Skull Type Research Articles

Modeling the frequency dependence of the electrical properties of the live human skull

An accurate impedance model of a skull plays an important role in the simulation research on source localization of EEG and brain EIT (electrical impedance tomography), etc. On the basis of the large number of impedance and resistivity data obtained from our previous measurement on the live human skull, in this study we established the equivalent circuit models of six types of skull samples in the 30 Hz–3 MHz frequency range and analyzed the fitting performance of the models. The six types of skull samples are standard tri-layer, quasi-tri-layer, standard compact, quasi-compact, dentate suture and squamous suture. The results showed that the difference of the real part between the CPE (constant phase model) model and the measured data was less than 1% for all skull tissue types when the optimized characteristic parameters (ρ0, ρ∞, α and fc) were adopted in the model. It is the first time studying the impedance model of different types of skulls, and it may provide accurate modeling of the skull to improve the accuracy of the related research on bioelectricity of the head and the biological effects of the electromagnetic field.

Skull Indices in a Population Collected From Computed Tomographic Scans of Patients with Head Trauma

It is important to find out the skull's anatomic indices with computed tomography (CT), especially the skull's dimensions according to the patients age and sex, because it can give important results in neurosurgery. We will also describe the skull's parameters among the Kerman population. Of the 2000 CT scans taken after head trauma injury in Kerman province from June 2002 to September 2006, we analyzed 1034 good quality films. The most frequent skull dimensions were measured on each film, and the data were computed and analyzed to assess the cranial indices in various ages and sexes. Two types of classifications were carried out: classic method, which uses cranial indices, and posterior fossa angle dimensions as an alternative method. Skull dimensions were statistically analyzed between groups, and any difference greater than 0.05 was considered significant. Of the 1034 films, 871 films belonged to the men and 184 to the women at age older than 5 years and younger than 70 years. Most of the CT films belonged to the patients with age older than 20 years and younger than 40 years in both sexes. Although the rates of various skull types were different according to the method of classification, the most frequent skull type was dolichocephalic followed by mesocephalic and brachycephalic in both sexes. In addition, in both sexes, the frequency of dolichocephaly was greater in children than adults, but brachycephaly was more frequent in adults than children. With CT scans as an accurate and suitable source of anthropometric evaluation of body dimensions, we found that, in our population, the most frequent skull type is dolichocephalic followed by mesocephalic, which seems to be closer to the Anglo-Saxon population considering the rates of dolichocephaly and mesocephaly.

Cloverleaf Skulls

Cloverleaf skulls (Kleeblattschädel-Syndromen, trilobular skulls) have different modes of development (pathogenetic variability). Synostosis may involve various sutures in different types of cloverleaf skulls. Their facial features, radiographic findings, and CNS anomalies are also reviewed. Different causes of cloverleaf skulls have been identified (etiologic heterogeneity). One table lists 26 different conditions with trilobular skulls identified under various etiologic headings: monogenic, chromosomal, disruptive, iatrogenic, and distinctive conditions of unknown cause. Discussed in detail are type 2 thanatophoric dysplasia, type 2 Pfeiffer syndrome, Apert syndrome, amniotic bands, Say-Poznanski syndrome, and COH syndrome. Another table summarizes the relative frequencies of the cloverleaf skull syndromes.

Polarization of Skull Shapes in Adult Lowland European Bison,Bison Bonasus Bonasus

The material consisted of 300 skulls (150 male and 150 female) of adult European bison from the Lowland line aged 5 to 27 years. The specimens belong to the museum collection of the Mammal Research Institute of the Polish Academy of Sciences in Bialowieza. On each skull three standard measurements (BP, EctEct, SmSm) were taken. The results were standardized separately for males and females. The sum of three normalized parameters describing each skull was treated as its standardised dimension and then Perkal's natural similarity coefficients were calculated. In adult males a remarkable polarization of skull shapes was observed. In one set of the male specimens the type of a long skull with a broad forehead and narrow face was predominant (27%). In another, opposite and almost equally numerous (24%) set of male specimens, the type of a short skull with a narrow forehead and broad face prevailed. Such a polarization was not found in adult females: the type of a long skull with a narrow forehead and narrow face dominated (28% of the examined material); the remaining variants were evenly distributed.

Pharmacokinetics of topically applied ciprofloxacin in tears of mesocephalic and brachycephalic dogs

To evaluate the pharmacokinetics of ophthalmic ciprofloxacin in the tear film of normal mesocephalic and brachycephalic dogs. Twenty mesocephalic dogs and 15 brachycephalic dogs. Thirty-five microliters of ciprofloxacin were placed on the cornea of both eyes of each dog. Five brachycephalic dogs were used twice. A tear-test strip placed in the ventral cul de sac for 30 s was used to obtain samples. The tear film of each eye was sampled once at eight time-points post administration, resulting in five samples at each time-point. Samples were evaluated using high performance liquid chromatography. Data from the two skull types were compared using the unpaired two-tailed t-test. The mean concentration of ciprofloxacin in the tears of mesocephalic dogs was 192.8 +/- 269.97, 140.6 +/- 91.06, 56.60 +/- 28.47, 13.6 +/- 6.3, 43.25 +/- 59.71, 16.6 +/- 10.62, 15.6 +/- 13.16 and 6.25 +/- 9.84 microg/g at 5, 10, 15, 30 min and 1, 2, 4 and 6 h, respectively. The mean concentration of ciprofloxacin in the tears of brachycephalic dogs was 272.6 +/- 106.21, 144.4 +/- 142.32, 131.2 +/- 147.07, 75 +/- 80.07, 40.8 +/- 30.35, 35 +/- 21.98, 52.75 +/- 51.87 and 8.6 +/- 12.10 microg/g at 5, 10, 15, 30 min and 1, 2, 4 and 6 h, respectively. There was no statistical difference in tear concentration at any time-point between skull types. Topical application of ciprofloxacin resulted in a mean tear concentration of ciprofloxacin that remained above the MIC(90) levels for most pathogenic bacteria for 6 h in normal mesocephalic and brachycephalic dogs.

Skull morphology and its neurosurgical implications in the Hippocratic era.

Differences in skull morphological characteristics among various human populations were first described by Herodotus of Halicarnassus. The Hippocratic treatise On Head Wounds provided the first detailed description of human skull anatomy. The Hippocratic author presented the first systematic attempt to create a classification system of skull and cranial suture morphology. Detailed descriptions of various human skull types and cranial sutures were provided along with information regarding the macroscopic structure and thickness of different parts of the skull. The significance of skull thickness in patients with head injuries was also presented in the Hippocratic text. The authors discuss the influence of this treatise on the later development of descriptive skull anatomy and on the development of modern neurosurgery.

Skull morphology and its neurosurgical implications in the Hippocratic era

✓Differences in skull morphological characteristics among various human populations were first described by Herodotus of Halicarnassus. The Hippocratic treatise On Head Wounds (Περι των εν κεφαλη τρωματων) provided the first detailed description of human skull anatomy. The Hippocratic author presented the first systematic attempt to create a classification system of skull and cranial suture morphology. Detailed descriptions of various human skull types and cranial sutures were provided along with information regarding the macroscopic structure and thickness of different parts of the skull. The significance of skull thickness in patients with head injuries was also presented in the Hippocratic text. The authors discuss the influence of this treatise on the later development of descriptive skull anatomy and on the development of modern neurosurgery.

Characterisation of the genomic canineFgf8locus and screen for genetic variants in 4 dogs with different face types

We are investigating the genetic basis of morphological differences in skull shape between domestic dogs of different breeds using a candidate gene approach to identify genes involved in the genetic regulation. One such candidate is Fgf8. Fgf8 is a signalling molecule important in the embryonic development and patterning of the craniofacial region. Mice conditional null for the expression of Fgf8 after E9.5 have a short foreface and a wide skull (Trumpp et al. 1999). Using a combination of bioinformatics and PCR cloning, we have characterised the genomic loci of the canine Fgf8 gene. Like the mouse homologue, it is composed of six exons and we also predict that like the mouse, there are eight alternative isoforms that are generated by alternative splicing events. We have identified a short 200 bp sequence upstream of the Fgf8 gene that is highly conserved between species and have predicted putative transcription factor binding sites using the Transfac database. Genetic analysis of 4 dogs with different skull types identified genetic variation. None of the variants however, were predicted to have any functional significance.

Prenatal diagnosis and molecular analysis of type 1 thanatophoric dysplasia

Thanatophoric dysplasia (TD) is one of the most common lethal skeletal dysplasias with an estimated frequency of nearly 1 in 20000 births. It is characterized by extreme rhizomelia i.e. a normal trunk length but a narrow chest and a large head with a prominent forehead. The abnormality is classified into TD type 1 (TD 1) where patients always have curved femurs and sometimes a cloverleaf skull and TD type 2 (TD 2) where patients always have straight femurs and always a cloverleaf skull. The prenatal diagnosis of TD can be established by ultrasonography in the second trimester of gestation. However it is not always possible to differentiate TD from others skeletal dysplasias by ultrasonography alone and molecular genetic analysis of the fibroblast growth factor receptor 3 (fgfr3) gene is useful for prenatal diagnosis of TD. In this report 3 fetuses with TD 1 were diagnosed ultrasonographically in the second trimester and molecular analyses of the fgfr3 gene confirmed the prenatal diagnoses. (excerpt)

Head co‐ossification, phragmosis and defence in the casque‐headed tree frog Corythomantis greeningi

Some anurans have a peculiar casqued head with the skin co-ossified with the underlying bones. This type of skull usually is associated with phragmosis, a protective behaviour in which the animal enters a hole and closes it with the head. Although co-ossification of the head in lissamphibians frequently has been associated with water economy, recent studies of Corythomantis greeningi, a casque-headed tree frog from semi-arid areas in north-eastern Brazil, suggest that cranial co-ossification contributes little to conservation of water in the frog. Instead, during phragmotic behaviour, the co-ossified head protects the animal against predators and indirectly enhances water balance. Thus, the primary role of co-ossification is defence, a hypothesis that is the focus of this study, which describes the morphology of the head of C. greeningi with an emphasis on the co-ossification and the venom glands. We report on behavioural features and on the toxicity of the cutaneous secretion produced by the abundant venom glands that are associated with large spicules on the skull.

Study on Skull Asymmetry

The aim of this study is to determine the type of skull as well as to examine its internal appearance and configuration of skull base. Special attention is given to the direction and position of the pyramid of the temporal bone, the volume and appearance of all the three cranial fossas, and the direction and appearance of crista alaris--all of those compared to the skull type. Considering the obtained results (specially for crista alaris and middle fossa) we can ascertain outstanding independence of sphenoid bone and its parts in the formation of cranial base. Located in the middle of the skull, in front of strong pyramids transversal axis and two vertical axis, frontal crest and internal occipital crest, it by itself with her lesser wing presents an important transversal axis of cranial base. Cases in which crista alaris with its position does not follow the type of skull (in 20 % cases crista alaris does not follow skull protuberances), may probably be explained by strong and independent development of this bone, which is placed among other bones of cranial base like a peg. It also, by itself dictates form and configuration of the middle part of skull. That is also confirmed by middle fossa which, according to its position in the middle of cranial base and relation with sphenoid bone, shows significant deviation with respect to posterior fossa (follows the type of skull in 47 % cases).

Disparity and geometry of the skull in Archosauria (Reptilia: Diapsida)

A metric comparison of 155 fossil and extant species in lateral view based on the proportions of three homologous units (braincase, orbit and rostrum) reveals the existence of an archosaurian skull geometry. An empirical morphospace depicting skull proportions shows that the most variable unit is the rostrum. Three skull types based on rostral proportion are proposed: meso-, longi- and brevirostral. These types depend, on one hand, on a direct numerical relationship between the braincase and the orbit, with a mean ratio of 1:1; never surpassing a 2:1 or 1:2 ratio limit. On the other hand, skull types show a significant negative correlation between braincase and rostrum proportions. Close relationships have been obtained between orbit and the rostrum, although with lower significance and a geometric meaning specific to each group. Skull types depend mainly on the proportional relationship between the rostrum and the braincase. Mesorostral types account for more natural occurrences within morphospace, implying a plesiomorphic condition in Archosauria. Skulls with highest longirostral values (flying forms) display a more restrictive braincase–orbit ratio relationship. Brevirostrals are limited to the smallest skull lengths, up to approximately 180 mm. 85% of brevirostral modern birds have altricial post-hatchling development. General allometric pattern is very similar for all sampled archosaurs, although giant taxa (i.e. non-avian theropods) display a different type of skull proportional growth, closer to isometry. Results reveal the existence of a constructional skull geometry, highlighting the importance of the deviance of the structural design from adaptive explanations on craniofacial morphology in macroevolution.

Hypophysectomy as a Treatment for Canine and Feline Cushing's Disease

The microsurgical technique of transsphenoidal hypophysectomy performed with the dogs and cats positioned in sternal recumbency enables the treatment of Cushing's disease, independent of skull type, in a safe and effective manner. In dogs, the short-term survival rate after hypophysectomy is comparable to that after treatment with o,p'-DDD, whereas the recurrence rate in this period is lower. When the surgeon has gone through a learning curve, the results of the 1- to 3-year follow-up interval may be better than those after adrenocorticolysis with o,p'-DDD. CT enables assessment of localization and size of the pituitary before surgery. In general, dogs with Cushing's disease and normal-sized pituitaries or moderately enlarged pituitaries (up to 12 mm in diameter) are suitable candidates for transsphenoidal surgery. In dogs with larger pituitary tumors and tumor extension rostrally or caudally over the dorsum sellae, transsphenoidal debulking surgery may be only a palliative treatment. The main complications are postoperative hypernatremia, keratoconjunctivitis sicca, diabetes insipidus, and secondary hypothyroidism. In cats, special attention should be paid to closure of the soft palate. The neurosurgeon must be familiar with these complications so as to recognize them as early as possible and to treat them immediately and effectively. It is concluded that microsurgical transsphenoidal hypophysectomy in dogs and cats with Cushing's disease is an effective method of treatment.

The effect of obliquity on the radiographic appearance of the temporomandibular joint in dogs.

The temporomandibular joint is formed between the condyloid process of the mandible and the mandibular fossa of the temporal bone. The basic anatomy of this joint was assessed and described in a series of skulls including dolichocephalic, mesaticephalic and brachycephalic breeds. The facial index and rotational angles were measured with the facial index providing a useful method of classifying skull types but the rotational angle being of limited use in assessment of the temporomandibular joint until normal breed values are established. Equipment was designed to allow repeatable positioning of the temporomandibular joint for radiography at a variety of lateral and long axis rotational angles relative to the central x-ray beam. The regions of the joint and anatomic features visualized in each view are demonstrated. 10 degrees rotation was required in either axis to project the joints independently of each other. Lateral rotational angles of 10 to 30 degrees in mesaticephalic and dolichocephalic breeds and 20 to 30 degrees in brachycephalics and long axis rotational views of 10 to 30 degrees depending on the region of interest were considered to be the most useful.

New information about the skull and dentary of the Miocene platypus Obdurodon dicksoni, and a discussion of ornithorhynchid relationships.

A reconstruction of the skull, dentary and dentition of the middle Miocene ornithorhynchid Obdurodon dicksoni has been made possible by acquisition of nearly complete cranial and dental material. Access to new anatomical work on the living platypus, Ornithorhynchus anatinus, and the present comparative study of the cranial foramina of Ob. dicksoni and Or. anatinus have provided new insights into the evolution of the ornithorhynchid skull. The hypertrophied bill in Ob. dicksoni is seen here as possibly apomorphic, although evidence from ontogenetic studies of Or. anatinus suggests that the basic form of the bill in Ob. dicksoni (where the rostral crura meet at the midline) may be ancestral to the form of the bill in Or. anatinus (where the rostral crura meet at the midline in the embryonic platypus but diverge in the adult). Differences in the relative positions of cranial structures, and in the relationships of certain cranial foramina, indicate that the cranium may have become secondarily shortened in Or. anatinus, possibly evolving from a more elongate skull type such as that of Ob. dicksoni. The plesiomorphic dentary of Ob. dicksoni, with well-developed coronoid and angular processes, contrasts with the dentary of Or. anatinus, in which the processes are almost vestigial, as well as with the dentary of the late Oligocene, congeneric Ob. insignis, in which the angular process appears to be reduced (the coronoid process is missing). In this regard the dentary of Ob. insignis seems to be morphologically closer to Or. anatinus than is the dentary of the younger Ob. dicksoni. Phylogenetic conclusions differ from previous analyses in viewing the northern Australian Ob. dicksoni as possibly derived in possessing a hypertrophied bill and dorsoventrally flattened skull and dentary, perhaps being a specialized branch of the Obdurodon line rather than ancestral to species of Ornithorhynchus. The presence of functional teeth and the robust, flattened skull and dentary in Ob. dicksoni argue for differences in diet and lifestyle between this extinct ornithorhynchid and the living Ornithorhynchus.

Computed tomography reveals further details ofExcalibosaurus, a putative ancestor for the swordfish-like ichthyosaurEurhinosaurus

ABSTRACT Excalibosaurus costini, a Lower Jurassic ichthyosaur discovered in England in 1984, is re-examined using computed tomography. The species is characterized by its elongated snout, which extends beyond the mandibles by an amount equivalent to 35% of the snout length. Only in the later Lower Jurassic species Eurhinosaurus longirostris is there a similar development of the snout, but here the overbite approaches 60% of the snout length. Excalibosaurus may have given rise to Eurhinosaurus, and it is therefore important to verify that its overbite is real rather than a result of preservation. Radiography verifies this, and also confirms that the naris has a complex, bilobed structure. The forefin has four digits, as previously suspected; the coracoid is discoidal, with only an incipient anterior notch. Leptopterygius tenuirostris, geologically slightly older, shares many features with Excalibosaurus costini, including a tendency to develop an overbite. E. costini also has much in common with Eurhinosaurus longirostris, which is geologically younger. Simple modelling shows that one skull type can be derived from the previous one by changing the relative lengths of the snout and mandible. It is conceivable that the three species represent segments of an evolutionary lineage.

Parallelism among gliridae (rodentia): The genusglira vusStehlin and Schaub

Defined mainly by dental features, the Paleogene genus Gliravus Stehlin and Schaub appears heterogeneous on the basis of the structure of the infra‐orbital and masseteric region. The type‐species G. majori Stehlin and Schaub (Quercy undet.), and a new species G. itardiensis described from Itardies (Quercy, new collections) have a protrogomorphous skull. The species G. prisais Stehlin and Schaub, allocated to a new genus Glamys, is characterized by a “myomorphous”; skull (from Mas de Got, Quercy, new collections). That two types of skulls, allied by a very similar dental pattern, coexisted since at least the beginning of the Middle Oligocene and probably since the Upper Eocene, proves on the one hand that this “myomorphy”; probably derives from a primitive protrogomorphy; it is a pseudo‐myomorphy by comparison with the myomorphy of the Cricetidae, which has arisen from hystricomorphous ancestors. On the other hand, it shows that these glirids evolved at different rates, the Glamys lineage being the more pr...

Localização topográfica da papila parotidea em cães de raça

It was studied the topographic situation of the parotid papilla related to the upper premolar and molar teeth, in 230 dogs of different breeds grouped in the MEGNIN'S read types. Generally the parotid papilla is seem at the level of the space between the 4th pre molar and 1sl molar of the upper jaw but it also is seem related to other teeth or interdental spaces, according to the diverse head types, that are associated to the three skull types; i.e.: DoIicocephaIic , MesaticephaIic and Brachycefalic.

Morphological clues to genetic species: multivariate analysis of greater Galago sibling species.

Several studies conducted in diverse fields indicate the presence of a genetic discontinuity within the taxon Galago crassicaudatus E. Geoffroy--the thick-tailed bushbaby. One of these areas is morphology. This contribution details a statistical analysis of skull material classified under this taxon in order 1) to confirm the objective existence of two morphotypes, and 2) to investigate the characters that allow the skull types to be distinguished. Emphasis is placed on multivariate techniques, although univariate and bivariate techniques are included where they are felt to be appropriate. All statistical analyses point to the reality of the morphological discontinuity between the groups. This is true even when size considerations have been reduced by rescaling the data. The results support separation of the populations at a specific level: G. crassicaudatus and G. garnettii. In addition, the structural changes observed in the two taxa--including an increase in overall size in G. crassicaudatus--are indicative of a divergence in preferred habitats: G. garnettii is adapted to more mesic environmental conditions, and to a softer, less fibrous diet than is its more robust sibling.

The Lateral Craniographic Method of Facial Reconstruction

Abstract Fifty-four lateral cephalographs with clear soft tissue profiles of American Caucasians (17 males, ages 14 to 36; 37 females, ages 14 to 34) were traced and measured to establish the ranges and means of midline soft tissue depths and facial angles. With these data it is possible to reconstruct “approximate” profiles over X-ray tracings of unidentified skulls. The lateral craniographic method of facial reconstruction requires four steps: (1) a cephalometric analysis is first made to determine the facial proportions and individual skull type; (2) the mean soft tissue thicknesses and angles are then plotted against the basic midline anthropometric points to establish the average dimensions of the nose, lips, and chin; (3) the points are connected and “harmonized” in accordance with the known anthropological data (sex, age, race); and (4) the profile is finally “humanized” by adding tone, a stylized eye, hair patterns, age lines, and any other features that can be determined from an anatomic examination of the skull. The validity of the method is illustrated with three study cases of living orthodontic patients.