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Designing for Head and Neck Anatomy
Published in Karen L. LaBat, Karen S. Ryan, Human Body, 2019
The skull balances on the top section of the spine, a stacked column of seven cervical (neck) vertebrae. It is a little like stabilizing a bowling ball on a pile of blocks. The condyles of the skull’s occipital bone articulate with the first cervical vertebra, C1, called the atlas. The atlas is named after the mythological Greek figure who carried the world on his shoulders. C1 has a unique shape; it is more ring-like than the lower vertebrae. C2 through C7 are structurally similar to one another, with a body, arch, and spinous process (see Figure 3.10, transverse section). C2 has an additional bony feature, the dens—also called the odontoid process—a tooth-like structure which projects upward from the body of C2 to articulate with the anterior arch of the atlas (Teton Data Systems & Primal Pictures Ltd., 2001). A ligament inside the anterior arch of the atlas braces the dens against the atlas. The dens acts as an axis of rotation for the skull on the spine.
Repetitive TasksRisk Assessment and Task Design
Published in R. S. Bridger, Introduction to Human Factors and Ergonomics, 2017
The cervical spine has several functions—principally to support the weight of the head and to provide a conduit for nerves and attachment points for the muscles which control the position of the head. It consists of seven vertebrae designed to permit complex movements of the head. The first two cervical vertebrae (known as the atlas and the axis) are different from other vertebrae in the spinal column. The remaining vertebrae have the same general structure as vertebrae in other parts of the spine and are surrounded by anterior and posterior ligaments. The cervical spine consists of vertebral bodies and intervertebral disks, facet joints, bony processes for the attachment of ligaments and muscles, and the intervertebral foramen through which the spinal cord passes.
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.
Mechanisms of cervical spine injury and coupling response with initial head rotated posture – implications for AIS coding
Published in Traffic Injury Prevention, 2022
Narayan Yoganandan, Jamie Baisden, John Humm, Vicky Varghese
The mean age, stature, total body mass, body mass index of the five subjects were as follows: 63 ± 9.8 years, 1.7 ± 0.01 m, 78.0 ± 11.7 kg, 28.1 ± 3.9 kg/m2, respectively. The mean peak axial force and coronal, sagittal, and axial bending moments were: 754 ± 184 N, and 36.8 ± 3.9 Nm, 14.8 ± 5.3 Nm, 9.5 ± 3.1 Nm, respectively. All but one specimen sustained injury. Two specimens sustained left anterior inferior lateral mass fractures (one was through the entire lateral mass) of the atlas without medial involvement. While the transverse atlantal ligament was intact in the injury, some capsular ligament involvement was observed in the computed tomography images. In the other two specimens, although the same injury was noted, joint diastasis of the atlas-axis joint was also identified (Figure 1 and 2). All these injuries were considered stable. According to the Abbreviate Injury Scale, AIS 2015-version, they were scored at the AIS 2 level severity. Bone mineral densities are given in Figure 3. The lateral mass at the midline and anterior regions had the lowest densities. Data for these regions are the average of the left and right sides.
Design and application of personalized surgical guides to treat complex tibial plateau malunion
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2020
Chi-Pin Hsu, Shang-Chih Lin, Aamer Nazir, Chen-Te Wu, Shih-Sheng Chang, Yi-Sheng Chan
Tibial plateau malunion (TPM) is a complex problem for orthopedic surgeons. When the fractured parts of the tibial plateau are depressed, the articular surfaces become unable to transmit the knee loads and increase the stress borne by the articular cartilage. Moreover, axial malalignment of the lower limb occurs, and the weight-bearing axis is shifted to the side of the depression. In cases of height differences of the articular surfaces greater than 2 mm, osteotomy and osteosynthesis are recommended to restore the anatomic position of the fracture parts and the mechanical axis of the lower limb (Abdel-Hamid et al. 2006; Huang et al. 2008; Kfuri and Schatzker 2017; Wang et al. 2017, 2018). Subsequently, the surgeon uses unilateral or bilateral internal fixation to stabilize the reconstructed configuration of the articular surfaces and enhance the bone union (Wang et al. 2017).
Technique analysis in elite athletes using principal component analysis
Published in Journal of Sports Sciences, 2018
Øyvind Gløersen, Håvard Myklebust, Jostein Hallén, Peter Federolf
The athletes’ movements were recorded at a frame rate of 250 Hz using a 3D motion analysis system consisting of nine cameras (Oqus 400, Qualisys AB, Gothenburg, Sweden) controlled by the Qualisys Track Manager software (Qualisys AB, Gothenburg, Sweden). Forty-one retro reflective markers were attached to the athletes’ skin and skiing equipment (Figure 1). Specifically, markers were placed on the tibialis anterior, knee joint axis (laterally), rectus femoris, trochanter major, anterior superior iliac spine, os sacrum, sternum, 10th thoracal vertebra, 12th rib, 7th cervical vertebra, acromion, biceps brachii, elbow joint (laterally), mid forearm and on the distal end of the radius. The athletes wore a custom-built hat with five markers. One marker was attached to the lateral side of each ski boot near the ankle. Additional markers were placed close to the distal tip on the poles and three markers were attached to each ski: posterior, anterior and 10 cm superior to the ski (Hoset, Rognstad, Rølvåg, Ettema, & Sandbakk, 2014; Myklebust, Gløersen, & Hallén, 2015). If marker trajectories exhibited gaps, then they were filled by interpolation (short gaps) or by a PCA-based reconstruction algorithm (Federolf, 2013; Gløersen & Federolf, 2016).