HY USMLE Q #1571 – MSK / Anatomy

Added: 2026-05-11

[00:00:00]How's it going guys? We have a pass little question from his K Anatomy. We have a 51-year-old man. We have a left hand on the left here that is a normal healthy patient.

[00:00:12]We have the left hand of the patient here on the right. This is what's called a positive froment sign. F R O M E N T sign. You've gone through my clips. I've made clips talking about this before.

[00:00:28]High yield for your similar. So this is when the patient is unable to keep a piece of paper between the thumb and the index finger without flexing the interfallengeal joint of the thumb.

[00:00:41]Okay. So let's walk through the answers here.

[00:00:45]Impairment of which the follow is most likely patient. Choice say abduction of the fingers. Correct answer. Now this is er nerve injury. Now in terms of our correct answer the interosius muscles of the hand pad dab. So palmer interosius muscles is finger adduction all of the fingers. Okay. And then dab which is dorsal interosius muscles for abduction of all the fingers.

[00:01:14]This is er nerve. Okay. The exception being abduction of the thumb which is actually median and radial nerve. But for all the fingers separating and closing the fingers that's er nerve which is why a is our correct answer.

[00:01:28]positive from sign. You need to know that thumb adduction is ulner nerve.

[00:01:33]Holy [ __ ] You say that's weird because the thumb is on the lateral aspect of the hand. Isn't that media nerve? It's not. This is the high yield point for you similar. I said it's past level.

[00:01:43]Okay. So, thumb adduction thumb contacted to index finger.

[00:01:50]Okay. Without bending the thumb, that is er nerve.

[00:01:56]However, thumb opposition choice D wrong [ __ ] answer that's media nerve that's thumb to pinky.

[00:02:03]Okay. So, hook of hammate fracture which is distal at the level of the wrist can be avid cyclists. Uh handlebar impaction. So that's gian canal syndrome. That's what causes this positive forman sign. You can have cubital tunnel syndrome which is er nerve enttrapment at the level of the elbow proximally where you get paristhesas down the medial forearm plus or minus the fment sign. Okay. So you need to know cubital tunnel syndrome proximal ular nerve enttrapment that's medial epicondular fracture and then gian canal syndrome hook of handmade fracture and that's distal at the level of the wrist. Okay so let's just whip through the others. form supernation's [ __ ] wrong. So that's radial nerve.

[00:02:50]So the pneummonic slacronym is best extensors. So brachio radiialis just a forearm muscle you don't have to worry about. Extensors supenator triceps extensors again for redundancy but I don't know what to tell you. It's the pneummonic. So best extensors is radial nerve. So if you have and also wrist extension is radial nerve. B& or [ __ ] run. So if you have a radial nerve injury, as you guys know, that's going to be a midshaft fracture of the humorris. They could say fracture at the radial groove, which is obvious.

[00:03:25]Saturday night Pauly, dude falls asleep with his arms over the back of the chair drunk on a Saturday night. So radial nerve injury, you get a forearm that is pronated and with a wrist drop. That's the classic presentation. Say dude was in a bar fight, pronated arm with a wrist drop. That's radial nerve injury.

[00:03:45]Wrong [ __ ] answer.

[00:03:49]Choice C. Second finger flexion. So our index finger flexion. That's going to be our median nerve. Okay. So I mean I don't really know what to tell you. So most of the forearm muscle is median nerve. As we already said, thumb opposition, thumb to pinky is media nerve. If you if you have carpal tunnel syndrome, obviously you're talking about medial medial [ __ ] am I saying? Medial nerve enttrapment at the wrist. Okay, so uh that's going to be your index finger, but it doesn't apply in this case. Wrong [ __ ] answer.

[00:04:25]Thumb opposition as I already said that's median nerve and then wrist extension as as I already said that's radial nerve. So your short point of consolidation is your positive fromman sign very buzzy. This is going to be er nerve on you similly thumb adduction ular nerve even though thumb is on the lateral aspect of the hand and sounds a little bit weird.

[00:04:49]Wrong [ __ ] answer.