and clinical significance of their intracerebral segments.Stroke 1985;16:1022-1029

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KEY WORDS • posterior cerebral artery • occipital lobeocclusive cerebrovascular disease • visual symptomcomputed tomography

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S V Marinkovic, M M Milisavljevic, V Lolic-Draganic and M S Kovacevicoccipital lobe infarcts.

Distribution of the occipital branches of the posterior cerebral artery. Correlation with

Print ISSN: 0039-2499. Online ISSN: 1524-4628 Copyright © 1987 American Heart Association, Inc. All rights reserved.

is published by the American Heart Association, 7272 Greenville Avenue, Dallas, TX 75231Stroke doi: 10.1161/01.STR.18.4.728

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