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
Introduction: The atlas, the first cervical vertebra, supports the head. It is unique in that it fails to incorporate acentrum. Because it supports the skull, it was named after Atlas who, according to Greek mythology, supportedthe earth on his shoulders. Frequently bony spurs arise from the anterior and posterior margins of the groove forthe vertebral artery. These are sometimes referred to as Ponticles, and they occasionally convert the groove intoa foramen. More often the foramen is incomplete superiorly. Arcuate foramen also known as ponticulus posticus(Latin for “little posterior bridge”).Aims and Objectives: To study the proportion and various types of ponticuli.Materials and methods: Present study was conducted on 100 adult human atlas vertebrae, collected from thedepartment of Anatomy, Mysore Medical College and Research Institute, Mysuru.Observations and Results: Out of 100 atlas vertebrae examined, 20 atlas vertebrae showed ponticuli of varioustypes. 27 Ponticuli was observed in twenty (20) atlas vertebra as follows: a) Ponticulus posticus -15. b) Ponticuluslateralis -07. c) Ponticulus posterolateral -05. d) Complete Ponticulus -11. e) Incomplete Ponticulus -16.e) Bilateral Ponticulus -07. f) Unilateral Ponticulus -13. g) Right side -17 and Left side -10.Conclusion: Proper identification of this anomaly on preoperative lateral radiographs should alert the surgeonto avoid using the ponticulus as a starting point for a lateral mass screw in order to not injure the vertebralartery. It is also useful to surgeons who face regularly the patients complaining about the symptoms ofvertebrobasilar insufficiency like headache, vertigo, migraine.
ABSTRACT
Background: Atlas, the first cervical vertebra, has an oblique ligament which bridges the groove for vertebralartery. This ligament may ossify sometimes converting groove into foramen. These foramina are called asponticulus posterior or arcuate foramen of the atlas. The ponticuli can distort vertebral artery. They havetendency to cause vertebra basic insufficiency. During any manipulation of cervical spine, these variations ofatlas should be kept in mind.Objectives: To study the presence of ponticuli, their other features like whether complete or incomplete, unilateralor bilateral, sidedness- right or left.Material and Methods: A total of 50 fully dried adult human atlas were collected from the Department ofAnatomy, Government Medical College, Jammu and from the students of the first year MBBS, Government MedicalCollege, Jammu. Bones were intact and free from osteophytes. The superior surface of posterior arch was observedcarefully in each atlas for presence of ponticulus.Results: In the present study, 50 human atlas vertebrae were observed out of which 4 atlas (8%) had ponticuli. Itwas incomplete in 2 vertebrae (4%) and was complete in 2 atlas vertebrae (4%). It was unilateral in 3 atlasvertebrae (6%) and bilateral in 1 atlas vertebra (2%). 2 ponticuli were on the right side, 1 on left side and 2 werefound on both sides. All were ponticuli posterior except one which was lateral ponticulus.Conclusion: The presence of ponticuli can cause cervical pain and pressurize vertebral artery leading tocerebrovascular accidents. Detailed knowledge about the variations in the cervical region is very helpful toneurosurgeons, orthopaedicians and otolaryngologists to avoid any mishap. Spinal surgeons must be fullyaware about these ponticulus to prevent any complications during surgeries
ABSTRACT
BACKGROUND: The first cervical vertebra, atlas plays a vital role in the movement of skull & neck. The anatomy of atlas is complex due to its three dimensional structure. There is a groove on superior surface of posterior arch of atlas for passage of 3rd part of vertebral artery and first cervical spinal nerve (suboccipital nerve). Sometimes the oblique ligament of atlas which is present at the lower border of posterior atlanto-occipital membrane may ossify and convert this groove into a foramen. This foramen may be complete or incomplete, In some cases a bony bridge also extends from lateral masses of atlas to the posterior root of transverse process and form an additional foramen through which vertebral artery travels. The vertebral artery is prone to compression in its entire course between foramen transversarium and foramen magnum during extreme rotation movement of head & neck. This condition may be aggravated by the presence of these ponticuli & results in compromised blood flow and causes vertebrobasilar insufficiency presenting with dizziness, fainting, vertigo, transient diplopia & various neurological disturbances. MATERIALS & METHODS: The present study was carried out on 118 (Male-62, Female-56) dried fully ossified adult human atlas of known sex for the presence of complete or incomplete ring for vertebral artery i.e. different ponticuli on the superior surface of the atlas vertebra. RESULTS: We observed 21.17% cases of ponticulus posterior in which 7.62% specimens had complete ring while 13.55% specimens had incomplete ring & ponticulus lateralis was reported only in 5.93% cases (unilateral: 2.54% & bilateral: 3.39%). Incidence of ponticulus posterior as well as lateralis were more common in male as compared to female. Complete ponticulus posterior was more common in right side, while incomplete ponticulus posterior as well as ponticulus lateralis were more commonly bilaterally. CONCLUSION: As indicated by our study, ponticulus posterior as well as lateralis are not so rare anomaly in the population of Bihar. So, the detail knowledge about these variations is very helpful to the neurophysicians, neurosurgeons, orthopedicians & otolaryngologists who faces regularly the patients complaining about the symptoms of vertebrobasilar insufficiency. These informations are also important for the spine surgeons to prevent vascular complications during spinal surgeries especially in those patients who required screw placements in the lateral mass of atlas.
ABSTRACT
Background: Hypermobility of Atlanto-Occipital joints give rise to symptoms related to vascular compromise viz syncope, vertigo, transient impairment of visual field, altered consciousness. Surgical management of congenital anomalies of craniovertebral junction requires a precise identification of underlying pathophysiological condition. For this reason variation in superior articular facets of atlas vertebrae in terms of its morphology should be known. Method: The morphology of 100 atlas vertebrae had been studied and observations of total 200 facets were noted. Measurements were taken with a vernier callipers and a compass. Result :In the present study, typical oval, elongated or kidney shaped outline was found in 74.5% facets. Constrictions or notches were present on 48% facets. Complete separation (4.5%) is suggestive of tendency towards possible restriction of movement at atlanto-occipital joint as part of evolutionary changes. Roughly circular pressure facets had been observed in 78% of vertebrae indicating possibly greater pressure at this site during movement at atlanto-occipital joint.Conclusion: Knowledge of this variation in craniovertebral junction is of significant importance for Neurosurgeons and Orthopaedic surgeons doing various surgeries in this region.
ABSTRACT
Introduction: Arcuate foramen is less known trait of the human atlas vertebra formed by a delicate bony spiculum, which arches backward from the posterior end of the superior articular process. Method: Examination of 100 human atlas vertebra done. Result: Study revealed that the trait was present in 13% of the samples. The mean length of the arcuate foramen form was 7.16 mm on the left side and 9.99 mm on the right side in bilateral positive samples while it was 8.14 mm and 9.26 mm respectively in unilateral positive samples. The mean vertical height of this foramen was 6.57 mm on the left side and 6.52 mm on the right side in bilateral positive samples while it was 4.91 mm and 5.38 mm respectively in unilateral positive samples. The sides did not show any statistical significant differences. Conclusion: The importance of the arcuate foramen lies in the external pressure it may cause on the vertebral artery as it passes from the foramen transversaium of the first cervical vertebra to the foramen magnum of the skull.