Thoracic Wall Flashcards
What does the Thoracic Wall extend between?
- The superior thoracic aperture
- The inferior thoracic aperture
What is the Superior Thoracic Aperture bordered by?
- T1
- First rib
- Manubrium of the sternum
What is the Inferior Thoracic Aperture bordered by?
- T12
- Rib XII
- End of Rib XI
- Costal margin
- Xiphoid process of the sternum
How many Thoracic Vertebrae are there?
12
How many sites does a typical thoracic Vertebra have for articulation with the ribs?
3
What are the sites of Articulation for the thoracic Vertebra with the ribs?
Two Demifacets are located on the superior and inferior aspects of the body for articulation with corresponding sites on the heads of adjacent ribs
Superior Costal Facet –> part of the head of its own rib
Inferior Costal Facet –> Part of the head of rib below
Articulation of Vertebra 1 with Rib 1?
Superior Costal Facets are complete and ariticulate with a single facet on the head of its own rib - i.e head of Rib 1 does not articulate with CV11
Articulation of Vertebra TX ( and often TIX) with ribs?
Articulate only with their own ribs and therefore lack inferior demifacets
Articulation of Vertebra XI and XII with their ribs?
Articulate only with the heads of their own ribs - lack costal facets and have only a single complete facet on the side.
What 3 things is the posterior portion of a rib characterised by?
- Head
- Neck
- Tubercle
What are the two components of a tubercle of the rib?
- Articular Surface : attaches to transverse process of associated vertebra
- Raised non articular part : Roughened by Ligament attachments
What two joints are formed with the articulation of the ribs with the vertebrae
- Costovertebral
- Costotransverse
What movement is seen at the Costovertebral joint?
Allows neck of ribs to rotate in the longitudinal axis ( upper ribs)
To ascend and descend ( lower ribs)
Combined movement of all rib is essential for altering thoracic volume during breathing.
What movement is seen at the costotransverse joint?
Slight Gliding Movements
What 3 ligaments are involved in the Costotransverse joint?
1) Costotransverse Ligament –> attaches to neck of rib at transverse process
2) Lateral Costotransverse Ligament –> Tip of transverse process to the non-articular portion of tubercle
3) Superior Costotransverse Ligament –> Superior surface of the neck of the rib and transverse process of vertebra above
What types of Joint are seen in the Sternocostal Joints?
Rib 1 –> Fibrocartilaginous connection
Second to Seventh –> Synovial
Where are interchondral Joints seen? What is their purpose?
Occur between the Costal Cartilages of adjacent ribs, mainly between costal cartilages of VII to X ( but maybe V and VI)
- Provide indirect anchorage to the sternum
Why is the manubriosternal joint easily palpable? What feature can you feel?
What rib articulates here?
- Manubrium angles posteriorly on the body of the sternum, forming a raised feature –> sternal angle
- Elevation marks the site of articulation of Rib II ( Rib I can’t be felt as it goes inferior to the clavicle.)
Where do Intercostal nerves and associated major vessels lie?
- Costal groove along the inferior margin of the superior rib and passes in the plane between the inner two layers of muscle.
Describe the location of the vein, nerve and artery in the Costal Groove. Which one is most at risk?
- In each space the vein is the most superior structure
- Artery is inferior to the vein
- Nerve is inferior to the artery and is not protected by the groove
Therefore the NERVE is the structure most at risk when objects perforate the upper aspect of the intercostal space
Where are collaterals present in the Costal Groove?
Small collateral branches of the major vessels are often present superior to the inferior rib below
What are the three muscles between the vertebrae and the ribs posteriorly?
- Levatores Costarum
- Serratus Posterior Superior
- Serratus Posterior Inferior
What are the 3 intercostal muscles?
- External Intercostals ( most superior)
- Internal Intercostals ( middle)
- Innermost intercostal muscles ( deepest)
What is the innervation of the intercostal muscles?
Intercostal nerves : T1-T11
Describe Arterial Supply to the Thoracic Wall.
Subclavian Arteries –> Internal Thoracic Arteries –> Posterior and Anterior Intercostal Arteries.
Aorta –> Internal Thoracic Arteries –> Posterior and Anterior Intercostal Arteries.
What two arteries does the internal thoracic artery split into at the level of the 6th intercostal space? Where do the split arteries go?
1) Superior Epigastric Artery –> continues Inferiorly into the abdominal wall
2) Musculophrenic artery –> Passes along the costal margin, goes through the diaphragm and ends near the last intercostal space.
Describe Venous Drainage in the Central part of the Thoracic wall.
Intercostal veins –> Azygous System or Internal Thoracic Veins which connect with the brachiocephalic veins
Describe Venous Drainage in the left part of the Thoracic wall.
Upper posterior intercostal veins on left side –> Left Superior Intercostal vein –> Left Brachiocephalic
Describe Venous Drainage in the right part of the Thoracic wall.
Upper Posterior Intercostal veins on right side –> Right Superior Intercostal Veins –> Azygous Vein
What are the 3 main sites of lymph drainage in the thoracic wall?
1) Parasternal Nodes –> Nodes associated with the internal thoracic Arteries
2) Intercostal Nodes –> Heads and necks of ribs
3) Diaphragmatic Nodes –> Diaphragm
Where do the 3 main sets of nodes in the thoracic wall drain?
Parasternal –> Bronchomedistinal
Intercostal (upper thorax) –> Bronchomediastinal
Intercostal ( lower thorax) –> Thoracic Duct
Diaphragmatic nodes –> Interconnect with : Parasternal, Paravertebral and juxta-oesophageal nodes, brachiocephalic nodes and lateral aortic/lumbar node.
What are the 5 (Peripheral) Attachments of the Diaphragm?
- Xiphoid process of the Sternum
- Costal Margin of the Thoracic Wall
- Ends of Ribs XI and XII
- Ligaments that span across structures of the posterior abdominal wall
- Vertebrae of the Lumbar Region.
NB : From these peripheral fibres, muscle fibres converge to join the central tendon. The pericardium is attached to the middle part of the central tendon.
