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The Skull and Brain
Published in Melanie Franklyn, Peter Vee Sin Lee, Military Injury Biomechanics, 2017
Tom Gibson, Nicholas Shewchenko, Tom Whyte
The vertebrae consist of a thin surface layer of dense cortical bone enclosing a less dense core of porous trabecular bone. C1 interacts superiorly with the occipital condyles at the base of the skull, and C7 interacts inferiorly with the first thoracic spinal vertebra, T1. At the upper cervical spine there are two atypical vertebrae with unique anatomy called the atlas (C1) and the axis (C2). The atlas is a wide, ring-like bone which supports the skull. It has no vertebral body and consists of two lateral masses joined anteriorly and posteriorly by arches. The atlas can be thought of as a ‘washer’ that moves with and supports the head with the only substantial degree of relative motion between the skull and C1 in flexion–extension (or nodding) (Nelson 2011). The axis has a spindle-like protrusion called the dens or odontoid process about which the atlas rotates.
Thermal Physiology and Thermoregulation
Published in James Stewart Campbell, M. Nathaniel Mead, Human Medical Thermography, 2023
James Stewart Campbell, M. Nathaniel Mead
When a subject is cooled in a standing or sitting position, the muscles over the posterior neck and upper back are under constant tension. The atlas bone (first cervical vertebra) supports the entire weight of the cranium, face, and jaw on a pivot posterior to the balance point of the head. The inferior portions of the anterior skull also support the pharynx, larynx, and upper trachea. When the body is upright, the weight of these structures anterior to the atlas pivot would rotate the head forward if not for the pull of the posterior cervical muscles, mainly the trapezius. Any tension in the anterior neck muscles requires the posterior muscles to contract more, as does leaning the head forward.
Head-Mounted Displays
Published in Cary R. Spitzer, Uma Ferrell, Thomas Ferrell, Digital Avionics Handbook, 2017
The human head weighs approximately 9–10 lb and sits atop the spinal column (Figure 16.15). The occipital condyles on the base of the skull mate to the superior articular facets of the first cervical vertebra (C1, or the Atlas).93 These two small oblong mating surfaces on either side of the spinal column are the pivot points for the head.
Hybrid rendering of exploded views for medical image atlas visualization
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2018
Tim McGraw, Alejandro Guayaquil-Sosa
A medical image ‘atlas’ containing a description and visualisation of human anatomy is often consulted during diagnoses, surgical planning or for educational purposes. The atlas images are often acquired from dissection photographs or histological slices which have been labelled by an expert. The labels may describe the tissue classes or outline specific anatomical structures. In medical image analysis, the term ‘atlas’ is also applied to images generated from a collection of data-sets which are processed to obtain a representation of an average subject. The construction of an atlas involves registering multiple images of the same modality, e.g. MRI, into a common coordinate system, then processing them to construct a single representative image. The result is an image which is independent of the minor anatomical variations in the individual images. From this ‘template’ image a ‘label’ image can be created to describe the tissues and structure in the atlas. The atlas can be used to plan surgical procedures, as educational material (Kikinis et al. 1996), or as source of prior anatomical knowledge in automated medical image analysis tasks such as segmentation (Lötjönen et al. 2010; Wang et al. 2013) and image reconstruction (Custo et al. 2010).