Mediastinum & Circulatory System Flashcards
where is the mediastinum?
central area of thorax between the two pleural cavities
where does mediastinum extend?
superiorly to thoracic outlet and root of neck, inferiorly to diaphragm, anteriorly to sternum, posteriorly to thoracic verterbrae
what is contained within the mediastinum?
thymus, heart and large blood vessels, trachea and oesophagus, thoracic duct and lymph nodes, vagus and phrenic nerves, sympathetic trunks
how are the viscera of the mediastinum connected?
by loose connective tissue and fat, surrounded by blood vessels and nerves
what is mediastinum divided into?
superior and inferior compartments
what is the transverse thoracic plane?
horizontal plane from sternal angle to T4/T5 intervertebral disc separating mediastinum
superior mediastinum structures, anterior to posterior?
thymus, large veins, large arteries, trachea, oesophagus and thoracic duct, sympathetic trunks
inferior mediastinum structures, anterior to posterior?
thymus, heart within pericardium with phrenic nerves either side, oesophagus and thoracic duct, descending aorta, sympathetic trunks
superior boundary of the superior mediastinum?
thoracic inlet
inferior boundary of the superior mediastinum?
continuous with inferior mediastinum at level of sternal angle
anterior boundary of superior mediastinum?
manubrium of sternum
posterior boundary of superior mediastinum?
vertebral bodies of T1-4
lateral boundary of superior mediastinum?
pleurae of lungs
structures contained within the superior mediastinum?
aortic arch, superior vena cava, vagus nerve, phrenic nerves, cardiac nerves, sympathetic trunk, thymus, trachea, oesophagus, thoracic ducts and lympathic vessels, muscles
muscles in superior mediastinum?
sternohyoid, sternothyroid, inferior longus colli muscle
where is the inferior mediastinum?
between transverse thoracic plane and diaphragm
boundaries of inferior mediastinum?
sternum and lower 8 thoracic vertebrae
what divides the anterior and posterior mediastinum?
the fibrous pericardium
pericardial sac further subdivides the inferior mediastinum into…
anterior, middle and posterior mediastinum
anterior mediastinum?
space between fibrous pericardium and sternum
middle mediastinum?
pericardium and heart
posterior mediastinum?
between fibrous pericardium and vertbral column at T5-12 vertebrae
middle mediastinum contains?
pericardium, heart, origins of great vessels, various nerves, smaller vessels, lymphatics, tracheal bifurcation
posterior mediastinum contains?
thoracic aorta (descending), oesophagus, thoracic duct, azygous system of veins, sympathetic trunks
what is the pericardium?
fibro serous sac surrounding the heart and roots of the great vessels. consists of fibrous and serous pericardium
what is fibrous pericardium?
tough connective tissue outer layer, defines boundaries of middle mediastinum
what is the serous pericardium?
thin, consists of the parietal and visceral layers
what is the parietal layer of the serous pericardium?
lines inner surface of fibrous
what is the visceral layer of the serous pericardium?
aka epicardium, adheres to heart forming its outer covering
where are the parietal and visceral layers of the serous pericardium continuous?
at the roots of the great vessels anteriorly at arteries and posteriorly at veins
what is the pericardial cavity and what is its function?
narrow space between parietal and visceral serous pericardium layers, contains fluid, allows potential space for movement of heart
what is the oblique pericardial sinus?
J shaped cul-de-sac zone of reflection surrounding veins
what is the transverse pericardial sinus?
the passage between the two sites of reflected serous pericardium
where does the transverse pericardial sinus lie?
anterior to superior vena cava, posterior to aorta and pulmonary trunk, superior to left atrium
fibrous pericardium base attachment?
to central tendon of diaphragm and on left side of diaphragm
fibrous pericardium apex attachment?
continuous with the adventitia of the great vessels
anterior attachments of fibrous pericardium?
posterior sternum by sternopericardial ligaments; retain heart position and limits distension
which nerves pass through the fibrous pericardium?
phrenic (C3, 4 ,5- innervate diaphragm)
which vessels are located within and supply the fibrous pericardium?
pericardiacophrenic vessels
what arteries supply the pericardium?
branches of the internal thoracic, pericardiacophrenic, musculophrenic, inferior phrenic arteries and thoracic aorta
what are the veins draining the pericardium?
enter the azygous system of veins and the internal thoracic and superior phrenic veins
what nerves supply the pericardium?
arise from the vagus (X) nerve, sympathetic trunks and phrenic nerves
why does pain from parietal pericardium often get referred to as from the supraclavicular region?
somatic (pain) sensation is carried by somatic afferent fibres in phrenic nerves
what systems is the blood vascular system split into?
pulmonary circulation and systemic circulation
how much blood does the average adult contain?
5 litres
why is the blood system “closed”?
blood never leaves the system
what is the valve between the right atrium and right ventricle?
tricuspid valve
what valve is between the right ventricle and the pulmonary trunk?
the semilunar valve
where does the pulmonary trunk bifurcate?
at level of sternal angle
what branches are given off before the blood vessels enter the lung?
the lobar branch to supply the superior lobe
what do lobar branches give rise to and what do they supply?
to segmental branches, supplying the bronchopulmonary segments
what organ/tissue is NOT supplied by the systemic circulation?
the parenchyma of the lungs, supplied by the pulmonary circulation
valve between left atria and left ventricle?
mitral valve (bicuspid)
valve between left ventricle and aorta?
aortic valve
what does aortic artery branch into after the diaphragm?
iliac, renal and suprarenal arteries
how are portal veins different? eg?
eg hepatic portal vein, combines with capillaries of liver rather than leading directly back to the heart
where do the right and left coronary arteries begin?
near the origin of the aorta
where does blood from the coronary veins return?
into the coronary sinus, then into the right atrium
what valve prevents backfloow of blood during atrial systole?
thebasian valve
where do the smallest cardiac veins drain into?
directly into the chambers
where does the anterior brain circulation arises? what does it supply?
arises from the internal carotid arteries and supplied front of the brain
where does the posterior brain circulation arise? what does it supply?
arises from the vertebral arteries, supplies back of brain and brainstem
what % of the cardiac output does the renal circulation receive?
20%
where does the renal circulation branch from?
from the abdominal aorta
how does blood return to heart from renal circulation?
via the ascending vena cava
which is the first branch off the aortic arch?
the brachiocephalic artery/trunk
what does the brachiocephalic bifurcate into?
the right common carotid and the right subclavian artery
what is the 2nd branch off the aortic arch?
left common carotid artery
what is the 3rd branch off the aortic arch?
left subclavian artery
where do the carotid arteries bifurcate and what into?
divide in the neck, into internal and external carotid arteries
when does the subclavian artery become the axillary artery?
at the 1st rib
