The Skulls Full Movie Download
Ceferino Blunt
Skulls is a highly interactive experience, inviting you to touch, draw, and even reimagine your eyesight through various skulls. Experience vision as both predator and prey, try your hand at sketching skulls, and examine dozens of high-res, 3D skull images.
Methods: Morphometric analyses were performed in 22 Caucasian skulls. Measurements of the mental foramen (MF) included height (MF-H), width (MF-W), and location in relation to other known anatomical landmarks. Presence or absence of anterior loops (AL) of the inferior alveolar nerve (IAN) was determined, and the mesial extent of the loop was measured. Additional measurements included height (G-H), width (G-W), thickness (G-T), and volume (G-V) of monocortical onlay grafts harvested from the mandibular symphysis area, and thickness of the lateral wall (T-LW) of the maxillary sinus. The independent samples t test, and a two-tailed t test with equal variance were utilized to determine statistical significance to a level of P < 0.05. Multiple regression analyses were performed to determine if each one of these measurements was affected by age and gender.
The human skull is the bone structure that forms the head in the human skeleton. It supports the structures of the face and forms a cavity for the brain. Like the skulls of other vertebrates, it protects the brain from injury.[5]
Although the skulls of fossil lobe-finned fish resemble those of the early tetrapods, the same cannot be said of those of the living lungfishes. The skull roof is not fully formed, and consists of multiple, somewhat irregularly shaped bones with no direct relationship to those of tetrapods. The upper jaw is formed from the pterygoids and vomers alone, all of which bear teeth. Much of the skull is formed from cartilage, and its overall structure is reduced.[9]
The skulls of the earliest tetrapods closely resembled those of their ancestors amongst the lobe-finned fishes. The skull roof is formed of a series of plate-like bones, including the maxilla, frontals, parietals, and lacrimals, among others. It is overlaying the endocranium, corresponding to the cartilaginous skull in sharks and rays. The various separate bones that compose the temporal bone of humans are also part of the skull roof series. A further plate composed of four pairs of bones forms the roof of the mouth; these include the vomer and palatine bones. The base of the cranium is formed from a ring of bones surrounding the foramen magnum and a median bone lying further forward; these are homologous with the occipital bone and parts of the sphenoid in mammals. Finally, the lower jaw is composed of multiple bones, only the most anterior of which (the dentary) is homologous with the mammalian mandible.[9]
Living amphibians typically have greatly reduced skulls, with many of the bones either absent or wholly or partly replaced by cartilage.[9] In mammals and birds, in particular, modifications of the skull occurred to allow for the expansion of the brain. The fusion between the various bones is especially notable in birds, in which the individual structures may be difficult to identify.
Dating back to Neolithic times, a skull operation called trepanning was sometimes performed. This involved drilling a burr hole in the cranium. Examination of skulls from this period reveals that the patients sometimes survived for many years afterward. It seems likely that trepanning was also performed purely for ritualistic or religious reasons. Nowadays this procedure is still used but is normally called a craniectomy.
In the mid-nineteenth century, anthropologists found it crucial to distinguish between male and female skulls. An anthropologist of the time, James McGrigor Allan, argued that the female brain was similar to that of an animal.[27] This allowed anthropologists to declare that women were in fact more emotional and less rational than men. McGrigor then concluded that women's brains were more analogous to infants, thus deeming them inferior at the time.[27] To further these claims of female inferiority and silence the feminists of the time, other anthropologists joined in on the studies of the female skull. These cranial measurements are the basis of what is known as craniology. These cranial measurements were also used to draw a connection between women and black people.[27]
Research has shown that while in early life there is little difference between male and female skulls, in adulthood male skulls tend to be larger and more robust than female skulls, which are lighter and smaller, with a cranial capacity about 10 percent less than that of the male.[28] However, later studies show that women's skulls are slightly thicker and thus men may be more susceptible to head injury than women.[29] However, other studies shows that men's skulls are slightly thicker in certain areas.[30] As well as some studies showing that females are more susceptible to head injury (concussion) than males.[31] Men's skulls have also been shown to maintain density with age, which may aid in preventing head injury, while women's skull density slightly decreases with age.[32][33]
Male skulls can all have more prominent supraorbital ridges, glabella, and temporal lines. Female skulls generally have rounder orbits and narrower jaws. Male skulls on average have larger, broader palates, squarer orbits, larger mastoid processes, larger sinuses, and larger occipital condyles than those of females. Male mandibles typically have squarer chins and thicker, rougher muscle attachments than female mandibles.[34]
Trepanning, a practice in which a hole is created in the skull, has been described as the oldest surgical procedure for which there is archaeological evidence,[35] found in the forms of cave paintings and human remains. At one burial site in France dated to 6500 BCE, 40 out of 120 prehistoric skulls found had trepanation holes.[36]
The purpose of this study was to evaluate the relationship of alveolar bone morphology to tooth shape and form. 111 dry skulls were evaluated at Baylor College of Dentistry (Dallas, Texas). The skulls were arbitrarily divided into flat, scalloped and pronounced scalloped anatomic profiles according to alveolar bone anatomy. The number of buccal dehiscences and fenestrations was determined for each skull according to their anatomic morphotype. 10 skulls from each group were selected for bone height measurements. The measurements were made with a periodontal probe and ruler from the height of the interproximal bone to the buccal alveolar crest. Kodachrome slides were used to measure mesial-distal tooth width and length from ten skulls from each anatomic category. The average number of fenestrations for each group was 3.5. The mean number of dehiscences for flat and scalloped skulls was 0.5. The average number of dehiscences for pronounced scalloped was 1.2. There were no significant differences when the groups were compared. The mean distance from the height of the interdental bone to the alveolar crest was statistically significant when the groups were compared (flat 2.1 mm, scalloped 2.8 mm, pronounced 4.1 mm) (Tukey, p = 0.05). There were no significant differences when tooth shapes were compared with bone anatomy. Pronounced scalloped anatomic profiles were slightly narrower when compared with the other groups. The observations reported have treatment ramifications when patients with scalloped or pronounced scalloped morphotypes are being considered for dental implant placement.
The overall design of the See-Shells is shown in Fig. 1a. A motorized stereotaxic instrument was used to profile the skull surface covering the dorsal cortex of an 8-week-old C57BL/6 mouse at 85 points (see Methods). These 85 coordinates provided a point cloud representation of the skull surface used to interpolate a three-dimensional (3D) surface that accurately mimicked the skull morphology (Supplementary Figs. 1 and 2). Previous cranial morphometry studies of commonly used inbred laboratory mouse strains have shown that intra-species variations in cranial bone shape and size are minimal16. Further, postnatal size and shape of the skull are established within the first 3 weeks and change minimally after reaching adulthood17. Thus the interpolated surface from a single mouse skull served as a template to digitally design generalized transparent skulls (See-Shells) using computer-aided design (CAD) software. The frame was 3D-printed out of polymethylmethacrylate (PMMA) onto which a thin, flexible and transparent polyethylene terephthalate (PET) film was bonded (Fig. 1a and Supplementary Fig. 3). The 3D-printed frame also incorporated screw holes for fastening a custom-designed titanium head-plate for head-fixing the animal during experiments.
We developed See-Shells, transparent, morphologically conformant polymer skulls that allow optical access to a large part of the dorsal cerebral cortex for high-resolution structural and functional imaging. These windows can be implanted for long periods and remain functional for over 300 days. In line with estimates from recent studies using curved glass windows14, See-Shells provide optical access to 1 million neurons from the cortical surface. In addition, optical imaging with See-Shells can be combined with other modalities. Perforation of the PET film allows access to the brain underneath the implant and here we demonstrated wide-field Ca2+ imaging with simultaneous intracortical microstimulation and electrophysiological recordings.
The optical properties of PET compare favorably with glass coverslips when evaluated by 2P or FLIM imaging. The latter opens up the possibility for FLIM intra-vital brain imaging of auto-fluorescence using PET windows30,31. For example, the intrinsically fluorescent metabolites nicotinamide adenine dinucleotide hydrogen and flavin adenine dinucleotide are widely used in vivo to record label-free cellular activity based on their oxidation state32,33,34. Changes in the lifetime of both coenzymes are used to monitor the biological microenvironment32, including in intra-vital studies35. Thus, while the current goal is to use PET to realize transparent skulls for cortex-wide imaging, the flexibility, optical clarity, and biocompatibility demonstrate the feasibility of engineering anatomically realistic windows for intra-vital imaging in a wide variety of organs, such as mammary gland36 and lung37.
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