Fascia – Cutaneous Innervation and Venous Drainage of Upper Limb

00:01 In this lecture, we are going to look at the superficial structures and cutaneous innervations of the upper limb. So we are going to look at the fascia of the upper limb. This connective tissue layer. We'll look at the superficial and deep fascia. We'll then look specifically at an example we'll look at the brachial fascia. We'll then look at the venous drainage. We will look at the cephalic vein, the basilic vein and how they run into the axillary vein and we will also look at the communication between the two known as the median cubital vein.

00:37 We'll then look at the cutaneous innervation of the upper limb. We'll look at the dermatomal distribution and then we'll move on to some specific cutaneous nerves. So here we can see we have got both an anterior and a posterior view of the upper limb. And we can see that covering all of these muscles which we are go in to detail, is a white glistening layer and this is the deep fascia. We have deep fascia and we call it deep fascia. Because we also have superficial fascia and the superficial fascia which we can't see on these pictures because that lies deep to the skin and the skin has been removed. The deep fascia is what we can see surrounding the muscles, on the superficial fascia is this loose connective tissue and fatty layer. So we can't see that because it has been removed. But it is made up of loose connective tissues and varying amounts of fats. The superficial fascia lies deep to the skin and it is therefore pierced by cutaneous nerves that supply the skin and also superficial veins. Lying between the superficial fascia and the skeletal muscle, biceps brachii for example we have the deep fascia. And the deep fascia we can see on both this anterior and this posterior view, this is white glistening layer, this white glistening membrane.

02:11 And we can see that it is covering all of the muscles we could see in the upper limb. It is made up of dense, well organized connective tissue and there is no fat. So this is just a membranous layer that surrounds the muscle. We are going to look at the example of the fascia.

02:32 Bearing in mind, we have the deep fascia lying over all of the musculature of the upper limb.

02:37 Specifically we are going to look at what's known as the brachial fascia. We can see it here anteriorly it is covering the arm. We can see it here anteriorly and we can see it here posteriorly. So this brachial fascia encloses the musculature of the arm.

02:54 So this tight cuff that is surrounding the musculature within the arm. It is continuous with superior structures of the upper limb. So it is continuous superiorly with fascia covering the deltoid, fascia covering the pectoral muscles and fascia lining the axilla. So this deep fascia is continuous across the entire upper limb. And we are just looking at the brachial fascia here anteriorly and we can see it here posteriorly. Again the continuous layer with the deltoid fascia, the axillary fascia and we can see here anteriorly the pectoral fascia.

03:32 Inferiorly, the deep fascia is going to be continuous, with what's known as the antebrachial fascia. Now antebrachial indicates the fascia surrounding the forearm. So here we have the anterior aspect of forearm and we have the antebrachial fascia covering it. And we can see we've got this continuous layer. It is also the brachial fascia attaching to the epicondyles of the humerus. And this helps to anchor it down in position. We will talk about that later on when we mention the bicipital aponeurosis. So here we can see this deep fascia running all the way along the upper limb. Some important features of it. It also extends between the muscles, so whilst it is just covering the muscles of the upper limb, it also extends deep into the arm and it attaches to the humerus. And as we'll see later on when we look at the arm in more detail. There are, in fact, two compartments in the arm and these compartment are created by the deep fascia passing down and attaching to the humerus. Therefore more known as medial and lateral intermuscular septae. So here we can see deep fascia and here we can just see this medial intermuscular septum. And this septum here is actually going to pass deep into the arm and attaches to the humerus. We also have a lateral line that is going to be on this lateral side. Here we can see it, this lateral intermuscular septum. So here we can see we have got these two septa that are passing deep attaching to the humerus.

05:14 Everything that are folded anterior to it is going to be in the anterior compartment and everything posterior to it is going to be in the posterior compartment. And here we have the two compartments of the arm. A similar arrangement occurs in most regions of both the upper limb and the lower limb. So for example in the forearm, we also have an anterior and a posterior compartment.

05:38 And when we go and look in the leg region, we will see that we have an anterior and posterior and the lateral compartments that are similarly formed via these pieces of fascia passing deep into the limb. Have a note the fascia that I have mentioned, I said the pectoral fascia that is running over the pectoralis muscles, we have got the deltoid fascia, we have got the axillary fascia and we have got the brachial fascia extending down deep into the antebrachial fascia. And these are really important. We will come back to them throughout the course when we talk about various muscles.