ABSTRACT
Background: Atlas(C1) is an atypical cervical vertebra shaped like a ring. Important structures like the vertebral artery, suboccipital plexus of veins and first cervical nerve pass through it. Knowledge of the variability of C1 is important for neurosurgeons, orthopaedicians, otorhynologists and other physicians who in everyday practice are in contact with disorders of the spine and their consequences. So, this study was undertaken to assess the various dimensions of the C1 in relation to the vertebral artery groove. Methods and materials: Fifty dried human atlas vertebrae were studied. Various measurements were done and statistically analysed. Results: Antero-posterior diameter (APD) of Foramen transversarium(FT) was measured as 7.73 ± 1.04mm on the right and 7.62 ± 0.90mm on left side. Transverse Diameter(TD) of FT was observed as 6.12 ± 0.97mm on the right side and 6.02 ± 0.97mm on the left side. Outer Distance of Vertebral Artery Groove(VAG) was measured as 26.22 ± 2.32mm and 25.84 ± 1.85mm on the right and left sides, respectively. Inner Distance of VAG was observed as 13.10 ± 1.66mm on right and 13.17 ± 1.57mm on the left side. APD of Superior Articular Facet(SAF) was 21.52 ± 2.36mm on right and 21.51 ± 2.07mm on left side.TD of SAF was 11.21 ± 1.47mm on right and 11.32 ± 1.53mm on left side. APD of Inferior Articular Facet(IAF) was observed as 17.54 ± 1.50mm on right and 17.70±1.60mm on left side. TD of IAF was observed as 14.99 ± 1.65mm on the right side and 14.94 ± 1.51mm on left side. Distance between lateral-most edge of both Foramen Transversaria was measured as 56.37 ± 4.11mm and distance between medial-most edge of both Foramen Transversaria was 44.78 ± 3.67mm. MaximumTD of Atlas was measured as 72.09± 5.59mm. Conclusion: The study will generate information that would be useful for geometric modelling of vertebrae and give necessary morphometric data on human atlas vertebra in Indian population.
ABSTRACT
The aim of this study was to emphasize the clinical importance of morphometry and the surgical parameters of the cervical vertebrae. The present study was carried out on ninety six adult dry cervical vertebrae (C3-C7, 96) of unknown gender of Turkish population. The various dimensions of the cervical vertebrae (from C3 to C7) were measured with using a digital caliper accurate to 0.01 mm. Linear parameters including vertebral body anteroposterior width (14.03 mm), vertebral body transverse width (24.45 mm); vertebral body height (10.64 mm); pedicle length (R:5.65±1.91 mm, L:5.65±1.76 mm); pedicle width (R:3.72 mm, L:3.61 mm); lamina height (R:9.87 mm, L:9.86 mm); lamina transverse length (R:13.41 mm, L:13.49 mm); superior articular process anteroposterior width (R:7.26 mm, L:7.46 mm); superior articular process transverse diameter (R: 9.87 mm, L:9.58 mm); superior articular process height (R:16.41 mm, L:16.08 mm); inferior articular process anteroposterior width (R: 7.67 mm, L:7.44 mm); inferior articular process transverse diameter (R: 10.32 mm, L:10.09 mm); inferior articular process height (R:12.72 mm, L:12.67 mm); spinous process length (17.91 mm); uncinate process width (R:4.37 mm, L:3.78 mm); uncinate process height (R:4.58 mm, L:3.93 mm); uncinate process length (R:9.28 mm, L:9.12 mm); vertebral foramen anteroposterior width (13.85 mm); vertebral foramen transverse diameter (20.88 mm); foramen transversarium anteroposterior width (R:4.23 mm, L:4.28 mm); foramen transversarium transverse diameter (R:4.78 mm, L:4.95 mm) were measured. Additionally, the distance of the apex of the uncinate process to foramen transversarium (R:2.91 mm, L:2.70 mm), and the distance of the apex of the uncinate process to intervertebral foramen (R: 5.77 mm, L:5.66 mm) were also calculated. There were found significant differences between two sides in the uncinate process width and height, and distance between uncinate process and foramen transversarium. Present measurements suggest that parameters relevant cervical vertebrae can be used as reference and anatomical landmark for evaluating pathologic changes and minimizing complications in the cervical spine.
El objetivo de este estudio fue enfatizar la importancia clínica de la morfometría y los parámetros quirúrgicos de las vértebras cervicales. El presente estudio se realizó en noventa y seis vértebras cervicales secas adultas (C3-C7) de sexo desconocido de la población turca. Las diversas dimensiones de las vértebras cervicales (C3 a C7) se midieron utilizando un calibrador digital con una precisión de 0,01 mm. Se determinaron parámetros lineales incluyendo ancho anteroposterior del cuerpo vertebral (14,03 mm), ancho transversal del cuerpo vertebral (24,45 mm); altura del cuerpo vertebral (10,64 mm); longitud del pedículo (R: 5.65 ± 1,91 mm, L: 5.65 ± 1,76 mm); ancho del pedículo (R: 3,72 mm, L: 3,61 mm); altura de la lámina (R: 9,87 mm, L: 9,86 mm); longitud transversal de la lámina (R: 13,41 mm, L: 13,49 mm); Diámetro anteroposterior del proceso articular superior (R: 7,26 mm, L: 7,46 mm); Diámetro transversal del proceso articular superior (R: 9,87 mm, L: 9,58 mm); Altura articular superior del proceso (R: 16,41 mm, L: 16,08 mm); Diámetro anteroposterior del proceso articular inferior (R: 7,67 mm, L: 7,44 mm); Diámetro transversal del proceso articular inferior (R: 10,32 mm, L: 10,09 mm); Altura del proceso articular inferior (R: 12,72 mm, L: 12,67 mm); longitud del proceso espinoso (17,91 mm); ancho del proceso uncinado (R: 4,37 mm, L: 3,78 mm); altura de proceso uncinado (R: 4,58 mm, L: 3,93 mm); longitud del proceso uncinado (R: 9,28 mm, L: 9,12 mm); Ancho anteroposterior del foramen vertebral (13,85 mm); Diámetro transverso del foramen vertebral (20,88 mm); Ancho anteroposterior del foramen transverso (R: 4,23 mm, L: 4,28 mm); Diámetro transverso del foramen transverso (R: 4,78 mm, L: 4,95 mm). Además, la distancia del vértice del proceso uncinado al foramen transverso (R: 2,91 mm, L: 2,70 mm) y la distancia del vértice del proceso uncinado al foramen intervertebral (R: 5,77 mm, L: 5,66 mm) Se encontraron diferencias significativas entre los dos lados, en el ancho y la altura del proceso uncinado, y la distancia entre el proceso uncinado y el foramen transverso. Las mediciones actuales sugieren que los parámetros relevantes de las vértebras cervicales se pueden usar como referencia y punto de referencia anatómicos para evaluar los cambios patológicos y minimizar las complicaciones en la columna cervical.
Subject(s)
Humans , Cervical Vertebrae/anatomy & histology , TurkeyABSTRACT
Introduction: Cervical vertebrae constitute the skeletal framework of vertebral column in the region. The most important feature to identify the cervical vertebra is the presence of foramen transversarium. Vertebral artery, vertebral vein and sympathetic chain run through this foramen as a single unit. Compartmentalization or absence of the foramen may alter the course of these structures. Material and methods: The study was performed on 240 dry human cervical vertebrae of both sexes, which were collected from Anatomy department of MSYMCH, Meerut and HIMS, Varanasi. The variations in number and shape were observed, recorded and analyzed. The intact cervical vertebrae without any degenerative or traumatic disorders were included in this study. Result: Out of 240 cervical vertebrae, 63 vertebrae were found to have variations in the transverse foramina. Complete double transverse foramina were observed in 48 vertebrae (20%), out of which unilateral double foramina were found in 29 vertebrae (12%) and bilateral double foramina were found in 19 vertebrae (8%). Similarly, incomplete double transverse foramina were observed in 15 vertebrae (6%), of which the foramina were unilateral in 8 vertebrae (4%) and bilateral in 5 vertebrae (2%). Conclusion: In our study, we observed the double foramen transversarium in 26.25% of the cases. These variations may alter the course of vertebral artery. Presence of compartmentalization suggests the chances of compression of neurovascular bundle. Spicules of incomplete septation between the two foramina may pierce the vascular or neural structures resulting into vascular insufficiency or persisting pain. These findings may suggest a cue to the spinal surgeons in planning preoperative procedures for surgeries related to this region
ABSTRACT
To find the incidence of accessory foramen transversarium in dried cervical vertebrae. 150 dried cervicalvertebrae were collected from Postgraduate department of Anatomy Government Medical College Jammuand examined for the accessory foramen transversarium.Out of 150 cervical vertebrae, only 24 hadaccessory foramen transversarium with preponderance in sixth cervical vertebrae. Amongst the vertebraewith accessory foramen transversarium, 14 were bilateral and 10 were unilateral. In the present study theincidence of accessory foramen transversarium was 16%. This is important for Radiologists to interpretComputed Tomography Images and Magnetic Resonance Imaging of cervical spine.
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Background: The lateral outgrowth from the superior articular facet(SAF) to the posterior root of the transverseprocess of the atlas forms the partial lateral bridge(PLB) and when complete forms the supratransverse foramen(STF). Presence of such bridges may predispose to vertebrobasilar insufficiency. Since there are fewer studies onthe lateral bridge therefore the present study was aimed to know the incidence of lateral bridges and STF and alsoto know the dimensions of STF as the knowledge about such dimensions helps in interpretation of radiologicalfindings, provide guidance for neurosurgical intervention.Materials and methods: A total of 80 undamaged, dry human atlas vertebrae were obtained from the Departmentof Anatomy, Government Medical College and SGRDIMSAR, Amritsar, Punjab, India. The Partial lateral bridge(PLB)and Supratransverse Foramen(STF) were identified following the criteria used by Mitchell (1998a, 1998b).Measurements were taken of the maximum dimensions of the STF in (Supero-inferior and Medio-lateral planes)and ipsilateral Foramen Transversarium (FT) in (Ventro-dorsal and Medio-lateral planes). The cross-sectionalarea of STF and ipsilateral FT was calculated.Results: Total 7 (8.75%) lateral bridges in atlas vertebrae occurred. 6 (7.5%) lateral bridges occurred in associationwith the posterior bridges and 1(1.25%) isolated partial lateral bridge occurred on the left side. Partial lateralbridges were found in 2 bones(2.5%) on right side and 4(2.5%)bones on left side. 1 (0.625%) Complete lateralbridges forming STF was observed on right side. Rt. Supra-Transverse Foramen Height (STFH) and Width (STFW)was found to be 5.4mm and 6.2mm. Ipsilateral Foramen Transversarium Length (FTL) and Width (FTW) was foundto be 6.4mm and 5.9mm. The cross-sectional area of Rt. STF was 26.28mm2 and the cross-sectional area ofipsilateral FT was 29.64mm2 and ipsilateral FT area was smaller than STF.Conclusion: The findings in the present study indicate a higher prevalence of lateral bridges on the left side.Difference in the cross sectional area of STF and ipsilateral FT may lead to compression of V.A and this compressionbecomes evidently symptomatic in extreme manipulations of the neck. Patients presenting with vertebrobasilarinsufûciency or cervicogenic syndromes should be evaluated to explore the possibility of the presence of lateralatlas bridges as etiological factor
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Introduction: Cervical vertebrae are having foramen transversarium in their transverse process. Foramentransversarium’s dimensions and its variations are important for clinicians while handling vertebro basilarinsufficiency cases and also useful for spinal surgeons in spinal decompression procedures like foraminectomy,foraminotomyMaterials & Methods: The present study was done in 90 sub axial vertebrae (C3 to C7) which was collected fromRajah Muthiah Medical College, Chidambaram. Among 90, 56 were typical type and 34 were seventh cervicalvertebrae. Damaged vertebrae were excluded. Antero posterior length, transverse length & depth of foramentransversarium were measured using double tipped compass and digital vernier caliper. Double foramens andabsent foramens were noted.Result: The average antero posterior length of foramen transversarium of typical cervical vertebrae and seventhcervical vertebrae were 5.45 mm ± 0.12 mm and 5.66 mm ± 0.88 mm respectively. The average transverse lengthof foramen transversarium of typical and seventh cervical vertebrae was 6.72 mm ± 0.22 mm and 6.76 mm ± 0.08mm respectively.Conclusion: Anatomical knowledge on the dimensions of foramen transversarium and its variations are importantfor clinicians and neurologists for the various clinical conditions and spinal decompression procedures.
ABSTRACT
The seven cervical vertebrae found in the human body are classified into typical and atypical vertebrae. Their transverse processes contain foramen transversarium (FT) and traditionally there is one foramen present on each side, of similar size. However, variations of this foramen regarding its shape, size, number, laterality, location and osteometric characteristics have been documented in the literature. This morphological and morphometric study was conducted on 126 cervical vertebrae (82 typical and 44 atypical) obtained from the osteological bank at the University of Kwa-Zulu Natal to produce a database which may serve as a useful guideline to medical personnel. There were variations observed regarding shape, number of FT, laterality and position, which have not previously been reported. The most types of variations were evident in the typical cervical vertebrae, then secondly, the seventh cervical vertebrae. The axis vertebrae did not display any accessory FT or variations.
Las siete vértebras cervicales que se encuentran en el cuerpo humano se clasifican como vértebras típicas y atípicas. Sus procesos transversos presentan un foramen transverso (FT) y normalmente este foramen es de tamaño similar en cada lado. Sin embargo, se han reportado en la literatura variaciones de este foramen, con respecto a su forma, tamaño, número, lateralidad, ubicación y características osteométricas. Este estudio morfológico y morfométrico se realizó en 126 vértebras cervicales (82 típicas y 44 atípicas) obtenidas del banco de Osteología de la Universidad de Kwa-Zulu Natal, para producir una base de datos que pueda servir como una guía útil para el personal médico. Se observaron variaciones con respecto a la forma, el número de FT, la lateralidad y la posición, que no se habían reportado anteriormente. La mayoría de los tipos de variaciones eran evidentes en las vértebras cervicales típicas y en segundo lugar en las séptimas vértebras cervicales. Los axis no mostraron ningún FT accesorio o variaciones.
Subject(s)
Humans , Cervical Vertebrae/anatomy & histology , Anatomic Variation , Vertebral Artery/anatomy & histologyABSTRACT
Introduction: Seven cervical vertebrae constitute the skeletal framework of the neck. Along with the otheridentification points, the cardinal feature of a cervical vertebra whether typical or atypical is the presence ofForamen transversarium on the transverse process. This foramen transmits the Vertebral artery, Vertebral veinand Sympathetic nerves. These foramina are known to have variations in size, shape and numbers and may beabsent, incomplete or duplicate, which may lead to various symptoms. Their etiology is related with the variationsin the course of the Vertebral artery due to developmental reasons.Materials and methods: Three hundred dry human cervical vertebrae were collected and studied in the departmentof Anatomy, PSG Institute of Medical Sciences and Research, Coimbatore. We included all the Cervical vertebraeincluding Atlas, Axis and all other cervical vertebrae. We observed the presence, size, shape and variations ofForamen transversarium of cervical vertebrae during our study.Observations and results: Out of three hundred Cervical vertebrae, One hundred and twenty five cervical vertebrae(42%) had variations of Foramen transversarium like Complete / incomplete Accessory foramen, triple foramenon one side, absence of foramen on one side and unequal size of foramen on both the sides. The different typesof shapes of foramen transversarium were also analysed and tabulated. The areas of foramen transversariumwere measured after measuring all the diameters.Conclusion: Variations in the Foramen transversarium may indicate, the variation in the course of the Vertebralartery. The present study was important clinical implications for Head and neck and vascular surgeries. Thesevariations should be kept in our mind during surgeries on cervical spine.
ABSTRACT
The cervical vertebrae are recognized mainly by the presence of the foramen transversarium, which is crossed by the vertebral artery and vein, accompanied by sympathetic fibers. The main objective of this study was to observe and describe the anatomy and variations in the foramen transversarium. 121 cervical vertebrae were analyzed, including the macroscopic characteristics, shape and diameter and presence of the foramen transversarium, as well as the accessory foramen transversarium. All cervical vertebrae presented the foramen transversarium, with a mean diameter of 5.60 mm and a mean diameter of 4.40 mm on the right and 5.92 mm - 5.56 mm on the left, respectively. With regard to shape classification according to Taitz et al. (1978), 90.08 % presented the same shape on both sides, and 9.91 % had different shapes. The presentation of the different shapes was as follows: shape 1 41.32 %; shape 2 4.13 %; shape 3 18.8 %; shape 4 14.04 %; and shape 5 12.39 %. Regarding the presence of accessory foramen transversarium, 17.35 % of the vertebrae presented it, 66.6 % unilateral, 57.14 % on the right side and 42.85 % on the left side. Osteophytes, were presented in 5.7 %. The anatomical knowledge of these variations is useful for spine surgeons in preoperative planning and for preventing vertebral vessel and sympathetic nerve injuries during cervical surgical approaches.
Las vértebras cervicales son reconocidas principalmente por la presencia del foramen transverso (FT), por el cual transita la arteria y vena vertebral además de fibras simpáticas. Las variaciones en el FT pueden estar asociadas con una alteración en el calibre y el curso de la arteria vertebral. El objetivo del presente estudio fue observar y describir la anatomía así como las variaciones en el FT. Fueron analizadas 121 vértebras cervicales, en las cuales el FT fue observado macroscópicamente de manera bilateral así como el foramen transverso accesorio (FTA) en las que se encontrara presente. La forma y diámetros máximo y mínimo del FT fue medido de manera bilateral con ayuda de un cáliper digital. De 121 vértebras cervicales, la totalidad presentaron FT con diámetros máximo y mínimo derecho de 5,60 y 4,40 mm respectivamente y de 5,92 y 5,56 mm máximo y mínimo del lado izquierdo. Con respecto a la clasificación de forma de Taitz et al. (1978) el 90,08 % presentó la misma forma de manera bilateral y un 9,91% formas distintas. La forma 1 se presentó en un 41,32 %, la 2 en un 4,13 %, forma 3 18,8 %, 4 14,04 % y 5 en 12,39 %. Con respecto a la presencia de FTA, un 17,35 % lo presentó, siendo 66,6 % unilaterales, un 57,14 % derecho y 42,85 % izquierdo. La anatomía y variaciones en el FT y la arteria vertebral y los componentes nerviosos están interrelacionados. Su conocimiento morfológico es clínicamente importante, ya que el curso de la arteria vertebral puede distorsionarse en tales situaciones. Por lo que es importante a la hora de adoptar medidas cautelares para salvaguardar la arteria vertebral en las cirugías de columna cervical.
Subject(s)
Humans , Anatomic Variation , Cervical Vertebrae/anatomy & histology , Vertebral Artery/anatomy & histologyABSTRACT
Background & Objective: The foramen transversarium in the transverse process is the characteristic feature for cervical vertebrae and distinguish it from other vertebrae. It transmits the vertebral artery, vertebral vein and sympathetic nerves. These foramina show variations in its size, shape and number. The present study was done to find out the incidence of accessory foramen transversarium and compare it with other study. Methodology: A total 150 dried cervical vertebrae were observed macroscopically for accessory foramen transversarium in the department of anatomy. Results: Out of 150 vertebrae, accessory foramen transversarium was found in 41(27.33%) vertebrae. Among 41 vertebrae unilateral accessory foramen transversarium was found in 27(18%) vertebrae and bilateral was found in 14(9.33%) vertebrae. Conclusion: The knowledge of accessory foramen transversarium is useful for spine surgeons in surgery around cervical vertebrae. It helps radiologists in interpretation of computed tomogram and magnetic resonance image scans. It is also helpful for anatomist, anthropologist and clinicians.
ABSTRACT
Foramen transversarium is formed by the vestigial costal element fused to the body and the true transverse process of the vertebra. Present study carried out on 60 cervical vertebrae that showing variations in the presentation of foramen transversarium. Among them, 25 vertebrae show double (accessory) foramen transversarium, 15 vertebrae having double bubble appearance (incomplete double foramen transversarium) and 20 vertebrae having asymmetrical foramen transversarium. The results of present study shows incidence of variations more common on right side as compare to left in which unilateral accessory foramen transversarium more common than bilateral, even incomplete double foramen transversarium and narrowing of foramen transversarium more common on right side. Conclusion from this study etiology of variation in foramen transversarium may be related with the variation in the course of vertebral artery due to development reason.
ABSTRACT
Background: Variation in number, size & shape of foramen transversarium affects the anatomical course of the vertebral vessels, which may cause pathological conditions like vertebrobasilar insufficiency. Since, inner ear derive it’s blood supply from vertebral and basilar arteries, any spasm of these arteries due to irritation of sympathetic plexus, may causes labyrinthine or hearing disturbances along with neurological symptoms. The objective of present study is to study the incidence of accessory foramen transversarium in dried cervical vertebrae in Indian population & compare it with incidence among various races of world. Methods: A total of 174 cervical vertebrae (Typical-126 & Atypical-48) of unknown sex & age are analyzed to see the accessory foramen transversarium. Results: Out of the 174 cervical vertebrae, accessory foramen transversarium is found in 25 (14.36%) vertebrae. Among these 25 vertebrae, 16 (9.19%) are typical and 9 (5.17%) are atypical cervical vertebrae. We observed in these 16 typical cervical vertebrae, 10 (5.75%) vertebrae have accessory FT on right side while 3 (1.72%) vertebrae have on left side and 3 (1.72%) vertebrae have bilateral accessory FT. Among 9 atypical cervical vertebrae, 4 (2.3%) vertebrae have accessory FT on right side while 3 (1.72%) vertebrae have on left side and 2 (1.15%) vertebrae have bilateral accessory FT. Accessory foramen transversarium are more common on right side in both typical & atypical cervical vertebrae. No any accessory FT is found on axis vertebra. Conclusion: Knowledge of accessory foramen transversarium is important for clinicians because it may affect the course of vertebral vessels & nerves, which causes various symptoms to patients. It is also helpful for spine surgeons in planning surgery around the cervical vertebrae and to avoid post-operative complications. These variations are also of importance and helpful for anatomist, anthropologist and radiologist.
ABSTRACT
Anatomical knowledge of variations is of utmost clinical importance to all of us as they may be one of the reasons as etiological as well as of surgical importance. Vertebral region also presents many variations. Foramen transversarium are typical feature of cervical vertebrae and give way to neurovascular bundle, like vertebral artery, vertebral veins and sympathetic plexus around them throughout. Foramen transversarium and spine or spinous process of cervical vertebrae are important to all of medical specialists as well as for surgeons specially the surgeons dealing with head & neck surgeries. Knowledge of anatomical/surgical variations is very important for neurosurgeons and radiologists for reporting and planning for surgeries as this type of variation if ignored may be a cause for fatal or undesirable outcome of the surgical procedure or may lead to a different planning/approach at the time or during the surgical procedure. In the present case we observed very uncommon finding of bilateral double foramen transversarium as well as a nonbifid spinous process in sixth cervical vertebra which is extremely rare. Right and left both main foramen transversarium were bilateral symmetrical and rounded in shape. Right accessory foramen transversarium was complete while left was incomplete. Finding of present study is important in neurosurgery for posterior approaches of the cervical vertebrae and also useful for radiological studies to avoid erroneous counting of cervical spines in clinical observations as surface landmark.
ABSTRACT
Introduction: Foramen transversaria are located on transverse processes of each cervical vertebra and transmit the vertebral artery, vertebral vein, and sympathetic nerves. These foramina are known to exhibit variations in size, shape and numbers and may be absent, incomplete or duplicate, which may lead to various symptoms. Their etiology is related with the variations in the course of vertebral artery due to developmental reasons. Objective: The present study was conducted to find the incidence of accessory foramina transversaria in the cervical spine.The recognition of these variations provide accurate and safety for the posterior surgical approaches of the cervical spine. Methodology: 210 dry cervical vertebrae of both sexes were studied in the Department of Anatomy, GCS Medical College, Ahmedabad. During our study we excluded all broken, damaged cervical vertebrae and observed the variations of foramen transversarium both in right and left transverse process of each cervical vertebra. Result: Variations in foramina were found unilaterally as well as bilaterally. 34 (16.19%) out of total 210 vertebrae studied presented accessory foramen transversarium. Conclusion: Variations in foramina may indicate, the variation in course of vertebral artery.The present study has important clinical implications for head and neck and vascular surgeons and radiologists
ABSTRACT
Background: Since scanty literature is available on the absence of costal element forming foramen transversarium of atlas vertebra therefore this study was undertaken. Atlas vertebrae were examined to see the presence of foramen transversarium and their boundaries. Methods: Hundred foramina transversaria of 50 atlas vertebrae were examined grossly. Results: Foramen transversarium was seen to be present in all the transverse processes of the atlas vertebrae examined. Costal element was found to be missing in seven foramina tranversaria out of 100 foramina seen. It was found to be absent on the right side in three vertebrae and in two it was absent bilaterally. Conclusions: In case the costal element of the foramen transversarium is absent, the second part of vertebral artery passing through this foramen is liable to be damaged while operating at the level of atlanto-occipital joint the operating surgeon should be aware of such variations so as to avoid injury of second part of vertebral artery and subsequently preventing any kind of neurological involvement. Radiologists must also know about such variations so as to correctly interpret radiological image of the craniovertebral region.