Session 1.2a - Gray's Anatomy for Students: Chapter 3 - Thorax - Conceptual overview Flashcards
https://www.clinicalkey.com/#!/content/book/3-s2.0-B9780702051319000031 - General description - Functions - Component parts - Relationship to other regions
What is the shape of the thorax?
An irregularly shaped cylinder
Describe the superior and inferior openings of the thorax.
Narrow opening superiorly
Relatively large opening inferiorly
(Fig. 1)
What is the superior opening of the thorax called?
Superior thoracic aperture
What is the inferior opening of the thorax called?
Inferior thoracic aperture
Which apertures of the thorax are open and closed?
The superior thoracic aperture is open
The inferior thoracic aperture is closed
What is the significance of the superior thoracic aperture being open?
It allows continuity with the neck
What is the significance of the inferior thoracic aperture being closed?
It is closed by the diaphragm
Fig. 3.1
Label and caption the image
- Diaphragm
- Ribs
- Right pleural cavity
- Vertebral column
- Superior thoracic aperture
- Mediastinum
- Left pleural cavity
- Rib I
- Manubrium of sternum
- Sternal angle
- Body of sternum
- Xiphoid process
- Inferior thoracic aperture
Thoracic wall and cavity.
Describe the thorax wall.
The musculoskeletal wall of the thorax is flexible.
What does the thorax wall consists of?
Segmentally arranged vertebrae, ribs, and muscles and the sternum.
What is the thoracic cavity enclosed by?
The thoracic wall and the diaphragm
The thoracic wall and the diaphragm enclosed what? How is this subdivided?
The THORACIC CAVITY is subdivided into three major compartments
What are the three compartments of the thoracic cavity?
- left pleural cavity
- right pleural cavity
- mediastinum
What do the left and right pleural cavities surround?
Each surrounds a lung
Describe the structure of the mediastinum
Thick, flexible soft tissue partition
Where is the mediastinum located?
Oriented longitudinally in a median sagittal position.
What does the mediastinum contain?
- Heart
- Oesophagus
- Trachea
- Major nerves
- Major systemic blood vessels
How are the pleural cavities separated from each other?
They are completely separated from each other by the mediastinum.
What is the clinical significance of the pleural cavities being separated from each other?
Abnormal events in one pleural cavity do not necessarily affect the other cavity.
What is the surgical significance of the pleural cavities being separated from each other by the mediastinum?
The mediastinum can be entered surgically without opening the pleural cavities.
Where do the pleural cavities extend?
Above the level of rib I.
Where does the apex of each lung extend?
Into the root of the neck
What is the signifiance of the apex of the lungs extending into the root of the neck?
Abnormal events in the root of the neck can involve the adjacent pleura and lung, and vice versa.
What are the functions of the thorax?
- Breathing
- Protection of vital organs
- Conduit
What does the thorax contain to aid in breathing?
One of the most important functions of the thorax is breathing. The thorax not only contains the lungs but also provides the machinery necessary - the diaphragm, thoracic wall, and ribs.
As well as the lungs, what is the machinery necessary for breathing, and what do they do?
Diaphragm, thoracic wall, and ribs - for effectively moving air into and out of the lungs.
What movements of the diaphragm change the volume of the thoracic cavity?
Up and down movements of the diaphragm
What movements of the thoracic wall change the volume of the thoracic cavity?
Changes in the lateral and anterior dimensions of the thoracic wall, caused by movements of the ribs
Movements in the diaphragm and thoracic wall alter the volume of the thoracic cavity. These are ___
key elements in breathing.
The thorax houses and protects ___
Vital organs such as:
- heart
- lungs
- great vessels
How does the thoracic wall offer protection?
Because of the domed shape of the diaphragm, the thoracic wall also offers protection to some important abdominal viscera.
What organ(s) lie under the right dome of the diaphragm?
Much of the liver lies under the right dome of the diaphragm
What organ(s) lie under the left dome of the diaphragm?
Stomach and spleen
What organ(s) lie on the diaphragm?
The posterior aspects of the superior poles of the kidneys
Where are the kidneys in relation to the ribs?
Right: anterior to rib XII
Left: anterior to ribs XI and XII
The mediastinum acts as a conduit for ___
for structures that:
- pass completely through the thorax from one body region to another
- connect organs in the thorax to other body regions
Which structures pass between the abdomen and neck, and therefore pass through the mediastinum?
Oesophagus
Vagus nerves
Thoracic duct
The oesophagus, vagus nerves, thoracic duct pass where?
Between the abdomen and neck via the mediastinum
What innervates the diaphragm?
The phrenic nerve
Where do the phrenic nerves pass?
Originate in the neck, penetrate and supplies the diaphragm - therefore passes through the mediastinum
What structures pass within the mediastinum to and from major visceral organs in the thorax?
Trachea
Thoracic aorta
Superior vena cava
The trachea, thoracic aorta and superior vena cava travel where?
These course within the mediastinum en route to and from major visceral organs in the thorax.
What are the component parts of the thorax?
- Thoracic wall
- Superior thoracic aperture
- Inferior thoracic aperture
- Diaphragm
- Mediastinum
- Pleural cavities
What does the thoracic wall consist of?
Skeletal elements and muscles (Fig. 3.1)
What is the thoracic wall made up of posteriorly?
12 thoracic vertebrae and their intervening intervertebral discs
What is the thoracic wall made up of laterally?
Formed by RIBS (12 on each side) and three layers of flat muscles, which span the intercostal spaces between adjacent ribs, move the ribs, and provide support for the intercostal spaces.
How many intercostal muscles are there?
3 layers
What sort of muscles are intercostal muscles?
Flat
Where do the intercostal muscles span?
Intercostal spaces between adjacent ribs
What do intercostal muscles do?
Move the ribs
Provide support for the intercostal spaaces
What is the thoracic wall made up of anteriorly?
The STERNUM
What makes up the sternum?
The manubrium of sternum, body of sternum and xiphoid process.
Where is the manubrium of sternum angled?
Angled posteriorly on the body of sternum at the manubriosternal joint
What is the manubriosternal joint also known as?
The sternal angle
What part of the sternum is a major surface landmark used by clinicians in performing physical examinations of the thorax?
The sternal angle
What is found at the anterior (distal) end of each rib?
Costal cartilage
Where is costal cartilage found?
The anterior (distal) end of each rib
What does costal cartilage contribute to?
The mobility and elasticity of the wall.
What do all ribs articulate with posteriorly?
Thoracic vertebrae
Which ribs have three articulations with the vertebral column?
Rib II to IX (most ribs)
Most ribs (from rib II to IX) have _____ articulations with the vertebral column.
three
What do the head of each rib articulate with?
The body of its own vertebra and the body of the vertebra above (Fig. 3.2)
As the ribs curve posteriorly, what do they also articulate with?
The transverse process of its vertebra
Which part of the rib articulates with the vertebra?
The head
Fig. 3.2
Label and caption the image
- Superior articular process
- Superior costal facet
- Costal facet of transverse process
- Intervertebral disc
- Vertebral body
- Inferior costal facet
- Inferior articular process
- Sternum
- Rib V
- Costal cartilage
Joints between ribs and vertebrae.
Anteriorly, the costal cartilages of rib I to VII articulate with ___?
The sternum
Anteriorly, the sternum articulates with ___?
The costal cartilages of ribs I to VII
The costal cartilages of ribs VIII to X articulate with ___?
the inferior margins of the costal cartilages above them.
Ribs XI and XII are called ________ ____?
Floating ribs
Why are ribs XI and XII called floating ribs?
Because they do not articulate with other ribs, costal cartilages or the sternum.
Describe the costal cartilages of ribs XI and XII.
They are small, only covering their tips
The skeletal framework of the thoracic wall provides extensive attachment sites for muscles of the ___?
Neck, abdomen, back and upper limbs.
Name 2 functions of the muscles that attach to the framework of the thoracic wall.
- A number of these muscles attach to ribs and function as accessory respiratory muscles
- Some of them also stabilise the position of the first and last ribs
Muscles that aid breathing by attaching to the ribs are known as ___?
Accessory respiratory muscles
Some muscles attaching to the framework of the thoracic wall help to stabilise the position of the _____ and _____ ribs
first and last
What is the superior thoracic aperture surrounded by?
Completely surrounded by skeletal elements
What is found posterior to the superior thoracic aperture?
The body of T1
What is found on each side of the superior thoracic aperture?
The medial margin of rib I
What is found anteriorly to the superior thoracic aperture?
Manubrium
Where is the superior margin of the manubrium?
In approximately the same horizontal plane as the intervertebral disc between vertebrae TII and TIII.
How does the first rib articulate with the manubrium?
The first ribs slope inferiorly from their posterior articulation with vertebra TI to their anterior attachment to the manubrium.
How does the plane of the superior thoracic aperture (STA) sit, and why?
At an oblique angle.
The first ribs slope inferiorly from their posterior articulation with vertebra TI to their anterior attachment to the manubrium.
Consequently, the plane of the STA is at an oblique angle, facing somewhat anteriorly.
Where does the STA face?
Somewhat anteriorly (an at oblique angle)
Where do the pleural cavities lie at the STA?
At the STA, the superior aspects of the pleural cavities, which surround the lungs, lie on either side of the entrance to the mediastinum (Fig. 3.3)
Fig. 3.3
Label and caption the image
- Rib II
- Subclavian artery and vein
- Apex of right lung
- Rib I
- Superior thoracic aperture
- Vertebra TI
- Common carotid artery
- Oesophagus
- Trachea
- Internal jugular vein
- Manubrium of sternum
Structures that pass between the upper limb and thorax pass over ___?
Rib I and the superior part of the pleural cavity as they enter and leave the mediastinum
Structures that pass between the upper limb and thorax enter and leave the ___?
mediastinum
Describe the passage of structures that pass between the neck and head and the thorax.
These structures pass more vertically through the STA.
Describe the inferior thoracic aperture (ITA).
It is large and expandable.
What forms the margin of the ITA.
Bone, cartilage and ligaments (Fig. 3.4A).
Fig. 3.4A
Label and caption the image
- Xiphoid process
- Inferior thoracic aperture
- Distal cartilaginous ends of ribs VII to X; costal margins
- Rib XI
- Rib XII
- Vertebra TXII
Inferior thoracic aperture
Fig. 3.4B
Label and caption the image
- Right dome
- Central tendon
- Left dome
- Oesophageal hiatus
- Aortic hiatus
Diaphragm
What is the ITA closed by?
The diaphragm
Structures passing between the abdomen and thorax _______ to the _______
pierce or pass posteriorly to the diaphragm.
Where are the skeletal elements of the ITA?
- Posteriorly
- Posterolaterally
- Anterolaterally
- Anteriorly
What is the skeletal element to the ITA posteriorly?
The body of vertebra TXII
What is the skeletal element to the ITA posterolaterally?
Rib XII and the distal end of rib XI
What is the skeletal element to the ITA anterolaterally?
The distal cartilaginous ends of ribs VII to X, which unite to form the costal margin anterolaterally
What is the skeletal element to the ITA anteriorly?
The xiphoid process
The joint between the ______ ______ and sternum lies roughly in the ____ _________ _____ as the _______________ ____ between vertebrae ___ and __.
The joint between the costal margin and sternum lies roughly in the same horizontal plane as the intervertebral disc between vertebrae TIX and TX.
Describe the relation between the posterior and anterior margin of the ITA.
The posterior margin of the inferior thoracic aperture is inferior to the anterior margin.
When viewed anteriorly, the ITA is tilted __________
When viewed anteriorly, the ITA is tilted superiorly.
What sort of tissue is the diaphragm
Musculotendinous