Week 2 Blog

This week, I researched and studied the anatomy of the metacarpal region of the hand or the palm area. I discovered that muscles in this region cause the bone to expand outwards when the hand makes a fist. My goal for my hand is the flexion and extension of fingers and the opposition of the thumb.

In my last week’s blog post, I discussed creating individual fingers, including a thumb with two phalanges. Now, my focus shifts to testing whether this design is capable of forming a fist or the flexion of all the fingers. Flexion is the act of curling the fingers to close the hand.

At the start of week two, I researched the muscles responsible for finger flexion. This led me to the dorsal interosseous muscles, a group of paired intrinsic muscles of the hand located between the metacarpals. The four dorsal interosseous muscles in both flexion and extension of the fingers. As the fingers curl up, they move the metacarpals outward, creating enough space for the fingers to curl into a fist. The diagram below provides an anterior view, illustrating how the muscles function and their placement.

The first model I planned to build does not replicate those mussels or the movement of the metacarpals so before I built the physical model my initial hypothesis was that while the fingers would curl properly, it might be somewhat challenging. The result might not resemble a proper fist.

To test if my design applies to making a fist I would have to repeat the finger model I made last week. This took considerable time as I had to hand-carve all the pieces.

I then designed a hinge joint where I could attach all the phalanges to the meta cables, the same as the knuckle mechanical joint I used but with a slight modification so that it could attach to a plate.

As mentioned in my blog last week, I anticipate resolving these issues once I can 3D print my parts. Next week, I aim to learn how to use Fusion 360 for 3D modeling each piece of the build. Furthermore, I’ll focus on tweaking the hinge joint where the phalanges and metacarpals join to improve sturdiness and enable a better fist structure.