Posted by For my steam project, I choose to focus on the movements of the hand, more specifically, the thumb, and how missing certain muscles in the thumb can affect the mobility of the thumb. Because I was born missing a few muscles in my right hand. As a little kid, my mom said I picked up cheerios up weirdly (she doesn’t remember how I picked them up but it wasn’t normal). The objective is “Design instructions integrating muscles and bones that you pick.” I’m explaining the limitations of my own hand because of the missing muscles. For my medium, I’m painting the muscles and tendon I am missing on my hands, so we can see the visible difference between the two hands.
There is a visible difference between my hands, when looking at the palms of my hands, the muscles of my right thumb are flatter and the carpometacarpal joint is protruding out more since it’s not covered by the muscles. I can’t bend my right thumb completely at the interphalangeal (IP) joint, (the first joint or the joint closest to the tip of the thumb), and in the metacarpophalangeal (MCP), I have maybe 40% mobility in my right hand. I think I’m missing the abductor pollicis brevis and the opponens pollicis and maybe also something about the flexor pollicis longus tendon. The abduction of the thumb is the movement of the thumb away from the other fingers, I have almost no mobility with this action. For flexion curling the thumb up in the palm and extension (the opposite of flexion), I only have about 20% of flexion motion in my thumb and my extension is better than my flexion. For opposing, I have zero of this motion in my right hand.
References
Hand anatomy. Sidney Physiotherapy. (n.d.). https://www.sidneyphysio.com/Injuries-Conditions/Hand/Hand-Anatomy/a~280/article.html
Body anatomy: Upper extremity muscles: The hand society. Body Anatomy: Upper Extremity Muscles | The Hand Society. (n.d.). https://www.assh.org/handcare/safety/muscles
Acosta, J. R. (2023, August 8). Anatomy, shoulder and upper limb, hand adductor pollicis. StatPearls [Internet]. https://www.ncbi.nlm.nih.gov/books/NBK526059/#:~:text=The%20four%20extrinsic%20muscles%20influencing,flexes%20the%20MCP%2FIP%20joints.
This project demonstrates muscles within the hand, especially the thenar muscle group (those by the thumb). The thenar muscle group consists of 3 separate parts: Abductor Polliscis Brevis, Opponens Pollicis, and the Flexor Pollicis Tendon. In the right hand we see an abnormality about where the Opponens Pollicis would be. There is a visible difference compared from the left hand, as in the left hand a more rounded bulge is seen at the base of the thumb. In the right hand we don’t see this bulge, this is due to missing muscles, most likely the Opponens Pollicis and maybe the Abductor Pollicis Brevis. The absence of these muscles result in loss of mobility, restricting the thumb from normal movements such as flexion. The name of each muscle indicates what type of movement occurs when contracting, The Flexor Longus Pollicis is responsible for the flexion of the thumb, the Abductor Pollicis Brevis makes an abduction movement, and lastly the Opponens Pollicis is what turns the thumb out from the palm, (opposition). The illustration shows where these muscles are located and where the difference in the hands are visible. Everyday actions that can be affected the absence of any of these muscles, including: gripping objects, opening of the hand, and movements that require mobility of the thumb such as typing or playing piano. This goes to show the importance of each muscle, without any one of them movement of the body can change drastically.