THORAX III Flashcards
What are the superior, posterior, anterior, lateral and inferior boundaries of the superior mediastinum?
Superior boundaries: Manubrium, T1, ribs 1
Posterior: T1-T4
Anterior: Manubrium
Lateral: Lungs and mediastinal pleura
Inferior: Transverse thoracic plane (T4/5)
Before entering the root of the right lung, what does the right pulmonary artery pass posterior too?
The ascending aorta and the superior vena cava
Was does the left pulmonary artery run anterior to before entering the left lung root?
The descending thoracic aorta
What side of the body does the azygous vein run in?
The right side of the body
What’s the function of the azygous vein?
To transport deoxygenated blood from the posterior walls of the thorax and abdomen into the superior vena cava
At what level is the azygous vein formed?
T12
What is the azygos vein formed from?
The union of the ascending lumbar vein with the right subcostal vein
What does the azygous vein arch over after ascending in the posterior mediastinum?
The right main bronchus at the root of the right lung
What are the 2 tributaries to the azygous vein?
The hemiazygous vein and the accessory hemiazygous vein
What forms the hemiazygous vein?
The oesophageal and mediastinal tributaries, the common trunk of the left ascending lumbar vein and left subcostal vein, and the lower of the 3 posterior intercostal veins
The hemiazygous vein ascends anterior to the vertebral column before crossing posterior to the aorta, oesophagus and thoracic duct at what vertebral level?
T8
What forms the accessory hemiazygous vein?
Veins from the 4th to 8th intercostal spaces and sometimes by the left bronchial veins
At what level does the accessory hemiazygous vein cross to join the azygous vein?
T7
From what spinal segments does the right phrenic nerve arise?
C3, C4, C5
What does the phrenic nerve provide motor innervation to?
The diaphragm
What does the phrenic nerve provide sensory innervation to?
The central part of the diaphragm, the pericardium and the mediastinal part of the parietal pleura
What vessels does the right phrenic nerve descend lateral to?
The right brachiocephalic vein and the superior vena cava
Does the right phrenic nerve run anterior or posterior to the root of the right lung?
Anterior to the hilum of the right lung
What vessel does the left phrenic nerve run lateral to?
The left subclavian artery
What nerve does the left phrenic nerve cross superficially as it approaches the aortic arch?
The left vagus nerve
Does the left phrenic nerve run anterior or posterior to the root of the left lung?
Anterior
What does phrenic nerve damage lead to?
Diaphragmatic paralysis
What is the sensory innervation by the vagus nerve?
Innervates the skin of the external acoustic meatus and the internal surfaces of the laryngopharynx and larynx. Provides visceral sensation to the heart and abdominal viscera
What’s the special sensory innervation by the vagus nerve?
Provides taste sensation to the epiglottis and the root of the tongue
What is the motor innervation by the vagus nerve?
Provides motor innervation to the majority of the muscles of the pharynx, soft palate and larynx
What’s the parasympathetic innervation by the vagus nerve?
Innervates the smooth muscle of the trachea, bronchi and gastro-intestinal tract and regulates heart rhythm
Where does the vagus nerve originate?
The medulla oblongata of the brainstem
Via what foramen does the vagus nerve exit the cranium?
The jugular foramen
What branch arises from the vagus nerve within the cranium?
The auricular branch
What does the right vagus nerve pass anterior to to enter the thorax?
The right subclavian artery
What does the left vagus nerve pass between to enter the thorax?
The left common carotid and the left subclavian arteries
What does the right vagus nerve form in the thorax?
The posterior vagal trunk
What does the left vagus nerve form in the thorax?
The anterior vagal trunk
What plexus do branches of the vagal trunks contribute to?
The oesophageal plexus
What branches off the right vagus nerve just inferior to the right subclavian artery?
The right recurrent laryngeal nerve
What’s the relationship between the right vagus nerve and the right subclavian artery?
The right vagus nerve’s right recurrent laryngeal branch hooks around the right subclavian artery and ascends into the neck between the trachea and oesophagus
How does the posterior vagal trunk enter the diaphragm?
With the oesophagus via the oesophageal hiatus at T10
What’s the relationship between the left vagus nerve and the aortic arch?
The left vagus gives rise to the left recurrent laryngeal, which hooks around the aortic arch to the left of ligamentum arteriosum to then ascend between the trachea and oesophagus
Where does the sympathetic chain span from?
From the base of the skull to the coccyx
What are the 3 ganglia within the chain that are of interest?
The superior, middle and inferior cervical ganglia
What vertebrae is the superior cervical ganglion anterior to?
C1-C4
What vertebra is the middle cervical ganglion anterior to?
C6
What vertebra is the inferior cervical ganglion anterior to?
C7
What is partial ptosis and what causes it?
Partial ptosis is drooping of the upper eyelid, due to paralysis of the superior tarsal muscle, which acts to help open the eyelid
What is miosis and what causes it?
Constriction of the pupil due to paralysis of the dilator pupillae, a muscle located within the eye that acts to dilate the pupil
What is anhydrosis and what causes it?
Decreased sweating affecting the same side of the face as the lesion, due to a loss of innervation to the sweat glands of the face
Why are white rami white?
They have more myelinated preganglionic sympathetic fibres than unmyelinated fibres, unlike in grey rami
What’s the functions of the upper oesophageal sphincter?
Prevent food from going down the windpipe. Involved when eating, breathing, belching and vomiting
What’s the functions of the lower oesophageal sphincter?
Prevent stomach acid and contents from traveling backwards from the stomach (regurgitation)
Why are the cartilaginous rings of the trachea C-shaped (incomplete)?
To allow the trachea to collapse slightly when swallowing, so food can pass more easily down the oesophagus
What’s gastro-oesophageal reflux disease?
A common condition where acid from the stomach leaks up into the oesophagus, usually occurring as a result of weakening of the LOS
How many cartilaginous rings are there in the trachea?
20
What’s the name of secondary bronchi?
Lobar bronchi
What’s the name of tertiary bronchi?
Segmental bronchi
What causes tracheal deviation?
Unequal intrathoracic pressure within the thoracic cavity, which may be due to large pleural effusion or tension pneumothorax, pulmonary fibrosis or mediastinal masses
What vertebral levels does the oesophagus lie between?
C6-T11
What are the names of the 3 constrictions of the oesophagus?
Upper (pharyngeal) constriction
Middle (aortic) constriction
Inferior (diaphragmatic) constriction
What’s the purpose of the upper constriction of the oesophagus?
Prevent food going into the trachea
What’s the purpose of the middle constriction of the oesophagus?
Make room for the heart
What’s the purpose of the inferior constriction of the oesophagus?
Stop food refluxing from stomach into the oesophagus
What is dysphagia and what causes it?
Dysphagia is the inability to swallow. It can be caused by cancer, achalasia, myasthenia gravis, myotonic dystrophy and foreign bodies
What is GORD?
Gastro-oesophageal reflux disease
What is Barrett’s oesophagus?
Abnormal metaplastic change in the mucosal cells lining the lower portion of the oesophagus from normal stratified squamous epithelium to simple columnar epithelium with goblet cells
What is the thoracic duct?
The largest lymphatic vessel in the lymphatic system, of about 40cm in length in adults
What does the thoracic duct arise from in the abdomen?
The cisterna chyli in the root of the mesentery of the small intestine
Where does the thoracic duct empty?
The point where the internal jugular and left subclavian veins join in the neck
What does the thoracic duct drain?
It drains the abdomen, pelvis, left thorax, head, neck and both lower limbs
What is Chylothorax?
A condition in which there’s lymph in the pleural cavity
What’s a common cause of Chylothorax and why?
Mistakes leading to laceration of the thoracic duct during surgery, which is easy because the thoracic duct is thin-walled and may be colourless
What are the 4 main groups of tracheobronchial lymph nodes?
Tracheal, bronchial, bronchopulmonary and pulmonary
Where are tracheal lymph nodes found?
Either side of the trachea
Where are bronchial lymph nodes found?
In the angles between the lower part of the trachea and bronchi and in the angle between the 2 bronchi
Where are the bronchopulmonary lymph nodes found?
In the hilum of each lung
Where are the pulmonary lymph nodes found?
In the parenchyma, on the larger branches of the bronchi.
