hi everyone this is dr fox let's talk about the thorax
in this video we'll discuss the osteological and muscular boundaries of the thorax
and also the divisions and the major contents of the thoracic so let's start with the bones
the thorax is probably best conceptualized as a bony cage there are 12 thoracic vertebrae from t1
to t12 and each of these vertebrae is associated with a pair of ribs or costi
10 of the 12 ribs are going to connect along the medial border to a sternum via costal cartilages
this is hyaline cartilage between these ribs are intercostal spaces and the intercostal spaces
are comprised of three major layers of muscle external internal and innermost intercostal
as well as the neurovasculature that serves these muscles
now two of the ten ribs are known as floating ribs
because they typically do not connect to the sternum and we'll discuss these more when we
discuss the kidneys now if we look along the antero inferior border
of the rib cage we have a cartilaginous margin called the costal margin
or costal arch this is the inferior most osteological feature of the anterolateral ribcage
and it's along this margin anterolaterally that the diaphragm is going to connect that diaphragm
is a muscular division between the thoracic cavity superiorly and the abdominal pelvic
cavity inferiorly now let's take a closer look at the sternum the sternum is going to overlay
the mediastinum which is going to be a central feature of the thoracic cavity as we'll see
and there are important viscera in the mediastinum such as the heart
the sternum is tripartite there's a manubrium a body and a xiphoid process
the manubrium is the most superior element of the sternum and at its superior edge there's
a jugular notch you can go ahead and palpate that jugular notch and along its inferior border
it creates a sternal angle with the body this sternal angle sometimes called the angle of
lewis is what sets the anterior border for the thoracic plane so if we were to imagine
moving posteriorly from this sternal angle back to the intervertebral disc of t4 t5
that will be the thoracic plane it's also here at this sternal angle
that the second ribs are going to attach via their costal cartilages
now let's take a deeper look at the thoracic cavity
so there are three spaces within the thoracic cavity there are paired pulmonary cavities
laterally these pulmonary cavities are going to contain the lungs and the serosal
membranes that encase the lungs called the pluri the pluri are a double membrane so there is a
parietal part which will adhere to the external walls and floors and medial contents and then
there's a visceral part that adheres directly to the lungs themselves and then there will be
a pleural cavity in between the parietal and visceral part medial to these pulmonary cavities
is an area called the mediastinum that mediastinum is the central element
of the thoracic cavity it's going to contain a lot of key viscera such as the heart within the
pericardium the great vessels that are delivering blood to and from the heart the thymus gland um
various neurovasculature throughout and this will be a a focus of some of our subsequent sessions
so we've discussed the bony thorax and some of the muscular portions of the walls and floor
of the thorax we've talked about the features of the osteology we've discussed the thoracic cavity
and its divisions the pulmonary cavities and
the mediastinum and their major contents this is your summary slide thank you for your time