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Home , Confluence of sinuses, Dural venous sinuses, Occipital sinus, Sigmoid sinus, Straight sinus

Research Article

Anatomical observation and morphometric analysis of impressions of in dry human M. Sagana1, K. Yuvaraj Babu2, Karthik Ganesh Mohanraj2*

ABSTRACT

Introduction: The bone has numerous impressions formed by many important structures related to it. The impressions which are formed serve as an important tool for many purposes. Among them, the normal impressions of dural venous sinuses and their variations are of relatively significant value as it is used for neurosurgeons, radiologists, for investigating, and diagnosing various pathologies of dural venous sinuses such as , embolism, and fistula. In such case, clear information on the morphometrical study of dural venous sinuses is lacking in literature. Thus, the study focuses on the morphometric evaluation of an impression of dural venous sinuses on skull bones. Materials and Methods: In the present study, a total of 50 dry human skull bones of unknown sex and without any gross breakage were collected from the Department of Anatomy, Saveetha Dental College and Hospitals, Chennai. The bones were subjected to visual and morphological analysis and evaluated. The present study involved the examination of an impression of superior sagittal , right and left transverse sinus, , and in the skull. The length and width of these sinuses were measured with Vernier caliper. Results: The mean length of the is 25.74 ± 1.13. The mean length of right and left transverse sinus is 4.87 ± 0.32 and 5.11 ± 0.48, respectively. The mean length of right and left sigmoid sinus is 3.84 ± 0.65 and on left sigmoid sinus is 3.91 ± 0.43. The mean length of the occipital sinus is 4.23 ± 0.54. The mean width of the superior sagittal sinus is 1.15 ± 0.072. The mean width of the right transverse sinus is 0.80 ± 0.044 and of the left transverse sinus is 0.82 ± 0.035. The mean width of the right sigmoid sinus is 0.91 ± 0.049 and of the left sigmoid sinus is 0.94 ± 0.027. The mean width of occipital sinus is 0.53 ± 0.022. The mean width of the is 1.36 ± 0.051. All the observed values are tabulated and expressed as mean ± standard deviation. Conclusion: It is concluded that this study will be valuable definitely for vascular neurosurgeons during pre-operative planning and radiologist to avoid misdiagnosis and misinterpretation.

KEY WORDS: Dural venous sinus, Impressions, Morphometry, Occipital bone, Sulcus

INTRODUCTION from two vascular systems, namely the vertebrobasilar arterial branches posteriorly and the internal carotid The human skull is considered as one of the most branches anteriorly.[1] As a result, an efficient, reliable bones for assessment of several anatomical as well as an effective vascular supply, had to be studies and evaluation. The inner surface of the skull established to allow to leave the restricted and bone has numerous features referred to as impressions restrained compartment.[2] As a matter of fact, the formed by the underlying soft tissues during the period venous drainage of the central nervous system does of in utero to the period of postnatal development. One not follow its arterial course. Instead, they drain into among them is the impressions formed by the dural the dural venous sinuses, which subsequently drain venous sinuses on the inner surface of the skull bones. into the internal jugular and then to the vena The human has the highest demand for oxygen of cava system.[3] In general, the walls of these drainage any tissue in the . It receives blood supply pathways are formed by visceral periosteum and dural reflection, both lined with .[3] The straight Access this article online sinus and inferior sagittal sinus are exemptions to this anatomical organization, as they both lack bony Website: jprsolutions.info ISSN: 0975-7619 components as a part of their wall.

1Department of Anatomy, Saveetha Dental College, Saveetha Institute of Medical and Technical Sciences, Saveetha University, Chennai, Tamil Nadu, India, 2Department 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: 14-04-2018; Revised on: 21-05-2018; Accepted on: 26-06-2018

Drug Invention Today | Vol 10 • Issue 11 • 2018 2139 M. Sagana, et al.

Dural venous sinuses are venous space, the walls of the study focuses on the morphometric evaluation of which are formed by and have an inner an impression of dural venous sinuses on skull bones. lining of endothelium alone without muscular layer.[4] They serve in receiving venous blood from the brain, MATERIALS AND METHODS , and bones of the skull. (CSF) is also poured into some of these sinuses. There In the present study, a total of 50 dry human skull bones are seven paired dural venous sinuses such as the with vault removed and showing the cranial cavity of transverse, cavernous, greater petrosal, lesser petrosal, unknown sex and without any gross breakage were sphenoparietal, sigmoid, and basilar sinuses and five collected from the Department of Anatomy, Saveetha unpaired sinuses such as the superior and inferior Dental College and Hospitals, Chennai. The bones were sagittal and straight, occipital, and intercavernous subjected for morphological analysis visually, evaluated, dural sinuses. Most of these dural venous sinuses are and photographed. The present study involved the in close contact with the inner surface of the cranial examination of impressions of dural venous sinuses such cavity, thus forming prominent impressions from as the superior sagittal sinus, right and left transverse their origin to termination during the course.[5] These sinus, sigmoid sinus, and occipital sinus in the cranial impressions serve as an important tool to determine cavity. The length and width of these sinuses were the normal anatomical course and their variations.[6] measured with Vernier caliper. The mean and standard A thorough knowledge of the course of dural venous deviation (SD) of the values were found and analyzed. sinuses is necessary for diagnosing various pathologies related to brain and its vascular circulation. This article RESULTS has analyzed the diameter and varied course of most The mean length of the superior sagittal sinus is 25.74 of these sinuses and can give a relevant anatomical ± 1.13. The mean length of the right transverse sinus is correlation of venous sinuses with respect to sulcus. 4.87 ± 0.32 and of the left transverse sinus is 5.11 ± 0.48. Thus, the skull bone has numerous impressions The mean length of the right sigmoid sinus is 3.84 ± 0.65, formed by many important structures related to it. and the mean length of left sigmoid sinus is 3.91 ± 0.43. Such impression serves as an important tool for many The mean length of the occipital sinus is 4.23 ± 0.54. The purposes. Among them, the normal impressions of dural mean width of superior sagittal sinus is 1.15 ± 0.072. The venous sinuses and their variations are of relatively mean width of the right transverse sinus is 0.80 ± 0.044, significant value as it is used for neurosurgeons, and the mean width of the left transverse sinus is 0.82 ± radiologists,[7] for investigating and diagnosing various 0.035. The mean width of the right sigmoid sinus is 0.91 pathologies concerned with dural venous sinuses ± 0.049, and the mean width of the left sigmoid sinus is such as thrombosis, embolism, and fistula.[8] In such 0.94 ± 0.027. The mean width of the occipital sinus is case, clear information on the morphometrical study 0.53 ± 0.022. The mean width of confluence of sinuses of dural venous sinuses is lacking in literature. Thus, is 1.36 ± 0.051. All the observed values are tabulated and expressed as the mean ± SD [Figure 1 and Table 1].

DISCUSSION Cranial venous sinuses communicate with outside the skull through . These communications help to keep the pressure of blood in the sinuses constant. The dural venous sinuses apart from receiving venous blood from brain, meninges, and skull bones, they also help to maintain the intracranial pressure through venous and CSF circulation.[9] It is obvious that the size and diameter of the dural venous sinuses are associated with alteration in the intracranial pressure.[10] As much as the venous sinuses are larger or smaller, it influences the Figure 1: The different anatomical dural venous sulcus and intracranial pressure drastically causing hypertension or impressions formed by dural venous sinuses hypotension. Furthermore, various anomalies of dural

Table 1: The morphometrical measurements of right and left side sulcus of transverse and sigmoid sinuses and the central occipital sinuses Dural venous sinus Transverse sinus Sigmoid sinus Occipital sinus Right Left Right Left Length mean±SD 5.1±0.62 5.26±0.74 4.15±0.67 4.63±0.94 4.03±0.11 SD: Standard deviation

2140 Drug Invention Today | Vol 10 • Issue 11 • 2018 M. Sagana, et al. venous sinuses are related to idiopathic intracranial anatomy of dural venous sinuses will be valuable to hypertension[11] and hypotension conditions,[12] and neurosurgeons during venography, shunt surgeries, etc. glaucoma.[13] Blockage of some venous sinuses such Variation of dural venous sinuses is relatively important as the sigmoid sinus in the left side (dominant side) for clinicians for investigations and diagnosing different may trigger venous hypertension.[14] In situations of pathological conditions of dural venous sinuses such as corrective surgical procedures on such dural venous thrombosis, embolism, and fistula. sinuses often cause surgical complications because they cannot be clamped if lacerated unintentionally. REFERENCES Furthermore, the venous sinuses are mostly related to 1. Thamke S, Kalra S, Khandelwal AJ. Morphometric evaluation many important structures, for instance, the sensory root of dural venous sinuses: Anatomical study with its implications of the trigeminal nerve lies immediately inferior to the in surgical interventions. Morphol Sci 2016;33:83-9. .[15] 2. Dutta AK, editor. Introduction to skull. Essentials of Human Anatomy Head and Part II. 3rd ed. Calcutta: Current Books Since, there is no much data available for morphometric International; 1999. p. 1-69. 3. Mwachaka PM, Hassanali J, Odula P. Sutural morphology of features of dural venous sinuses in the cranial cavity the pterion and asterion among adult Kenyans. Braz J Morphol of dry human skull bones, studies like the present one Sci 2009;26:4-7. might be useful for others to follow upon. The above 4. Xia Y, Li XP, Han DM, Zheng J, Long HS, Shi JF, et al. observations suggest further necessitating studying the Anatomic structural study of cerebellopontine angle via endoscope. 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Surface diagnosis of thrombosis of cerebral venous sinuses.[16] and superficial surgical anatomy of the posterolateral cranial base: Significance for surgical planning and approach. Balak et al., 2010, studied the occipital sinus using Neurosurgery 1996;38:1079-83. histomorphometric analysis. In this study, the length 9. Uz A, Ugur HC, Tekdemir I. Is the asterion a reliable landmark of the occipital sinuses was measured using Vernier for the lateral approach to posterior fossa? J Clin Neurosci Caliper. It was reported that there was no occipital 2001;8:146-7. [17] 10. Singh R. Incidence of sutural bones at asterion in adult Indian sinus in about 6.6% of total 30 cases studied. . Int J Morphol 2012;30:1182-6. 11. Romanes, GJ. Cunningham’s Manual of Practical Anatomy: Thamke et al., 2016, reported that the superior sagittal Head Neck Brain, The Cranial Cavity. 15th ed. 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