Preoperative and postoperative assessment of temporal and masseter muscle size with magnetic resonance imaging in patients undergoing unilateral temporomandibular joint surgery

The aim of this study was to assess any change between the preoperative and postoperative sizes of temporal and masseter muscles with magnetic resonance imaging (MRI) in patients undergoing unilateral temporomandibular joint surgery.This study was designed and implemented retrospectively. For clinical evaluation, a visual analog scale (VAS) and maximum mouth opening (MMO) were used. In order to make a preoperative diagnosis and perform a 6-month control, muscle size was measured in millimeters (mm) on T1 axial sections in MRI. Statistical analyses were performed using the SPSS 23.0 software package. Numeric variables were compared between two dependent groups using the Wilcoxon signed rank test. Statistical significance was set at p < 0.05.Twelve patients who underwent unilateral discectomy plus dermis-fat grafting, with classical preauricular inverse L incision, were included in the study, and data for eleven female patients were evaluated. The difference in size between the operated and non-operated sides was found to be statistically insignificant at the preoperative stage for both masseter muscle (operated side m^M: 13.264 ± 1.822 mm; non-operated side m^M: 13.264 ± 2.315 mm; p^M = 0.929) and temporal muscle (operated side m^T: 20.345 ± 2.609 mm; non-operated side m^T: 20.582 ± 2.366 mm; p^T = 0.594). There was a significant size reduction in the masseter muscle on the operated side in the postoperative period (preop m^M: 13.264 ± 1.822 mm; postop m^M: 12.036 ± 1.728 mm; p^M = 0.018). Although there was also a size reduction in the operated side of the temporal muscle in the postoperative period, that difference did not reach statistical significance (preop m^T: 20.345 ± 2.609 mm; postop m^T: 19.445 ± 1.603 mm; p^T = 0.182). On the non-operated side, there were no significant postoperative changes in the sizes of either the masseter muscle (preop m^M: 13.264 ± 2.315 mm; postop m^M: 12.682 ± 2.059 mm; p^M = 0.248) or the temporal muscle (preop m^T: 20.582 ± 2.366; postop m^T: 19.891 ± 3.487 mm; p^T = 0.625).Considering the study findings as a whole, a size reduction was observed in the operated side of the masseter muscle after TMJ surgery. The etiology of this change may be surgical trauma to the temporal and masseter muscles, skeletal alteration resulting from condylar change secondary to discectomy, and patients restraining themselves from application of maximum bite force as a result of a self-protection mechanism due to postoperative pain.     

Recovery profiles of eccentric hamstring strength in response to cooling and compression

IntroductionThe effectiveness of different forms of cryotherapy and combined compression (cryo-compression) commonly used in sport to enhance recovery following exercise are not fully understood. Therefore, the exploration of protocols that use contemporary cryo-compression is warranted. The purpose of the study was to investigate the effectiveness of using a cryo-compression device to recover hamstrings eccentric strength following a fatiguing exercise.MethodsEighteen healthy male adult footballers were randomly allocated to receive cryo-compression or rest following a lower limb fatiguing protocol. Cryo-compression was applied for 15-min, target temperature of 10 °C, and high intermittent pressure (5–75 mm Hg) using the Game Ready® device. Rest consisted of 15-min in a prone position on a plinth. To induce hamstring fatigue, participants performed the Yo-Yo intermittent fatigue test (IFT). Skin surface temperature (T_sk) and hamstring eccentric strength measures were taken at three time points; pre-IFT, immediately post-fatigue test (IPFT), and immediately post-intervention (IPI) (rest or Game Ready®). Participants returned one week later and performed the Yo-Yo IFT again and were exposed to the opposite intervention and data collection.ResultsSignificant decreases in T_sk over the posterior thigh were reported for all timepoints compared to pre cryo-compression temperatures (p=<0.05). Overall data displayed no significant main effects for timepoint or condition for PT or AvT (p=<0.05). There was no timepoint × condition interaction for PT or AvT (p=<0.05). Collapse of the data by condition (CC/R) demonstrated no significant effect for time for PT or AvT (p=>0.05).ConclusionsNo significant changes in HES occurred after exposure to cryo-compression or rest applied immediately following the Yo-Yo IFT. Further investigations to maximise beneficial application of contemporary cryo-compression applications in sport are required. Multiple measures of performance over rewarming periods, within competitive training schedules after sport-specific training are required to develop optimal cooling protocols for recovery.     

Balance and Strength—Estimating the Maximum Prey‐Lifting Potential of the Large Predatory Dinosaur Carcharodontosaurus saharicus

Motivated by the work of palaeo‐art “Double Death (2011),” a biomechanical analysis using three‐dimensional digital models was conducted to assess the potential of a pair of the large, Late Cretaceous theropod dinosaur Carcharodontosaurus saharicus to successfully lift a medium‐sized sauropod and not lose balance. Limaysaurus tessonei from the Late Cretaceous of South America was chosen as the sauropod as it is more completely known, but closely related to the rebbachisaurid sauropods found in the same deposits with C. saharicus. The body models incorporate the details of the low‐density regions associated with lungs, systems of air sacs, and pneumatized axial skeletal regions. These details, along with the surface meshes of the models, were used to estimate the body masses and centers of mass of the two animals. It was found that a 6 t C. saharicus could successfully lift a mass of 2.5 t and not lose balance as the combined center of mass of the body and the load in the jaws would still be over the feet. However, the neck muscles were found to only be capable of producing enough force to hold up the head with an added mass of 424 kg held at the midpoint of the maxillary tooth row. The jaw adductor muscles were more powerful, and could have held a load of 512 kg. The more limiting neck constraint leads to the conclusion that two, adult C. saharicus could successfully lift a L. tessonei with a maximum body mass of 850 kg and a body length of 8.3 m. Anat Rec, 298:1367–1375, 2015. © 2015 Wiley Periodicals, Inc.     

Muscles Involved in Naris Dilation and Nose Motion in Rat

In a number of mammals muscle dilator nasi (naris) has been described as a muscle that reduces nasal airflow resistance by dilating the nostrils. Here we show that in rats the tendon of this muscle inserts into the aponeurosis above the nasal cartilage. Electrical stimulation of this muscle raises the nose and deflects it laterally towards the side of stimulation, but does not change the size of the nares. In alert head‐restrained rats, electromyographic recordings of muscle dilator nasi reveal that it is active during nose motion rather than nares dilation. Together these results suggest an alternative role for the muscle dilator nasi in directing the nares for active odor sampling rather than dilating the nares. We suggest that dilation of the nares results from contraction of muscles of the maxillary division of muscle nasolabialis profundus. This muscle group attaches to the outer wall of the nasal cartilage and to the plate of the mystacial pad. Contraction of these muscles exerts a dual action: it pulls the lateral nasal cartilage outward, thus dilating the naris, and drags the plate of the mystacial pad rostrally to produce a slight retraction of the vibrissae. On the basis of these results, we propose that muscle dilator nasi of the rat should be re‐named muscle deflector nasi, and that the maxillary parts of muscle nasolabialis profundus should be referred to as muscle dilator nasi. Anat Rec, 298:546–553, 2015. © 2014 Wiley Periodicals, Inc.     

计算机辅助定量评价肌肉急性挫伤后高频超声二维图像纹理特征变化

目的 采用超声回波强度界面多级分解法定量评价急性钝挫伤后人体肌肉高频超声二维图像纹理特征的变化,初步探讨其临床应用价值。方法 采用高频超声检测10例男性上臂肌肉单纯急性挫伤患者的局部肌肉二维超声图像,于脱机状态下通过Matlab 7.0软件选取患者同一图像上的肌纹理正常感兴趣区（ROI）和肌纹理疑似损伤ROI,提取两个ROI的纹理灰度值的均值（Mean）、灰度值的标准差（SDev）、纹理的密致性（NOB）、纹理基元形状的不规则度（IRGL）、纹理基元的平均大小（SOB）、纹理分布的均匀性（HOD）、纹理分布的方向性（DOD）和纹理分布的周期性（POD）8个特征参数,采用超声回波强度界面多级分解法自动计算两个ROI之间8个纹理特征的相似度差值。选取10名男性健康志愿者同部位正常肌肉二维超声图像作为对照,任意选取两个ROI,计算两个ROI之间上述8种纹理特征的相似度差值。对上臂肌肉挫伤患者和健康志愿者8个纹理特征的相似度差值进行对比分析。结果 急性上臂肌肉挫伤区局部肌束回声增强,肌纤维层次紊乱,纹理模糊,回声变化较周边肌纹理正常区显著。急性上臂肌肉挫伤患者肌纹理疑似损伤ROI和肌纹理正常ROI之间IRGL、DOD、POD、Mean和SDev等5个纹理特征相似度差值与健康志愿者任意两个ROI之间该5个纹理特征相似度差值差异有统计学意义（P均<0.01）。结论 基于超声回波强度界面多级分解法的计算机辅助定量评价技术能够对急性挫伤后肌肉高频超声二维图像纹理特征变化做出较人眼识别更精细的量化诊断,可能具备一定的临床实用价值。     

Upregulated Expression of AQP 7 in the Skeletal Muscles of Obese ob/ob Mice

Aquaporin (AQP) is suggested to be regulated by leptin through the phosphatidylinositol 3-kinase/Akt/mammalian target of rapamycin pathway. AQP7 and AQP9 are membrane proteins with water and glycerol channels, the latter of which is essential for triglyceride synthesis. We conjectured that the expression of AQP7 and AQP9 would be altered in the skeletal myofibers in obese leptin deficient ob/ob mice as compared with that of wild mice. RNA and protein levels were studied in the quadriceps femoris muscles of ob/ob and wild mice. Real time quantitative RT-PCR analysis showed that mouse AQP7 mRNA levels in skeletal muscles were significantly higher in ob/ob mice than in wild mice (P<0.01), whereas mouse AQP9 mRNA level was not different between the two groups (P>0.05). Histologically the type 1 myofibers of ob/ob mice contained numerous lipid droplets in oil red O stain samples. Immunohistochemical staining of ob/ob mouse muscles revealed enhanced expression of AQP7 at myofiber surface membranes, while AQP9 expression appeared to be similar to that of wild mice. The findings suggest that the upregulated expression of AQP7 in ob/ob mouse muscles facilitates the secretion of glycerol from myocytes.     

The mechanisms of human ejaculation – a critical analysis

The current mechanism for human ejaculation is a two-part model consisting of a postulated “pressure chamber” created in the prostatic urethra by initial closure of both distal and proximal sphincters with secretions loaded in by adrenergic-mediated smooth muscle contractions of the vas deferens and capsules of the internal genital organs. The pressure build up is claimed then to “trigger” the intermittent relaxation/contraction of the distal sphincter and activate the contractions of the striated pelvic musculature, especially that of the bulbocavernosus, which forcefully expels the semen along the urethra by powerful, rhythmical spurts. A number of difficulties with this model are examined critically against experimental findings which indicate that the so-called pressure chamber is unlikely to be the valid trigger for ejaculation. The most recent finding of a specialised group of lumbar sacral neurons in the spinal cord of rat that function as the spinal ejaculation generator is more likely to be the “trigger” for ejaculation but confirmation that these cells also exist in the human cord is waiting.     

Effect of natural mediotrusive contact on electromyographic activity of jaw and cervical muscles during chewing

Abstract

Objective. This study evaluated the effect of a natural mediotrusive contact on the electromyographic (EMG) activity of the anterior temporalis and sternocleidomastoid muscles during chewing in healthy subjects. Materials and methods. The study sample included two groups of 15 subjects each (Group 1: with natural mediotrusive contact; Group 2: without natural mediotrusive contact). Bilateral surface EMG activity was recorded on anterior temporalis and sternocleidomastoid muscles during unilateral chewing of a half cookie and unilateral chewing of a piece of apple. Anterior temporalis and sternocleidomastoid muscle activity was normalized against activity recorded during maximal voluntary clenching in intercuspal position and maximal intentional isometric head–neck rotation to each side, respectively. The partial and total asymmetry indexes were also calculated. Data were analyzed using Mann-Whitney, Wilcoxon and unpaired t-test. Results. EMG activity of anterior temporalis and sternocleidomastoid muscles showed no significant difference between the groups. EMG activity of anterior temporalis was similar between working and non-working sides during chewing in both groups. EMG activity of sternocleidomastoid muscle was higher in the working side than in the non-working side in Group 2 subjects. Asymmetry indexes were not significantly different between groups. Conclusions. The similar EMG pattern and asymmetry indexes observed suggest the predominance of central nervous control over peripheral inputs on anterior temporalis and sternocleidomastoid motor neuron pools.