Assume you have a 10-lb weight in your right hand. Explain why it is easier to flex the right elbow when your forearm is supinated than when it is pronated.

Video transcript

Hi, everyone. Let's take a look at this practice problem together, which of the following muscles has its origin, insertion and action incorrectly paired. So for this question, we'll go through one answer option at a time and discuss it completely before we move on to the next, we will review all answer options together. So option a biceps, bray, eye origin, scapula, insertion, radius, action, elbow flexion forearm. So, so the biceps is one of our arm muscles. Now recall that it has two origins and both are on the scapula. So origin is correct, the insertion is correct as well. It does insert on the radial tuberosity of the radius. And since it does cross that elbow joint, it does flex and supinate the forearm. So the action is correct. So option A is all correctly stated. So we can eliminate option A. Option B, the vastu intermedius origin femur, insertion, tibial tuberosity, action, knee extension. So the vastest intermedius recall is a muscle of the quadriceps in our legs. It does originate from the femur. So the origin is correct. The insertion is correct. It inserts on the tibial tuberosity via the quadriceps tendon and the action is correct as well, knee extension. So we can eliminate option B, option C, the rectus abdominus origin pubis, insertion, sternum and coastal cartilages of ribs, five through seven action, vertebral column, rotation and flexion. So, recall that this is the long, vertically paired muscles of the abdomen. Now, they do originate from the pubis and the insertion is the sternum and coastal cartilages and that's what makes it such a long muscle. Now, when it contracts, it does help with spinal flexion. So the action is correct as well and we can eliminate option C. Our last option, option D is Massad origin maxilla and mandible near molar insertion, orbicularis, oris and action, hip extension, cheek compression. So option D is the correct answer. The origin, insertion and action are all incorrect. The mass, the origin is the Zygomatic process. The insertion is the mandible and the action is for mastication or chewing. So the correct answer again is option D maser origin maxilla and mandible near molar insertion, ocular aus and action, hip extension, cheek compression. All right, everyone. I hope you found this helpful and I'll see you soon for the next practice problem.