Radius – Bones and Surface Anatomy of Upper Limb

00:01 So now let's look at the radius, this is the bone that lies on the lateral aspect of the forearm and again we've got anterior, posterior and the medial or an ulnar view which we can see in this picture here on the slide. The radius is shorter than the ulna and it's positioned more laterally.

00:24 Proximally we have got some details that I'd like to talk about. We have got the head of the radius and that is going to articulate with the capitulum of the humerus. But importantly the head also articulates with the radial notch of the ulna and these two bony features articulations with the capitulum, articulations with the radial notch allow a complex arrangement of movement. So we can see we have flexion of the wrist joint and we also have the ability to supinate and pronate, where we turn the forearm over. The two bones of the forearm can turn over and that supination and pronation we'll talk about that later on. But this is allowed to happen because of the bony features we can see on the radius. So the head of the radius here, it is going to articulate with the capitulum of the humerus and then the head of the radius also articulates with the radial notch of the ulna. So we can see the head here. We can see the head on this posterior view and also on this medial or the ulna view of the radius. The shaft, again it has got the sharp interosseous border, just like the ulnar did, allowing interosseous membrane to articulate and the shaft of the radius is going to widen quite distally. And again we have a radial styloid process that can be palpated on the lateral aspect of the radius.

01:53 If you have a few more details looking at this distal end of the radius, then we can see we have an ulnar notch. We can see here in this allows articulation with the head of the ulna, we can see this clearly on the medial view which is the ulnar view so we can see that clearly here. We have got the ulnar notch allowing articulation with the head of the ulna. As I have mentioned we have got the radial styloid process and we have also got the radial styloid notch as well, most laterally within the radial.

02:27 We also have what is known as the dorsal tubercle and this dorsal tubercle is important as it acts as a pulley for the extensor muscles of the thumb and we will cover these in more detail when we look the extensor muscles within the forearm. And it's important to remember this dorsal tubercle on this posterior surface of the radius allowing various muscles to attach the joint at a slightly different angle. So here we can see how series of bony landmarks on the radius.