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Journal of Orthopaedic Research :... May 2011The objective of the present study was to determine the instantaneous moment arms of 18 major muscle sub-regions crossing the glenohumeral joint in axial rotation of the...
The objective of the present study was to determine the instantaneous moment arms of 18 major muscle sub-regions crossing the glenohumeral joint in axial rotation of the humerus during coronal-plane abduction and sagittal-plane flexion. The tendon-excursion method was used to measure instantaneous muscle moment arms in eight entire upper-extremity cadaver specimens. The results showed that the inferior subscapularis was the largest internal rotator; its rotation moment arm peaks were 24.4 and 27.0 mm during abduction and flexion, respectively. The inferior infraspinatus and teres minor were the greatest external rotators; their respective rotation moment arms peaked at 28.3 and 26.5 mm during abduction, and 23.3 and 22.1 mm during flexion. The two supraspinatus sub-regions were external rotators during abduction and internal rotators during flexion. The latissimus dorsi and pectoralis major behaved as internal rotators throughout both abduction and flexion, with the three pectoralis major sub-regions and middle and inferior latissimus dorsi displaying significantly larger internal rotation moment arms with the humerus adducted or flexed than when abducted or extended (p < 0.001). The deltoid behaved either as an internal rotator or an external rotator, depending on the degree of humeral abduction and axial rotation. Knowledge of moment arm differences between muscle sub-regions may assist in identifying the functional effects of muscle sub-region tears, assist surgeons in planning tendon transfer surgery, and aid in the development and validation of biomechanical computer models.
Topics: Aged, 80 and over; Cadaver; Female; Humans; Humerus; Male; Muscle, Skeletal; Range of Motion, Articular; Rotation; Rotator Cuff; Scapula; Shoulder; Shoulder Joint
PubMed: 21064160
DOI: 10.1002/jor.21269 -
The Tohoku Journal of Experimental... Apr 2000Effects of loading the long head of the biceps brachii (LHB) and arm rotation on the strain of the superior labrum (anterior and posterior) in 10 fresh frozen cadaveric...
Effects of loading the long head of the biceps brachii (LHB) and arm rotation on the strain of the superior labrum (anterior and posterior) in 10 fresh frozen cadaveric shoulder joints were studied. Loads were applied to the rotator cuff muscles to stabilize the humeral head. The strain of the anterior and posterior portions of the labrum with the biceps loaded with 0.42 kg, 1.36 kg, and 2.31 kg were measured using linear transducers. The humerus was rotated externally (30, 45, 60, and 90 degrees) and internally (30, 45, and 60 degrees) with the arm elevated 60 degrees at glenohumeral joint (simulated 90 degrees elevation of arm to the trunk). The strain increased with an increase in the weight of the load to LHB and with increase in rotation angle both internally and externally. Since the strain in the posterior portion was larger than that of the anterior portion it seems likely that the labrum, especially the posterior portion, is subject to large strain during biceps loading and arm rotation.
Topics: Aged; Aged, 80 and over; Biomechanical Phenomena; Cadaver; Cartilage, Articular; Female; Humans; Male; Middle Aged; Muscle, Skeletal; Rotation; Shoulder; Stress, Mechanical
PubMed: 10877508
DOI: 10.1620/tjem.190.261 -
Nature Communications Jul 2016Gaze stabilization is an almost ubiquitous animal behaviour, one that is required to see the world clearly and without blur. Stomatopods, however, only fix their eyes on...
Gaze stabilization is an almost ubiquitous animal behaviour, one that is required to see the world clearly and without blur. Stomatopods, however, only fix their eyes on scenes or objects of interest occasionally. Almost uniquely among animals they explore their visual environment with a series pitch, yaw and torsional (roll) rotations of their eyes, where each eye may also move largely independently of the other. In this work, we demonstrate that the torsional rotations are used to actively enhance their ability to see the polarization of light. Both Gonodactylus smithii and Odontodactylus scyllarus rotate their eyes to align particular photoreceptors relative to the angle of polarization of a linearly polarized visual stimulus, thereby maximizing the polarization contrast between an object of interest and its background. This is the first documented example of any animal displaying dynamic polarization vision, in which the polarization information is actively maximized through rotational eye movements.
Topics: Animals; Crustacea; Eye Movements; Fixation, Ocular; Light; Rotation; Vision, Ocular
PubMed: 27401817
DOI: 10.1038/ncomms12140 -
Neuroscience Apr 2015Imagery and perception are thought to be tightly linked, however, little is known about the interaction between imagery and the vestibular sense, in particular,...
Imagery and perception are thought to be tightly linked, however, little is known about the interaction between imagery and the vestibular sense, in particular, self-motion perception. In this study, the observers were seated in the dark on a motorized chair that could rotate either to the right or to the left. Prior to the physical rotation, observers were asked to imagine themselves rotating leftward or rightward. We found that if the direction of imagined rotation was different to the physical rotation of the chair (incongruent trials), the velocity of the chair needed to be higher for observers to experience themselves rotating relative to when the imagined and the physical rotation matched (on congruent trials). Accordingly, the vividness of imagined rotations was reduced on incongruent relative to congruent trials. Notably, we found that similar effects of imagery were found at the earliest stages of vestibular processing, namely, the onset of the vestibular-ocular reflex was modulated by the congruency between physical and imagined rotations. Together, the results demonstrate that mental imagery influences self-motion perception by exerting top-down influences over the earliest vestibular response and subsequent perceptual decision-making.
Topics: Adult; Attention; Cues; Eye Movements; Female; Humans; Imagination; Male; Motion Perception; Proprioception; Reflex, Vestibulo-Ocular; Rotation; Self Concept; Sensory Thresholds; Young Adult
PubMed: 25637805
DOI: 10.1016/j.neuroscience.2015.01.021 -
Nature Communications Oct 2022The rational engineering of photoresponsive materials, e.g., light-driven molecular motors, is a challenging task. Here, we use structure-related design rules to prepare...
The rational engineering of photoresponsive materials, e.g., light-driven molecular motors, is a challenging task. Here, we use structure-related design rules to prepare a prototype molecular rotary motor capable of completing an entire revolution using, exclusively, the sequential absorption of two photons; i.e., a photon-only two-stroke motor. The mechanism of rotation is then characterised using a combination of non-adiabatic dynamics simulations and transient absorption spectroscopy measurements. The results show that the rotor moiety rotates axially relative to the stator and produces, within a few picoseconds at ambient T, an intermediate with the same helicity as the starting structure. We discuss how such properties, that include a 0.25 quantum efficiency, can help overcome the operational limitations of the classical overcrowded alkene designs.
Topics: Humans; Rotation; Photons; Stroke
PubMed: 36307476
DOI: 10.1038/s41467-022-33695-x -
Scientific Reports May 2024Clear aligners are employed daily for the treatment of several malocclusions. Previous clinical studies indicated low accuracy for the correction of tooth rotations. The...
Clear aligners are employed daily for the treatment of several malocclusions. Previous clinical studies indicated low accuracy for the correction of tooth rotations. The aim of this study was to evaluate the predictability of tooth rotations with clear aligners. The sample comprised 390 teeth (190 mandibular; 200 maxillary), measured from the virtual models of 45 participants (21 men, 24 women; mean age: 29.2 ± 6.6 years old). For each patient, pre-treatment (T0) digital dental models (STL files), virtual plan (T1) and post-treatment digital dental models (T2) of both the mandibular and maxillary arches were imported onto Geomagic Control X, a 3D metrology software which allows angular measurements. Rotations were calculated by defining reproducible vectors for all teeth in each STL file and superimposing both T0 with T1 to determine the prescribed rotation, and T0 with T2 to determine the achieved rotation. Prescribed and achieved rotations were compared to assess movement's accuracy. The Wilcoxon signed-rank test and paired t-test were used to assess differences between the prescribed and achieved movements (P < 0.05). The overall predictability of rotational movement was 78.6% for the mandibular arch and 75.0% for the maxillary arch. Second molar accuracy was the lowest in both arches. Clear aligners were not able to achieve 100% of the planned movements.
Topics: Humans; Female; Male; Adult; Malocclusion; Tooth Movement Techniques; Maxilla; Rotation; Mandible; Young Adult; Models, Dental
PubMed: 38762583
DOI: 10.1038/s41598-024-61594-2 -
Vision Research Feb 2007A novel class of vivid motion and velocity illusions for contrast-defined shapes is presented and discussed. The illusions concern a starlike wheel that, physically,... (Review)
Review
A novel class of vivid motion and velocity illusions for contrast-defined shapes is presented and discussed. The illusions concern a starlike wheel that, physically, rotates with constant velocity between stationary starlike inner and outer shapes but that, perceptually, shows pulsations, jolts backwards, jolts forwards, and accelerations, each time it aligns with the inner and outer shapes. These dynamic effects turn from one into another when contrasts in the image change gradually, and seem to be caused by colour assimilation and ambiguous figure-ground segregation.
Topics: Acceleration; Contrast Sensitivity; Field Dependence-Independence; Humans; Lighting; Motion Perception; Optical Illusions; Psychophysics; Rotation
PubMed: 17239916
DOI: 10.1016/j.visres.2006.12.004 -
Sensors (Basel, Switzerland) 2011A 3D gyroscope provides measurements of angular velocities around its three intrinsic orthogonal axes, enabling angular orientation estimation. Because the measured...
A 3D gyroscope provides measurements of angular velocities around its three intrinsic orthogonal axes, enabling angular orientation estimation. Because the measured angular velocities represent simultaneous rotations, it is not appropriate to consider them sequentially. Rotations in general are not commutative, and each possible rotation sequence has a different resulting angular orientation. None of these angular orientations is the correct simultaneous rotation result. However, every angular orientation can be represented by a single rotation. This paper presents an analytic derivation of the axis and angle of the single rotation equivalent to three simultaneous rotations around orthogonal axes when the measured angular velocities or their proportions are approximately constant. Based on the resulting expressions, a vector called the simultaneous orthogonal rotations angle (SORA) is defined, with components equal to the angles of three simultaneous rotations around coordinate system axes. The orientation and magnitude of this vector are equal to the equivalent single rotation axis and angle, respectively. As long as the orientation of the actual rotation axis is constant, given the SORA, the angular orientation of a rigid body can be calculated in a single step, thus making it possible to avoid computing the iterative infinitesimal rotation approximation. The performed test measurements confirm the validity of the SORA concept. SORA is simple and well-suited for use in the real-time calculation of angular orientation based on angular velocity measurements derived using a gyroscope. Moreover, because of its demonstrated simplicity, SORA can also be used in general angular orientation notation.
Topics: Rotation
PubMed: 22164090
DOI: 10.3390/s110908536 -
Journal of Traditional Chinese Medicine... Oct 2019To analyze the effect of different twirling and rotating acupuncture manipulation techniques on the blood flow perfusion at acupoints to provide a reference for the...
OBJECTIVE
To analyze the effect of different twirling and rotating acupuncture manipulation techniques on the blood flow perfusion at acupoints to provide a reference for the study of acupoint specificity and the quantification and effectiveness of acupuncture methods.
METHODS
Twenty healthy male or female college students each received four different acupuncture manipulation techniques, including simple acupuncture, uniform reinforcing-reducing needling, twirling reinforcing needling, and twisting reducing needling. The self-control method was applied. Acupuncture was performed by an acupuncture manipulation simulator at Neiguan (PC 6) and Zusanli (ST 36). The process of twirling and rotating was divided into seven timepoints. The PeriCam Perfusion Speckle Imager (PSI) System was used to collect the blood flow perfusion data at each acupoint. The specificity of twirling and rotating acupuncture manipulation was analyzed based on changes in the curve, video, and numerical blood flow perfusion data at each timepoint.
RESULTS
There were two peaks in the blood flow perfusion curve of twirling and rotating acupuncture manipulation; one appeared after 3 min of needle retention, and the other appeared 3 min after needle removal. The blood flow perfusion parameters showed that the greatest differences between the four manipulation techniques occurred after 5 and 10 min of needle retention. The specificity of various manipulation techniques was most obvious at these two timepoints. There were significant differences between the four manipulation groups in the blood flow perfusion and the relative change rates of blood flow perfusion at each timepoint.
CONCLUSION
Laser speckle imaging enables the real-time, non-invasive, rapid, and accurate collection of blood flow perfusion data during acupuncture. This imaging technique enables the easy attainment of various parameters such as visual images, two-dimensional curves, and data tables. At various timepoints, the four groups significantly differed regarding changes in blood flow perfusion and relative change rates of blood flow perfusion, which facilitated the differentiation of the four acupuncture manipulation methods. Based on this, further analysis could be conducted to study spatial distribution characteristics such as the influence area and flare area. The frequency domain analysis of acupuncture manipulation curves is important in the study of the dose-effect relationship and specificity of acupuncture manipulation.
Topics: Acupuncture Points; Adult; Blood Circulation; Female; Healthy Volunteers; Humans; Male; Rotation; Time Factors
PubMed: 32186124
DOI: No ID Found -
Journal of Neurotrauma Apr 2019We investigated whether humans could sustain high head rotational velocities without brain injury. Rotational velocity has long been implicated for predicting concussion...
We investigated whether humans could sustain high head rotational velocities without brain injury. Rotational velocity has long been implicated for predicting concussion risk, and has recently been used to develop the rotational velocity-based Brain Injury Criterion (BrIC). To assess the efficacy of rotational velocity and BrIC for predicting concussion risk, we instrumented 9 male subjects with sensor-laden mouthguards and measured six-degree-of-freedom head accelerations for 27 rapid voluntary head rotations. The fastest rotations produced peak rotational velocities of 12.6, 17.4, and 25.0 rad/s in the coronal, sagittal, and horizontal planes, respectively. All of these exceeded the corresponding medians from padded sports impacts (8.9, 10.7, and 8.4 rad/s, respectively) and, in the case of sagittal and horizontal rotation, were within 1 standard deviation of published concussion averages. In the horizontal plane, four voluntary rotations exceeded the concussive impact median BrIC. The area under the precision-recall curve was lower in BrIC (0.49) than just using horizontal rotational acceleration (0.8), which distinguished concussive and subconcussive motions better. Voluntary motions produced less than 4% max principal strain (MPS) in finite element simulation, 5 times below predictions from dummy impacts used to develop BrIC. Despite having the highest critical velocity in BrIC, coronal rotation produced more tract-oriented strain in the corpus callosum than other planes. Baseline and post-experiment neurological testing revealed no significant deficits. We find that the head can tolerate high-velocity, low-acceleration rotational inputs too slow to produce substantial brain deformation. These findings suggest that the time regime over which angular velocities occur must be carefully considered for concussion prediction.
Topics: Acceleration; Adolescent; Adult; Brain Concussion; Brain Injuries; Finite Element Analysis; Head Movements; Humans; Male; Models, Biological; Risk Assessment; Rotation; Young Adult
PubMed: 29848152
DOI: 10.1089/neu.2016.4758