Anatomy question...?

Question

What does the radius rotate upon?

A) Superglenoid tubercle

B) Glenoid cavity

C) Lateral border

D) Inferior angle

E) Acromion

I was going to say acromion but am I right??

Answer 1

The radius rotates on the radial notch of the ulna (forming the proximal radioulnar joint, completed by the annular ligament.)  The radial notch is on the lateral surface of the ulna. I'd choose C.

The acromion and glenoid cavity are related to the shoulder joint, and the supraglenoid tubercle and inferior angle are on the scapula.  Of course the radius doesn't participate in that!