Anatomy of the Lymphatic System: Introduction

00:01 In this topic, we're going to have a look at the lymphatic system across the abdominopelvic region.

00:07 So, let's first of all just remind ourselves of some basic principles of the lymphatic system.

00:13 So, here we can see the left side of the heart, which is very much giving rise to arteries that go to supply various organs with oxygenated blood via the various capillaries.

00:23 That blood is then going to pass through the organs via capillaries and returned to the right side of the heart via the venous system.

00:31 As a consequence of this activity at the cellular level, there's often some excess fluid that also needs to be drained away.

00:40 And this is done via the lymphatic system.

00:42 Primarily associated with the organs, we have a number of lymphatic vessels, and these will pass through lymph nodes, as they then ultimately go towards the right side of the heart like series of collecting ducts, which we'll come to in a moment or so.

00:57 So, there's a series of tubes really.

01:00 Some associated taking oxygenated blood and nutrients to organs.

01:05 Others then taking that venous blood back to the heart or elsewhere for it to be replenished.

01:12 But there's also another set of tubes.

01:14 These lymphatic vessels that form the lymphatic system that helped to take some of the extracellular fluid back towards the heart so it can enter into the circulatory system.

01:25 So, let's have a look at a typical lymph node, which is going to receive these afferent lymphatic vessels.

01:32 So, these afferent lymphatic vessels are going to arrive at the lymph node.

01:36 They're going to pass through the lymph node, and they're going to leave via these efferent lymphatic vessels.

01:43 Here if we look at a lymph node, we can see it's surrounded by a capsule.

01:47 And there's various segments within this node, which are demarcated by these trabecular.

01:52 We can see inside the node there is a cortex and an inner medulla.

01:57 And these helps a lymph node to carry out its function.

02:00 Partly starting to filter some of this fluid that's passing into them.

02:05 So with that basic structure, let's just have a look at some of the flow of how the lymph moves through the various lymph nodes.

02:12 So, here we can see the afferent lymphatic vessels is taking the lymphatic fluid towards the lymph node, and then it passes to some subcapsular sinus here.

02:21 We also have an intermediary sinus that allows the lymphatic fluid to pass through the node and allowing the filtering process to occur.

02:29 We're going to see enters into this medullary sinus before it passes out via an efferent lymphatic vessel.

02:36 And there's always fewer efferent lymphatic vessels leaving the lymph node than there are afferent vessels entering into it.

02:43 So here let's have a look at the general overview of the lymphatic system within the body.

02:49 So, it's intimately associated with the venous system because that's how the lymphatic fluid can then pass towards the right side of the heart.

02:57 Here we have the left internal jugular vein and the left subclavian vein indicated.

03:02 And this is important because the thoracic duct passes into the connection between these two venous structures.

03:09 On the right hand side we have a slightly different pattern.

03:12 Here we have the right internal jugular vein and the right subclavian vein.

03:17 And here we have the right lymphatic duct that passes.

03:20 But actually if we were to look outwards, we can see the distribution and the map of lymphatic drainage is quite different.

03:28 The thoracic duct which I indicated previously takes the lymph fluid from the vast majority of the body except this upper right quadrant.

03:38 The upper right quadrant is served just by the right lymphatic duct.

03:42 The thoracic duct will receive the lymph from the rest of the body, so the lower half of the body and the upper left quadrant.