UW 1702- anatomy

[zeevee]

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The objective states that pectoralis major causes inferior displacement of the LATERAL segment of clavicle.Pectoral major is attached inferomedially shouldnt it displace the MEDIAL clavicle inferiorly ?

What am I missing here ?

 

[Ophthoseidon]

Think of it like a hinge. You're pulling on the medial 2/3ish of the clavicle, but the lateral side of the clavicle is moving downward

 

[zeevee]

Think of it like a hinge. You're pulling on the medial 2/3ish of the clavicle, but the lateral side of the clavicle is moving downward

cannot seem to imagine how

 

[aspiringmd1015]

bc the SCM is controlling the medial part

 

[zhopv10]

All good explanations, I'll just say, as stupid as it sounds if you flex your pectoralis major this motion is seen, it's dumb but it helps me remember those questions (yup im totally gonna be that guy in the test trying to use his own anatomy to figure out the anatomy questions)


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[Ophthoseidon]

cannot seem to imagine how

Imagine if you attached two strings to a door, one close to the hinge and one in the middle. You then stood on the hinge-side of the door, 5 feet away, and pulled those strings. The door would close, right? The "knob" side of the door comes towards you. In reality, the knob side of the door is the lateral side of the clavicle, except in a different orientation (going down, not towards you). The physics isn't perfect because the insertion on the clavicle is 100% in that orientation, but it's an easy visual.

 

[zeevee]

bc the SCM is controlling the medial part

sounds logical but look at the insertion of pectoralis major .It shud only act to bring the medial side down not lateral .

All good explanations, I'll just say, as stupid as it sounds if you flex your pectoralis major this motion is seen, it's dumb but it helps me remember those questions (yup im totally gonna be that guy in the test trying to use his own anatomy to figure out the anatomy questions)


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Yup I use my limb and trunk anatomy all the time too .I dont mind what they think of me in the test centre 🙂 .
But if you move your shoulder to use the pec major it still acts on the medial side not lateral .

I think what the question is trying to say is that in clavicular fracture the medial side STAYs in its place due to pec major ( and as aspiring md also mentioned above) and the upward pulling SCM is also in place so medial portion doesnt sag ....while the lateral part of clavicle moves down because it is unsupported by muscles and the weight of the arm is also pulling it down

 

[aspiringmd1015]

pec major also causes adduction, extension and i think internal rotation of the arm, all those features are associated with the clavicle moving inferiorly if you do it on yourself

 

[zhopv10]

Del. Misread that last post


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