So the first muscle I want to talk about is IP flexor or the thumb. So the prime mover is the flexor pollicis longus. Okay, right here. If you look at this muscle, yeah, it ends at the distal part. So it will bend the IP joint of the thumb.
But it also has rolls on the MCP and CMC joint. Okay, okay, so thumb extension or radial abduction And then I'm gonna combine that with thumb palmar abduction because they you know the three muscles working on you know helping each other but the prime mover for radial abduction is the extensor porsus brevis and longus Okay, but if you look at The abductor pollicis longus, you see that the tendon kind of go, you know, the direction is very consistent with the two extensors. So the abductor pollicis longus has a huge role in radial abduction. Okay.
And when the thumb needs to do palmar abduction, which kind of bring the thumb. up when the form is in supination put a thumb up that way you see here the abductor palsy stone because it has a better mechanical advantage of doing that so the apl is the point mover for that okay so um so there are a couple more intrinsic muscles for thumb and for the little finger for the thumb It's called thinner muscles and for the little fingers called hypothymena muscles. There are four thinner muscles These muscles are considered as the positioning muscles really the position of thumb for the hand movement or the hand function so we have On the outside we have abducted causes brevis And inside we have a flexor pollicis brevis. And if we take, we see this as the superficial layer.
If we take this out, we will see opponent's pollicis right there. So you will see the similar pattern for the hypothenar muscle. Let me jump. So let's look at the hypothenar muscle.
So, from the outside we have abductor digi mini me, inside we have flexor digi mini me, and then the second layer, or the deeper layer, we have opponents digi mini me, which is the same pattern as the femur muscles. That's how I memorize those. So on the outside that's abductor, inside that's flexor, and then deeper layer that's opponents. Okay. and then remember there are four uh thinner muscles okay and we just talked about three the fourth um thinner muscles is huge it's called a doctor a doctor policies right here a doctor policies is usually partnered with the flexor process brevis for pinch movement it's really to position the thumb or pinch okay so if if you pick up an object let's say pick up your the pen from the table and then pay attention to the thumb the thumb doing the movement of the thumb is really primarily on the cmc joint okay so the cmc joint is doing adduction and then the mcp joint may be doing some flexion Maybe or maybe not.
So if you look at this motion, it's really the pair function between the adductor plexus and the flexor plexus brevis. Okay, and then if you want to use the distal part, then the flexor plexus longus will kind of jump in and play that. So... when we pick up when we when if we use the the pad of the thumb index finger and the middle finger that's called tripod pinch or palmer pinch So then it's a really combination of the adductor pollicis, the flexor pollicis bragus, and then the longus.
That kind of position of thumb for the palmar and tip pinch. Okay. And then if we are holding the key, that kind of position is called lateral pinch. Of course, it's also called key pinch. So again...
The AP, FPB, and FPL position the thumb for this little pinch. And here comes my favorite muscle of the hand, which is the first dorsal interossei. So it's on the outside. When we hold the key and really press it, you see that lump of the muscle?
That's the fork. first dorsal interocci so this muscle again is dorsal interocci so its main function is to abduct the digit which is the index finger okay so to do a key pinch it really rely on you know the thumb muscles and the force into the oci to kind of do this job okay and for palmer pinch and tip pinch it requires requires the index finger and middle finger to coordinate with each other. So that the finger extensors and finger flexors, no matter if it's extrinsic or intrinsic, they all have to come into play together to afford a person to do a pinch. So I know this is long and I tried. So these are the basic hand muscles and hand functions for that.
We will talk more about the mechanism between recent hand and then the pathology for the recent hand. Oh, and then hand function, of course.