ELECTROMYOGRAPHIC ANALYSIS OF GLUTEAL RECRUITMENT: AN EXPLORATION OF ACTIVATION DURING JUMPING TASKS

Background:Inability to maintain proper alignment of the pelvis and femur due to gluteal muscle weakness has been associated with numerous lower extremity pathologies. Therefore, many lower extremity rehabilitation and injury prevention programs employ exercises that target gluteal muscle strength and activation. While information regarding muscle activation during exercises that are typically done in the beginning stages of rehabilitation is available, evidence regarding the gluteal muscle activity during more functional and advanced exercises used during later stages of rehabilitation is sparse.Purpose:To explore the recruitment of the gluteal muscles during jumping tasks in healthy participants to determine which jumping exercise best elicits gluteal muscle activation.Study Design:Prospective cohort designMethods:Eighteen healthy recreational athletes (23.5 ± 3.8 years, 8M/10F, 67.56 ± 3.2 inches, 66.73 ± 9.5 kg) completed three trials of four jumping tasks: hurdle jump, split jump, V2 lateral jump, and cross-over jump in random order. Surface EMG electrodes were placed on each participant''s bilateral gluteus medius (GMed) and maximus (GMax) to measure muscle activity during the jumping tasks. Maximal voluntary isometric muscle contraction (MVIC) was established for each muscle group in order to express each jumping task as a percentage of MVIC and allow standardized comparison across participants. EMG data were analyzed for all jumps using a root-mean-square algorithm and smoothed with a 62.5 millisecond time reference. Rank ordering of muscle activation during jumping tasks was performed utilizing the peak percent MVIC recorded during each jumping task.Results:Three of the jumping tasks produced greater than 70% MVIC of the GMed muscle. In rank order from highest EMG value to lowest, these jumping tasks were: crossover jump (103% MVIC), hurdle jump (93.2% MVIC), and V2 lateral jump (84.7% MVIC). Two of the exercises recruited GMax with values greater than 70% MVIC. In rank order from highest EMG value to lowest, these jumping tasks were: hurdle jump (76.8% MVIC) and split jump (73.1% MVIC). Only the hurdle jump produced greater than 70% MVIC for both GMed and GMax muscles.Conclusions:The jumping task that resulted in greatest activation of the GMed was the crossover jump, while hurdle jump led to the greatest activation of the GMax. The high %MVIC for the GMed during the crossover jump may be attributed to lack of maximal effort or lack of motivation during performance of maximal contractions during the manual muscle testing. Alternatively, substantial co-contraction of core muscles during the crossover jumping task may have led to higher values.Level of Evidence:2b Individual Cohort Study     

Relationship between iliotibial band syndrome and hip neuromechanics in women runners

BackgroundAtypical frontal plane hip kinematics are associated with iliotibial band syndrome in women runners. Gluteus medius is the primary muscle controlling the hip adduction angle during the loading response of stance. It is unclear if differences exist in gluteus medius activity magnitude and activity duration between runners with previous iliotibial band syndrome and controls. Furthermore, hip neuromechanics may change after a prolonged run.Research QuestionDo differences exist in the hip adduction angle and gluteus medius activity between women with previous iliotibial band syndrome and controls at the beginning and end of a 30-minute moderate paced treadmill run?MethodsThirty women participated (n = 15 controls). Lower extremity kinematics and gluteus medius activity were recorded at the start and end of a 30-minute treadmill run at participants’ self-selected pace. Hip kinematics and gluteus medius activity were analyzed via separate two-way (group x time) mixed-model analysis of variance with time as the repeated measure.ResultsHip neuromechanics were similar at the start and end of a 30-minute treadmill run in women with previous iliotibial band syndrome and controls. However, hip adduction excursion was less in women with previous iliotibial band syndrome compared to controls. Average gluteus medius activity magnitude and activity duration were not significantly different between groups.SignificanceThese findings support the growing body of literature that smaller hip adduction motion is related to previous iliotibial band syndrome in women. Regardless of injury history, gluteus medius activity was similar between groups during the loading phase of stance.     

Proximal Femoral Musculoskeletal Morphology of Chimpanzees and its Evolutionary Significance: A Critique of Morimoto et al. (2011)

Based on the analysis of computed tomography (CT) scan imagery, Morimoto et al. (Anatomical Record 2011 ; 294:1433–1445) concluded that the proximal femoral shaft attachment of the chimpanzee gluteus maximus (GM) lies in a position similar to that of modern humans (medial to a longitudinal bony structure that runs superoinferiorly along the lateral proximal shaft), contradicting the previous reports of similarity with the other extant apes. Based on a broader comparative osteological perspective and examination of some of the same CT imageries, we here demonstrate that: 1) although the chimpanzee insertion of the GM appears to lie more posteromedially than it does in gorillas and orangutans, the validity of the extent of this reassessment remains in doubt, pending crossvalidation of CT analyses by parallel dissections of the imaged specimens, and 2) the chimpanzee and human conditions are, nevertheless, distinct. We agree with Morimoto et al. (Anatomical Record 2011 ; 294:1433–1445) that these observations support the interpretation that superficially similar osteological topographies of the proximal femur were acquired independently by chimpanzees and gorillas, but we disagree about the significance of their suggested human–chimpanzee similarities. Although Morimoto et al. (Anatomical Record 2011 ; 294:1433–1445) considered these to be shared‐derived features of the chimpanzee–human clade, we instead argue that the shared absence of strong anterolateral displacement of the GM attachment among chimpanzees, basal hominids (such as Orrorin and Ardipithecus), and humans likely reflects the primitive condition characteristic of a wide range of Miocene apes. Anat Rec, 2012. © 2012 Wiley Periodicals, Inc.     

岛状臀大肌肌皮瓣在修复骶尾部褥疮的应用

目的 探讨带臀上动脉岛状臀大肌肌皮瓣修复骶尾部褥疮的临床效果。方法 2000年6月-2003年5月,对12例骶尾部褥疮患者手术治疗进行回顾性分析,褥疮范围最大12cm×10cm,最小8cm×5cm,治疗采用带臀上动脉岛状臀大肌肌皮瓣修复。结果 12例肌皮瓣全部成活,I期愈合10例,2例经换药Ⅱ期愈合。随访6个月-36个月,肌皮瓣及供区软组织弹性良好,无复发。结论 带臀上动脉岛状臀大肌肌皮瓣修复骶尾部褥疮是一种较好的治疗方法,具有操作简便,肌皮瓣血运丰富,成活率高,旋转角度大,可一期修复等优点,值得推广。     

针刀治疗臀小肌肌筋膜炎临床方法和机理研究

目的：通过使用针刀对41例臀小肌肌筋膜炎患者的治疗,观察针刀治疗肌筋膜炎的临床疗效,并阐述其作用机理。方法：在臀小肌敏感压痛点及硬结处行针刀纵向切割或横行切割。把足太阳和足少阳经筋循行路线与41例臀小肌肌筋膜炎患者的引传痛的范围进行比较。结果：针刀治疗的总有效率为92.68%。足太阳和足少阳经筋循行路线与臀小肌肌筋膜炎引传痛的范围是多数重合的。结论：经筋是古代关于肌肉和筋膜的结构、功能、病理和临床诊断与治疗的表述方法。提出的＂续络整筋-针切性假炎-肌组织修复重建学说＂是阐述针刀治疗肌筋膜炎本质的机理。     

Effect of the Photoperiod and Administration of Melatonin on the Pars Tuberalis of Viscacha (Lagostomus maximus maximus): An Ultrastructural Study

The pituitary pars tuberalis (PT) is a glandular zone exhibiting well‐defined structural characteristics. Morphologically, it is formed by specific secretory cells, folliculostellate cells, and migratory cells coming from the pars distalis. The purpose of this work was to investigate differences in specific cellular characteristics in the PT of viscachas captured in summer (long photoperiod) and winter (short photoperiod), as well as the effects of chronic melatonin administration in viscachas captured in summer and kept under long photoperiod. In summer, the PT‐specific cells exhibited cell‐like characteristics with an important secretory activity and a moderate amount of glycogen. In winter, the PT‐specific granulated cells showed ultrastructural variations with signs of a reduced synthesis activity. Also, PT showed a high amount of glycogen and a great number of cells in degeneration. After melatonin administration, the ultrastructural characteristics were similar to those observed in winter, but the amount of glycogen was higher. These results suggest possible functional implications as a result of morphological differences between long and short photoperiods, and are in agreement with the variations of the pituitary‐gonadal axis, probably in response to the natural photoperiod changes through the pineal melatonin. The ultrastructural differences observed in PT, after melatonin administration, were similar to those observed in the short photoperiod, thus supporting the hypothesis that these cytological changes are induced by melatonin. Anat Rec, 293:871–878, 2010. © 2010 Wiley‐Liss, Inc.     

膀胱截石位臀大肌注射定位尺的制作及应用

目的 探讨成年女性患者在膀胱截石位下臀大肌肌内注射精准定位的范围,为进一步推广使用膀胱截石位臀大肌注射定位尺提供理论依据。方法 选取我院2018年1月2日—16日在门诊手术室行非气管插管静脉全麻手术并需要臀大肌肌内注射的患者268例,先后采用连线法、定位尺进行定位,再以B超机验证两种定位方法的准确性。最后,结合患者的年龄、BMI值确定定位尺的刻度与角度范围。结果 定位尺定位准确率为98.1%,与传统定位准确率（68.6%）比较,差异有统计学意义（P<0.001）。结论 膀胱截石位臀大肌注射定位尺定位准确率高,对照参数表中的年龄及BMI值,调节定位尺上下限值和角度即可准确定位,操作方便简单。     

Gluteus maximus agenesia

Absence of the gluteus maximus muscle is a rare congenital abnormality. In this case the buttock asymmetry was so marked that correction with a silicone prosthesis was indicated. In addition to the absent muscle, abnormal innervation and bony deformity in the region were detected.     

臀中肌滋养血管在臀肌挛缩症松解术的应用解剖

目的根据臀中肌及其周围组织的局部解剖,重点解剖、观察臀中肌滋养血管,探讨臀肌挛缩症术式改良及其注意事项。方法解剖无下肢疾患的8例16侧成人尸体臀部标本,观察滋养臀中肌的起点、入肌点以及分支、分布。结果臀中肌的血供主要来自臀上动脉的深支,入肌点在臀中肌的内侧缘深面,髂后上棘下方者占81.25%,髂后下棘上方者占18.75%,一般分为2~3支,臀中肌下方内侧区尚有少量臀下动脉分布。结论手术松解挛缩组织时应在臀中肌上部偏外沿肌纤维方向进行,宜靠近股骨大转子,以尽量避免血管神经的不必要损伤,同时可避免损伤髋关节。     

Superior gluteal nerve: safe area in hip surgery

Injuries to the superior gluteal nerve are very bad complications in hip surgery. An exact knowledge of its course may be helpful in avoiding such problems. Nineteen half pelvises from ten male and female adult cadavers were dissected. Dissections revealed that the nerve divided into two (89.48%) or three (10.52%) branches after leaving the pelvis. The more caudal branch was responsible for innervation of tensor fascia latae. The distance and the angle from the entry points of all branches of the superior gluteal nerve into the deep surface of the gluteus medium and minimus muscles to the mid-point of the superior border of the greater trochanter were measured. The branch that innerved the tensor fascia latae was also followed. These data were subjected to several statistical tests. Based on these findings, and in order to prevent nerve damage, we propose to define a 2–3 cm safe area above the great trochanter.