Today, we will discuss the upper extremities ... those are the arms.
There is a lot of detail here. We will not go too crazy into every little muscle, but rather focus on presenting the material in a way that is conceptually understandable. See, it is difficult for most of us to visualize some random name on a structure. We get the material much better when we understand its functionality. Asking the question of what a specific muscle does makes it much easier to understand and remember it.
Let's have a look and see who's moving your arms around...did you ever wonder?
First though, if you can, print the labelling exercise (my pre-homework) together with the term list. While you watch the videos, please label as many terms from the list as you can on the pictures. Please hand it in before class, so that I can give you credit for it:)
To learn about muscles, you best learn which part of a bone they attach to. I consolidated muscle attachment information on this spreadsheet, which I will use to teach the material. Print it out if you can to refer to it during lecture and lab.
10.1. I consider the extremity muscles in groups of their main function. In the shoulder, we find muscles that hold the scapula to the trunk, some that hold the humerus into the shoulder joint, and then we have a bunch that move the upper arm around. First, let’s anchor the shoulder to the trunk. Most of those muscles attach at the medial / vertebral area of the scapula and reach upward in the back or wrap around the ribcage pulling the shoulder towards it. In the back, we got one named Levator Scapula. I want you to visualize the muscle as it reaches from the medial, upper border of the scapula up to the side of the upper neck vertebrae (C1-4). What do you think is this muscles action?
10.2. The other muscle on the back attaching the scapula to the spine reaches from the vertebral border to the spinous processes of the upper back. What is that muscle called?
10.3. If you put the palm of your hand on top of your shoulders, you can squeeze the next muscle. It usually feels good when it is worked, because it gets tired holding the shoulder blade up over time. It is a broad one that is most superficially covering most of the upper back as well as the back of the neck. What is that muscle? (we’ve already talked about it once)
10.4. If you watch boxing, you know of this one, because it holds the scapula/shoulder to the chest. Punching things will make that muscle very strong. You can see fingerlike bulges following the ribs on the side of the chest when it contracts. To palpate it, you have to kind of reach under your armpit. The insertion onto the ribs of this muscle looks kind of like a serrated knife’s edges. What muscle am I talking about?
10.5. Lastly in this bunch, we have one muscle that starts in the front on the coracoid process. It reaches down and inward and attaches on the ribs. It’s underneath a big arm muscles that we’ll discuss soon. Can you think of the muscle that I’m talking about?
10.6. The next group of our little, red, contractile animals are concerned with holding your humerus, the upper arm bone, into the shoulder joint (the glenoid cavity). The shoulder is very flexible, yet strong. The rotator cuffs are four muscles, three of them spanning from the back of the scapula to the greater tubercle (the bump on the outside of your upper arm bone), and one reaching from underneath the scapula to the lesser tubercle (more in the front of the shoulder). Can you name those four muscles?
10.7. Raise your arm up in front (shoulder flexion). What muscles bulge and contract when you do that? The one on top of the shoulder is definitely involved. What do you call that muscle?
10.8. Another muscle that helps lift the arm up is attached in the front of your chest, right there by the ribs and chest plate. That muscle’s main pull of the humerus is towards the midline (adduction). What is that muscle called?
10.9. A thin muscle found on your side towards the back can be activated by resisting the upper arm from going backwards (extension). We find this muscle to be very developed in swimmers. Gimmy that name!
10.10. Now, let’s focus on the motion of the elbow. It mainly bends and then straightens back out. There are many muscles that help in the bending motion. Can you name two of the main ones?
10.11. And then, there is one main muscle that straightens the elbow out (extension). Which one is it?
10.12. The wrist motions are produced in the forearm. Many of the anterior forearm muscles attach to the distal humerus on the inside (medial epicondyle) and reach towards the wrist. One of them actually crosses the upper forearm and pulls the radius across the ulna, so that the palm goes down (pronation). Can you name that muscle?
10.13. Now look at the names of the other muscles in the front that flex the wrist; they are quite descriptive, especially the two that sound similar. Flexor describes the motion and carpi the insertion site. What else is described in their name?
10.14. Looking at the back of the forearm, one of the superficial muscles reaches all the way to the fingertips. What muscle is that?
Here are the youtube videos of a class lecture on the upper extremities:
The Anatomy Academy for the upper extremities is helpful if you like to read explanations of the muscles. It is not mandatory. However, I recommend you looking at the table of muscles I made on the last couple pages. It might help you have an overview of the material.
As in the last section, here are the muscle flashcards again. Use them to help you create retrieval exercises, such as flashcards. If you have to search for a muscles name in your memory and remember it, you can recall it easier at a later time, such as a test or in real life.
To study the muscle terms, here is the video them on the models used for the test.