Flashcards in Mediastinum Deck (81)
Where is the superior mediastinum located?
between the superior thoracic aperture and the horizontal transverse thoracic plane
The SVC, brachiocephalic veins, arch of aorta, thoracic duct, trachea, esophagus, thymus, vagus nerves, left recurrent laryngeal nerve, and phrenic nerve are contained where?
Where is the inferior mediastinum?
between the transverse thoracic plane and the diaphragm
What is contained in the anterior mediastinum?
remnants of the thymus, lymph nodes, fat, and connective tissue
What is contained in the middle mediastinum?
heart, roots of the great vessels, arch of azygos vein, and main bronchi
What is contained in the posterior mediastinum?
esophagus, thoracic aorta, azygos vein, thoracic duct, vagus and splanchic nerves
Where is the anterior mediastinum?
between the body of the sternum and the transversus thoracis anteriorly and the pericardium posteriorly
What is the function of the pericardium?
encloses the heart and the roots of the great vessels
Where is the pericardial sac?
posterior to the body of the sternum and the 2nd to 6th costal cartilages at the level of T5-T8 vertebrae
What is the function of the fibrous pericardium?
protects the heart against sudden overfilling
What is the pericardial cavity?
space between the parietal and visceral layers of serous pericardium
The arterial supply of the pericardium is mainly from where?
The nerve supply of the pericardium is from where?
phrenic nerves (C3-C5), vagus nerves (CN X), and sympathetic trunks
Where is the apex of the heart located?
posterior to the left 5th intercostal space
What are the four surfaces of the heart?
anterior (sternocostal), diaphragmatic (inferior), left and right pulmonary surfaces
What are the four borders of the heart?
right (slightly convex), inferior (horizontal), left (oblique), and superior border
From where does the right atrium receive blood?
SVC, IVC, and coronary sinus
Where is the right auricle?
projects from the right atrium, overlapping the ascending aorta
Where is the opening of the coronary sinus?
between the right AV orifice and the IVC orifice in the posterior right atrium
The _____, separates the atria and has and oval depression, the _______.
interatrial septum; oval fossa
The right atrium has a rough, muscular wall composed of _______.
Where is the opening of the SVC?
superior right atrium, at level of right 3rd costal cartilage
Where is the opening of the IVC?
inferior right atrium, almost in line with SVC at level of 5th costal cartilage
What are the irregular muscular elevations in the right ventricle?
What is the tricuspid valve?
guards the right AV orifice
What is the function of the chordae tendineae?
prevent separation of the valve cusps and their inversion during ventricular systole (prevents from being driven into right atrium)
What is the function of the papillary muscles?
begin to contract before contraction of the right ventricle, tightening the tendinous cords and drawing the cusps together
What is the interventricular septum?
strong, obliquely placed partition between the right and left ventricles
Where is the pulmonary valve?
at the apex of the conus arteriosus at the level of the left 3rd costal cartilage
What is the left auricle?
forms the superior part of the left border of the heart and overlaps the pulmonary trunk
What are the openings of the pulmonary veins?
right and left superior and inferior, entering the posterior wall of the left atrium
What is the mitral valve?
closes the orifice between the left atrium and left ventricle, and has two cusps
Where is the mitral valve located?
posterior to the sternum at the level of the 4th costal cartilage
Where is the aortic valve located?
posterior to the left side of the sternum at the level of the 3rd intercostal space
Where is the opening of the right coronary artery?
in the right aortic sinus
Where is the opening of the left coronary artery?
in the left aortic sinus
What are the branches of the RCA?
SA nodal, right marginal, posterior IV, and AV nodal
What are the branches of the LCA?
anterior IV, circumflex, and posterior IV
What is the origin of the left marginal artery?
circumflex branch of the LCA
What does the RCA supply?
right atrium, SA and AV nodes, and posterior part of IV septum
What does the right marginal artery supply?
right ventricle and apex of heart
What does the posterior IV artery supply?
right and left ventricles and posterior 1/3 of septum
What does the LCA supply?
most of left atrium and ventricle, IV septum, and AV bundles
What does the anterior IV artery supply?
right and left ventricles, anterior 2/3 of IV septum
What does the circumflex artery supply?
left atrium and left ventricle
What does the left marginal artery supply?
What does the posterior IV artery supply?
right and left posterior 1/3 of IV septum
What is the main vein of the heart?
The coronary sinus receives the _____ at its left end and the ____ and ______ at its right end
great cardiac vein; middle and small cardiac veins
Where are the cardiac plexuses located?
anterior to the bifurcation of the trachea and posterior to the ascending aorta
From where is the sympathetic supply of the heart?
presynaptic fibers with cell bodies in the lateral horns of the superior 5 or 6 thoracic segments and postsynaptic sympathetic fibers with cell bodies in the cervical and superior thoracic paravertebral ganglia
From where is the parasympathetic supply of the heart?
presynaptic fibers of the vagus nerves (CN X)
From anterior to posterior, the contents of the superior mediastinum are:
thymus, great vessels (brachiocephalic V., superior SVC, bifurcation of pulm. trunk and roots of pulm. A., arch of aorta, vagus and phrenic N., cardiac plexus, left recurrent laryngeal N., trachea, esophagus, thoracic duct
What unites to form the SVC?
brachiocephalic veins, at the level of the 1st right costal cartilage
What is the function of the SVC?
returns blood from all structures superior to the diaphragm, except the lungs and heart
Where is the SVC located?
right side of superior mediastinum, anterolateral to the trachea and posterolateral to the ascending aorta; ends at level of 3rd costal cartilage and enters right atrium
Where is the right phrenic nerve?
between the SVC and the mediastinal pleura
Where is the ligamentum arteriosum?
passes from the root of the left pulmonary artery to the inferior surface of the arch of aorta
Where is the left recurrent laryngeal nerve?
hooks beneath the arch immediately lateral to the ligamentum arteriosum and then ascends between the trachea and esophagus
What is the origin of the vagus nerve?
8-10 rootlets from medulla of brainstem
What is the origin of the phrenic nerve?
anterior rami of C3-C5 nerves
What is the origin of the intercostal nerves (1-11)?
anterior rami of T1-T11 nerves
What is the origin of the subcostal nerve?
anterior ramus of T12 nerve
What is the origin of the recurrent laryngeal nerve?
What is the origin of the cardiac plexus?
cervical and cardiac branches of vagus nerve and sympathetic trunk
What is the origin of the pulmonary plexus?
vagus nerve and sympathetic trunk
What is the origin of the esophageal plexus?
vagus nerve, sympathetic ganglia, and greater splanchic nerve
What does the vagus nerve innervate?
pulmonary plexus, esophageal plexus, and cardiac plexus
What does the phrenic nerve innervate?
central portion of diaphragm
What do the intercostals innervate?
muscles in and skin over intercostal space; lower nerves innervate muscles and skin of anterolateral abdominal wall
What does the subcostal nerve innervate?
abdominal wall and skin of gluteal region
What does the recurrent laryngeal nerve innervate?
intrinsic muscles of larynx (except cricothyroid); sensory inferior to level of vocal cords
What does the cardiac plexus innervate?
impulses pass to SA node; parasympathetic fibers slow rate, reduce force of heartbeat, and constrict coronary arteries; sympathetic fibers have opposite effect
What does the pulmonary plexus innervate?
parasympathetic fibers constrict bronchioles; sympathetic fibers dilate them; afferents convey reflexes
What does the esophageal plexus innervate?
vagal and sympathetic fibers to smooth muscle and glands of inferior 2/3 of esophagus
What is the origin of the ascending aorta?
aortic orifice of left ventricle
What is the origin of the arch of aorta?
continuation of ascending aorta
What is the origin of the thoracic aorta?
continuation of arch of aorta
What are the branches of the ascending aorta?
right and left coronary arteries
What are the branches of the arch of aorta?
brachiocephalic, left common carotid, left subclavian