Session 2 - Bony thorax and Chest Wall Flashcards
What is the bony thorax made up of?
Thoracic vertebrae Ribs Intercostal spaces Sternum Costal Cartilages
How many ribs and thoracic vertebrae in the bony thorax?
12
What is the sternum made up of?
- Manubrium
- Body
- Xiphisternum
How are ribs 1-7 connected to the sternum?
• Via the costal cartilages
How are ribs 8-10 connected?
• Connected to the costal cartilages above
Why are ribs 11 & 12 known as “floating ribs”
• End free in the abdominal muscles
What is the sternal angle?
• The junction of the manubrium and body
How can we identify the 2nd costal cartilage?
Articulates with the ribs at the level of the costal cartilage
Outline the features of a typical rib and the number of articular facets on each
• The head - has 2 articular facets, for articular with corresponding vertebrae and vertebra above
• Neck - Connects the head of the rib with the body
• The tubercle - has 1 articular facet, articulation with transverse process of corresponding thoracic vertebra
• The shaft - thin, flat and curved
Costal groove of the shaft, protects intercostal nerves and vessels
What is the joint of the head of the ribs called?
Costoverterbral joint
What are the articulations involved in the costoverterbral joint?
• The head of the rib articulates with the body of the corresponding verterbra and the verterbra above
Where do the movements of the costoverterbral joints occur?
Joint of the rib head
Costotranverse joint
What are the articulations of the costotransverse joint?
• The articular facet on the tubercle of the rib articulates with the transverse process of the corresponding vertebra
How many thoracic vertebrae are there and describe their size
• 12 thoracic vertebrae
• Increase in size as you move inferiorly
Are medium sized.
Give some distinguishing features of thoracic vertebrae
- Have facets on the side of the body (demi facets) for articulating with the head of the ribs.
- Have facets on the transverse process (except T11 & T12). Are costal facets for articulations with tubercles of the rib
- Have small and circular vertebral foramen
How many processes do the thoracic vertebra have for articular connections?
Seven
Where are bilateral costal facets located?
• Ön the vertebral bodies, usually occurring in inferior and superior pairs
Articulate with the heads of ribs
What are the costal facets?
• Found on the transverse processes for articulation with the tubercles of ribs
Not found on inferior two or three thoracic vertebra
What is the joint of the rib head?
• The head of the rib articulates with the corresponding vertebra an the vertebra above
What is the costotransverse joint?
• The articular facet on the tubercle of the rib articulates with the tranverse process of the corresponding vertebra
Give some identifying features of the first rib
- First rib is shortest, broadest & most curved
- The head has a single facet for articulation with T1
- Two transversely directed grooves crossing its superior surface for subclavian vessels
What are the transverse grooves of the first rib seperated by?
Scalene tubercle
Give two distinct features of the second rib
- Two articular facets for articulation with the bodies of T1 and T2
- Rough area on its upper surface, the tuberosity for serratus anterior
How are the 10th - 12th rib weird?
• Single articular facet for articulation with single vertebra
How are the 11th and 12th ribs different from the rest?
- Both floating
- single facet on head
- no tubercles
What muscles lie in the intercostal spaces?
• 3 intercostal muscles
○ External
○ Internal
○ Innermost
What is the neurovascular bundle?
• The neurovascular bundle runs in the costal groove at the lower border of the rib
What are the nerve roots of the intercostal rami?
T1 - T12
Where do the intercostal nerves run?
Internal & innermost intercostal muscles
What do the intercostal nerves supply?
• Supply intercostal muscles, the parietal pleura , overlying skin
Which way do the fibres of the external intercostal muscles run?
Downwards and anteriorly
What is the function of the external intercostal muscles?
- Inspiratory muscles
- Its action elevates the ribs in a “bucket hand” type of movement to increase antero posterior and transverse diameters of the chest
- Responsible for 30% of chest expansion during quiet respiration
What is the function of the internal intercostal muscles?
• Muscle fibres run downwards & posteriorly from the rib above to the rib below, pulling the ribs down from their position of chest expansion
Used during forced expiration
What is the function of the innermost intercostal muscles?
Similar to internal intercostal muscles but less well developed
What is the main muscle of inspiration?
The diaphragm
Give the three openings of the diaphragm
• Vena cava - T8
• Oesophagus - T10
Aorta - T12
Name the arteries which give rise to the anterior intercostal artery
• Brachiocephalic/Aortic Arch à Subclavian à Internal Thoracic/Musculophrenic (later) à Anterior Intercostal
Name the arteries which give rise to the posterior intercostal arteries
Brachiocephalic/Aortic Arch à Subclavian -> Costocervical trunk -> Superior intercostal -> Posterior intercostal
How do anterior intercostal arteries drain?
Into internal thoracic -> Subclavian
Where do the posterior arteries of the intercostal spaces drain?
• Into the azygous vein on the right and the hemizyagous vein on the left, and then into the inferior vena cava (some into internal thoracic vein)
What lies in the intercostal groove of the ribs?
Intercostal vein, artery and nerve (VAN)
Why is it clinically significant that the intercostal vein, artery and nerve run in the intercostal groove
• Important during pleural aspiration or insertion of a chest drain, when the needle should be inserted at the upper border of the rib to avoid injury
What do intercostal arteries supply?
• Intercostal muscles, parietal pleura and overlying skin
Where do the anterior intercostal arteries arise?
• The internal thoracic artery and its continuation (the musculophrenic artery)
Where do the intercostal nerves arise from?
• Anterior rami of thoracic spinal nerve T1-T12
