God invented carpals just to make anthropologists sad, and this is true even if you don’t believe in God.
Luckily for the one single person who actually enjoyed reading the first Honest Anatomy lesson and then requested a second, I have a convoluted way of understanding the carpals that I’m going to share with you. Unfortunately for that person, I haven’t yet entirely mastered the muscles of the hand, so this is going to be mostly a lesson in osteology. After all, does anyone really know the muscles? The carpal tunnel is for anthropologists what the tunnel of light is for dying hospital patients, only instead of a choir of angels greeting us at the end, we are welcomed only by darkness and an overwhelming sense of despair.
Let’s begin. It is crucial that you start with the lunate for this lesson, or else nothing will make sense. Notice that the lunate has a crescent shape, much like a crescent moon. In fact, that’s where the lunate gets its name. The lunate has to articulate with the radius because the sun radiates light toward the moon. It articulates laterally.
The scaphoid also articulates with the radius. This makes sense. Think of the scaphoid as a magnifying glass. The radius is the sun. What do you use to incinerate ants in sunlight? A magnifying glass. Thus, the scaphoid has to articulate with the radius. The scaphoid also articulates with the lunate because in this story, Galileo’s telescope is broken, so he has to use a stupid ass magnifying glass. The magnifying glass isn’t working, so he keeps trying to get closer and closer to the moon (lunate) to see it better, until he is finally touching it. Thus, the lunate articulates with the scaphoid.
The capitate also articulates with the lunate. Many people like to think of the capitate as Darth Vader because the articular surface for the third metacarpal looks like the base of his helmet. For the purposes of this story, Darth Vader has a vacation home on the moon, which is why the capitate articulates with the lunate. The capitate also articulates with the third metacarpal, which is the only one of the metacarpals to have a styloid process. Metacarpal is abbreviated as “MC,” which brings to mind “MC Hammer.” Now, Darth Vader wasn’t allowed to be openly gay on the Death Star, but when he’s on the moon (lunate), he resumes a casual sexual relationship with MC Hammer (MC III). To spell it out, you know that the styloid process of the third metacarpal articulates with the distal portion of the capitate because it’s MC Hammer sticking his, erm, styloid process in Darth Vader’s undercarriage.
When Darth Vader (capitate) goes to his vacation home on the moon (lunate) he sometimes likes to wear cowboy boots. Which carpal looks like a boot? The trapezoid! That’s why the trapezoid and capitate articulate. The trapezoid also articulates with the trapezium because the trapezium is saddle-shaped, and obviously you need cowboy boots to ride anything with a saddle. The saddle-shaped articular facet on the trapezium articulates with the saddle-shaped facet on the first metacarpal.
Then we have the triquetral and pisiform. This one is a bit of a stretch, but hear me out. Triquetral has the letters “que” in it, which happen to be the first three letters in the word “queso.” Queso is made from milk and cheese, which come from cows. Cows pee A LOT. Like, gallons. That’s why the triquetral and pisiform articulate. The triquetral also articulates with the lunate because in the nursery rhyme, the cow jumped over the moon.
Finally, we have the hamate. The hamate is a pig, first because it has the word ham in it, and second because it has a little pig ear. Or a butcher hook, whatever comes to mind. The hamate articulates with the lunate because when the cow (triquetral) jumped over the moon, she got lonely and called up the pig (hamate). The hamate also articulates with the fifth metacarpal because the fifth metacarpal is a tiny bitch and needs to eat more animal protein.