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JK SCIENCE

ORIGINAL ARTICLE

Anatomic Variations In Ovale and Berjina Farooq, Sangeeta Gupta, Sunanda Raina Abstract An anatomical study was conducted to observe the shapes of and foramen spinosum with their anatomical variants. The foramen ovale being one of the important foramina in the middle cranial , is present in the superior surface of greater wing of sphenoid . Foramen spinosum is located posterolateral to foramen ovale. We studied seventeen and three sphenoid (i.e. total 40 foramen ovale and 40 foramen spinosum were studied, since foramen of right as well as left sides were taken for study). They were obtained from the Post graduate Department of , Government Medical College, Jammu. Posterior part of the greater wing of sphenoid was observed for visualising the foramen ovale and foramen spinosum. Oval, round, almond and slit like foramen ovale were found. The maximum number was that of oval shaped foramina followed by almond, round and slit like foramen . Moreover, bony outgrowths in the form of spines were observed in two foramen ovale, and in the form of bony plate was seen in one foramen ovale. Furthermore, confluent foramen ovale and spinosum was seen on left side in one and on right side in another skull. Double foramen spinosum was seen in one skull on right side. Absence of foramen spinosum was observed in one of the skulls on right side. Foramen ovale is of surgical importance in percutaneous trigeminal in trigeminal neuralgias. For surgical procedures in the middle , the knowledge about the variations of these foramina should be taken into account. This data will add to the knowledge of clinicians as well as anatomists.

Keywords Foramen Ovale, Foramen Spinosum, Skull, Trigeminal Neuralgia, Anatomical Variation

Introduction The foramen ovale being one of the important is possible via it in cases of trigeminal foramina in the , is present in neuralgias (4,5). A careful observation of these the superior surface of greater wing of sphenoid foramina will be helpful in the diagnosis of the bone. It opens into the (1). It lesions present in the nasopharynx and middle gives passage to important structures i.e. cranial fossa. Neuroma of the fifth cranial , the accessory meningeal , can lead to enlargement of the foramen ovale (6). the lesser petrosal nerve and the emissary (2). Moreover, bony outgrowths in the form of spurs, It is one of the foramen of importance which is can compress the passing mandibular nerve and present between the intracranial and extracranial henceforth could lead to dysfunction of the muscles structures. Venous part of foramen ovale may be supplied by it (7). separated from other structures of the foramen by Foramen spinosum being a circular foramen, means of a bony . These spurs are located is present in the greater wing of the sphenoid, anteriorly and medially (3). posterolateral to foramen ovale. It is present at It is usually oval in shape but its shape shows root of spine of sphenoid. It gives passage to middle variations when compared to rest of the foramina meningeal artery (8,9,10). In 0.4% of cases, in the skull. It is of great significance to foramen spinosum may be absent and in that case neurosurgeons as transcutaneous approach to skull the arises from ophthalmic From The: Department of Department of Anatomy Govt Medical College, Jammu, J&K-India Correspondence to : Dr. Sangeeta Gupta Associate Professor, PG Department of Anatomy, GMC, Jammu, J&K-India

112 www.jkscience.org Vol. 20 No. 3, July.-Sept 2018 JK SCIENCE artery. Moreover, foramen spinosum can be duplicated The has two type of centres in some cases (11). i.e. the intramembranous and endochondral ossification Material and Methods centres which form body, lesser wings and greater wings The study was conducted on seventeen human skulls (7). Foramen ovale shows variations in shape and size and three sphenoid bones (i.e. in total on the 40 foramen throughout natural life. In the 7th fetal month, the earliest ovale and 40 foramen spinosum) obtained from the Post formation of ring shaped foramen ovale was observed graduate Department of Anatomy, Government Medical and latest it was observed at 3 years after (12). College, Jammu. Posterior part of the greater wing of Foramen ovale is of significance in various invasive and sphenoid was observed for visualising the foramen ovale diagnostic procedures. In cases going for and foramen spinosum. Their patency was checked by amygdalohippocampectomy, the electroencephalographic means of bristle. Skulls used for study were not damaged analysis is done by placing electrodes at the foramen or broken. For each skull, general features and anatomical ovale. It provides good neurophysiological information variations of the foramen ovale and spinosum were (13). Percutaneous of cavernous tumours carefully noted. Bony spur in the form of spine, can be successfully achieved through foramen ovale or bony plate, in any foramen ovale was noticed. which definitely is of significance before making any Results move for open surgical procedures (14). Nasopharyngeal The study was conducted on a total of 40 sides in 17 dry carcinoma spreads intracranially and usually spreads via adult human skulls and three sphenoid bones. On foramen ovale (15). Anatomical variations of foramen visualizing the foramen ovale, it was seen that 28 ovale are of importance in operative treatment of foramina out of 40 foramina had an oval shaped foramen trigeminal neuralgia which is performed through the (Fig 1) (Table 1), 7 foramina showed almond shaped opening of foramen ovale. Moreover, any stenosis or foramen (Fig 2) (Table 1), 4 foramina showed round bony plate leads to reduced patency and difficulty in shaped foramen (Fig 3) (Table 1)and 1 foramina showed approaching for surgical procedures through this route slit shaped foramen (Fig 4) (Table 1). Incidences of (16,17). oval, almond, round and slit shaped foramen were 70%, Yanagi reported that foramen ovale in majority cases 18%, 10% and 2% respectively. Out of 40 sides, 2 was found to be oval in shape and furthermore they were foramina showed the presence of bony spine (Fig 5) irregular in shape in comparison to the other foramina (Table 2), 1 foramina showed the presence of bony plate present in the sphenoid bone (12). In our study also, the (Fig 6) (Table 2) and foramen with a tubercle was seen majority of the foramen ovale were oval in shape in none. Incidence of spine and bony plate were 5% and (Table1)( Fig 1). There are some developmental 3% respectively. reasons for the variations in the shape of foramen ovale Confluency of foramen ovale and spinosum (Fig 7)was (18). Tubbs et al., in their work revealed that seen in two skulls, in one, on the right side and in other, pterygospinous ( of Civinini) and pterygoalar on the left side. Moreover, double/duplicated foramen (ligament of Hyrtl) lead to division of foramen spinosum (Fig 8) was seen on right side in one skull and ovale into two compartments. These ligaments could absence of foramen spinosum ( Fig 9)was also seen on make transcutaneous needle placement into the foramen the right side in one of the skulls. ovale very difficult (19). Ray et al., observed in their Discussion study on anatomic variations of foramen ovale that a Table 1. Variations in Appearance of Foramen Ovale spine was present on the margin of the foramen ovale. Shape Right (n=20) Left(n=20) Total(n=40) Oval 17 11 28 Almond 3 4 7 Round 3 1 4 Slit shaped 1 0 1

Table 2. Bony Outgrowths Seen in Foramen Ovale Bony outgrowths Right(n=20) Left(n=20) Total(n=40) Spine 0 2 2 Tubercle 0 0 0 Bony plate 1 0 1

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Fig 1-3. Skull Showing Foramen Ovale of Oval Shape, Sphenoid Bone with Almond Shaped Foramen & Skull Showing Round Shaped Foramen Ovale

Fig 4-6. showing slit like foramen ovale; base of skull showing bony spine in left foramen ovale &base of skull showing bony plate in right foramen ovale

Fig 7-9. showing base of skull with confluent foramen ovale and foramen spinosum on right side;base of skull showing double foramen spinosum on right side & skull showing absence of foramen spinosum on right side

It was seen in 3 cases (3). In our study, we also (21). Berge and Bergman conveyed that the foramen appreciated two bony spines on the margins of foramen spinosum was found to be unilateral in (1%) skulls or ovale in two different skulls and both were present on (0.5%) of foramina which were examined had no left side (Table 2) (Fig 5) Moreover, 1 bony plate was evidence of assimilation with foramen ovale (22). also seen on foramen ovale in our study(Table 2) (Fig Lindblom observed that the foramen spinosum was small 6). and was not present in 0.4% cases. It was observed by Studies on the of foramina of greater him in his roentgenographic study of the vascular channels wings of sphenoid have revealed variations in the of the skull (23). In the present study, foramen spinosum foramen spinosum. The foramen spinosum may be was absent in one skull and that too on the right side absent, when the meningeal artery arises from ophthalmic (Fig 9). artery instead of arising from maxillary artery or in Lindblom and Sondheimer also reported a variant in circumstances, when meningeal artery enters the cranial which double foramen spinosum were found on the same cavity through foramen ovale (20). Ginsberg et al., also side of the skull. A bony bar was a partition which lead observed that the foramen spinosum may be absent when to the duplication of foramen spinosum which can be middle meningeal artery follows an aberrant pathway because of division of middle meningeal vessels before

114 www.jkscience.org Vol. 20 No. 3, July.-Sept 2018 JK SCIENCE entering the foramen spinosum (23,24).Our study also 9. Sinnatamby CS. Last's Anatomy: Regional and Applied. revealed a skull with double foramen spinosum on the 10th Edition. Edinburgh, Churchill Livingstone, 1999. same side of the skull i.e. the right side. They were 10. Standring S. Gray's Anatomy; The Anatomical Basis of Clinical Practice. 39th ed. London, Elsevier Churchill separated from each other by a thin bony margin (Fig Livingstone 2005.pp.462-67 8). Osunwoke et al., made thorough study on 87 dried 11. Khan AA, Asari MA,Hassan A. Anatomic variant of human skulls from the southern Nigerian population and foramen ovale and spinosum in human skulls. Int J Morphol they noticed that all skull had foramen. They were not 2012: 30(2); 445-49. able to find any skull with absence of foramen spinosum 12. Yanagi S. Developmental studies on the , foramen ovale and foramen spinosum of the human (25). sphenoid bone. Hokkaido Igaku Zasshi 1987: 62(3) ;485- Conclusion 96. The present study was conducted to provide information 13. Wieser HG and Siegel AM. Analysis of foramen ovale regarding the foramen ovale and foramen spinosum as electrode-recorded seizures and correlation with outcome the knowledge about these foramina is still scarce. Some following amygdalohippocampectomy. Epilepsia 1991: 32; 838-50. foramen ovale present with or bony plates. The 14. Sindou M, Chavez JM, Saint Pierre G, et al. Percutaneous mandibular nerve passes through the foramen ovale and biopsy of tumours through the foramen it is via this foramen that trigeminal rhizotomy is done. ovale. Neurosurgery1997: 40: 106-11 So, the patency of the foramen ovale is very important 15. Chong VF, Fan YF, Khoo JB. Nasopharyngeal carcinoma for this procedure. In case of stenosis of foramen ovale with intracranial spread:CT and MR characteristics. J Comput Assist Tomogr 1996: 20; 563-9. as is seen in foramen with tubercles, the 16. 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