Research Article

An osteologic study of the cranial opening of optic in dry human Saishree Anchana Rajeswaran, Karthik Ganesh Mohanraj*, K. Yuvraj Babu

ABSTRACT

Aim: The study aimed to evaluate the cranial opening of the through various osteological parameters and to correlate it with anatomical variations. Objective: The present study analyses the size, shape, diameter, and structural variations of the cranial opening of the optic canal through osteological parameters using a Vernier caliper. The anatomical significance of these variations is also touched on. Materials and Methods: A total of 70 dry human of unknown sex and without any gross abnormality were collected from the Department of Anatomy at Saveetha Dental College, Chennai, for evaluation. With the help of a Vernier caliper, and ruler, dimensions of the cranial opening of the optic canal were measured, and the results obtained were analyzed, tabulated, and represented graphically. Results: The left cranial opening of the optic canal had an average diameter of 0.55 cm while the right diameter was 0.54 cm. Conclusion: The findings recorded here intend reference beneficence to medical practitioners during surgeries involving invasive procedures, or of its contents. KEY WORDS: Cranial opening, Optic canal, Osteology

INTRODUCTION retina to the vision centers of the brain. It enters the through the optic canal along with ophthalmic The optic canal, a cylindrical canal, runs oblique, artery.[6] through the lesser wing of the sphenoid and joins the body of sphenoid at its base.[1] The , The is a branch of the internal carotid ophthalmic artery, and branches from the periarterial artery. It supplies all structures in the orbit, including sympathetic plexuses pass through it. In the base of the the nose, , and meninges.[7] The ophthalmic artery skill, the pitch canal opens out in the optic foramen.[2] arises in the , enters the orbit through Optic canal acts as a channel, communicating between the optic canal, and divides at the medial end of the the orbit and .[3] The orbital upper eyelid into its terminal branches – supratrochlear opening and cranial opening are observed to form its artery and dorsal nasal branches.[8] two ends. The anatomical variation related to the optic canal was studied with respect to some osteological Its observed that any anomaly in the vascularization parameters to analyze them in different human skulls. of the orbit and dural covering of the brain can be correlated.[9] This is because of the relationship At the cranial opening, which is considered in this between the development of the embryonic system of study, the optic canal is ovoid in shape, with the the stapedial artery, with the ophthalmic artery, and he transverse diameter being more than the vertical middle meningeal artery.[10] diameter.[4] Variations in the optic canal are insights to several Optic nerve or the nerve of vision is located in the bone-related conditions such as osteoporosis, back of the eye. Its the second cranial nerve or cranial brachymicrocephaly, neurofibromatosis, osteopetrosis, nerve II.[5] It transmits visual information from the Cruzon syndrome, or even mental retardation.[11] The present study aimed to observe variability in morphology Access this article online and morphometry in the cranial opening of an optic canal which intend reference beneficence to medical Website: jprsolutions.info ISSN: 0975-7619 practitioners during surgeries involving invasive

Department of Anatomy, Saveetha Dental College, Saveetha Institute of Medical and Technical Sciences, Saveetha University, Chennai, Tamil Nadu, India

*Corresponding author: Karthik Ganesh Mohanraj, Department of Anatomy, Saveetha Dental College, Saveetha Institute of Medical and Technical Sciences, Saveetha University, 162, Poonamallee High Road, Chennai - 600 077, Tamil Nadu, India. Phone: +91-9940545168. E-mail: [email protected]

Received on: 18-05-2019; Revised on: 20-06-2019; Accepted on: 24-07-2019

Drug Invention Today | Vol 12 • Issue 9 • 2019 2051 Saishree Anchana Rajeswaran, et al.

With the help of a Vernier caliper, and ruler, the measurements such as length, breadth, and diameter of the cranial opening of the optic canal were measured. The results obtained were analyzed, tabulated, and represented graphically.

RESULTS The mean diameter of the right cranial opening of optic canal is 0.54 cm and for the left side, it is 0.55 cm. The graphical representation of variation in the mean diameter of cranial opening of optic canal in right and left side is shown in Figure 1. The cranial cavity showing the cranial opening of optic canal is depicted as photographic image in Figure 2. Figure 1: Graphical representation of variation in the mean diameter of the cranial opening of optic canal in the right and left side DISCUSSION The study is illustrative of the fact that there is a slight variation in the anatomical diameters of the cranial opening of the optic canal at the left side compared to that of the right side. With the left side being an average of 0.55 cm, it is larger than the right side cranial opening of the optic canal which is about 0.54 cm.

This observation does not include any consideration of differences in the parameters between different sexes.

This would be a reference source for medical practitioners in case of invasive surgeries, as the study illustrates how the right and left side structures are not exactly symmetrical. Apart from that, such variations are indices to assess bone-related disorders such as osteoporosis and osteopetrosis, or any other measure Figure 2: Anatomical samples of the cranial opening observed for variations of the bone density relative to the region. CONCLUSION procedures, or of its contents. Especially, with the optic nerve passing through it, studying the optic Thus, the variations in the optic canal have been canal is of great importance. Any form of a visual recorded with respect to several osteological disturbance involving the optic nerve has the need to parameters. These findings intend reference have knowledge regarding the variations of the optic beneficence to medical practitioners during surgeries canal during surgical interventions.[12] involving invasive procedures, or of its contents.

MATERIALS AND METHODS REFERENCES In the present study, a total of 70 dry human skull bones 1. Thale A, Jungmann K, Paulsen F. Morphological studies of the optic canal. Orbit 2002;21:131-7. of unknown sex and without any gross abnormality 2. Radunovic M, Vukcevic B, Radojevic N, Vukcevic N, were collected from the Department of Anatomy at Popovic N, Vuksanovic-Bozaric A, et al. Morphometric Saveetha Dental College, Chennai, for evaluation. characteristics of the optic canal and the optic nerve. Folia Faulty skulls with cracks or fracture lines in the orbital Morphol (Warsz) 2018;78:39-46. 3. Kalthur S, Periyasamy R, Kumar S, Gupta C, Souza AS. region were excluded from the study. The optic canal A morphometric evaluation of the optic canal: Comparative with the cranial opening was present in both orbits, study between computerized tomographic study and direct i.e. bilaterally. The optic canal was measured at the anatomic study. Saudi J Med Med Sci2016;3:204-8. cranial opening along its maximum diameter with the 4. Nayak G, Biswa B, Mohanty B, Saurjya R, Das SR. Study of help of Vernier caliper, along the transverse axis of duplicated optic canals in Eastern Indian human skulls. Asian J Pharm Biol Res 2016;9:85-6. the canal. Measurement along the vertical axis of the 5. Slavin KV, Dujovny M, Soeira G. Optic canal: Microanatomic canal was also taken. study. Skull Base Surg 1994;4:136-44.

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6. Hart WM Jr. In: Podos SM, Yanoff M, editors. Textbook of 10. Manjunath KY. Anomalous origin of the middle meningeal Ophthalmology. Vol. 6. London: Mosby; 1994. p. 1.14. artery a review. J Anat Soc India 2001;50:179-83. 7. Morrison JC, Van Buskirk EM. Ciliary process microvasculature 11. Ogeng’o J. Clinical significance of anatomical variations. Anat of the primate eye. Am J Ophthalmol 1984;97:372-83. J Africa 2013;2:57-60. 8. Forrester JV, Dick AD, McMenamin PG, Roberts F, Pearlman E. 12. Purohit BJ, Singh PR. An osteologic study of cranial The Eye. 4th ed. United Kingdom: Saunders Ltd., Elsevier; opening of optic canal in Gujarat region. J Clin Diagn Res 2016. 2016;10:AC08‑11. 9. Seker A, Martins C, Rhoton AL. Meningeal Anatomy. Source of support: Nil; Conflict of interest: None Declared In: Meningiomas. Amsterdam: Elsevier; 2010. p. 11-51.

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