Anatomy of the Thorax Flashcards
What is the general shape of the thorax?
The thorax is an irregularly shaped cylinder with a narrow superior thoracic aperture and a wider/larger interior thoracic aperture
Describe the anatomy of the superior thoracic aperture
The narrow opening at the top of the thorax that is completely surrounded by skeletal elements
What are the skeletal elements involved in the superior thoracic aperture?
- The body of vertebrae TI posteriorly
- The medial margin of rib I on each side
- the manubrium anteriorly
Describe the main functions of the thorax
- Breathing
- Protection of vital organs (including the heart, lungs, and great vessels within it and the liver, stomach, and spleen under the dome of the diaphragm)
- Conduit (channel) - the mediastinum acts as a channel for structures that pass completely through the thorax (oesophagus, vagus nerves, and thoracic duct, phrenic nerves, trachea, thoracic aorta, and superior vena cava)
What are the major compartments of the thoracic cavity?
- the left and right pleural cavity, which each surround a lung
- the mediastinum
What are the components of the thoracic wall?
- Posteriorly - 12 thoracic vertebrae and intervertebral discs
- Laterally, the wall is formed by ribs (12 on each side)
- Three layers of flat muscles that span the intercostal space between adjacent ribs
- Anteriorly, the wall is made up of the sternum
What are the components of the sternum and how are they connected?
- the manubrium
- the body
- the xiphoid process
The manubrium and the body of the sternum are connected by the manubriosternal joint (this forms the sternal angle)
Describe the positioning of the sternum (and its components) in the thoracic wall
- The manubrium of the sternum is angled posteriorly on the body of the sternum at the manubriosternal joint (forms the sternal angle)
- The sternal angle is the point where the costal cartilage (major surface landmark for examinations of the thorax)
Describe how the ribs articulate with the thoracic vertebrae (posterior and anterior)
- posterior
- The head of the rib has two articulate facets separated by bone. One facet articulates with the numerically corresponding vertebrae. The other facet articulates with the vertebrae above
- Each rib also articulates with the transverse process of its own vertebrae
- Anterior
- the costal cartilages (end of rib) of ribs 1 to 7 articulate with the sternum
- The costal cartilages of ribs VIII to X articulate with the inferior margins of the costal cartilages above them
- Rib 11 and 12 are floating ribs as they do not articulate with other ribs or the sternum
Name the skeletal elements of the inferior thoracic aperture
- Posteriorly, the body of the vertebrae TXII
- Rib XII and the distal end of rib XI posterolaterally
- The distal cartilaginous ends of ribs VII to X which merge to form the costal margin
- Xiphoid process
Describe the structure and key features of the diaphragm
- The diaphragm seals the inferior thoracic aperture
- The diaphragm is a combination of muscles and tendons, these arise from the margins of the inferior thoracic aperture and converge to form a central tendon
- The diaphragm is not flat - it balloons superiorly on the left and right hand sides to form domes (the right dome is higher)
What structures pass through the diaphragm?
- The esophagus and inferior vena cava
- Terminal branches of the right phrenic nerve
- Right and left vagus nerves
What is the mediastinum?
A thick midline partition that extends from the sternum anteriorly to the thoracic vertebrae posteriorly, and from the superior thoracic aperture to the inferior thoracic aperture
Describe the different sections of the mediastinum
Horizontal plane passing through the sternal angle and the intervertebral disc between vertebrae TIV and TV and separates the mediastinum into the superior and inferior
The inferior mediastinum is further subdivided by the pericardium
How is the inferior mediastinum subdivided?
Anterior mediastinum lies between the sternum and pericardium
The middle mediastinum is made up of the pericardium and heart
The posterior mediastinum lies between the pericardium and thoracic vertebrae
Where do you find the pleural cavities?
On either side of the mediastinum within the thoracic cavity, surrounding the lungs
Describe the linings of the pleural cavities
Each pleural cavity is lined by a mesothelial membrane called the pleura
The pleura lining the internal walls of the thoracic cavity is the parietal pleura
The pleura covering the outer surface of the lungs is the visceral pleura
There is a potential space between the visceral and parietal pleura known as the pleural cavity
What is the name the space at the bottom of the lungs/above the diaphragm?
Costodiaphragmatic recess
