Thoracic cavity anatomy Flashcards
Discuss the thoracic cavity inlet
Ring of bone and cartilage
T1, first ribs and costal cartilages, manubrium
Slopes antero-inferiorly to T2/3
Apex of lung extends upwards to level of T1 and neck of first rib i.e. 2-3cm above anterior part of first rib and clavicle
Structures that pass between the thorax and upper limb
Lie on the first rib
Subclavian vein (scalenus anterior)
Subclavian artery
Inferior trunk of brachial plexus
Structures that pass between the thorax and neck
Vessels that supply and drain the head and neck
Trachea
Oesophagus
Nerves - right and left vagus (and recurrent laryngeal), right and left phrenic (sole motor supply to diaphragm)
Discuss thoracic outlet
Closed by diaphragm - T12
12th and 11th ribs
Costal cartilages of ribs 10, 9, 8, 7 (costal margin)
Xiphoid cartilage (roughly opposite T9/10)
Structures passing through the diaphragm
3 openings
T8 - caval opening - IVC, right phrenic nerve
T10 - oesophageal opening - oesophagus, vagal trunks, left gastric vessels
T12 - aortic hiatus (behind) - aorta, azygos vein, thoracic duct
Mediastinum - structures in midline of thorax, between left and right pleural cavities - name the different parts of it, their borders etc
Superior mediastenum - lies between the inlet and the plane between the sternal edge and T4/5, behind menubrium and anterior to T3 and T4 vertebrae
Inferior mediastinum - lies inferior to plane between sternal angle and T4/5 and the thoracic outlet (i.e. diaphragm)
Middle mediasinum - contents of pericardium (i.e. heart and great vessels)
Posterior mediastinum - aorta, oesphagus, throacic duct, azygos veins
Where does the anterior mediastinum lie and what does it contain?
Lies behind the manubrium and sternum, anterior to superior mediastinum and the upper part of the inferior mediastinum
It contains the thymus
What is the thymus?
It is a bi-lobed structure in the anterior mediastinum
Extends from jugular notch to 4th CC and possibly beyond
Active throughout life particularly in childhood and puberty
Increasing fibro-fatty infiltration (and atrophy) with age
Functions to program T-lymphocytes, recognise ‘self’
related to pericardium, SVC and aorta, left and right brachiocephalic veins, pleura, phrenic nerves, trachea
Blood supply from internal thoracic and inferior thyroid arteries and venous drainage to left BCV
What does the azygos system do?
Drains the posterior wall of the trunk and connects IVC to SVC
Thoracic duct - what drains into it and where does it drain into?
Drains lymph from the lower limbs and abdomen - enters the left BCV (on the left), usually having received the left jugular lymph trunk (head and neck), left subclavian lymph trunk (UL), left bronchomediastinal trunk (left thorax)
Opposite for the right - into the right BCV - separate trunks may all enter right BCV separately but may all fuse together before entry to form the right lymphatic duct
Where does right vagus lie?
Lateral to trachea
Medial to arch of azgos vein
Posterior to lung hilium
Reaches oesophagus and forms oesophageal plexus with left vagus
They reform as anterior (mainly left) and posterior (mainly right) vagal trunks as oesophagus leaves thorax
Where does left vagus lie?
Also passes posteriorly to lung hilium to reach oesophagus
Both vagal nerves give preganglionic branches to autonomic plexuses - pulmonary, cardiac, oespphageal
Discuss recurrent laryngeal nerves
Supply laryngeal musculature
Important branches of vagus nerves but courses different on R and L
Right - hooks around right 4th arch (right subclavian artery)
Left - hooks around 6th arch (aortic arch)
What can hoarseness of voice be caused by?
Tumour, or affected enlarged lymph nodes compressing the left vagus and/or left recurrent laryngeal nerves
