Description

This video covers the diaphragm, including its parts, origin points, openings, and coverings.

Diaphragm Parts

• Central Tendinous Part
• Muscular Part
• Main Muscle of Inspiration

Origin Points

• Lumbar Part
  • Right Crus: Crus dextrum
  • Left Crus: Crus sinistrum
  • Suspensory Muscle of Duodenum: (Muscle of Treitz)
• Lateral Arcuate Ligament (Quadratus Lumborum Muscle)
• Median Arcuate Ligament (Aorta)
• Medial Arcuate Ligament (Psoas Major Muscle)
• Costal Part
• Sternal Part
• Xiphoid Process of Sternum

Openings of the Diaphragm

Caval Opening (Foramen Venae Cavae)

• Structures Passing Through:
  • Inferior Vena Cava
  • Right Phrenic Nerve

Oesophageal Hiatus (Hiatus Oesophageus)

• Structures Passing Through:
  • Esophagus
  • Vagus Nerve (N. Vagus)

Aortic Hiatus (Hiatus Aorticus)

• Structures Passing Through:
  • Aorta
  • Thoracic Duct

Sternocostal Triangle (Trigonum Sternocostale)

• Structures Passing Through:
  • Internal Thoracic Vein
  • Internal Thoracic Artery

Lumbocostal Triangle (Trigonum Lumbocostale)

• Also known as “Bochdalek’s Foramen“

Lumbar Part (Pars Lumborum)

• Structures Passing Through:
  • Sympathetic Trunk
  • Splanchnic Nerves
  • Azygos Vein

Coverings of the Diaphragm

• • Endothoracic Fascia (Fascia Endothoracica)
  • Diaphragmatic Part of Parietal Pleura

• Endoabdominal Fascia (Fascia Endoabdominalis)
• Peritoneum

Transcript

Introduction
0:03
What’s up. Meditay here and in this video, we’ll be covering the whole anatomy of the Diaphragm.
0:08
Aight, so here you see the anterior view of the thorax and the abdomen. The Lungs, as you see
Diaphragm Function
0:13
here, are located within the thoracic cavity. While organs like your liver, and intestines,
0:18
are a part of the abdominal cavity. Now between the Thoracic cavity and the abdominal cavity,
0:24
there’s gonna be a large muscle called the Diaphragm, which is our muscle for today.
0:26
Just by looking at the diaphragm, you can see that it consists of two main parts. There’s a
0:31
central tendinous part, and a muscular part around the central tendinous part. And the main reason
0:37
why we need to diaphragm, is because when the muscle fibers contract, they’ll pull the central
0:42
tendinous part down. That’ll increase the volume of the thoracic cavity, and decrease the pressure,
0:48
so that air can easily come in into the lungs. So the diaphragm is our main muscle of
0:52
inspiration. One that e can’t live without. So let’s go ahead and isolate the diaphragm
Content
0:57
and understand the actual anatomy of it. So in this video, we’ll first cover the
1:02
three origin points. Which are the Lumbar part, the costal part and the sternal part.
1:06
After that, we’re going to look at the openings of the diaphragm, basically which
1:10
structures go through it. and then we’ll see what type of coverings it has from both sides.
1:15
So, let’s start with the origin points, and do the lumbar part first.
Lumbar Origin
1:19
Now the lumbar attachment of the diaphragm is from this area so let’s go ahead and focus on that.
1:24
The main thing you can see looking at the lumbar part of the diaphragm
1:28
are two muscular fibers going down along the vertebral column, called the Right crus,
1:33
and the Left Crus. The right crus being longer than the left crus as you see here.
1:38
Don’t get confused by this long structure here, it’s called suspensory muscle of the duodenum. It
1:43
just goes down and grabs the duodenum to keep a certain part of it flexed. It’s not a part
1:49
of the origin points and it’s not a part of the lumbar part, so don’t mind this structure for now.
1:54
Aight. So the right Crus is going to go down, and attach at the vertebral bodies of L1 to L4.
2:00
It really depends on person to person on how long this crus will reach,
2:04
as you see here. But generally, L1-L4 vertebral bodies are where the right crus will attach on.
2:10
The Left crus is going to attach on the vertebral bodies of L1 to L3. So that’s these. Another thing
2:17
you’ll find in the lumbar region, are certain ligaments that’s going to provide extra attachment
2:22
points for the diaphragm. These are the Lateral Arcuate Ligament, and the Medial Arcuate Ligament.
2:27
The Medial Arcuate ligament is going to attach from the bodies of around L1-L2,
2:33
and to the costal process of L1. And then the Lateral arcuate ligament will go from the costal
2:38
process of L1, to the 12th rib. The Third Ligament which make up kind of a border for the diaphragm
2:45
and provide extra attachment points, is the median arcuate ligament, as you see here going
2:50
between the right and left crus. Now. Underneath the lateral arcuate ligament, you’ll see the
2:55
Quadratus lumborum being bordered by it. And under the Medial Arcuate ligament, you’ll find the Psoas
3:01
Major muscle. Now can you guess what structure go underneath the median arcuate ligament?
3:07
Here’s a hint. It’s the Aorta! So that was the main points that
3:10
I wanted to get across when we talk about the Lumbar part of the origin points of the diaphragm.
Costal Origin
3:15
Other origin areas are the costal part, or costal attachment. Because as you see here. It’s also
3:21
going to originate at the inner surface of the 12th to the 7th rib, as you see here. And then
Sternal Origin
3:26
when it reaches the top side of the diaphragm, it’s going to originate behind the sternum as
3:31
the sternal part. So if we focus on this region. You’ll see that it originates also
3:36
from the xiphoid process of the Sternum. So that was all the origin points of the
3:42
Diaphragm. The Lumbar Part, The costal part and the Sternal Part. So fibers go from these areas,
3:48
and they insert at the central tendinous part, to pull it down, and help bring air into the lungs.
3:54
Awesome. I hope the diaphragm make a little more sense now.
Openings of the Diaphragm
3:57
Now let’s talk about the openings of the Diaphragm.
4:00
The main openings here are the Caval Opening, or foramen vena cava.
4:04
The Esophageal Hiatus, and the Aortic Hiatus! Other openings we can find are the Sternocostal
4:11
Triangle, and the Lumbocostal Triangle. As well as a small opening on the lumbar part as well.
4:16
So let’s start by looking at the diaphragm from this perspective
4:19
We’ll see that it look like this. Again the three main openings
4:23
are the Aortic Hiatus. Esophageal Hiatus, and the Caval Opening.
4:28
From the Aortic Hiatus, you’ll find mainly the aorta going through it,
4:32
as well as the thoracic duct. It’s a lymph duct. The Esophageal Hiatus is going to provide an
4:38
opening for the Esophagus to continue as the stomach. As well as a passageway for nervus vagus.
4:43
The Caval Opening, is going to provide an opening for the Inferior Vena Cava to bring
4:48
blood back into the right atrium of the heart. As well as a passageway for the right phrenic nerve.
4:53
So that was the three main openings of the diaphragm.
Sternocostal Triangle
4:56
Then we have other small openings on the Diaphragm.
5:00
You see we have the Costal Cartilage, The sternum and the diaphragm.
5:03
These three structures are going to form a triangle called the sternocostal triangle.
5:08
Through the Sternocostal triangle, mainly you gonna see the Internal Thoracic Vein and the
5:13
Internal Thoracic Artery. So that’s this one. The Next triangle is a little special one.
Lumbocostal Triangle (Bochdalek’s Foramen)
5:18
It’s called the Lumbocostal Triangle. Chances are you’ve probably been searching around trying
5:23
to understand the lumbocostal triangle, but there’s not much written about it anatomically.
5:28
The reason is because It’s not a structure we should have.
5:31
The lumbar triangle is actually a defect in the diaphragm, at around in this region. It is
5:37
formed by the incomplete closure of the canal between the pericardium and the peritoneum,
5:42
called pericardioperitoneal canal. It’s it usually closed off by the pleuroeritoneal membrane.
5:48
This defect look like this. And in sources you might find the lumbocstal triangle being
5:53
called Bochdalek’s foramen. Now this opening in adults is a potential opening for hernia,
5:59
where a part of the intestine can get squeezed out so that it bulges into the thoracic cavity.
6:04
SO that’s this one. Then we have numerous structures perforating the muscular part of
Lumbar Openings
6:09
the lumbar region of the diaphragm. Those can be structures like the azygos vein, and the
6:14
Splanchnic trunk and the sympathetic trunk. Now lastly, let’s understand how
Coverings of the Diaphragm
6:19
the diaphragm is covered. Aight. The Part of the Diaphragm
6:22
that faces the thoracic cavity, is covered by the Endothoracic Fascia, which is a fascia that covert
6:28
eh internal lining of the thoracic cavity. The endothoracic fascia have a diaphragmatic part,
6:36
in which it’s going to go over the diaphragm and cover it as well. Another thing that’s going to
6:41
covert he diaphragm is the parietal pleura of the lungs. That’s the coverings of the
6:44
lungs. The part covering th diaphragm is called the Diaphragmatic Surface.
6:50
The Part of the Diaphragm that faces the Abdominal Cavity, it covered by the endoabdominal fascia,
6:55
as well as the peritoneum. So that was everything I had for the anatomy of the Diaphragm. I really
7:01
hope this video made sense and that it helped you get a complete overview of the Diaphragm.