1. The thoracic cavity Flashcards
name the boundaries of the thoracic cavity
- anterior = sternum + costal cartilages
- posterior = thoracic vertebral bodies
- lateral = ribs
- inferior = diaphragm
name the 3 parts of the sternum
- manubrium
- body
- xiphoid process
which bony structure marks the level of the 2nd costal cartilage
sternal angle (articulation of manubrium and sternal body) - found at T4 vertebral level
describe the articulation of ribs (in general)
All 12 ribs articulate posteriorly with vertebrae:
- costovertebral joint: between head of rib and superior costal facet of corresponding vertebrae and inferior costal facet of vertebrae above
- costotransverse joint: between tubercle of rib and transverse costal facet of corresponding vertebrae
Anterior attachment of ribs vary:
- ribs 1-7 (TRUE RIBS): attach independently to sternum
- ribs 8-10: attach to costal cartilage superior to them
- ribs 11-12 (FLOATING RIBS): no anterior attachment
name 4 features which distinguish thoracic vertebrae from other vertebrae
- presence of DEMI-FACETS on sides of each vertebral body - articulate with heads of ribs
- presence of COSTAL FACETS on transverse processes - articulate with tubercles of ribs
- heart-shaped vertebral body
- spinous processes are long and slant inferiorly
how does the bony chest wall move on inspiration/expiration
on inspiration:
- sternum moves anteriorly and superiorly (‘pump handle’ mov.)
- rib mov. upwards increases lateral dimension of thorax (‘bucket handle’ mov.)
how does the diaphragm move on inspiration/expiration
- contracts downwards on inspiration
- relaxes upwards on expiration
name the primary muscles of inspiration and expiration - how does this enable air to flow in
Inspiration:
1. diaphragm
2. external intercostal muscles
Expiration: none - elastic recoil of lungs
name the accessory muscles of inspiration and expiration
Inspiration:
- SCM
- Upper latissimus dorsi
- Scalene muscles
- Pec. minor
- Serratus anterior
Expiration:
- Internal intercostal muscles (fibres run
- Transversus thoracis
- External obliques, internal obliques and rectus abdominis
name 3 structures that pierce the diaphragm and the vertebral level at which this occurs
- vena cava - T8
- oesophagus (+ vagus n) - T10
- aortic hiatus (+ azgous v) - T12
describe the innervation and vasculature of the diaphragm
- innervation: R and L phrenic nn. (C3-5)
- arterial supply: mainly inferior phrenic aa. (from abdo. aorta)
- venous drainage: mainly inferior phrenic vv.
describe the innervation and vasculature of the intercostal muscles
intercostal nn. (T1-T11), arteries and veins located in intercostal neurovascular bundle running in costal groove on inferior aspect of ribs, between internal and innermost ICs
the azygous venous system collects venous blood from IC veins, draining into main azygous v. and then SVC
why are inhaled foreign bodies more likely to enter R bronchus
R main bronchus has more vertical orientation than L which is more horizontal
describe the vasculature of the lung
lungs have dual blood supply:
- for gas exchange and supply to alveoli:
- deoxygenated blood supply: paired pulmonary aa.
- oxygenated blood drainage: 4 pulmonary vv. - for supply to bronchial tree:
- oxygenated blood supply to tissue: bronchial aa. (arise from descending aorta)
- venous drainage: bronchial vv.
describe the nerve supply to the lungs
nerves derived from pulmonary plexuses:
- parasympathetics - derived from vagus n. (stimulate secretion from bronchial glands, contraction of bronchial SM and vasodilation of pulmonary vessels)
- sympathetics - derived froom sympathetic trunks (stimulate relaxation of bronchial SM and vasoconstriction of pulmonary vessels)
- visceral afferents - conduct pain impulses to sensory ganglia of vagus n.
