Would you expect to find larger motor units in the postural muscles of the back or the muscles of the hand? Explain your answer.

Video transcript

Hey, everyone. Let's take a look at this question together which of the following has large motor units. Is it answer choice? A the muscles of the tongue? Answer choice B, the triceps rachi in the upper arm, answer choice C the extra ocular muscles in the eyes or answer choice D the orbicularis oris in the face. Let's work this problem out together to try to figure out which of the following answer choices contains large motor units. So in order to solve this question, we have to recall what large motor units are responsible for and where they are found to determine which of the following answer choices is the correct answer. And we know that large motor units are found in muscles involved in forceful actions. Since those muscles require larger motors to generate enough strength for actions such as pushing or pulling, which those actions of pushing or pulling are sometimes related to parts of the arms and the legs which we can see. Answer choice B which says the triceps, brachii in the upper arm, which we know that the triceps bra in the upper arm is a powerful extensor muscle that is used to straighten the elbow joint of which the triceps bra in the upper arm is an example of a muscle with larger motor units. So answer choice B is the correct answer and answer choice. AC and D are all in correct. Since the muscles of the tongue, the extraocular muscles in the eyes and the orbicularis oris in the face are all muscles involved in fine or delicate movements which utilize small motor units and not large motor units. So they are incorrect. And answer choice. B is the only correct answer choice. I hope you found this video to be helpful. Thank you and goodbye.