Difference Between Angle You Can Bend Your Left Wrist Back vs Your Right Wrist Jenna Priest Science Department Altoona High School January 25, 2017
Background 1- The wrist joint (also known as the radiocarpal joint) is a synovial joint in the upper limb, marking the area of transition between the forearm and the hand. The wrist joint is formed distally the proximal row of the carpal bones (except the pisiform) and proximally the distal end of the radius, and the articular disk. The ulna is not part of the wrist joint it articulates with the radius, just proximal to the wrist joint, at the distal radioulnar joint. It is prevented from articulating with the carpal bones by a fibrocartilaginous ligament, called the articular disk, which lies over the superior surface of the ulna. The joint capsule and ligaments contribute to the stability of the wrist. The joint capsule, like any synovial joint, is dual layered. The fibrous outer layer attaches to the radius, ulna and the proximal row of the carpal bones. The internal layer consists of a synovial membrane, which secretes synovial fluid and lubricates the joint. There are four important ligaments in the wrist joint, one for each side of the joint. The palmar radiocarpal is found on the palmar (anterior) side of the hand. It passes from the radius to both rows of carpal bones. Its function, apart from increasing stability, is to ensure that the hand follows the forearm during supination. The dorsal radiocarpal is found on the dorsum (posterior) side of the hand. It passes from the radius to both rows of carpal bones. It contributes to the stability of the wrist, but also ensures that the hand follows the forearm during pronation. The ulnar collateral runs from the ulnar styloid process to the triquetrum and pisiform. Works in union with the other collateral ligament to prevent excessive lateral joint displacement. The radial collateral runs from the radial styloid process to the scaphoid and trapezium. Works in union with the other collateral ligament to prevent excessive lateral joint displacement. The wrist is an ellipsoid type synovial joint, allowing for movement along two axes. This means that flexion, extension, adduction and abduction can all occur at the wrist joint. All the movements of the wrist are performed by the muscles of the forearm. Flexion is produced mainly by the flexor carpi ulnaris, flexor carpi radialis, with assistance from the flexor digitorum superficialis. Extension is produced mainly by the extensor
carpi radialis longus and brevis, and extensor carpi ulnaris, with assistance from the extensor digitorum. Adduction is produced by the extensor carpi ulnaris and flexor carpi ulnaris. Abduction is produced by the abductor pollicis longus and the flexor carpi radialis (Jones, 2016). There have been no previous studies performed based on movement of right and left wrist that were similar enough to mine. Studies show that being right or left handed can affect affect different aspects of movement (advantage in athletics, school performance, speech and language, etc) but have found no evidence that support that your right or left wrist has (Dean, 2016). Background 2- Another independent variable that could affect my dependent variable is medical conditions in the wrist that prevent it from moving properly. For example, wrist tendonitis occurs when tendons become irritated and inflamed and they do not slide across the wrist or through the surrounding tissues well. Wrist tendons slide between other soft tissues and through slipper tunnels called tendon sheaths. Irritation, swelling and scarring can lead to friction in these tissues when the tendon moves. One or more tendons on the palm side or back side of the wrist or below the thumb can be affected (Madden, 2009). Another independent variable that could affect my dependent variable is cold weather. Studies have found a strong relationship between short, cold, damp days and arthritis flare-ups. Research from Tufts University suggests changes in barometric pressure worsen knee pain in people with arthritis, while colder temps can cause painful changes in joint fluid thickness (Reale, 2015). Background 3- I think there will not be a significant difference in my data because though being right or left handed can affect school or athletic performance, there is no evidence to support that it affects the joints in the wrist. Problem- The problem is determining the difference between the angle you can bend back your left wrist and right wrist. Null Hypothesis- There is no significant difference between the angle you can bend your left wrist back vs your right wrist.
Procedure1- Independent variable- left or right wrist Dependent variable- angle wrist can be bent back Control group- right wrist Experimental group- left wrist Constants- tool used to measure angle (protractor), position of arm when being measured, trials done to each wrist, directions given to participants, data table results recorded in, number of replicates tested Variables- location of testing, time it takes to get measurements, time of day measurements are taken at, number of times procedure is performed a day Procedure 2-1. Get a replicate that is able to move both of the their arms 2. Have replicate place their left full forearm on a flat surface and make sure it does not rise off the the flat surface throughout the procedure 3. Have the replicate raise their wrist off the the flat surface and bend it back (into the air) as far as they can 4. Use a protractor to measure the angle at which their wrist is bent 5. Place the protractor on the inside of the wrist you are measuring and record the degree that they stop bending their wrist at 6. Record data 7. Then have the same replicate repeat steps 2-3 with their right arm/wrist and repeat steps 4-6 yourself 8. Repeat steps 2-6 until 20 9. replicates have been tested with their left and right wrists
Results 1- Table 1: Results of How Far You Can Bend Back Your Left and Right Wrist Replicates Left wrist (in degrees) Right wrist (in degrees) 1 66 65 2 70 72 3 73 74 4 68 68 5 71 70 6 69 70 7 72 71 8 70 69 9 80 78 10 74 74 11 71 72 12 68 69 13 70 72 14 76 77
15 68 67 16 70 72 17 71 71 18 73 75 19 64 66 20 72 70 Results 2- Difference Between How Far You Can Bend Back Your Left and Right Wrists Figure 1: How far left and right wrist can be bent back
Analysis- I chose a t test, two-sample assuming equal variances because I am analyzing two sets of data that have the same amount of variability. The t test was chosen because the data follows a normal distribution. We assume the variances of both data sets to be equal, hence equal variances. t-test: Two-Sample Assuming Equal Variances Variable 1 Variable 2 Mean 70.8 71.1 Variance 12.27368421 11.56842105 Observations 20 20 Pooled Variance 11.92105263 Hypothesized Mean Difference 0 df 38 t Stat -0.274766607 8 P(T<=t) one-tail 0.3924919726 t Critical one-tail 1.685954405 P(T<=t) two-tail 0.7849839452 t Critical two-tail 2.024394147
Ten facts: 1. The mean of the left wrist data is 71.1 degrees. 2. The mean of the right wrist data is 71.7 degrees. 3. The median of the left wrist data is 70.5 degrees. 4. The median of the right wrist data is 71 degrees. 5. The mode of the left wrist data is 70 degrees. 6. The mode of the right wrist data is 72 degrees. 7. The range of the left wrist data is 64-80 degrees. 8. The range of the right wrist is 65-78 degrees. 9. The highest overall number is 80 degrees. 10. The lowest overall number is 64 degrees. An error that could occur during my experiment is not testing the left and right wrist of the same person. If the person does not remain the same for both the left and right wrist, the data could vary because not everyone has the same range of motion in their wrists. Another error that could occur is not explaining that the replicate must keep their forearm on a flat surface the whole time. If they do not do this then they could bend their wrist back very far and this would affect the data. Another error that could occur is forgetting to record data after you test a replicate. If the data is not recorded than it is no good for the experiment. Conclusion 1- I agree with my null hypothesis because my p value of 0. 7849839452 is greater than.05 therefore there is no significant difference. Conclusion 2- My conclusion agrees with science because there have been no studies that suggest that being left or right handed affects the movement of the joint in the wrist or that there is a difference in movement between the two. Conclusion 3- If I were to do this experiment again I would ask if the replicate was right or left handed just to see if there was a pattern between the data of people who were the same with their dominant hand. Another thing I would do differently is hold the replicates forearm down with my hand to
make sure if was not elevated off the table at all. This would make my procedure more consistent for all my replicates. Another thing I would do differently is ask the replicate if they ever had broken their wrist or had any joint problems in their wrist. If they had, I would not include them in my experiment. This change would result in more accurate data. Bibliography- Dean, Jeremey. "Psychological Effects Of Being Right- Or Left-Handed." PsyBlog. N.p., 30 July 2016. Web. 25 Jan. 2017. Jones, Oliver. "The Wrist Joint." TeachMeAnatomy. N.p., 03 Jan. 2017. Web. 27 Jan. 2017. Madden, Christopher. "Wrist Tendonitis." Wrist Tendonitis SelfCareNavigator: Sports Medicine. N.p., Nov. 2009. Web. 26 Jan. 2017. Reale, Joan. "Does Cold Weather Cause Joint Pain?" The Weather Channel. N.p., 2015. Web. 25 Jan. 2017.