Orbital suppy and anastomoses. This is typically a diminutive branch which enters the orbit through the superior orbital fissure. In early life mm embryo stagethis derivative of the MMA is in hemodynamic balance with embryonic dorsal and ventral ophthalmic arteries, tentorium Thrombophlebitis.
The ventral ophthalmic initially arises from the ACA A1 segment, and is eventually replaced by the adult ophthalmic artery. If this adult ophthalmic artery fails to develop for some reason, the MMA is first in line to pick up orbital territory as the meningo-ophthalmic artery even before dorsal ophthalmic which in adult form is very rare.
Lateral ECA injection demonstrates opacification of the internal carotid artery brown arrow via the middle meningeal artery red arrow. Notice a large tentorium Thrombophlebitis of the MMA entering the orbit and tentorium Thrombophlebitis opacifying the ICA through collaterals with lacrimal arteries. Vessels the Neurointerventionalist Needs tentorium Thrombophlebitis Know. AJNR ; 30 8 ICA injections above demonstrate no ophthalmic artery.
Note incidentally MHT supply to the pituitary gland with a characteristic pituitary blush, tentorium Thrombophlebitis. ECA tentorium Thrombophlebitis projection injection of the same case below demonstrate a prominent meningo-ophthalmic artery. The internal carotid artery in this case is opacified via reflux of contrast medium from a proximal ECA catheter position. On the right, the ophthalmic arises from the MMA. We have several other cases with MRA and angio imaging of the same variant, with less obvious correlation.
One strategy for catching these is to look at ophthalmic artery origin. It is usually seen although bone and flow direction make it relatively poorly visible. Selective injection of the petrosquamosal branch demonstrates a fistula in the tentorium Thrombophlebitis sinus region opacifying the sinus blue arrows.
The fistula was embolized with glue from the branch with the leftmost red tentorium Thrombophlebitis. Patient with bilateral Moya-Moya, post bilateral dural synangiosis and burr hole see Intracranial Collateral Pathways for the remainder of this case. Anastomoses with middle meningeal petrosquamosal and basal tentorial and occiptal branches are clearly demonstrated.
These arteries frequently participate in supply of sigmoid sinus dural fistulas. This process is more robust in younger patients, and so is often encountered in angiographic evaluation of Moya Moya disease.
In this 4 year old patient, an impressive autosynangiosis recruiting the middle meningeal artery tentorium Thrombophlebitis to supply mesial posterior frontal and anterior parietal lobes, in response to progressive narrowing of right ICA Varizen Löwen left A1 segments.
Notice also a faint autosynangiosis between ethmoid arteries from the ophthalmic and frontal lobe base, tentorium Thrombophlebitis. The right A1 is closed, with both anterior cerebral territories supplied through a moderately diseased left A1. The situation is therefore most tenuous at the right superior convexity, where the above autosynangiosis has developed.
Persistent Stapedial Artery — images courtesy of Drs. Peter Kim Nelson and Eytan Raz. This is a key variant to understanding embryology of the craniofacial circulation. See some images below. Persistent Stapedial Artery — another example. In the same way the inferior tympanic-carotidotympanic connection results in tentorium Thrombophlebitis pharyngeal reconstitution of the petrous carotid artery, a persistent inferior tympanic can maintain an embryonic connection to the middle meningeal artery via the petrous branch of the MMA that makes us the facial nerve arcade.
Embryonically, the middle meningeal artery does not belong to the IMAX — it instead arises from the petrous ICA via the primitive hyoid artery, tentorium Thrombophlebitis. The hyoid connects to the inferior tympanic, which goes thru the stapes crura called stapedial artery at this point and then via the facial arcade supplies what is ultimately the Von Krampfadern im Detail. This connection is rudimentary in adulthood for most of us.
However, tentorium Thrombophlebitis, in some cases the ascending pharyngeal-inferior tympanic-petrous-MMA connection persists, tentorium Thrombophlebitis. Simply put, the MMA is a branch of the ascending pharyngeal, tentorium Thrombophlebitis. These can often be recruited following craniotomy with destruction of the proximal MMA.
In this patient status post pterional craniotomy white arrowsthe parietal branch of the MMA red is being reconstituted via a prominent falx cerebelli artery orage.
Notice a groove in which the MMA runs on the unsubtracted image. Tentorium Thrombophlebitis example, even tentorium Thrombophlebitis prominent, post bilateral pterional craniotomies, tentorium Thrombophlebitis. The artery of the tentorium cerebelli tentorium Thrombophlebitis gives rise to the posterior meningeal artery, whose territory has considerably extended due to bilateral MMA sacrifice, demonstrating an impressive meningeal network yellow arrows.
Same, in beautiful stereo, tentorium Thrombophlebitis. Recurrent Meningeal Artery — this disposition is tentorium Thrombophlebitis to the meningo-ophthalmic situation. Here, it is the ophthalmic artery that supplies territory of the middle meningeal artery through its recurrent meningeal branch Letter F in figures above.
This branch arises from the proximal ophthalmic artery and projects posteriorly through the superior orbital fissure or through its own foramen. Recurrent Meningeal Artery purple arising from the ophthalmic artery orange and heading posteriorly into the middle cranial fossa. The artery assumes territory of the meningeal branch for the sphenoid ridge red, foreshortened in lateral projection and contiues as several branches of the frontoparietal inner table yellow, tentorium Thrombophlebitis.
Recurrent Meningeal Artery B giving rise to the artery of sphenoid ridge Cnormally a branch of the middle or accessory meningeal artery. Tentorium Thrombophlebitis Meningeal Artery 2: On head CT, aberrant MMA origin can be inferred by absence tentorium Thrombophlebitis foramen spinosum or a much smaller foramen than contralaterally, attesting to asymmetery in MMA size.
The contralateral foramen spinosum is labeled in blue. The recurrent meningeal artery travels along the sphenoid ridge orange arrows and then over the convexity red arrows. Petrous origin of the Middle Meningeal Artery. With continued development, tentorium Thrombophlebitis, the IMAX territory was annexed by the enlarging external carotid branch, which heretofore has been preoccupied with faciolingual and occpital territories.
In the following case, however, the MMA does not originate from the stapedial branch, tentorium Thrombophlebitis, but more anteriorly, from the mid-section of the horizontal petrous segment, in the expected Rotlauf mit Krampfadern of the vidian artery origin. Tentorium Thrombophlebitis what tentorium Thrombophlebitis the MMA becomes connected to the vidial segment I do not understand.
The following image shows absent of foramen spinosum on on the right yellow arrow on leftand origin of the right MMA from the vidian segment purple arrow. Angiogram of the same patient shows the MMA red arrows with its Vidian origin purple tentorium Thrombophlebitis frontal top left and stereoscopic tentorium Thrombophlebitis projections bottom.
Orbital suppy and anastomoses Meningo-lacrimal artery: Peter Kim Nelson and Eytan Raz This is a key variant to understanding embryology of the craniofacial circulation. The following image shows absent of foramen spinosum on on the tentorium Thrombophlebitis yellow arrow on lefttentorium Thrombophlebitis, and origin of the right MMA from the vidian segment purple arrow Angiogram of the same patient shows the MMA red arrows with its Vidian origin purple in frontal top left and stereoscopic lateral projections bottom.
Embryology and Phylogeny see dedicated Neurovascular Evolution and Vascular Neurombryology pages for details. The PCA originally belongs to the anterior, carotid circulation, arising as the carotid terminates into the cranial and caudal rami — the future ACA and Tentorium Thrombophlebitis, respectively.
In many mammals the vertebrobasilar system does not prominently figure in PCA supply, being confined to the brainstem and cerebellum. Whatever the case, you have every right to confidently pick your own definition. There is certainly an angiographic or MRA or CTA absence of these vessels, which means nothing except that your equipment is not good tentorium Thrombophlebitis to see it.
They are always present in fact, as embryologically required. Early development of the PCA is dominated by its supply of the lateral and third ventricular choroidal territory the choroidal stage, as best described in Surgical Neuroangiographytogether with the Anterior Choroidal Artery. In fact, from a phylogenetic tentorium Thrombophlebitis, it is the Anterior Choroidal and not the PCA that serves as the artery to the occipital and temporal lobar areas.
However, on occasion the tentorium Thrombophlebitis choroidal retains some of its formerly extensive cortical possessions, tentorium Thrombophlebitis, and as such might even be mistaken for a fetal PCA.
In the vast majority of cases, however, the PCA is responsible for the supply of the mesial Occipital, inferomesial Parietal, and tentorium Thrombophlebitis Temporal lobes, as well as the choroid plexus of the lateral together with the anterior choroidal and third ventricles, tentorium Thrombophlebitis. Importantly, it also contributes to the supply of the cerebral peduncles and the collicular plate, its phylogenetically older territories.
Importantly, by way of the collicular or circumcollicular arteries it also contributes to tentorium Thrombophlebitis of cerebral peduncles and the collicular plate, its phylogenetically older territories. In the lateral, there is frequent superimposition, which can be resolved by yawing the lateral tube to separate the two.
Tentorium Thrombophlebitis imaging can help decide which side is which, if knowledge is otherwise insufficient. The above image from the Tentorium Thrombophlebitis collection, with a corresponding drawing on the left, for reference:. A lateral image of the x-ray specimen, with colored arrows this time.
Nothing like a stroke to show what the territory was: Below is a typical angiographic image of the PCA. On the right, the P1 purple segment is smaller than on the left redRosskastanie Rezept von Thrombophlebitis streaming of tentorium Thrombophlebitis blood white through the right PCOM visible distal to its otherwise invisible confluence with the P1 segment.
There is tremendous variation in how the inferior tentorium Thrombophlebitis branches are organized. The important part to understand is where the branch tentorium Thrombophlebitis relation to the brain, tentorium Thrombophlebitis. Left vertebral injection in the same patient.
The left PCOM red is transiently retrogradely opacified by the force of the injection. Anything distal is P3, P4, and on. Because of the fetal disposition on the right, the lateral allows for left PCA tentorium Thrombophlebitis without superimposition.
The all-important calcarine branch black is the paramedian branch just above the tent where the calcarine cortex is. Importantly, it will be foreshortened in the Townes view because the tent will be sloping down. The parieto-occipital branch on the other hand pink is less foreshortened. It is typically large and should not be mistaken for the calcarine one.
Tentorium Thrombophlebitis notice several large posterior inferior temporal branches yellow. Because of the shape of the tent, which slopes down as it stretches laterally, the temporal branches will ovelap the cerebellum in both frontal and lateral views. It is very important to understand that. The calcarine branch will never do that in the lateral viewbecause the medial occipital lobe is always above the cerebellum. Ano th er fetal PCOM by my definitionon the left, tentorium Thrombophlebitis.
A small P1 segment is present orange. Notice how well the left tent is outlined by the hemspheric branch of the left SCA plastered up tentorium Thrombophlebitis it no arrows this time. A sizable basilar fenestration is shown by the brown arrow.
Thus, tentorium Thrombophlebitis, all PCA branches are superimposed on each other, with no good definition, except for one — the posterior lateral choroidal branch white arrow rises above the rest, to where the lateral ventricle would be, tentorium Thrombophlebitis. Notice the unfused long P1 segments above the superior cerebellar ostia arrow. See Basilar Artery page for details, tentorium Thrombophlebitis.
Posterior Communicating Artery Fenestration — not something you see everyday. Here is one, in association with a Trigeminal artery. The apparent origin of the PCA from the P1 segment is, in fact, directly tentorium Thrombophlebitis to the embryology of the basilar artery, which is formed by fusion of paired longitudinal neural arteries.
The extent of fusion determines the length of the basilar, and some of its variations. Imagine the basilar tentorium Thrombophlebitis as a zipper:. Below is an example of an embolus from the carotid artery into a fetal PCOM white arrow. This, unfortunately, is too often true with occipital infarcts. The medial occipital area is not well-supported via leptomeningeal collaterals, being at the distal end of both ACA and MCA territories, and cortical visual field deficits too often show minimal to no recovery.
Frank Netter drawing, emphasizing inferior location tentorium Thrombophlebitis the Calcarine branch in relation to the Parietooccipital branch which is situated in the sulcus of the same name. The temporo-occipital territory sits at the further edge of two potential sources of supply — anteriorly from the temporo-occipital branches of the MCA, and inferiorly from the posterior inferior temporal artery. Here is an illustration of this phenomenon, in a patient with the territory of interest demarcated by the parenchymal hemorrhage component.
Notice how far back the branch extends on the lateral view — again not to be confused with the calcarine branches greenwhich are superimposed on the nidus in the tentorium Thrombophlebitis projection. The parieto-occipital branches white are medial and do not contribute to the AVM. A normal posterior inferior temporal branch is marked with a purple arrow. The inferior temporal branches green will attempt to reconstitute the upper, perisylvian portions of the temporal lobe, tentorium Thrombophlebitis, while the parieto-occipital branch fills in variable territories of the superior parietal lobule, precuneus, and possibly the posterior frontal convexity, depending on whether or not the hemodynamic constraint affects the MCA, ACA, or both.
In this way, the inferior temporal branches can help salvage the Wernicke area. In most cases of acute occlusion, however, PCA cortical branches are too far posterior and inferior to effectively resupply the frontal lobe, which depends on the ACA in cases of insufficient MCA perfusion. In this ICA embolus case, the posterior inferior temporal branch red and middle tentorium Thrombophlebitis temporal branch purple leptomeningeal vessels help reconstitute a sizable portion of the temporal lobe light blue oval, parenchymal phaseretrogradely opacifying several inferior division temporal green and inferior parietal yellow branches of the MCA.
The extent of collateral support in the temporal lobe territory is fairly robust, tentorium Thrombophlebitis. The posterior pericalossal artery black arrow is normally a very poor collateral to the distal pericalossal light blue territory of the ACA. In this case, tentorium Thrombophlebitis, a small leptomeningeal network pink is trying its best. Notice normal-appearing posterior graymiddle brown and anterior orange inferior temporal branches on the right, tentorium Thrombophlebitis.
Here is another example of rather effective leptomeningeal collateral response through the parieto-occipital territory supporting the superior parietal lobule red and great inferior temporal support of tentorium Thrombophlebitis MCA inferior tentorium Thrombophlebitis green. Nearly the entire temporal lobe is adequately perfused.
As mentioned above, in the acute tentorium Thrombophlebitis the connection between the posterior pericalossal branch of the PCA and the distal pericalossal branch of the ACA is rather inadequate for meaningful reperfusion of either vessel by the other. However, any slowly progressive constraint is another matter, tentorium Thrombophlebitis. However, it need not be Moya-Moya — any slowly evolving process will do.
In the following patient, a giant shenoid wing meningioma resulted in occlusion of both supraclinoid ICAs, similar to a Moya-Moya pattern. Therefore, tentorium Thrombophlebitis, the primary method of reconstitution is via leptomeningeal PCA-MCA purple arrows and PCA-ACA light blue arrows collaterals, the posterior to anterior pericalossal yellow anastomosis, and left more than right middle meningeal artery auto-synangioses with the MCA territory on the left motor strip, tentorium Thrombophlebitis, purple oval and right MMA to left ACA territory as well white arrows.
Notice meningioma tumor blush orange oval. The P2 segment of the PCA swings around the cerebral peduncle, underneath the thalamus, towards the quadrigeminal plate, an further dorsal towards the occipital area. Branches of the PCA supply the thalamus inferior medial and lateral thalamus tentorium Thrombophlebitis geniculate areathe peduncle, and the collicular plate, tentorium Thrombophlebitis.
There is tentorium Thrombophlebitis variation in the description of this supply. Sometimes it is depicted as perforators arising directly from the P2 segment, which makes sense geographically.
For example, see diagram from none less than Netter below:, tentorium Thrombophlebitis. The artery red is beautifully depicted in this specimen x-ray from the Yun Peng Huang collection. Perforators to the peduncle pink are also visualized: The picture is one of large P2 and slender collicular vessel just medial to it, often too small and too superimposed on the PCA to be individually resolved on any modality.
Its importance comes from the territory it supplies — the cerebral peduncle and quadrigeminal plate. Thus, tentorium Thrombophlebitis, damage to the artery can lead to one instance of PCA-related hemiparesis, as seen in the image below with a developing infarct in the cerebral peduncle: At least on some occasions the Collicular artery can be resolved, both with MRA and angiography, tentorium Thrombophlebitis.
Here is an example of one red arrowslocated just medial to the P2 segment, tentorium Thrombophlebitis. Here is an MRA of a different patient, with the same artery seen bilaterally. Could this be the posteromedial choroidal artery instead?
Tentorium Thrombophlebitis angiography in frontal and lateral planes better displays the shunt following resolution of the hematoma, now faintly shows some superior vermian veins light blueand the Collicular Tentorium Thrombophlebitis red.
Superselective angiography with the microcatheter at tentorium Thrombophlebitis ostium of the Collicular artery red demonstrates perfectly its course outlining the cerebral peduncle, with a small AVM white at the collicular plate, draining via the Precentral Tentorium Thrombophlebitis purple into the straight sinus dark blueand retrogradely congesting paired superior cerebellar veins light blue.
Notice several slender perforators to the peduncle pink, tentorium Thrombophlebitis. The silly Percheron is orange. The top pair of frontal images is stereoscopic. Even trophische Geschwür am Bein behandelt Yekaterinburg its AVM-related enlarged state, the Collicular artery remains slender and difficult to differentiate from the P2 segment on nonselective vertebral angiography.
No wonder it is so often missing from descriptions. I hope that this case, and the image of the stroke, are convincing enough. I think that it is best to think of the Collicular artery as a perforator. For example, one sometimes finds a common trunk for a number of lenticulostriate perforators from the MCA, though more often they originate separately.
It may be that the Collicular artery is an example of one such common trunk, while at other times perforators to the peduncle could arise from the P2 segment geniculate branches tentorium Thrombophlebitis in Netter for example are direct P2 perforators. Below is another example of the Percheron whitea detail from one of the images shown above. The hypoplastic left P1 is orange.