Nerves and Veins of the Thorax Flashcards
What are the main nerves of the thoracic cavity?
The main nerves are the phrenic nerve, vagus nerve, intercostal nerves, and the sympathetic trunk.
What is the function of the phrenic nerve?
The phrenic nerve innervates the diaphragm, enabling breathing by controlling diaphragm contraction.
From which spinal roots does the phrenic nerve originate?
The phrenic nerve originates from cervical spinal roots C3, C4, and C5 (“C3, 4, and 5 keep the diaphragm alive”).
What role does the vagus nerve play in the thorax?
The vagus nerve provides parasympathetic innervation to the heart, lungs, and digestive tract, helping regulate heart rate and bronchoconstriction.
Which cranial nerve is the vagus nerve?
The vagus nerve is the tenth cranial nerve (CN X).
What are intercostal nerves, and what is their function?
Intercostal nerves are the anterior rami of thoracic spinal nerves (T1-T11) that innervate the intercostal muscles, skin, and pleura, playing a key role in breathing and sensation.
What is the function of the sympathetic trunk in the thorax?
The sympathetic trunk provides sympathetic innervation to thoracic organs, contributing to the “fight or flight” response by increasing heart rate, dilating bronchioles, and constricting blood vessels.
What is the azygos vein, and what does it do?
The azygos vein drains blood from the posterior thoracic wall and abdomen into the superior vena cava, serving as an alternate route for venous return.
Where does the azygos vein empty into the heart?
The azygos vein empties into the superior vena cava just before it enters the right atrium.
What are the hemiazygos and accessory hemiazygos veins?
These are veins on the left side of the thorax that assist the azygos vein by draining the left posterior thoracic wall and then crossing over to join the azygos vein.
What is the internal thoracic vein, and where does it drain?
The internal thoracic vein runs along the inner chest wall and drains into the brachiocephalic veins.
Which veins drain blood from the intercostal spaces?
The intercostal veins, which drain into the azygos system on the right and into the hemiazygos or accessory hemiazygos veins on the left.
What is the role of the pulmonary veins in the thorax?
Pulmonary veins return oxygenated blood from the lungs to the left atrium of the heart.
How many pulmonary veins are there, and where do they enter the heart?
There are typically four pulmonary veins (two from each lung), and they enter the left atrium of the heart.
What is the function of the thoracic duct?
The thoracic duct is the main lymphatic vessel, draining lymph from most of the body into the left subclavian vein at the venous angle.
Where does the thoracic duct run in relation to other structures in the thorax?
The thoracic duct runs posteriorly along the vertebral column, between the azygos vein and aorta.
