Key Features of Thoracic Anatomy

Hello, in this video we're going to look at anatomy of the thorax. So here I'm drawing the ribcage, the thorax area from an anterior view. And here at the back is our vertebrae, the thoracic vertebrae. We have 12 in total, so T1 all the way to T12. And I'm also adding the lumbar one, the lumbar vertebrae number one. Coming off the thoracic vertebrae 12, so T12. we have the 12th rib, which is a floating rib here. Here is our clavicle and scapula. Now the ribs originate from the vertebra and connect to the sternum. The ribs actually joining to the sternum form cartilage, allowing for the expansion of the thorax during respiration. The sternum itself forms three parts, the manubrium of the sternum, the body of the sternum, and the xiphod. process of the sternum. Drawing the sternum from a side view now, it is important to appreciate an important landmark which is marked by the sternal angle between the manubrium and the body of the sternum. This surface marking is also referred to as the angle of Louis. On the side view of the sternum we can see the insertion points of the ribs. Rib 1 attaches onto the manubrium, rib 2 to the sternal angle, rib 3 to 6 to the body of the sternum. And here is the zippisternal joint. And on top here is the clavicular notch where the clavicle attaches. The clavicle and sternum make up the sternoclavicular joint. Now as I said, the sternal angle or the angle of Lewy is an important landmark because many structures can be found along this angle. So if we were to cut straight along a horizontal plane along the sternal angle we will hit and find these things such as the joint between thoracic vertebra 4 and 5 so T45. The second rib articulation occurs here. We can find the aortic arch, zygus vein as well. I'm entering into the heart. We have the ligamentum arteriosus. We have the left recurrent laryngeal nerve. We can also find the bifurcation of the pulmonary trunk and bifurcation of the trachea. Now let's talk a bit more about ribs. So ribs can be divided into true, false, and floating. True ribs are also known as the vertebrocostal ribs, which are ribs one to seven. These are ribs that originate from the vertebra and join to the sternum through the costal cartilages. Then you have false ribs or vertebro-bronchocondral ribs, which are ribs 8, 9, 10. And these ribs originate from the vertebra and attach to the sternum by joining to the cartilages of ribs 6 and 7. Finally you have floating ribs or the vertebra free ribs which are ribs 11 and 12. These are the ribs that originate from the vertebra but don't attach anywhere. Our ribs can also be divided into typical and atypical. Typical ribs are ribs with similar features, typical features and these ribs are ribs 3 to 9. Atypical ribs are different from each other and other ribs. and our ribs 1, ribs 2, and ribs 10 to 12. Okay, now let's look at a posterior view of the thoracic the thorax, the rib cage. Here I'm drawing the vertebrae again, the clavicle and scapula, and here are the ribs, here are ribs 1 to 12. Here is the scapula and clavicle, and here is the lumbar vertebra 1. Let's talk about the vertebrae quickly, just for a quick recap. We are looking at a vertebra from a superior view. This is T1, and here is the body. The vertebral foramen is where the spinal cord goes through. The penuncle, we have the transverse process, and then we have the spinous process, which we can actually feel when we palpate along the spine. So here is the thoracic vertebra. 6, T6, which is very similar to the previous vertebra, but Something else that is very important to introduce is the facets where ribs articulate. And this is specifically for the thoracic vertebrae because they have ribs coming off them. Finally, we have T12. Very much the same with other thoracic vertebrae. But T12 especially becomes bigger when we go towards the lumbar vertebrae. Okay, next. Let's look at where organs and other things lie in respect to the thoracic cavity. So this is an anterior view again. Now roughly along the fifth rib is where the diaphragm sits. Important landmarks to remember is the midclavicular, which is essentially the site from if we draw a line from the middle of the clavicle down. So this is midclavicular. There's also midscapular, which is a landmark at the back, the middle of the scapula. The midaxillary is the landmark for the lateral aspects of the thorax along the armpits. These landmarks are important to know because of several reasons, one of which is to help identify where the lung sits in respect to the thoracic cavity and also the pleural flow or the pleura itself. So next, let's talk about... the surface landmarks of the lung itself and also the parietal pleura. So again the pleura is essentially a membrane that covers our lungs and the pleura can be divided into parietal and visceral pleura. Visceral pleura is the one that covers all our lungs and the parietal pleura is the layer above it. So the margins of the lung, midclavicular, it goes to the sixth rib, midaxillary to the eighth rib, and midscapula, the tenth rib. So the margins of the lung, midclavicular, it goes to the sixth rib, midaxillary to the eighth rib, and midscapula, the tenth rib. So if I were to draw it out on this diagram, it would be something like this. So Mid axillary it goes to the eighth rib, the lung, and then mid clavicular it is on the sixth rib, and at the back mid scapula the lung margin is on the tenth rib. The pleura here in blue goes further down. You essentially add two to find the margins of the pleura. So mid axillary it's at rib 10, mid clavicular it's rib 8. So margin of the pleura mid clavicular plus two is 8, mid axillary is 10, and mid scapula is 12. I hope that makes sense. Now the margins of the lung and pleura on the left side of the thorax is slightly different because of where the heart is situated. The heart sits somewhere here because remember the aorta goes up and it's behind the sternal angle. Again here in red I'm drawing the margins of the lung. The margins of the lung on the left side, instead of being mid clavicular on the sixth rib, it is mid clavicular on the fourth rib. It goes down to being mid axillary on the eighth rib, then everything else is the same. So it's just where the heart is that makes the left and right lung margins and pleura margins slightly different. Just to finish off this diagram, the liver or most of the liver can be found under our ribs for protection. Now let's look at what problems can occur in the thoracic cavity. Let's look at a pulmonary collapse, a result of a pneumothorax. A collapsed lung is also referred to as atelectasis. So normally here is our lung, surrounding our lung is the visceral pleura, then our parietal pleura. In between the visceral and parietal pleura we have the pleural cavity, which helps lubricate the layers and keep them stuck together. And here is the cardiac area where the heart sits. Remember air moves in and out as we inhale and exhale. A pneumothorax can occur because of something external puncturing the pleural layer. the parietal layer, resulting in air moving into the pleural cavity. This results in air filling the parietal pleura, the pleural cavity, and forcing the lungs to deflate essentially. So injury results in puncture, so injury results in puncturing of the parietal pleura. The punctured parietal pleura allows air to enter the pleural cavity. Air entering the pleural cavity compresses the lung resulting in a collapsed lung. However, what we looked at was pneumothorax occurring as a result of an external trauma. What is important to know is that a pneumothorax can also occur when the lung and visceral pleura is damaged. resulting in air filling the pleural cavity causing a pneumothorax as well. This can be seen in lung diseases such as COPD or in tall skinny people who have predisposition for spontaneous pneumothorax. So I hope you enjoyed this video, thank you for watching.

We have 12 in total, so T1 all the way to T12. And I'm also adding the lumbar one, the lumbar vertebrae number one. Coming off the thoracic vertebrae 12, so T12.

we have the 12th rib, which is a floating rib here. Here is our clavicle and scapula. Now the ribs originate from the vertebra and connect to the sternum. The ribs actually joining to the sternum form cartilage, allowing for the expansion of the thorax during respiration. The sternum itself forms three parts, the manubrium of the sternum, the body of the sternum, and the xiphod.

process of the sternum. Drawing the sternum from a side view now, it is important to appreciate an important landmark which is marked by the sternal angle between the manubrium and the body of the sternum. This surface marking is also referred to as the angle of Louis.

On the side view of the sternum we can see the insertion points of the ribs. Rib 1 attaches onto the manubrium, rib 2 to the sternal angle, rib 3 to 6 to the body of the sternum. And here is the zippisternal joint.

And on top here is the clavicular notch where the clavicle attaches. The clavicle and sternum make up the sternoclavicular joint. Now as I said, the sternal angle or the angle of Lewy is an important landmark because many structures can be found along this angle.

So if we were to cut straight along a horizontal plane along the sternal angle we will hit and find these things such as the joint between thoracic vertebra 4 and 5 so T45. The second rib articulation occurs here. We can find the aortic arch, zygus vein as well.

I'm entering into the heart. We have the ligamentum arteriosus. We have the left recurrent laryngeal nerve.

We can also find the bifurcation of the pulmonary trunk and bifurcation of the trachea. Now let's talk a bit more about ribs. So ribs can be divided into true, false, and floating.

True ribs are also known as the vertebrocostal ribs, which are ribs one to seven. These are ribs that originate from the vertebra and join to the sternum through the costal cartilages. Then you have false ribs or vertebro-bronchocondral ribs, which are ribs 8, 9, 10. And these ribs originate from the vertebra and attach to the sternum by joining to the cartilages of ribs 6 and 7. Finally you have floating ribs or the vertebra free ribs which are ribs 11 and 12. These are the ribs that originate from the vertebra but don't attach anywhere.

Our ribs can also be divided into typical and atypical. Typical ribs are ribs with similar features, typical features and these ribs are ribs 3 to 9. Atypical ribs are different from each other and other ribs. and our ribs 1, ribs 2, and ribs 10 to 12. Okay, now let's look at a posterior view of the thoracic the thorax, the rib cage. Here I'm drawing the vertebrae again, the clavicle and scapula, and here are the ribs, here are ribs 1 to 12. Here is the scapula and clavicle, and here is the lumbar vertebra 1. Let's talk about the vertebrae quickly, just for a quick recap. We are looking at a vertebra from a superior view.

This is T1, and here is the body. The vertebral foramen is where the spinal cord goes through. The penuncle, we have the transverse process, and then we have the spinous process, which we can actually feel when we palpate along the spine.

So here is the thoracic vertebra. 6, T6, which is very similar to the previous vertebra, but Something else that is very important to introduce is the facets where ribs articulate. And this is specifically for the thoracic vertebrae because they have ribs coming off them.

Finally, we have T12. Very much the same with other thoracic vertebrae. But T12 especially becomes bigger when we go towards the lumbar vertebrae. Okay, next.

Let's look at where organs and other things lie in respect to the thoracic cavity. So this is an anterior view again. Now roughly along the fifth rib is where the diaphragm sits. Important landmarks to remember is the midclavicular, which is essentially the site from if we draw a line from the middle of the clavicle down. So this is midclavicular.

There's also midscapular, which is a landmark at the back, the middle of the scapula. The midaxillary is the landmark for the lateral aspects of the thorax along the armpits. These landmarks are important to know because of several reasons, one of which is to help identify where the lung sits in respect to the thoracic cavity and also the pleural flow or the pleura itself. So next, let's talk about...

the surface landmarks of the lung itself and also the parietal pleura. So again the pleura is essentially a membrane that covers our lungs and the pleura can be divided into parietal and visceral pleura. Visceral pleura is the one that covers all our lungs and the parietal pleura is the layer above it. So the margins of the lung, midclavicular, it goes to the sixth rib, midaxillary to the eighth rib, and midscapula, the tenth rib. So the margins of the lung, midclavicular, it goes to the sixth rib, midaxillary to the eighth rib, and midscapula, the tenth rib.

So if I were to draw it out on this diagram, it would be something like this. So Mid axillary it goes to the eighth rib, the lung, and then mid clavicular it is on the sixth rib, and at the back mid scapula the lung margin is on the tenth rib. The pleura here in blue goes further down.

You essentially add two to find the margins of the pleura. So mid axillary it's at rib 10, mid clavicular it's rib 8. So margin of the pleura mid clavicular plus two is 8, mid axillary is 10, and mid scapula is 12. I hope that makes sense. Now the margins of the lung and pleura on the left side of the thorax is slightly different because of where the heart is situated.

The heart sits somewhere here because remember the aorta goes up and it's behind the sternal angle. Again here in red I'm drawing the margins of the lung. The margins of the lung on the left side, instead of being mid clavicular on the sixth rib, it is mid clavicular on the fourth rib.

It goes down to being mid axillary on the eighth rib, then everything else is the same. So it's just where the heart is that makes the left and right lung margins and pleura margins slightly different. Just to finish off this diagram, the liver or most of the liver can be found under our ribs for protection.

Now let's look at what problems can occur in the thoracic cavity. Let's look at a pulmonary collapse, a result of a pneumothorax. A collapsed lung is also referred to as atelectasis.

So normally here is our lung, surrounding our lung is the visceral pleura, then our parietal pleura. In between the visceral and parietal pleura we have the pleural cavity, which helps lubricate the layers and keep them stuck together. And here is the cardiac area where the heart sits.

Remember air moves in and out as we inhale and exhale. A pneumothorax can occur because of something external puncturing the pleural layer. the parietal layer, resulting in air moving into the pleural cavity. This results in air filling the parietal pleura, the pleural cavity, and forcing the lungs to deflate essentially.

So injury results in puncture, so injury results in puncturing of the parietal pleura. The punctured parietal pleura allows air to enter the pleural cavity. Air entering the pleural cavity compresses the lung resulting in a collapsed lung.

However, what we looked at was pneumothorax occurring as a result of an external trauma. What is important to know is that a pneumothorax can also occur when the lung and visceral pleura is damaged. resulting in air filling the pleural cavity causing a pneumothorax as well.

This can be seen in lung diseases such as COPD or in tall skinny people who have predisposition for spontaneous pneumothorax. So I hope you enjoyed this video, thank you for watching.

Transcript for:Key Features of Thoracic Anatomy

Transcript for:
Key Features of Thoracic Anatomy