Neurnradiolngg
Neuroradiology 13, 215-220 (1977)
© by Springer-Verlag 1977
The Anatomy of the Inferolateral Trunk (ILT) of the Internal Carotid Artery* P. Lasjaunias*, J. Moret**, and J. Mink Departments of Neuroradiology, *Fondation Ophtalmologique A. de Rothschild and **H6pital Bic6tre, Le Kremlin Bic6tre, Paris, France
Summary. The authors of the paper present the resuits of 20 anatomical dissections of the cavernous sinus area, correlated to 90 angiographies and to basic embryological knowledge; they emphasize the role played by the inferolateral trunk in the arterial blood supply of the cavernous area and its complex and the value of the internal maxillary angiogram for its visualization.
give a precise, radiologically useful description, particularly of the inferolateral trunk (ILT) of the C4 portion of the siphon (also called inferior or lateral artery of the cavernous sinus).
Key Words: Anatomy - Carotid arteries - Embryology, cavernous area.
A. Anatomical Material
The intracavernous collaterals of the internal carotid artery have been known since Luschka (1860) first described the posteroinferior hypophysial artery. Although Dandy [5] was interested in this work, it was Mac Connel [15], Stattin [26] and Parkinson [21] who rekindled serious interest in these arteries was.
The rapid progress in angiography made detailed descriptions of these arteries both a reality and a necessity. First identified during exploration for meningiomas [27], they have been described during procedures for lesions far from them [4, 18, 25, 26]. The role of these collaterals in the supply of the rete mirabile of other vertebrates has been discussed elsewhere [7, 8]; however, they have never been correctly correlated with basic human anatomy, phylogeny [6, 10] or embryology [3, 6, 14, 20]. Though recent anatomical and radioanatomical works [1, 2, 5, 9, 11, 12, 13, 16, 17, 24, 27] have been of some clinical and surgical value [18, 19, 23] it seemed to us that most of these papers did not Research Grants of Paris South University
Material and Methods
The common carotid arteries of 10 cadavers were injected soon after death (average 8 h) with a colored and radiopaque plastic; the dissections were performed under magnifying glasses. The smallest vessel injected in both the internal and external systems was 20 microns in caliber. B. Angiographic Material Ninety consecutive studies (performed for orbital pathology) with both internal carotid and internal maxillary angiograms were reviewed, of which 85% were magnified and substracted.
Anatomical Results A. Origin (Table 1) B. Collaterals (Fig. 1) After bending over the VI nerve, the inferolateral trunk usually gives rise to three branches: 1) A superior branch supplying the cavernous roof and the III and IV nerves as they enter the cavernous sinus area. 8/20 times, this ramus gave rise to the marginal tentorial artery.
216
P. Lasjaunias et al.: Inferolateral Trunk
Table 1. Origin of the inferolateral trunk Site of origin of the ILT
Number of cases
Remarks
C4
17
C4 - C 5
1
Absent
2
The ILT supplies the whole cavernous area The ILT arises with the posterior group of collaterals The A M A supplies the posterolateral half of the area The A M A supplies the whole cavernous area
Table 2.
ILT Collateral
Anastomotic artery
Anteromedial
Intraorbital ophthalmic artery (first portion via the deep recurrent ophthalmic artery) Internal maxillary artery (via the artery of the foramen rotundum) Middle meningeal artery (via its temporal rami) Accessory meningeal artery Middle meningeal artery (via its cavernous branch)
Anterolateral
Posteromedial Posterolateral
Fig. 1. Schematic drawing of the cavernous area. The C4 portion of the internal carotid (5) siphon, gives rise to the inferolateral trunk (ILT) (6), which rapidly branches in to three rami: - sr superior ramus (or tentorial); - rp posterior ramus; - ra anterior ramus. These branches anastomose with the ophthalmic artery by the deep recurrent ophthalmic artery (2) with the internal maxillary artery, by the artery of the foramen rotundum (11), with the accessory meningeal artery (9) and the cavernous ramus of the middle meningeal artery (10)
Fig. 2. Internal carotid angiogram. (meningioma of the anterior clinoid process) The intraorbital ophthalmic artery (3) gives rise to a deep recurrent branch (2) which anastomoses by the inferolateral trunk (6) with the C4 portion of the internal carotid siphon
Fig. 3. Normal internal maxillary angiogram. The artery of the foramen rotundum (11) fills the inferolateral trunk (6); the siphon (5) is faintly visible. 7 - Middle meningeal artery collateral; 9 - Accessory meningeal artery
P. Lasjaunias et al.: lnferolateral Trunk
217
Fig. 4. Normal case. A Internal maxillary angiogram, the accessory meningeal artery (AMA) originating from the middle meningeal artery (7) fills the inferolateral trunk (ILT) (6) B AP view. The arrows indicate the course of the AMA C Internal carotid angiogram (5) visualization of the ILT (6) 2) An anterior branch which divides in two: a medial r a m u s extending towards the inner part of the superior orbital fissure supplies the III, IV, V I nerves as they enter the orbit and terminates as the deep recurrent ophtalmic artery; a lateral ramus extending towards the foramen r o t u n d u m which supplies the dura of the adjacent temporal fossa and the
nerve. It terminates as the artery of the foramen rotundum. 3) A posterior branch which subdivides further into two rami: a medial branch to the V I nerve, the medial third of the gasserian ganglion, and the m o t o r root of the V nerve; a lateral branch to the middle (and usually the lateral) third of the gasse-
218
P. Lasjaunias et al.: Inferolateral Trunk
-
the artery of foramen rotundum (14 cases) (Fig. 3) - the intracranial branch of the accessory meningeal artery (10 cases) (Fig. 4) - the cavernous ramus of the middle meningeal artery (never alone) (3 cases). In 9 cases, the ILT was opacified by two branches (usually the accessory meningeal artery and the artery of the foramen rotundum ). In only 4/20 cases, the siphon was injected via the ILT (Fig. 5). C. Both the maxillary and internal carotid filled the ILT in 7 of 90 cases.
Fig. 5. Normal internal maxillary angiogram. Opacification of the inferolateral trunk (6) through the artery of the foramen rotondum (11) and the cavernous branch (10) of the middle meningeal artery (7). The deep recurrent ophthalmic artery (2) is opacified from the intraorbital ophtalmic artery (3)
rian ganglion and for the dural sheath in the same area. C. Anastomoses (Table 2)
The branches supplying this area always anastomose with the collaterals of the maxillary artery. In the two cases where the accessory m6ningeal artery was the only artery, there was no anastomotic channel between its collaterals and the internal carotid siphon. In the case of a common origin of the inferolateral trunk and the posterior group, there were anastomotic pathways with the ascending pharyngeal artery (via the lateral clivus artery) with the opposite siphon (via the medial clivus artery). These anastomoses were constant and varied only in caliber.
Angiographic Results
A. The ILT was visualized only on the internal carotidogram, 10 times of the 90 studies (Fig. 2) B. The inferolateral trunk was seen only on the internal maxillary angiogram 20 times of 90. It filled via:
D. The ophthalmic artery arose from the siphon one time of the 90 cases. Three times the deep recurent ophthalmic artery was identified (one of the three had cavernous pathology) (Fig. 2). When there is no reflux in the carotid siphon, the inferolateral trunk can be recognized because of its projection between the two opposing concavities of the: a) middle meningeal artery b) the superficial temporal artery, in the lateral projection. In most of the cases, the typical angiographical appearance of the very sinuous artery of the foramen rotundum (Fig. 3) makes its identification easy.
Embryology and Phylogeny (Fig. 6)
The ILT corresponds to the proximal (carotid) remnant of the dorsal ophthalmic artery of the human embryo, while the distal remnant corresponds to the deep recurrent ophthalmic artery. This artery was drawn by Poirier in 1898 as an anastomotic channel between the intraorbital ophthalmic artery and the carotid siphon. The human embryo presents two ophthalmic arteries at the beginning of the 12 mm stage: the ventral one arises from the anterior cerebral artery and the dorsal one from the internal carotid siphon. The former courses through the optic canal, the later through the superior orbital fissure (Fig. 6 A). This anatomical arrangement may be found in the dog, where the homologue of the dorsal ophthalmic arteriy is called the anastomic artery because of its anastomosis inside the orbit with the medial ophthalmic artery (homologue of the ventral ophthalmic artery). The C4 collateral of the dog presents several interesting anastomic channels through the foramen rotundum with the internal maxillary artery with branches of the middle
P. Lasjaunias et al.: Interolateral Trunk
219
Fig. 6. Superoposterolateral view of the
cavernous area. Schematic drawing. A Human embryo B Anatomy of the dog C Anatomy of the sheep (fete mirabile) D Human adult 1 - Orbital branch of the stapedial system (supra orbital artery); 2 - Dorsal ophthalmic artery (A. C.D.) anastomic artery (B) 3 -- Ophtalmic artery (D) Medial ophtalmic artery (B) Ventral ophtalmic artery (A) 4 - Ascending pharyngeal artery 5 - Internal carotid artery 6 - Inferolateral trunk 7 - Middle meningeal artery 8 - Anterior cerebral artery 9 Accessory meningeal artery (A-D) ramus anastomotieus (13) 10 - Cavernous branch of the middle meningeal artery 11 - Artery of the foramen rotundum
meningeal artery (which:enters the skull through the foramen ovale). These branches, arising from the intracranial middle meningeal artery, appear to be homologous of the accessory meningeal artery (AMA), and of the cavernous ramus in the human dispresure. If one studies the rete mirabile of the sheep one may find all these branches; the ophthalmic artery originates from the infra orbital artery and gives rise, inside the orbit to a recurrent branch coursing through the superior orbital fissure and the internal maxillary artery gives many branches to the fete (Fig. 6 C): one entering through the foramen rotundum; one arising from the middle meningeal after its entrance through foramen ovale. One can now understand how the internal maxillary artery may, in the adult (Fig. 6 D) be the only -
-
blood supply to the cavernous area, and how the ophthalmic artery may arise from the siphon by persistence of the dorsal opt~thalmic artery.
C o n c l u s i o n
We have attempted to demonstrate that the ILT belongs functionally to the internal maxillary artery system and to the internal carotid system. The internal maxillary artery supplies the cavernous area exclusively in 10% of our dissections and in combination with the internal carotid system in the other 90%. We were able to visualize the ILT in 27 (24/90) angiographic studies; the visualization of the vessel had no relation to the presence (one case) or absence (23 cases) of pathology. In addition the size of the vessel was quite variable (Figs. 3 and 5),
220 so n e i t h e r t h e a n g i o g r a p h i c d e m o n s t r a t i o n n o r t h e a c t u a l size of t h e I L T is p a t h o l o g i c a l w i t h o u t f u r t h e r corroborative evidence. T h e c o l l a t e r a l c i r c u l a t i o n of t h e c a v e r n o u s a r e a d e s c r i b e d in this p a p e r , a n d t h e facts e m p h a z i e d a b o v e , assign c o n s i d e r a b l e i m p o r t a n c e to t h e I L T in cases of c a v e r n o u s p a t h o l o g y e s p e c i a l l y c a r o t i d c a v e r n o u s fistulae. T h e vessels of t h e c a v e r n o u s a r e a m u s t b e i d e n t i f i e d a c c u r a t e l y in o r d e r t o p l a n p r o p e r t h e r a p y . W e r e c o m m e n d m a g n i f i e d e x a m i n a t i o n s of the cavernous area, during both internal carotid and i n t e r n a l m a x i l l a r y a r t e r y i n j e c t i o n s , as t h e b e s t w a y of o b t a i n i n g a c o m p l e t e a n a t o m i c a l m a p o f t h e a r e a .
References 1. Allen, W.E., Kier, E. L., Rothman, S. L. C.: The maxillary artery normal arteriographic anatomy. Amer. J. Roentgenol. 118, 517-527 (1973) 2. Baumel, J.J., Beard, D.Y.: Accessory meningeal artery in man. J. Anat. (Paris) 95, 386-402 (1961) 3. Congdon, E.D.: Transformation of the aortic arch system during the development of the human embryo. Contr. Embryol. Carneg. Instn 65, 47-110 (1922) 4. Cortes, O., Chase, N. E., Leeds( N.: Visualization of tentorial branches of the internal carotid artery in intracranial lesions other than meningiomas. Radiology 82, 1024-1028 (1964) 5. Dandy, W., Goetsch, E.: The blood supply of the pituitary body. Amer. J. Anat. 11, 137-150 (1911) 6. De Latorre, E., Netsky, M.G.: Study of the persistant primitive maxillary artery in fetus : some homologius of cranial arteries in man and dog. Amer. J. Anat. 106, 185-195 (1960) 7. Du Boulay, G., El Gammal, T., Trickey, S. E.: True and false carotid retia. Brit. J. Radiol. 46, 205-212 (1973) 8. Ernest, C.: Bilateral hypoplasia of the internal carotid with persistance of an admirable network. Nouv. Press. Med. 2, 1655-1658 (1973) 9. Faure, J., Binnert, D., Michotey, P., Salamon, G.: Etude radio-anatomique des branches collat6rales de l'art~re cartotide interne dans son segment intra caverneux. Neuro-Chir. 7, 561-579 (1972) 10. Jewell, P.A.: Anastomoses between internal and external carotid in the dog. J. Anat. (Paris) 86, 83-94 (1952) 11. Lasjaunias, P.: Art6re m6ning6e moyenne. Th~se du Doctorat en M6decine, Paris, 1975
P. Lasjaunias et al.: Inferolateral Trunk 12. Lasjaunias, P., Theron, J.: Radio-anatomy of the accessory meningeal artery. Radiology 121, 99-104 (1976) 13. Lasjaunias, P., Vignaud, J., Doyon, D.: Collat6rales intra caverneuse de la carotide interne. Kodak Ed. N o 14 (1975) 14. Lie, T.A.: Congenital anomalies of the carotid arteries. Amsterdam: Excepta Medi Found, Baltimore: Williams & Wilkins 1968 15. Mac Connel, E.M.: The arterial blood supply of the human hypophysis cerebri. Anat. Rec. 115, 175-203 (1953) 16. Manelfe, C., Tremoulet, M., Roulleau, J.: Etude arteriographique des branches intra caverneuses de la carotide interne. Neuro-Chirur. 7, 581-598 (1972) 17. Manelfe, C., Tremoulet, M., Roulleau, I.: Les collat6rales intra caverneuses de la carotide interne Etude angiographique. Ann. Radiol. 17, 267-270 (1974) 18. Margolis, M.T., Newton, T.: Collateral pathways between the cavernous portion of the internal carotid and external carotid arteries. Radiology 93, 834-836 (1969) 19. Newton, T.H., Kramer, R.A.: Dural arteriovenous shunts in region of cavernous sinus. Neuroradiology 1, 71-81 (1970) 20. Padget, D.H.: The development of th e cranial arteries in the human embryo. Contr. Embryol. Carneg. Instn 32, 205-206 (1948) 21. Parkinson, D.: Collateral circulation of cavernous carotid artery anatomy. Canad. J. Surg. 7, 251-268 (1964) 22. Parkinson, D.: A surgical approach to the cavernous portion of the carotid artery Anatomical studies and cases report. J. Neurosurg. 23, 474-483 (1965) 23. Roos, W.: The retrograde meningeal branches of the ophtalmic artery. Radiology 12, 441-444 (1972) 24. Santini, J.J., Laffont, J., Gouaze, A.: Les collat6rales intra caverneuses de la carotide interne. Etude anatomique. Ann. Radiol. 17, 265-266 (1974) 25. Schnurer, L.B., Stattin, S.: Vascular supply of the intracranial dura from internal carotid artery with special references to its angiographic significance. Acta radiol. 1, 441-450 (1963) 26. Stattin, S.: Meningeal vessel of the internal carotid artery and their angiographic significance. Acta Med. 55, 329 (1961) 27. Wickbom, I., Stattin, S.: Roentgen examination of intracranial meningioma. Acta radiol. 50, 175-186 (1958) Received." February 1, 1977
Dr. P. Lasjaunias Fondation ophtalmologique A. de Rothschild service de radiologie 25-29 rue Manin F-75019 Paris, France
Neuroradiology 13, 215-220 (1977)
© by Springer-Verlag 1977
The Anatomy of the Inferolateral Trunk (ILT) of the Internal Carotid Artery* P. Lasjaunias*, J. Moret**, and J. Mink Departments of Neuroradiology, *Fondation Ophtalmologique A. de Rothschild and **H6pital Bic6tre, Le Kremlin Bic6tre, Paris, France
Summary. The authors of the paper present the resuits of 20 anatomical dissections of the cavernous sinus area, correlated to 90 angiographies and to basic embryological knowledge; they emphasize the role played by the inferolateral trunk in the arterial blood supply of the cavernous area and its complex and the value of the internal maxillary angiogram for its visualization.
give a precise, radiologically useful description, particularly of the inferolateral trunk (ILT) of the C4 portion of the siphon (also called inferior or lateral artery of the cavernous sinus).
Key Words: Anatomy - Carotid arteries - Embryology, cavernous area.
A. Anatomical Material
The intracavernous collaterals of the internal carotid artery have been known since Luschka (1860) first described the posteroinferior hypophysial artery. Although Dandy [5] was interested in this work, it was Mac Connel [15], Stattin [26] and Parkinson [21] who rekindled serious interest in these arteries was.
The rapid progress in angiography made detailed descriptions of these arteries both a reality and a necessity. First identified during exploration for meningiomas [27], they have been described during procedures for lesions far from them [4, 18, 25, 26]. The role of these collaterals in the supply of the rete mirabile of other vertebrates has been discussed elsewhere [7, 8]; however, they have never been correctly correlated with basic human anatomy, phylogeny [6, 10] or embryology [3, 6, 14, 20]. Though recent anatomical and radioanatomical works [1, 2, 5, 9, 11, 12, 13, 16, 17, 24, 27] have been of some clinical and surgical value [18, 19, 23] it seemed to us that most of these papers did not Research Grants of Paris South University
Material and Methods
The common carotid arteries of 10 cadavers were injected soon after death (average 8 h) with a colored and radiopaque plastic; the dissections were performed under magnifying glasses. The smallest vessel injected in both the internal and external systems was 20 microns in caliber. B. Angiographic Material Ninety consecutive studies (performed for orbital pathology) with both internal carotid and internal maxillary angiograms were reviewed, of which 85% were magnified and substracted.
Anatomical Results A. Origin (Table 1) B. Collaterals (Fig. 1) After bending over the VI nerve, the inferolateral trunk usually gives rise to three branches: 1) A superior branch supplying the cavernous roof and the III and IV nerves as they enter the cavernous sinus area. 8/20 times, this ramus gave rise to the marginal tentorial artery.
216
P. Lasjaunias et al.: Inferolateral Trunk
Table 1. Origin of the inferolateral trunk Site of origin of the ILT
Number of cases
Remarks
C4
17
C4 - C 5
1
Absent
2
The ILT supplies the whole cavernous area The ILT arises with the posterior group of collaterals The A M A supplies the posterolateral half of the area The A M A supplies the whole cavernous area
Table 2.
ILT Collateral
Anastomotic artery
Anteromedial
Intraorbital ophthalmic artery (first portion via the deep recurrent ophthalmic artery) Internal maxillary artery (via the artery of the foramen rotundum) Middle meningeal artery (via its temporal rami) Accessory meningeal artery Middle meningeal artery (via its cavernous branch)
Anterolateral
Posteromedial Posterolateral
Fig. 1. Schematic drawing of the cavernous area. The C4 portion of the internal carotid (5) siphon, gives rise to the inferolateral trunk (ILT) (6), which rapidly branches in to three rami: - sr superior ramus (or tentorial); - rp posterior ramus; - ra anterior ramus. These branches anastomose with the ophthalmic artery by the deep recurrent ophthalmic artery (2) with the internal maxillary artery, by the artery of the foramen rotundum (11), with the accessory meningeal artery (9) and the cavernous ramus of the middle meningeal artery (10)
Fig. 2. Internal carotid angiogram. (meningioma of the anterior clinoid process) The intraorbital ophthalmic artery (3) gives rise to a deep recurrent branch (2) which anastomoses by the inferolateral trunk (6) with the C4 portion of the internal carotid siphon
Fig. 3. Normal internal maxillary angiogram. The artery of the foramen rotundum (11) fills the inferolateral trunk (6); the siphon (5) is faintly visible. 7 - Middle meningeal artery collateral; 9 - Accessory meningeal artery
P. Lasjaunias et al.: lnferolateral Trunk
217
Fig. 4. Normal case. A Internal maxillary angiogram, the accessory meningeal artery (AMA) originating from the middle meningeal artery (7) fills the inferolateral trunk (ILT) (6) B AP view. The arrows indicate the course of the AMA C Internal carotid angiogram (5) visualization of the ILT (6) 2) An anterior branch which divides in two: a medial r a m u s extending towards the inner part of the superior orbital fissure supplies the III, IV, V I nerves as they enter the orbit and terminates as the deep recurrent ophtalmic artery; a lateral ramus extending towards the foramen r o t u n d u m which supplies the dura of the adjacent temporal fossa and the
nerve. It terminates as the artery of the foramen rotundum. 3) A posterior branch which subdivides further into two rami: a medial branch to the V I nerve, the medial third of the gasserian ganglion, and the m o t o r root of the V nerve; a lateral branch to the middle (and usually the lateral) third of the gasse-
218
P. Lasjaunias et al.: Inferolateral Trunk
-
the artery of foramen rotundum (14 cases) (Fig. 3) - the intracranial branch of the accessory meningeal artery (10 cases) (Fig. 4) - the cavernous ramus of the middle meningeal artery (never alone) (3 cases). In 9 cases, the ILT was opacified by two branches (usually the accessory meningeal artery and the artery of the foramen rotundum ). In only 4/20 cases, the siphon was injected via the ILT (Fig. 5). C. Both the maxillary and internal carotid filled the ILT in 7 of 90 cases.
Fig. 5. Normal internal maxillary angiogram. Opacification of the inferolateral trunk (6) through the artery of the foramen rotondum (11) and the cavernous branch (10) of the middle meningeal artery (7). The deep recurrent ophthalmic artery (2) is opacified from the intraorbital ophtalmic artery (3)
rian ganglion and for the dural sheath in the same area. C. Anastomoses (Table 2)
The branches supplying this area always anastomose with the collaterals of the maxillary artery. In the two cases where the accessory m6ningeal artery was the only artery, there was no anastomotic channel between its collaterals and the internal carotid siphon. In the case of a common origin of the inferolateral trunk and the posterior group, there were anastomotic pathways with the ascending pharyngeal artery (via the lateral clivus artery) with the opposite siphon (via the medial clivus artery). These anastomoses were constant and varied only in caliber.
Angiographic Results
A. The ILT was visualized only on the internal carotidogram, 10 times of the 90 studies (Fig. 2) B. The inferolateral trunk was seen only on the internal maxillary angiogram 20 times of 90. It filled via:
D. The ophthalmic artery arose from the siphon one time of the 90 cases. Three times the deep recurent ophthalmic artery was identified (one of the three had cavernous pathology) (Fig. 2). When there is no reflux in the carotid siphon, the inferolateral trunk can be recognized because of its projection between the two opposing concavities of the: a) middle meningeal artery b) the superficial temporal artery, in the lateral projection. In most of the cases, the typical angiographical appearance of the very sinuous artery of the foramen rotundum (Fig. 3) makes its identification easy.
Embryology and Phylogeny (Fig. 6)
The ILT corresponds to the proximal (carotid) remnant of the dorsal ophthalmic artery of the human embryo, while the distal remnant corresponds to the deep recurrent ophthalmic artery. This artery was drawn by Poirier in 1898 as an anastomotic channel between the intraorbital ophthalmic artery and the carotid siphon. The human embryo presents two ophthalmic arteries at the beginning of the 12 mm stage: the ventral one arises from the anterior cerebral artery and the dorsal one from the internal carotid siphon. The former courses through the optic canal, the later through the superior orbital fissure (Fig. 6 A). This anatomical arrangement may be found in the dog, where the homologue of the dorsal ophthalmic arteriy is called the anastomic artery because of its anastomosis inside the orbit with the medial ophthalmic artery (homologue of the ventral ophthalmic artery). The C4 collateral of the dog presents several interesting anastomic channels through the foramen rotundum with the internal maxillary artery with branches of the middle
P. Lasjaunias et al.: Interolateral Trunk
219
Fig. 6. Superoposterolateral view of the
cavernous area. Schematic drawing. A Human embryo B Anatomy of the dog C Anatomy of the sheep (fete mirabile) D Human adult 1 - Orbital branch of the stapedial system (supra orbital artery); 2 - Dorsal ophthalmic artery (A. C.D.) anastomic artery (B) 3 -- Ophtalmic artery (D) Medial ophtalmic artery (B) Ventral ophtalmic artery (A) 4 - Ascending pharyngeal artery 5 - Internal carotid artery 6 - Inferolateral trunk 7 - Middle meningeal artery 8 - Anterior cerebral artery 9 Accessory meningeal artery (A-D) ramus anastomotieus (13) 10 - Cavernous branch of the middle meningeal artery 11 - Artery of the foramen rotundum
meningeal artery (which:enters the skull through the foramen ovale). These branches, arising from the intracranial middle meningeal artery, appear to be homologous of the accessory meningeal artery (AMA), and of the cavernous ramus in the human dispresure. If one studies the rete mirabile of the sheep one may find all these branches; the ophthalmic artery originates from the infra orbital artery and gives rise, inside the orbit to a recurrent branch coursing through the superior orbital fissure and the internal maxillary artery gives many branches to the fete (Fig. 6 C): one entering through the foramen rotundum; one arising from the middle meningeal after its entrance through foramen ovale. One can now understand how the internal maxillary artery may, in the adult (Fig. 6 D) be the only -
-
blood supply to the cavernous area, and how the ophthalmic artery may arise from the siphon by persistence of the dorsal opt~thalmic artery.
C o n c l u s i o n
We have attempted to demonstrate that the ILT belongs functionally to the internal maxillary artery system and to the internal carotid system. The internal maxillary artery supplies the cavernous area exclusively in 10% of our dissections and in combination with the internal carotid system in the other 90%. We were able to visualize the ILT in 27 (24/90) angiographic studies; the visualization of the vessel had no relation to the presence (one case) or absence (23 cases) of pathology. In addition the size of the vessel was quite variable (Figs. 3 and 5),
220 so n e i t h e r t h e a n g i o g r a p h i c d e m o n s t r a t i o n n o r t h e a c t u a l size of t h e I L T is p a t h o l o g i c a l w i t h o u t f u r t h e r corroborative evidence. T h e c o l l a t e r a l c i r c u l a t i o n of t h e c a v e r n o u s a r e a d e s c r i b e d in this p a p e r , a n d t h e facts e m p h a z i e d a b o v e , assign c o n s i d e r a b l e i m p o r t a n c e to t h e I L T in cases of c a v e r n o u s p a t h o l o g y e s p e c i a l l y c a r o t i d c a v e r n o u s fistulae. T h e vessels of t h e c a v e r n o u s a r e a m u s t b e i d e n t i f i e d a c c u r a t e l y in o r d e r t o p l a n p r o p e r t h e r a p y . W e r e c o m m e n d m a g n i f i e d e x a m i n a t i o n s of the cavernous area, during both internal carotid and i n t e r n a l m a x i l l a r y a r t e r y i n j e c t i o n s , as t h e b e s t w a y of o b t a i n i n g a c o m p l e t e a n a t o m i c a l m a p o f t h e a r e a .
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