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Anatomy of the Lower Face and Neck
Published in Neil S. Sadick, Illustrated Manual of Injectable Fillers, 2020
Evan Ransom, Stephen A. Goldstein
The single most dominant bony structure in the lower face is the mandible, which provides both support and contour for the overlying soft tissues. The mandible is generally larger in men, approximately 5 mm greater in height at the body and ramus, and approximately 5 mm thicker at the body. In the female face, the jawline is typically softer, with a smoother transition from the face to the upper cervical structures creating a less pronounced shadow effect than in males. Men have a more apparent mental protuberance, a prominent elevation of bone inferior to the symphysis. Two important anthropometric points are determined by the size and position of the mandible: the pogonion and the menton. The pogonion is the most anterior point of the mandible in the midline, while the menton is the lowest point of the mandible. A cleft chin occurs when there is incomplete inferior fusion of the right and left hemimandible during embryogenesis and fetal development. This is a heritable trait with varying penetrance. There are varying individual and cultural preferences related to the desirability of chin clefts.
Evolution of Form in the Craniofacial Complex
Published in D. Dixon Andrew, A.N. Hoyte David, Ronning Olli, Fundamentals of Craniofacial Growth, 2017
A pronounced mental protuberance is characteristic of modern humans, yet absent in all earlier hominid forms including H. erectus. As formulated some years ago (Sicher and DuBrul, 1940), manifestation of our “chin” resulted from the interplay between two phenomena: a reduction in tooth size, and a retention or actual increase in area enclosed by the mandibular corpus. Change in tooth size, a component of the evolutionary reduction in masticatory demands in our direct lineage, allowed for distal displacement (retrusion) of a smaller dental arcade relative to the mandibular corpus. Expansion of the area enclosed by the mandibular corpus, whether real or relative, largely was caused by the need to provide space for a highly mobilized tongue in association with articulate speech. In this evolutionary scenario the dentoalveolar structures became smaller and the size of mandibular corpus remained constant or actually increased. Displacement of the dentoalveolar structures distally relative to the mandibular corpus had the net effect of making the inferior border of the mandible more protrusive, giving rise to a mental protuberance. As pointed out earlier, H. erectus lacked a chin. While this could be taken as (weak) evidence that it also lacked fully articulate speech, Mac Laraon (1993) presents fascinating evidence from the vertebral column of an adolescent indicating that respiratory requirements associated with articulate speech had not yet fully evolved in H. erectus at the time of the Nariokotome specimen, which has been aged at 1.8 Ma.
Mandible Fractures
Published in Jeffrey R. Marcus, Detlev Erdmann, Eduardo D. Rodriguez, Essentials of CRANIOMAXILLOFACIAL TRAUMA, 2014
J. Alex Kelamis, Eduardo D. Rodriguez
On the buccal surface, a faint median ridge at the midline of the mandible marks the symphysis (Fig. 16-2). The symphysis divides near the inferior border, creating a triangle enclosing the mental protuberance. The base of this triangle is depressed at the center and raised at the ends, forming bilateral mental tubercles. The oblique line runs from each mental tubercle in a posterior and superior path, aiming just posterior to the third molar, where it blends into the anterior border of the ramus. The triangularis muscle attaches to the anterior half of the oblique line, with the quadratus labii inferioris muscle attachment superior and the platysma attachment inferior. The mental foramen is located below the second premolar approximately halfway between the superior and inferior borders; it allows passage of the mental neurovascular bundle. There is an incisive fossa on either side of the symphysis just below the lower incisors that serves as the origin for the mentalis and as the partial origin for the orbicularis oris muscle. On the lingual surface, the genloglossi muscles originate at the inferior border of the symphysis from bilateral mental spines, with a second pair of spines, or ridge, inferior to these, marking the origin of the geniohyoid muscles. Immediately below this on either side is the anterior margin of the mylohyoid line, which, like the oblique line, runs in a posterior and superior fashion toward the inferior margin of the third molar. This line is the origin for the mylohyoideus muscle.
A comparison of swallow-related submandibular contraction amplitude and duration in people with Parkinson’s disease and healthy controls
Published in International Journal of Speech-Language Pathology, 2021
Julie Kim, Christopher R. Watts
All participants underwent consenting procedures prior to their participation in the study, which was approved by a university institutional review board. Following consent, each participant was recorded in the same research laboratory on a university campus. Participants were recorded in one session. For electrode placement, the skin surface was cleaned with an alcohol wipe to remove any skin oils present. Next, the sEMG electrode patch was placed on the skin surface lying superficial to the submandibular hyolaryngeal muscles and superior to the hyoid bone, with the tab of each electrode patch located centrally and approximately 1 cm below the inferior rim of the mental protuberance of the mandible. This placement was to ensure the electrodes recorded the submental hyolaryngeal activity, as shown in Figure 1. The wired electrode heads communicated with the Swallowing Signals Lab software that plotted the sEMG waveform signal on the computer. Each waveform was saved for later analysis.
Electroneurography value as an indicator of high risk for the development of moderate-to-severe synkinesis after Bell’s palsy and Ramsay Hunt syndrome
Published in Acta Oto-Laryngologica, 2019
Haruki Nakano, Shin-Ichi Haginomori, Shin-Ichi Wada, Yusuke Ayani, Ryo Kawata, Ryuichi Saura
At 10–16 days after onset, ENoG was measured by recording CMAPs from the orbicularis oris using our previously reported midline method [5, 11, 12]. The main trunk of the facial nerve was stimulated percutaneously with electrodes placed as close as possible to the stylomastoid foramen. To record the CMAP from the orbicularis oris, the anode and cathode were placed on the mental protuberance and the philtrum, respectively. The ENoG value was calculated as the ratio of the CMAP amplitude on the paralyzed side to that on the normal side.
Evaluation Criteria and Surgical Technique for Transoral Access to the Thyroid Gland: Experimental Study
Published in Journal of Investigative Surgery, 2019
Alexander M. Shulutko, Vasiliy I. Semikov, Elkhan G. Osmanov, Sergey E. Gryaznov, Anna V. Gorbacheva, Alla R. Patalova, Gaukhar T. Mansurova, Airazat M. Kazaryan
This step was initiated by making an incision into the mucous membrane of the lower arch of the oral vestibule and the procedure was continued by creating a tunnel in the chin area until the area under platysma muscle had been reached. The incision in the oral cavity vestibule was transversely directed between the lower lip and the gingival tissues with the incision length of 2–2.5 cm. Visual control was used to partially dissect and laterally dislocate the bundles of the mentalis muscle while moving down to the mental protuberance and further along the protuberance to gain access under the platysma muscle, dissecting it in the area where it was attached to the mandible's lower border. Then the operation was continued under video-endoscopic control. Using blunt separation and sharp dissection, the platysma muscle was detached craniocaudally along the medial line from the mental protuberance to the jugular notch and laterally to the medial margin of the sternocleidomastoid muscle. We performed the detachment on one side (monolateral) in hemithyroidectomy cadavers, and in thyroidectomy cadavers—on both sides (bilaterally). During the detachment (at the level of the upper margin thyroid cartilage) a first Kirschner wire was introduced horizontally under the platysma muscle, with the traction of the wire creating insufficient angle of view for further detachment. At the level of the annular cartilage the second Kirchner wire was introduced similarly to the first. The wires were fixed with the Kirschner clamp that were further dislocated upward (creating the necessary operating space) and fixed on the L-shaped surgical arch. This type of cavity is limited on the top by the platysma muscle, and on the bottom by the anterior surface of the trachea, by the sternohyoid and sternothyroid muscles. We placed a 5 mm trocar for the introduction of surgical instruments on the opposite side from the operated lobe (on the anterior-lateral surface of the neck at the same moment) near the entrance point (or the exit point) of the second wire (through a skin incision).