superior and middle mediastinum prep Flashcards
where is the superior mediastinum
lie above a plane joining sternal angle to lower border of thoracic vertebrae
where is the inferior mediastinum
extends from the plane of sternal angle = T4 to diaphragm
it is subdivided
3 parts of the inferior mediastinum
anterior - lies between sternum and pericardium
middle - composes of pericardial sac and contents
posterior - behing the pericardium, extend inferiorly between diaphragm and posterior chest wall
what is the fibrous pericardium
collagenous layer fused with central tendon of diaphragm and adventitia of great vessels
adventitia
outermost connective tissue covering the vessel
serous pericardium
parietal layer - lines the fibrous pericardium and visceral layer - lines outer surface of the heart
provide heart with friction free surface to accommodate its sliding movements
pericardial cavity
space between parietal and visceral layers containing serous fluid
where does the ascending aorta leave
the LV
where does the pul trunk leave
RV
describe the path of the aorta
continues as the arch of aorta
curves posteriorly and to L over R pul artery
when does the aorta become the descending thoracic aorta
reaches the L side of T4
where is the brachiocephalic vein
lies behind the manubrium
anterior to aortic arch
what forms the superior vena cava
R and L brachiocephalic veins
veins in the neck area
brachiocephalic vein meets subclavian vein which drains arms, and jugular veins that drains head
where does azygos vein go
arches forward over root of R lung to enter superior vena cava
drains posterior and lateral parts of thoracic cage
what protects the great vessels other than the inf vena cava
manubrium
branch of the aortic arch
brachiocephalic artery - crosses over the right side of the trachea
divides into R subclavian artery - pass laterally over 1st rib - enters axilla and R common carotid artery that ascends into the neck to R of trachea
next branch = L common carotid artery - into neck L of trachea
L subclavian artery - into axilla
thyroidea ima artery - may run from arch to thyroid but inconsistent
branches in the aorta
brachiocephalic artery - trunk
left common carotid
left subclavian artery
what is anterior to the superior vena cava
1st costal cartilage
level of bifurcation of the trachea
T4/5
what lies in the subcarinal angle
lymph nodes
what does the anterior mediastinum contain
strands of thymus and adipose tissue
what are the 2 pockets of the pericardial cavity called
pericardial sinuses
describe the oblique sinus
blindly ending pocket of pericardial sac
posterior to LA and surrounded by 4 pul veins
describe the transverse sinus
between great arteries and SVC
pericardium lined tunnel
what happens when you bleed into the pericardial sac
cardiac tamponade
compress the heart
keep it from pumping as well as it should
phrenic nerve
supplies sensory nerves to fibrous pericardium, diaphragmatic pleura and peritoneum
terminate in diaphragm
path of vagus nerve
from carotid sheath
to neck in thorax
then posterior to lung roots to oesophagus
then form network (the oesophageal plexus)
what does the recurrent laryngeal nerve do
supplies skeletal muscle and sensation in the larynx
where does the laryngeal nerve go
leaves the L vagus at aortic arch
hook under acrh - run up to larynx in groove between trachea and oesophagus
difference between the L and R recurrent laryngeal nerves
r in neck
L inn thorax
both down groove between oesophagus and trachea and enter larynx
position of the heart
2/3 lies to L of mid sternal line
1/3 lies to the R
pericardial sac attached to diaphragm
cardiac dullness
area of cardiac dullness - triangle at front of chest - heart not covered by lungs
what is the apex beat
pulsation - caused by apex of L ventricle of heart when forced against anterior chest wall in contraction
where is the apex beat
may be in 4th ICS - children
5th - adults
6-10cm from midsternal line
how should patient be to take apex beat
sit on edge of bed
which side do you start palpating the apex beat
lateral side - move anteriorly
