scholarly journals Comparable behaviour of ring and little fingers due to an artificial reduction in thumb contribution to hold objects

2020 ◽  
Author(s):  
Banuvathy Rajakumar ◽  
Varadhan SKM
Keyword(s):  
Normal Force ◽  
Safety Margin ◽  
Ring Finger ◽  
Middle Finger ◽  
Human Hand ◽  
Mechanical Advantage ◽  
Free Condition ◽  
Normal Forces ◽  
Fixed Condition ◽  
Little Finger

AbstractBackgroundThe human hand plays a crucial role in accomplishing activities of daily living. The contribution of each finger in the human hand is remarkably unique in establishing object stabilization. According to the mechanical advantage hypothesis, the little finger tends to exert a greater normal force than the ring finger during a supination moment production task to stabilize the object. Similarly, during pronation, the index finger produces more normal force when compared with the middle finger. Hence, the central nervous system employs the peripheral fingers for torque generation to establish the equilibrium as they have a mechanical advantage of longer moment arms for normal force. In our study, we tested whether the mechanical advantage hypothesis is supported in a task in which the contribution of thumb was artificially reduced. We also computed the safety margin of the individual fingers and thumb.MethodologyFifteen participants used five-finger prismatic precision grip to hold a custom-built handle with a vertical railing on the thumb side. A slider platform was placed on the railing such that the thumb sensor could move either up or down. There were two experimental conditions. In the “Fixed” condition, the slider was mechanically fixed, and hence the thumb sensor could not move. In the “Free” condition, the slider platform on which the thumb sensor was placed could freely move. In both conditions, the instruction was to grasp and hold the handle (and the platform) in static equilibrium. We recorded tangential and normal forces of all the fingers.ResultsThe distribution of fingertip forces and moments changed depending on whether the thumb platform was movable (or not). In the free condition, the drop in the tangential force of thumb was counteracted by an increase in the normal force of the ring and little finger. Critically, the normal forces of the ring and little finger were statistically equivalent. The safety margin of the index and middle finger did not show a significant drop in the free condition when compared to fixed condition.ConclusionWe conclude that our results does not support the mechanical advantage hypothesis at least for the specific mechanical task considered in our study. In the free condition, the normal force of little finger was comparable to the normal force of the ring finger. Also, the safety margin of the thumb and ring finger increased to prevent slipping of the thumb platform and to maintain the handle in static equilibrium during the free condition. However, the rise in the safety margin of the ring finger was not compensated by a drop in the safety margin of the index and middle finger.

scholarly journals Comparable behaviour of ring and little fingers due to an artificial reduction in thumb contribution to hold objects

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9962
Author(s):  
Banuvathy Rajakumar ◽  
Varadhan SKM
Keyword(s):  
Normal Force ◽  
Safety Margin ◽  
Ring Finger ◽  
Middle Finger ◽  
Human Hand ◽  
Mechanical Advantage ◽  
Free Condition ◽  
Normal Forces ◽  
Fixed Condition ◽  
Little Finger

Background The human hand plays a crucial role in accomplishing activities of daily living. The contribution of each finger in the human hand is remarkably unique in establishing object stabilization. According to the mechanical advantage hypothesis, the little finger tends to exert a greater normal force than the ring finger during a supination moment production task to stabilize the object. Similarly, during pronation, the index finger produces more normal force when compared with the middle finger. Hence, the central nervous system employs the peripheral fingers for torque generation to establish the equilibrium as they have a mechanical advantage of longer moment arms for normal force. In our study, we tested whether the mechanical advantage hypothesis is supported in a task in which the contribution of thumb was artificially reduced. We also computed the safety margin of the individual fingers and thumb. Methodology Fifteen participants used five-finger prismatic precision grip to hold a custom-built handle with a vertical railing on the thumb side. A slider platform was placed on the railing such that the thumb sensor could move either up or down. There were two experimental conditions. In the “Fixed” condition, the slider was mechanically fixed, and hence the thumb sensor could not move. In the “Free” condition, the slider platform on which the thumb sensor was placed could freely move. In both conditions, the instruction was to grasp and hold the handle (and the platform) in static equilibrium. We recorded tangential and normal forces of all the fingers. Results The distribution of fingertip forces and moments changed depending on whether the thumb platform was movable (or not). In the free condition, the drop in the tangential force of thumb was counteracted by an increase in the normal force of the ring and little finger. Critically, the normal forces of the ring and little finger were statistically equivalent. The safety margin of the index and middle finger did not show a significant drop in the free condition when compared to fixed condition. Conclusion We conclude that our results does not support the mechanical advantage hypothesis at least for the specific mechanical task considered in our study. In the free condition, the normal force of little finger was comparable to the normal force of the ring finger. Also, the safety margin of the thumb and ring finger increased to prevent slipping of the thumb platform and to maintain the handle in static equilibrium during the free condition. However, the rise in the safety margin of the ring finger was not compensated by a drop in the safety margin of the index and middle finger.

Control of Grasp Stability in Humans Under Different Frictional Conditions During Multidigit Manipulation

1999 ◽  
Vol 82 (5) ◽  
pp. 2393-2405 ◽  
Author(s):  
Magnus K. O. Burstedt ◽  
J. Randall Flanagan ◽  
Roland S. Johansson
Keyword(s):  
Load Distribution ◽  
Safety Margin ◽  
Middle Finger ◽  
The Other ◽  
Surface Material ◽  
Tangential Load ◽  
Normal Forces ◽  
Grasp Stability ◽  
Contact Surfaces ◽  
Lift Off

Control of grasp stability under different frictional conditions has primarily been studied in manipulatory tasks involving two digits only. Recently we found that many of the principles for control of forces originally demonstrated for two-digit grasping also apply to various three-digit grasps. Here we examine the control of grasp stability in a multidigit task in which subjects used the tips of the thumb, index, and middle finger to lift an object. The grasp resembled those used when lifting a cylindrical object from above. The digits either all contacted the same surface material or one of the digits contacted a surface material that was more, or less, slippery than that contacted by the other two digits. The three-dimensional forces and torques applied by each digit and the contact positions were measured along with the position and orientation of the object. The distribution of forces among the digits strongly reflected constraints imposed by the geometric relationship between the object's center of mass and the contact surfaces. On top of this distribution, we observed changes in force coordination related to changes in the combination of surface materials. When all digits contacted the same surface material, the ratio between the normal force and tangential load ( F n: L ratio) was similar across digits and scaled to provide an adequate safety margin against slip. With different contact surfaces subjects adapted the F n: L ratios at the individual digits to the local friction with only small influences by the friction at the other two digits. They accomplished this by scaling the normal forces similarly at all digits and changing the distribution of load among the digits. The surface combination did not, however, influence digit position, tangential torque, or object tilting systematically. The change in load distribution, rather, resulted from interplay between these factors, and the nature of this interplay varied between trials. That is, subjects achieved grasp stability with various combinations of fingertip actions and appeared to exploit the many degrees of freedom offered by the multidigit grasp. The results extend previous findings based on two-digit tasks to multidigit tasks by showing that subjects adjust fingertip forces at each digit to the local friction. Moreover, our findings suggest that subjects adapted the load distribution to the current frictional condition by regulating the normal forces to allow slips to occur early in the lift task, prior to object lift-off.

Brush Development for Ship Hull Grooming

2015 ◽  
Author(s):  
Melissa E. Tribou ◽  
Geoffrey Swain
Keyword(s):  
Normal Force ◽  
Environmentally Friendly ◽  
Ship Hull ◽  
Operational Parameters ◽  
Free Condition ◽  
Independent Variables ◽  
Ship Hulls ◽  
Normal Forces ◽  
Different Types ◽  
Environmentally Friendly Method

Ship hull grooming is proposed as an environmentally friendly method of controlling fouling on ship hulls. It is defined as the frequent and gentle cleaning of a coating when the ship is idle to prevent the Establishment of fouling. Prior research by Tribou and Swain has evaluated the effectiveness of different methods and the frequency of grooming on different types of ship hull coatings. It was found that vertical rotating cup style Brushes provided the best method to maintain the coatings in a smooth and fouling free condition. This study investigated brush design and operational parameters in relationship to normal forces imparted by the brushes to the surface. A brush stiffness factor was developed and the independent variables for brush design non-dimensionalized for the normal force. A load cell was used to measure the forces imparted by different brushes and the models were validated using these non-dimensional terms. The knowledge gained by these studies will be used to optimize brush design for the implementation of grooming.

scholarly journals REGRESSION ANALYSIS TO DETERMINE STATURE FROM HAND ANTHROPOMETRY AMONG ILOCANO POPULATION IN PHILIPPINES FOR PERSON IDENTIFICATION

2021 ◽  
Vol 11 (1) ◽  
pp. 20
Author(s):  
T.Nataraja Moorthy
Keyword(s):  
Ring Finger ◽  
Middle Finger ◽  
Size Analysis ◽  
Human Hand ◽  
Regression Equations ◽  
Person Identification ◽  
Left Hand ◽  
Length Measurements ◽  
The Right ◽  
Hand Length

Stature determination aids the person identification during forensic investigation. The human hand research is the current topic of interest among forensic scientist, forensic medicine experts and anthropologists. Based on sample size analysis, the study involved consented 60 males and 60 females, age ranged from 18 to 55 years old. Stature and hand lengths measurements were made with Stadiometer and Vernier Calipers for analysis.  From each participant, ten hand length measurements, five from left and five from right hands were taken. The five length measurements in left hand are the inter-distance between the distal traverse crease of the wrist (LH) and tip of thumb (T), index finger (I), middle finger (M), ring finger (R) & little finger (L), as abbreviated LHT, LHI, LHM, LHR and LHL. Similarly, the right hand lengths indicated as RHT, RHI, RHM, RHR, and RHL.  The data were statistically analyzed by using SPSS software, version 23 and column chart. The information about age, gender, name, and place of origin of the participants was coded for easy reference. This study finally developed regression equations to determine stature from hand anthropometry among Ilocano population in Philippines for person identification

scholarly journals Analysis of the effect of fingertip size for sex differences in current perception thresholds with transcutaneous electrical stimulation in healthy subjects

2021 ◽  
Author(s):  
Shin-ichiro Seno ◽  
Hideaki Shimazu ◽  
Eiki Kogure ◽  
Atsushi Watanabe ◽  
Hiroko Kobayashi
Keyword(s):  
Sex Differences ◽  
Healthy Subjects ◽  
Index Finger ◽  
Ring Finger ◽  
Middle Finger ◽  
Perception Threshold ◽  
Left Hand ◽  
Current Perception Threshold ◽  
Males And Females ◽  
Little Finger

Abstract Objective This study aimed to measure the current perception threshold (CPT) of five fingertips of the left hand in healthy subjects and analyze whether sex differences in perception thresholds are suppressed when adjusting for fingertip size among males and females. Results For fingertips from the thumb to the little finger, the males’ CPT values were 1.03, 0.83, 0.86, 0.86, and 0.88 mA; the females’ results were 0.63, 0.55, 0.54, 0.51, and 0.50 mA. The CPTs were higher in males than in females for every fingertip. Upon adjusting for fingertip length, the log-transformed CPT values were found to have sex differences, except for the index finger: thumb, t(20.05) = 3.493, p = 0.002; middle finger, U(30) = 44.50, p = 0.005; ring finger, t(30) = 55.50, p = 0.018; little finger, U(30) = 30.00, p = 0.001. Similarly, the CPT values, transformed into log values when adjusting for the fingertip area, were found to have sex differences for three fingertips: thumb, t(18) = 2.649, p = 0.016; middle finger, U(20) = 12.00, p = 0.004; ring finger, t(18) = 2.206, p = 0.041. According to this study, sex differences in CPTs were not completely abolished by adjusting for fingertip length or area.

scholarly journals A Systematic Comparison of Perceptual Performance in Softness Discrimination with Different Fingers

2020 ◽  
Vol 82 (7) ◽  
pp. 3696-3709
Author(s):  
Aaron C. Zoeller ◽  
Knut Drewing
Keyword(s):  
Ring Finger ◽  
Middle Finger ◽  
Dominant Hand ◽  
Sensory Sensitivities ◽  
Motor Abilities ◽  
Soft Objects ◽  
Perceptual Performance ◽  
Improved Performance ◽  
Spontaneous Exploration ◽  
Little Finger

Abstract In studies investigating haptic softness perception, participants are typically instructed to explore soft objects by indenting them with their index finger. In contrast, performance with other fingers has rarely been investigated. We wondered which fingers are used in spontaneous exploration and if performance differences between fingers can explain spontaneous usage. In Experiment 1 participants discriminated the softness of two rubber stimuli with hardly any constraints on finger movements. Results indicate that humans use successive phases of different fingers and finger combinations during an exploration, preferring index, middle, and (to a lesser extent) ring finger. In Experiment 2 we compared discrimination thresholds between conditions, with participants using one of the four fingers of the dominant hand. Participants compared the softness of rubber stimuli in a two-interval forced choice discrimination task. Performance with index and middle finger was better as compared to ring and little finger, the little finger was the worst. In Experiment 3 we again compared discrimination thresholds, but participants were told to use constant peak force. Performance with the little finger was worst, whereas performance for the other fingers did not differ. We conclude that in spontaneous exploration the preference of combinations of index, middle, and partly ring finger seems to be well chosen, as indicated by improved performance with the spontaneously used fingers. Better performance seems to be based on both different motor abilities to produce force, mainly linked to using index and middle finger, and different sensory sensitivities, mainly linked to avoiding the little finger.

Puzzles

2011 ◽  
Author(s):  
Anany Levitin ◽  
Maria Levitin
Keyword(s):  
Ring Finger ◽  
Middle Finger ◽  
The Other ◽  
Left Hand ◽  
Matching Pair ◽  
The Right ◽  
Little Finger

1. A Wolf, a Goat, and a Cabbage A man finds himself on a riverbank with a wolf, a goat, and a head of cabbage. He needs to transport all three to the other side of the river in his boat. However, the boat has room for only the man himself and one other item (either the wolf, the goat, or the cabbage). In his absence, the wolf would eat the goat, and the goat would eat the cabbage. Show how the man can get all these “passengers” to the other side. 2. Glove Selection There are 20 gloves in a drawer: 5 pairs of black gloves, 3 pairs of brown, and 2 pairs of gray. You select the gloves in the dark and can check them only after a selection has been made. What is the smallest number of gloves you need to select to guarantee getting the following? (a) At least one matching pair (b) At least one matching pair of each color 3. Rectangle Dissection Find all values of n > 1 for which one can dissect a rectangle into n right triangles, and outline an algorithm for doing such a dissection. 4. Ferrying Soldiers A detachment of 25 soldiers must cross a wide and deep river with no bridge in sight. They notice two 12-year-old boys playing in a rowboat by the shore. The boat is so tiny, however, that it can only hold two boys or one soldier. How can the soldiers get across the river and leave the boys in joint possession of the boat? How many times does the boat pass from shore to shore in your algorithm? 5. Row and Column Exchanges Can one transform the left table in Figure 2.1 into the right table by exchanging its rows and columns? 6. Predicting a Finger Count A little girl counts from 1 to 1000 using the fingers of her left hand as follows. She starts by calling her thumb 1, the first finger 2, middle finger 3, ring finger 4, and little finger 5.

Stack Splinting Versus Kirschner Wire Treatment in Acute Closed Mallet Finger Doyle I

2021 ◽  
pp. 229255032110038
Author(s):  
Maria de los Angeles Mendoza Velez ◽  
Marco Aurelio Rendon Medina ◽  
Ricardo Pacheco Lopez ◽  
Hecly Lya Vazquez Morales ◽  
Ruben Hernandez Ordoñez
Keyword(s):  
Treatment Efficacy ◽  
Sports Injuries ◽  
Simple Procedure ◽  
Kirschner Wire ◽  
Ring Finger ◽  
Middle Finger ◽  
Mallet Finger ◽  
Best Management ◽  
Average Patient ◽  
Little Finger

Introduction: Mallet injuries are common and usually treated conservatively. Various systematic reviews have found a lack of evidence regarding the best management, and it is still unclear. Objective: To evaluate the treatment efficacy of Stack Splinting compared to a Kirschner wire immobilization of acute closed mallet finger Doyle I. Methods: From March 2019 to February 2020, 41 patients with acute close mallet finger Doyle I were treated; 19 patients were treated with Kirschner wire and 22 with Stack splinting for a mean of 6 weeks. The average patient age at the time of the injury was 43 years. Results: Twenty-eight males and 13 females were in this study. Among them, 17 patients were injured in the little finger, 15 in the middle finger, and 9 in the ring finger. Twenty-seven of injuries suffered an aggression, 11 from falling, and 3 from sports injuries. All the fingers had typical mallet malformation. Seventeen patients treated with Kirschner wire completed the treatment with full recovery, only 7 patients treated with Stack splint completed the treatment and 15 treated with Stack splint had relapse on mallet injury. Conclusion: Kirschner wire treatment is a simple procedure, and proves in this study that has better results in patients with acute closed mallet finger Doyle I compared to Stack splint.

Distribution of the Sensory Endings of the C7 Nerve Root and Its Clinic Significance

1994 ◽  
Vol 19 (1) ◽  
pp. 67-68 ◽  
Author(s):  
Y-D. GU
Keyword(s):  
Brachial Plexus ◽  
Nerve Root ◽  
Index Finger ◽  
Ring Finger ◽  
Middle Finger ◽  
Root Avulsion ◽  
Cutaneous Sensation ◽  
Little Finger ◽  
Sensory Endings

50 patients with root avulsion of the brachial plexus have been treated with contralateral C7 root neurotization. Abnormal cutaneous sensation was found on the index finger in 37 cases (74%), on the middle finger in 29 cases (58%), on the thumb in 19 cases (38%), on the ring finger in ten cases (20%), and on the little finger in one case (2%). Seven patients had no abnormal cutaneous sensation. It is suggested that the area of skin innervated by C7 is centred on the index finger together with the thumb and middle fingers.

A BIO-MECHANICAL DESIGNED PROSTHETIC HAND WITH MULTI-CONTROL STRATEGIES

2012 ◽  
Vol 09 (02) ◽  
pp. 1250013 ◽  
Author(s):  
HAI HUANG ◽  
YONG-JIE PANG ◽  
DA-PENG YANG ◽  
CHAO-YU SUN ◽  
LI JIANG ◽  
...  
Keyword(s):  
Control Strategy ◽  
Ring Finger ◽  
Middle Finger ◽  
Lateral Position ◽  
Support Vector ◽  
Human Hand ◽  
Prosthetic Hand ◽  
Loop Control ◽  
Emg Control ◽  
Close Loop Control

In order to mimic the natural appearance, motion, and perception of the human hand, a bio-mechatronic approach to design an anthropomorphic prosthetic hand — HIT/DLR Prosthetic Hand has been presented. It reproduces human hand in its fundamental structure such as appearance, weight, and dimensions. Its thumb can move along a cone surface in 3D space. Similar with that of human's, it combines with abduction and adduction from palmar position to lateral position. Actuated by only one motor, the middle finger, ring finger, and little finger can envelop complex-shaped objects. In addition, the bio-mechatronic integration and cosmetic designation make it much more like a genuine human hand. HIT/DLR Prosthetic Hand can be controlled through voice control strategy, Electromyography (EMG) control strategy, EMG, and electrocutaneous sensory feedback (ESF) close loop control strategy. In EMG control system, 10 types of hand posture are recognized through six electrodes on the basis of support vector machine (SVM). The last control strategy can help an amputee recover the grasp perception, further improve the efficiency of EMG control, and reduce the hand mis-manipulation and force delivery mistakes.

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