IJCRR

IJCRR - 5(14), July, 2013

Pages: 44-48

Date of Publication: 29-Jul-2013

MORPHOMETRIC STUDY OF FORAMEN SPINOSUM IN HUMAN SKULLS

Author: Jeyanthi Krishnamurthy, Lalitha Chandra, Shubha Rajanna

Category: Healthcare

Abstract:Foramen Spinosum is a foramen in the greater wing of Sphenoid bone transmitting Middle meningeal vessels and Nervous spinosus. In the present study, Foramen Spinosum was studied in Fifty dried human skulls of which 25 were male and 25 female. In each skull, the location and shape of foramen spinosum, it's relation to spine of sphenoid and foramen ovale were noted. Dimensions of the foramen were taken and data was analysed. Absence of foramen was noticed in 1%, confluence of foramen ovale and spinosum in 2%, asymmetry in shape and size were noted and in two skulls, foramen was present lateral to the spine of sphenoid. This knowledge will be useful to Neurosurgeons to identify and preserve the neurovascular structures while approaching middle cranial fossa.

Keywords: Foramen Spinosum, Variations, Skull

Full Text:

INTRODUCTION

Foramen Spinosum is a small circular foramen located in the greater wing of sphenoid near or at the root of spine of sphenoid, posterolateral to foramen ovale [Fig-1].  It transmits middle meningeal artery, Nervous spinosus to the middle cranial fossa and middle meningeal vein¹. Posterolateral to the FS, is the Spine of Sphenoid which is laterally related to auriculotemporal nerve². The FS may be absent, in which case the middle meningeal artery enters the cranial cavity through the foramen ovale. The FS may be duplicated or continuous with foramen ovale or more or less incomplete³.The foramen spinosum is an important landmark in skull base injury especially in middle cranial fossa and infratemporal fossa. The knowledge of foramen spinosum is helpful for Neurosurgeons.

MATERIAL AND METHODS

Fifty dried Human skulls of which 25 male and 25 female available in the department of Anatomy, Kempegowda Institute of Medical Sciences, Bangalore were taken for the study. For each Skull, features and variations of foramen spinosum were noted. Measurements were taken by placing the dividers anteroposteriorly for the length and transverse diameter  for the width and then carefully transferred to a meter rule for the readings⁴. Results were compared and Data analyzed statistically.

RESULTS

Out of 50 skulls foramen spinosum was present in 48 skulls on both sides. In one of  the male skull it was present on left side and absent on Right side and in one female skull, it was a common opening for foramen ovale and spinosum [Table-1] [Fig -2, 3].Three different shapes of FS like round, oval and irregular were observed of which round shape was more commonly seen and percentage has been shown in [Table-2] [Fig-4]. In one male and one female skull, on one side the FS was lying lateral to spine of sphenoid [Fig- 4]. In one Male Skull on the left side FS was lying posterior to foramen ovale [Fig-5]. The Mean length in Males was 2.58 mm [Rt side], 2.35 mm [Lt side] and width 2.18 and 2.02mm [Table-4]. In females the mean length was 2.68mm [Rt side], 2.52 mm [Lt Side] and width 2.37 and 2.24mm respectively [Table -5].

DISCUSSION

The Foramen Spinosum is one of the foramen that lies in the greater wing of Sphenoid, provides communication between middle cranial fossa and infratemporal fossa.  It lies posterolateral to foramen ovale. It transmits middle meningeal artery, Nervus Spinosus and middle meningeal vein.

Various studies have reported variations of FS. Khan etal³ reported absence of FS on the left side of one skull among 25 skulls taken for the study. Karan etal⁵ observed absence of FS on the Right side in one skull out of 100 skulls. In the present study, out of 50 skulls absence of FS was noticed on the Right side of one skull [2%]. The absence of FS may be when Middle Meningeal Artery arises from ophthalmic artery instead of Maxillary artery. Khan etal³ have reported confluence of foramen ovale and FS in one skull on the right side out of 25 skulls. Karan et al⁶ found confluence of foramen ovale and FS in three skulls out of 100 skulls. In the present study confluence of foramina was seen on both sides in one of the skull [4%].

According to Desai et al⁷, 52% of FS were round in shape, 42% Oval and 6% irregular in shape, Osunwoke et al⁴ in their study have reported, either circular or oval FS with only one triangular shape out of 87 human skulls. In the present study, 55% were round, 40% oval and 2% irregular.

According to Osunwoke etal⁴, the maximal length of foramen spinosum was 4.0mm and minimal length was 1.0mm. Majority of the length of the FS fall within 2 to 2.5 mm. The maximal width of the FS  was 2 mm and minimal width 1mm. A study carried out  by Lang et al⁸ the width of FS ranged from 1.5mm to 2.1mm in adults.

According to Karan etal⁵, mean diameter of FS was 2.3mm in male on the right, 2.4mm on the left side. In female it was 2.5mm on the Right side and 2.3mm on the left side. The maximum diameter in both male and female on both sides was 4.0mm and minimum1.0mm. In the present study the Mean length in male was 2.58 mm [Rt side], 2.35 mm [Lt side] and width 2.18 and 2.02mm. In female the mean length was 2.68mm [Rt side], 2.52 mm [Lt Side] and width 2.37 and 2.24mm.The length was ranging from 1.5- 4 mm and width 1-3.5mm in male whereas in female the length ranged from 2- 4 and width 1.5- 4mm. The dimensions of FS  were larger in female when compared to male. The asymmetrical size and shape, variations in the dimensions could be due to developmental reasons which may hamper clinical and diagnostic procedures.

In the present study, it was noted that FS was anteromedial to spine of sphenoid in most of the skulls. In two skull, on one side the FS was present lateral to the spine of Sphenoid. FS is an important landmark in microsurgeries of middle cranial fossa. The knowledge about the variations of normal, and abnormal position of FS is helpful in computerized tomography and magnetic resonance imaging examinations. Spine of Sphenoid is related to chordatympani nerve medially and auriculotemporal laterally. In supratentorial hematomas, surgical treatment includes a bone flap made over the greater diameter of the clot, with the exposure of FS⁹. Hence the relation of spine of sphenoid to FS is clinically important.

CONCLUSION

This study provides essential information for the detailed knowledge of anatomical variations of FS. The variations are of clinical significance in fractures of base of skull and in diagnosing any aneurysms or vascular lesions in cranial cavity. This knowledge will be useful to Neurosurgeons to identify and preserve the neurovascular structures while approaching middle cranial fossa.

Abbreviations used

FS - Foramen Spinosum, FO - Foramen Ovale, SS - Spine of Sphenoid

ACKNOWLEDGEMENTS

Authors are grateful to Department of Anatomy, KIMS and to the authors whose articles are cited and included in the references of the manuscript.

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