Clinical significance of presence of accessory foramen transversarium in typical cervical vertebrae

Background: The cervical vertebrae are smallest of all the vertebrae present in the vertebral column. It is characterized by a foramen in each transverse process. The foramen transversarium (FT) of 6th to 1st cervical vertebrae transmits vertebral vessels and sympathetic nerves. Presence of another foramen apart from FT in the transverse process of cervical vertebrae is called accessory FT. Anatomical knowledge of these variations are helpful for conducting cervical spinal surgeries by the surgeons in order to prevent injury to vertebral vessels and sympathetic nerves.Methods: The present study was conducted in the department of anatomy, UCMS and GTB Hospital, Delhi, India. A total number of 241 dried cervical vertebrae were collected from the bone bank of the Department of Anatomy. Presence of any variation from the normal anatomy of the cervical vertebrae were noted and photographed.Results: Out of 241 cervical vertebrae (typical and atypical), the accessory FT was noted in typical cervical vertebrae only. Accessory FT was seen in 37 (27.6%) vertebrae, out of 134 typical cervical vertebrae. These accessory FT were either bilateral complete in 4 (2.9%) or incomplete 9 (6.7%) or unilateral complete 6 (4.5%) and unilateral incomplete 12 (8.9%) were observed. Six (4.5%) typical cervical vertebrae showed presence of complete accessory FT on one side and incomplete accessory FT on the other side in the same vertebra.Conclusions: Knowledge of variations of the presence of accessory FT in the typical cervical vertebrae is not only important to anatomist but also to radiologist in identifying the presence of duplicate vertebral artery and hence helping the neuro surgeons in preventing accidental bleeding from the vertebral artery while performing surgery on the cervical spine

A morphometric study of foramen transversarium of dried cervical vertebrae

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.

Why sauropods had long necks; and why giraffes have short necks

The necks of the sauropod dinosaurs reached 15 m in length: six times longer than that of the world record giraffe and five times longer than those of all other terrestrial animals. Several anatomical features enabled this extreme elongation, including: absolutely large body size and quadrupedal stance providing a stable platform for a long neck; a small, light head that did not orally process food; cervical vertebrae that were both numerous and individually elongate; an efficient air-sac-based respiratory system; and distinctive cervical architecture. Relevant features of sauropod cervical vertebrae include: pneumatic chambers that enabled the bone to be positioned in a mechanically efficient way within the envelope; and muscular attachments of varying importance to the neural spines, epipophyses and cervical ribs. Other long-necked tetrapods lacked important features of sauropods, preventing the evolution of longer necks: for example, giraffes have relatively small torsos and large, heavy heads, share the usual mammalian constraint of only seven cervical vertebrae, and lack an air-sac system and pneumatic bones. Among non-sauropods, their saurischian relatives the theropod dinosaurs seem to have been best placed to evolve long necks, and indeed they probably surpassed those of giraffes. But 150 million years of evolution did not suffice for them to exceed a relatively modest 2.5 m.Comment: 39 pages, 11 figures, 3 table

Physiological maturation stage of cervical vertebrate index in cleft lip/palate and non-cleft lip/palate patients

Cleft lip and palate is one of the most common congenital anomalies. Cleft lip and palate patients encounter growth problems in lip and palate area, although their overall growth and development remains unknown. Cervical vertebral maturation are indicators of physiological maturation used in interceptive treatment and orthognathic surgery. The present study aims to determine physiological maturation stage of cervical vertebrae maturation index in cleft andnon-cleft patients. Lateral cephalogram of 26 cleft patients and 27 non-cleft patients with a range of chronological age from 8-16 years old were involved. The cervical vertebrae maturation were analyzed in six stages of cervical vertebrae maturation method of Hassel and Farman. Data were analyzed using t-test (p≤ 0.05). The result shows that physiologicalmaturation stage of cervical vertebrae maturation index in cleft and non-cleft patients has no significant difference in stage acceleration (p= 0.38), stage transition (p= 0.41) and deceleration (p= 0.39). Likewise, there is no significant difference in physiological maturation stage of cervical vertebrae maturation index between cleft and non-cleft patients.

Breaking evolutionary and pleiotropic constraints in mammals: On sloths, manatees and homeotic mutations

<p>Abstract</p> <p>Background</p> <p>Mammals as a rule have seven cervical vertebrae, except for sloths and manatees. Bateson proposed that the change in the number of cervical vertebrae in sloths is due to homeotic transformations. A recent hypothesis proposes that the number of cervical vertebrae in sloths is unchanged and that instead the derived pattern is due to abnormal primaxial/abaxial patterning.</p> <p>Results</p> <p>We test the detailed predictions derived from both hypotheses for the skeletal patterns in sloths and manatees for both hypotheses. We find strong support for Bateson's homeosis hypothesis. The observed vertebral and rib patterns cannot be explained by changes in primaxial/abaxial patterning. Vertebral patterns in sloths and manatees are similar to those in mice and humans with abnormal numbers of cervical vertebrae: incomplete and asymmetric homeotic transformations are common and associated with skeletal abnormalities. In sloths the homeotic vertebral shift involves a large part of the vertebral column. As such, similarity is greatest with mice mutant for genes upstream of <it>Hox</it>.</p> <p>Conclusions</p> <p>We found no skeletal abnormalities in specimens of sister taxa with a normal number of cervical vertebrae. However, we always found such abnormalities in conspecifics with an abnormal number, as in many of the investigated dugongs. These findings strongly support the hypothesis that the evolutionary constraints on changes of the number of cervical vertebrae in mammals is due to deleterious pleitropic effects. We hypothesize that in sloths and manatees low metabolic and activity rates severely reduce the usual stabilizing selection, allowing the breaking of the pleiotropic constraints. This probably also applies to dugongs, although to a lesser extent.</p

Pterodactylus scolopaciceps Meyer, 1860 (Pterosauria, Pterodactyloidea) from the Upper Jurassic of Bavaria, Germany:the problem of Cryptic Pterosaur Taxa in early ontogeny

The taxonomy of the Late Jurassic pterodactyloid pterosaur Pterodactylus scolopaciceps Meyer, 1860 from the Solnhofen Limestone Formation of Bavaria, Germany is reviewed. Its nomenclatural history is long and complex, having been synonymised with both P. kochi (Wagner, 1837), and P. antiquus (Sömmerring, 1812). The majority of pterosaur species from the Solnhofen Limestone, including P. scolopaciceps are represented by juveniles. Consequently, specimens can appear remarkably similar due to juvenile characteristics detracting from taxonomic differences that are exaggerated in later ontogeny. Previous morphological and morphometric analyses have failed to separate species or even genera due to this problem, and as a result many species have been subsumed into a single taxon. A hypodigm for P. scolopaciceps, comprising of the holotype (BSP AS V 29 a/b) and material Broili referred to the taxon is described. P. scolopaciceps is found to be a valid taxon, but placement within Pterodactylus is inappropriate. Consequently, the new genus Aerodactylus is erected to accommodate it. Aerodactylus can be diagnosed on account of a unique suite of characters including jaws containing 16 teeth per-jaw, per-side, which are more sparsely distributed caudally and terminate rostral to the nasoantorbital fenestra; dorsal surface of the skull is subtly depressed rostral of the cranial table; rostrum very elongate (RI = ∼7), terminating in a point; orbits correspondingly low and elongate; elongate cervical vertebrae (approximately three times the length of their width); wing-metacarpal elongate, but still shorter than the ulna and first wing-phalanx; and pteroid approximately 65% of the total length of the ulna, straight and extremely thin (less than one third the width of the ulna). A cladistic analysis demonstrates that Aerodactylus is distinct from Pterodactylus, but close to Cycnorhamphus Seeley, 1870, Ardeadactylus Bennett, 2013a and Aurorazhdarcho Frey, Meyer and Tischlinger, 2011, consequently we erect the inclusive taxon Aurorazhdarchidae for their reception

The effects of a common stainless steel orthodontic bracket on the diagnostic quality of cranial and cervical 3T-MR images: a prospective, case-control study

Abstract OBJECTIVES: To evaluate the effect of orthodontic stainless steel brackets and two different types of archwires (stainless steel and nickel-titanium) on the diagnostic quality of 3T-MR images. METHODS: This prospective, case-control study was conducted following STROBE guidelines. The imaging protocol consisted of the axial Fluid Attenuated Inversion Recovery (FLAIR) and axial oblique double echo proton density (PD) and weighted/turbo spin echo (TSE) T2-weighted sequences for brain, paranasal sinuses and cervical region evaluation; sagittal TSE T2w, sagittal TSE T1w and axial T2* Gradient echo sequences (GRE) sequences for the cervical vertebrae; axial and coronal TSE T2w images for the head and neck structures; and sagittal, axial and coronal PD and TSE T2-weighted sequences for the temporo-mandibular joint. Two experts in neuroradiology evaluated the images. The statistical analysis was performed at the level of anatomical districts. The following statistical methods were used: descriptive statistics, Cohen's kappa coefficient (k), Kruskal-Wallis test, pairwise comparisons using the Dunn-Bonferroni approach. Significance was set at p≤0.05. RESULTS: 80 patients were included, providing 80 MRI. The presence of stainless steel brackets with or without archwires negatively influenced the MR images of the cervical region, paranasal sinuses, head and neck region and cervical vertebrae but did not influence the MR images of brain and temporomandibular joint regions. CONCLUSIONS: Patients with a stainless steel multi-bracket orthodontic appliance should remove it before cervical vertebrae, cervical region, paranasal sinuses and head and neck MRI scans. The brain and temporomandibular joint regions MRI should not require the removal of such appliances

The effect of intervertebral cartilage on neutral posture and range of motion in the necks of sauropod dinosaurs

The necks of sauropod dinosaurs were a key factor in their evolution. The habitual posture and range of motion of these necks has been controversial, and computer-aided studies have argued for an obligatory sub-horizontal pose. However, such studies are compromised by their failure to take into account the important role of intervertebral cartilage. This cartilage takes very different forms in different animals. Mammals and crocodilians have intervertebral discs, while birds have synovial joints in their necks. The form and thickness of cartilage varies significantly even among closely related taxa. We cannot yet tell whether the neck joints of sauropods more closely resembled those of birds or mammals. Inspection of CT scans showed cartilage:bone ratios of 4.5% for Sauroposeidon and about 20% and 15% for two juvenile Apatosaurus individuals. In extant animals, this ratio varied from 2.59% for the rhea to 24% for a juvenile giraffe. It is not yet possible to disentangle ontogenetic and taxonomic signals, but mammal cartilage is generally three times as thick as that of birds. Our most detailed work, on a turkey, yielded a cartilage:bone ratio of 4.56%. Articular cartilage also added 11% to the length of the turkey's zygapophyseal facets. Simple image manipulation suggests that incorporating 4.56% of neck cartilage into an intervertebral joint of a turkey raises neutral posture by 15°. If this were also true of sauropods, the true neutral pose of the neck would be much higher than has been depicted. An additional 11% of zygapophyseal facet length translates to 11% more range of motion at each joint. More precise quantitative results must await detailed modelling. In summary, including cartilage in our models of sauropod necks shows that they were longer, more elevated and more flexible than previously recognised