Thoracic cage and Diaphragm Flashcards
What are the boundaries of the superior thoracic aperture
bounded posteriorly by T1, medially by rib I and anteriorly by manubrium
What are the boundaries of the inferior thoracic aperture
bounded posteriorly by T12, rib 12 and distal tip of rib 11, medially by costal cartilage and anteriorly by xiphoid process
What are the true and false ribs of the thoracic cage?
• 1st-7th ribs are true ribs • 8-12th ribs are false ribs. 8-10th are bound indirectly to the sternum by their adjacent costal cartilages; whilst 11th, 12th ribs are floating ribs which are not bound to sternum,and bound to vertebral bodies instead.
Describe the individual features of each rib
The ribs anteriorly are bounded by the costal cartilage and posteriorly they have a head, neck and tubercle. In the middle, the ribs have a shaft which bends around at an angle. Medially, they have a costal groove for intercostal neurovascular structures. The head of each rib normally has 2 articulations with the vertebrae: • Superiorly-inferior costal facet of the vertebrae above • Inferiorly-superior costal facet of its own vertebrae
Describe the different ribs: I, II, X, XI, XII
• Rib I-more flat and shorter. It only has 1 articulation with T1. In the shaft, there is a scalene tubercle which allows for attachment of scalenus anterior muscle. In between the tubercle, there is an anterior costal groove (subclavian vein) and posterior costal groove (for subclavian artery) • Rib II-also flat but twice as long as I. However, it has 2 articulations with the vertebrae • Rib X-only has 1 articulation with T10 • Rib XI, XII-no neck and tubercle posteriorly; only has 1 articulation each with T11, T12 respectively
Describe the sternum
• Manubrium of sternum -has a jugular notch in the middle and has 3 facets to articulate with adjacent structures: clavicle, 1st rib and demifacet for 2nd rib • Body of sternum -has facets to articulate with the other ribs: demifacet for 2nd rib; full facets for 3-6th rib and lastly demifacet for 7th rib • Xiphoid process -demifacet for 7th rib
What are the features of the thoracic vertebrae?
- Vertebral body
- processes-2 transverse processes and 1 spinous process
- Vertebral arch- bounded by laminae (~latin: layer) and pedicle (latin~little feet)
- Vertebral foramen-to allow CNS to go through
- Superior and inferior articular processes-to allow articulation with vertebrae above and below
- Superior, inferior and transverse costal facets- to allow articulation with ribs
Describe the joints of the thoracic wall: -within the sternum -between the sternum and ribs -between the ribs and vertebrae
Within the sternum: • Manubriosternal joint • Xiphisternal joint Within the sternum and ribs: • Sternocostal joint-between the sternum and costal cartilages of 1st-7th ribs • Interchondral joints-between the costal cartilages of 8th-1oth ribs Between thoracic vertebrae and ribs: • Costotransverse-between tubercle of ribs (~costo) and transverse process • Costovertebral-between head of ribs and vertebral body
Describe the boundaries of the diaphragm as well as its structure?
Describe the apertures of the diaphragm?
Describe the neurovascular structures of the diaphragm?
Diaphragm is a muscular structure in the inferior thoracic aperture. Its boundaries are:
- Xiphoid process and costal margin
- Inferior tips of ribs XI, XII and lumbar vertebrae
Medially, fibers converge to form the central tendon of diaphragm that attaches to pericardium. Inferiorly, it forms the median arcuate ligament in front of the aorta at T12.
Apertures of the diaphragm
- inferior vena cava-TVIII
- oesophagus and vagus nerve-TX
- Thoracic aorta, azygos vein, thoracic duct-TXII
Neurovascular structure
- Arterial supply-pericardiophrenic and musculophrenic from internal thoracic artery; superior phrenic artery from the thoracic aorta; inferior phrenic artery from abdominal aorta
- Venous drainage-azygous vein (draining into SVC)
- Nerve supply-phrenic nerve at C3, C4, C5
