thoracic wall Flashcards
(14 cards)
What are the 3 layers of intercostal muscles?
- External intercostal (fibers: hands-in-pockets). 2. Internal intercostal (fibers: opposite direction). 3. Innermost intercostal (deepest, discontinuous).
What is the action of external intercostal muscles?
Elevate ribs during inspiration (increase thoracic volume).
What is the action of internal intercostal muscles?
Depress ribs during forced expiration (decrease thoracic volume).
Which artery supplies the anterior intercostal spaces?
Anterior intercostal arteries (branches of internal thoracic/musculophrenic arteries).
Which artery supplies the posterior intercostal spaces?
Posterior intercostal arteries (branches of thoracic aorta, except 1st-2nd: from supreme intercostal artery).
What veins drain the intercostal spaces?
Anterior intercostal veins → internal thoracic vein. Posterior intercostal veins → azygos/hemiazygos veins.
Which nerve supplies the intercostal muscles?
Intercostal nerves (ventral rami of T1-T11).
What is the clinical significance of the neurovascular bundle?
Runs in the costal groove (order: VAN = Vein, Artery, Nerve from top to bottom).
Where is the neurovascular bundle located in the intercostal space?
Between internal intercostal and innermost intercostal muscles, under the rib’s inferior border.
What is the collateral neurovascular bundle?
Runs along the upper border of the rib below, supplying backup blood/nerve pathways.
Which intercostal space lacks anterior intercostal arteries?
Last 2 spaces (11th & 12th)—only posterior arteries supply them.
What is the lymphatic drainage of intercostal spaces?
Anterior: Parasternal nodes. Posterior: Intercostal nodes → thoracic duct.
What is the “triangle of auscultation”?
Thin intercostal space bounded by trapezius, latissimus dorsi, and scapula (best place to listen to lungs).
What is the “triangle of Petit”?
Lumbar hernia site bounded by external oblique, latissimus dorsi, and iliac crest (near 12th intercostal space).
