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Musculoskeletal system
Published in A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha, Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha
The temporomandibular joint (TMJ) is a synovial condyloid joint formed between the head (condyle) of the mandible and the mandibular fossa of the temporal bone (Fig. 3.50). The anterior part of the mandibular fossa, with which the head of the mandible articulates when the mouth is opened, is termed the articular tubercle. The joint capsule is attached superiorly to the rim of the articular surface and inferiorly to the neck of the mandible. The capsule is strengthened laterally to form the lateral or temporomandibular ligament. Intrinsically there is an interarticular disc (meniscus) that divides the joint into the superior and inferior cavities. It is attached to the periphery of the capsule and is situated over the head of the mandible, projecting anteriorly towards the tubercle. A number of small muscles combine to produce depression, elevation, protrusion, retraction and lateral movements of the mandible. These movements are complex, and the action of opening the mouth results in the head of the mandible moving downwards and forwards. Excessive movement can result in anterior dislocation of the head of the mandible on the articular tubercle. The joint derives its blood supply from the temporal and maxillary branches of the external carotid artery.
Designing for Head and Neck Anatomy
Published in Karen L. LaBat, Karen S. Ryan, Human Body, 2019
The lower portion of the face, the jaw, provides protection as well as the motion essential for chewing and talking. The maxillae are the paired stationary upper jawbones which you can feel as a U-shaped structure holding your upper teeth. Each maxilla reaches all the way to the lower border of the eye and abuts the nasal bones medially and the zygomatic bone laterally. The mandible (lower jawbone), also U-shaped, is separate from the skull and holds the lower teeth. The temporomandibular joint (TMJ), the articulation between mandible and temporal bone, just in front of the ear canal, allows movement of the lower jaw so that you can talk and chew (inset, Figure 3.3). Keep the movement of the lower jaw (up, down, forward and back, and side-to-side) in mind when designing headgear that is strapped under the chin and/or worn while eating or talking.
Finite element analysis in design of DMLS mandible implants
Published in Fernando Moreira da Silva, Helena Bártolo, Paulo Bártolo, Rita Almendra, Filipa Roseta, Henrique Amorim Almeida, Ana Cristina Lemos, Challenges for Technology Innovation: An Agenda for the Future, 2017
T.C. Dzogbewu, L. Monaheng, I. Yadroitsava, W.B. du Preez, I. Yadroitsev
The human mandible (lower jaw) is noted as the strongest bone of the skull and is capable of moving independently from the head movement. It supports the lower teeth and provides a place of attachment for the mastication muscles (Saladin 1998). The masseter muscle is the principal mastication muscle and is responsible for retracting and elevating the mouth (opening and closing of the mouth). It must be able to exert enough force for biting and chewing of food (Santana-Mora et al. 2014). The magnitude of the resultant force produced by the mastication muscles on the dental arches during clenching of the teeth in maximum intercuspation for normal humans ranges from 246.9 to 2091.9 N (Hattori et al. 2009). The resultant force during clenching of the teeth was found to act at an angle of approximately 69° to the occlusal plane. This is because the angle between the occlusal plane and the anterior boarder of the masseter muscle remains approximately 69° (Figure 2b, point D) based on the cephalogram analysis of Sato et al. (2007).
Morphological analysis of the temporomandibular joint in patients with anterior disc displacement
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Tinghui Sun, Bingmei Shao, Desmond Y. R. Chong, Zhan Liu
Temporomandibular disorders (TMD) are the most common issues when it comes to our jaw joints, sensitive bi-condylar joints that connect the mandible to the skull and regulate jaw movements during mastication, speech, expression, etc. There is a high prevalence of TMD in adults and the symptoms vary from mild discomfort to painful temporomandibular joint (TMJ) dysfunction. It was reported that 25% to 30% of the population has at least one TMD symptom (Solberg et al. 1979; Rugh and Solberg 1985; Koh and Robinson 2004) and the overall prevalence of TMD in females was much higher than in males with ratios varying from 2:1 to 8:1 in the different surveys (Solberg et al. 1979; Ingawale and Goswami 2009; de Godoi Gonçalves et al. 2010; Martins-Junior et al. 2010). Despite the high incidence of TMD, only a small amount of the patients would seek medical help, for the symptoms are mild at the early stage and many of them can be relieved spontaneously.
Biomechanical analysis of mandibular defect reconstruction based on a new base-fixation system
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2022
Haipo Cui, Liping Gao, Jing Han, Jiannan Liu
The mandible is located below the face and is the only movable bone of the skull. It is mainly involved in important functions such as chewing, swallowing, occlusion, language, and expression. Partial resection of the mandible becomes clinically necessary due to tumor, trauma, cancer, and other factors. In order to maintain the important functions of the mandible after surgery, it needs to be reconstructed. The ideal state of mandibular reconstruction includes the following three requirements: (i) the appearance of the face should be close to normal after restoration; (ii) dentition and occlusal relationships should be normal; (iii) mastication and the language function should be normal or nearly normal (Ciocca et al. 2012; Azuma et al. 2014; Rubio-Palau et al. 2016). At present, fibula free flap grafting is the most common method for repairing mandibular defects. Hidalgo first used the fibula to repair mandibular defects during surgery in 1989 (Hidalgo 1989). The fibula has gradually become the most common donor area for the repair of large-scale defects of the mandibular bone in clinics due to the following characteristics: the sufficient amount of bone tissue that is resident in the fibula, the dual blood supply of the periosteum and the bone flap, the ability to withstand greater masticatory force, the simple preparation of a bone flap, the easier three-dimensional shaping of a bone flap, and its suitability for the implementation of dental implants (Grohmann et al. 2015).
Dynamic characterisation of the temporomandibular joint disc using split Hopkinson pressure bars
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2020
A. Schmitt, D. Sory, L. Tappert, P. Lipinski, W. Proud, A. Baldit
The temporomandibular joint (TMJ) disc is a fibrocartilaginous intra-articular tissue that connects the skull and mandible, and ensures the correct motion of the jaw (Tappert et al. 2017). Unphysiological mechanical stress and trauma, such as in car crash, sport accidents or whiplash, are well-known causes of permanent TMJ disorders (Pérez del Palomar and Doblaré 2008). To date, the TMJ disc mechanical behavior has been mainly documented under reduced strain (e.g., 10%) and at low strain rates (<1 s−1), far to be representative of trauma and unphysiological conditions (Fazaeli et al. 2019). The exact aetiology of such trauma-induced disorders is complex and remains largely unresolved as a paucity of investigations exists into TMJ disc high rate behavior. In this study, we investigate the compressive mechanical properties of porcine TMJ discs at strain rates of 1118 ± 56 and 2553 ± 281 s−1. We used a modified split-Hopkinson pressure bar (SHPB) embedded with quartz crystal transducers to measure the loading forces. The displacements were obtained using digital image correlation (DIC). The experimental data were, then, fitted with established hyperelastic models, and parameters were extracted for 3-dimensional (3-D) finite element (FE) modelling (Pérez del Palomar and Doblaré 2008).