Research Article
Morphometric analysis of posterior fossa and foramen magnum in South Indian population Tahreem Fathima, M. S. Thenmozhi, Ganesh Lakshmanan*
ABSTRACT
Aim: This study aims to determine and analyze the morphology of posterior fossa and foramen magnum in South Indian population. Objective: Configuration and size of posterior fossa and foramen magnum play an important role in pathophysiology of various disorders of posterior fossa and foramen magnum. The cranial fossa houses the brain stem and cerebellum which is formed in the endocranium. Foramen magnum can be classified depending on its shapes such as oval, round, irregular, and tetragonal. Materials and Methods: Thirty adult dry human skulls of unknown sex of South Indian origin were investigated. The damaged skulls were excluded. The anteroposterior (AP) and transverse diameter was measured for posterior cranial fossa and foramen magnum using a Vernier caliper. Average and standard deviation were calculated using statistics. Results and Discussion: It was found from the study that the higher range of AP diameter in posterior fossa could be due to different genetic factors, habitus, belonging to different geography, races, and also due to demineralization of the dry skull and the lower range of AP diameter of foramen magnum could be due to demineralization of the dry skulls and the differences could also be due to genetic factors, habits, geographical, and races. Conclusion: The morphometry of foramen magnum and posterior cranial fossa is necessary for surgeon during the surgeries of foramen magnum meningiomas or posterior cranial fossa lesions. The variations of the shape of foramen magnum and posterior cranial fossa are important in neurological interpretation. KEY WORDS: Anteroposterior diameter, Foramen magnum, Morphometry, Posterior cranial fossa, Transverse diameter
INTRODUCTION oblongata with meanings, accessory nerves, vertebral arteries, and anterior and posterior spinal arteries.[4,5] Configuration and size of the posterior fossa and Foramen magnum can be used for sex determination. foramen magnum play an important role in the Foramen magnum can be classified depending on its pathophysiology of various disorders of the posterior shapes such as oval, egg shaped, round, tetragonal, [1] fossa and craniovertebral junction. Stenosis of pentagonal, hexagonal, and irregular.[4,6] foramen magnum causes brainstem compression manifested by respiratory complications, lower Dimensions of foramen magnum can be used in cranial nerve dysfunction, upper and lower extremity forensic identification field and anthropology for sex paresis hypotonia or hypertonia, hyperreflexia, or determination in human skulls.[7,8] This knowledge can clonus.[2] Thus, it is the fundamental knowledge of be applied in morphometric analysis when there is an normal anatomy for this region which is important involvement of other parts of the craniofacial skeleton for the clinician for diagnosis and treatment.[3] such as injuries, accidents, fire, or explosion. The aim Foramen magnum comes from a Latin word which of our study was to find out various measurements means largest aperture in skull which is formed by of posterior fossa and foramen magnum in Indian [4] the fusion of four occipital bone. It is situated in population. These results could help in the better [3] an anteromedian position. The major structures diagnosis, classification, treatment of diseases related to that pass through foramen magnum are medulla this region, and serve as a future reference. Although we agree that India is a very vast country and the dimensions Access this article online may vary in different regions. Although alignment of upper and lower cervical spine has been described, there Website: jprsolutions.info ISSN: 0975-7619 is no anatomical study about dimensions of posterior
Department of Anatomy, Saveetha Dental College and Hospitals, Saveetha Institute of Medical and Technical Sciences, Saveetha University, Chennai, Tamil Nadu, India
*Corresponding author: Dr. Ganesh Lakshmanan, Department of Anatomy, Saveetha Dental College and Hospitals, Saveetha Institute of Medical and Technical Sciences, Saveetha University, Chennai - 600 077, India. Phone: +91-9894999243. E-mail: [email protected]
Received on: 04-02-2019; Revised on: 12-03-2019; Accepted on: 15-04-2019
1854 Drug Invention Today | Vol 11 • Issue 8 • 2019 Tahreem Fathima, et al. fossa and foramen magnum for the Indian population to RESULTS the best of our knowledge. The posterior cranial fossa is a part cranial cavity and is located between the foramen The results of various dimensions of foramen magnum magnum and tentorium cerebella. are listed in Figure 1 and Figure 2. The brain is comprised the medulla oblongata, DISCUSSION pons, and midbrain and continues down through the foramen magnum to reach the spinal cord. Anteriorly, Foramen magnum has a transition zone between spine it extends to apex of petrous temporal and posteriorly, and skull. It forms a fundamental component in the it is enclosed within the occipital bone. The posterior complex interaction of bony, ligamentous, and muscular cranial fossa is formed in the endocranium and mostly structures composing the craniovertebral junction; thus, holds the basal parts of the brain. The short height of it plays an important role as a landmark due to its close posterior cranial fossa leads to downward herniation relationship to structures such as brain, spinal cord, in adult.[9] Morphometry is an efficient method for the and vertebral arteries. The shape and size (AP and TD) evaluation of morphological characteristics such as [Figure 3] of the foramen magnum is a vital parameter gender, age, diet, and shapes of bone.[10] for the manifestation of clinical signs and symptoms; furthermore, they have been found to be independent Hence, this study aims to conduct the morphometric risk factors in patients with craniovertebral anomalies in analysis of the posterior cranial fossa and foramen the present study mean AP and TD of foramen magnum magnum in South Indian population. and posterior cranial fossa in 30 skulls were assessed.
MATERIALS AND METHODS In the study, we obtained that the average of TD of posterior fossa is 27.07 and the average of AP diameter of Thirty adult dry human skulls of unknown sex of South posterior fossa is 32.24, the higher range of AP diameter Indian origin were investigated. The damaged skulls in posterior fossa could be due to different genetic were excluded. The skulls were obtained from the factors, habitus, belonging to different geography, races, Department of Anatomy, Saveetha Institute of Medical and also due to demineralization of the dry skull.[11] We and Dental Sciences, Chennai, Tamil Nadu, India. All also obtained that the average of TD of foramen magnum the parameters were measured in the following planes: Distance from center of IOF to IOM along sagittal plane. 40 The AP and transverse diameter (TD) was measured. The measurements were taken using Vernier calipers to 35 measure the AP and transverse distance. From the above 30 measurements, mean, standard deviation, median, and 25 mode were calculated using statistics. 20 The parameters that were measured are as follows: 15 • Foramen magnum length/AP diameter 10 • Foramen magnum width/TD 5 • Posterior cranial fossa length/AP diameter 0 • Posterior cranial fossa width/TD 12 The prongs of the Vernier caliper were placed over the described landmark. The length and the width of Figure 1: Comparison between TD and AP diameter for posterior cranial fossa posterior fossa and foramen magnum were recorded over the metallic scale on the Vernier caliper. 105 100 95 90 85 80 75 12 Figure 2: Comparison between TD and AP diameter for foramen magnum
Drug Invention Today | Vol 11 • Issue 8 • 2019 1855 Tahreem Fathima, et al.
Figure 3: Different shapes of foramen magnum is 95.27 and the average of AP diameter of foramen 2. Kumar A, Dave M, Anwar S. Morphometric evaluation magnum is 91.53; the lower range of AP diameter of of foramen magnum in dry human skulls. Int J Anat Res foramen magnum could be due to demineralization of 2015;3:1015-23. 3. Rajkumar S, Kattimuthu P, Manik P, Singh V. Morphometric the dry skulls and the differences could also be due to analysis of the foramen magnum of dry human skulls in North [11] genetic factors, habits, geographical, races, etc. Indian population. Int J Anat Res 2017;5:3480-84. 4. Praveen T, Singh P. A North Indian skull based study of a CONCLUSION morphological and morphometrical measurements of foramen magnum. Indian J Appl Res 2018;8: 346-51. The effort of the study was to study the morphometric 5. Segen JC. Mc Graw Hill Concise Dictionary of Modern analysis of posterior cranial fossa and foramen Medicine. New York: Mc Graw Hill Companies Inc.; 2002. magnum in South Indian population. The 6. Radhika PM, Shetty S, Prathap KJ, Sheshgiri C, Jyothi KC. Morphometric study of the foramen magnum in adult human morphometry of foramen magnum and posterior skulls in Indian population. Asian J Med Clin Sci 2014;3:68-72. cranial fossa is necessary for surgeon during the 7. Edwards K, Viner MD, Schweitzer W, Thali MJ. Sex surgeries of foramen magnum meningiomas or determination from the foramen magnum. J Forensic Radiol posterior cranial fossa lesions. The variations of the Imaging 2013;1:186-92. shape of foramen magnum and posterior cranial fossa 8. Kanchan T, Gupta A, Krishan K. Craniometric analysis of are important in neurological interpretation. Diameter foramen magnum for estimation of sex. Int J Med Health Biomed Pharm Eng 2013;7:111-3. of foramen magnum and posterior cranial fossa and 9. Nishikawa M, Sakamoto H, Hakuba A, Nakanishi N, Inoue Y. its variations are important not only for anatomists Pathogenesis of chiari malformation: A morphometric study of but also for anesthetist, neurosurgeons, orthopedic, the posterior cranial fossa. J Neurosurg 1997;86:40-7. and radiologists.[2] The knowledge of dimensions of 10. Fathima KF, Babu Y. Evaluating the shape of foramen magnum foramen magnum also helps in the determination of and overlapping of occipital condyle on the the foramen. Int J malformation (Arnold-Chiari syndrome).[11] Sci Res 2016;5:1078-82. 11. Tubbs RS, Elton S, Grabb P, Dockery SE, Bartolucci AA, Oakes WJ, et al. Analysis of the posterior fossa in children with REFERENCES the chiari malformation. Neurosurgery 2001;48:1050-4.
1. Kanodia G, Parihar V, Yadav YR, Bhatele PR, Sharma D. Morphometric analysis of posterior fossa and foramen magnum. J Neurosci Rural Pract 2012;3:261-6. Source of support: Nil; Conflict of interest: None Declared
1856 Drug Invention Today | Vol 11 • Issue 8 • 2019