thorax 4 (gross anatomy) Flashcards
what sits on either side of the mediastinum?
right and left lung pleural cavities
what does the mediastinum contain?
every thoracic structure besides the lungs and their associated pleura
what is the mediastinum bound by superiorly?
superior thoracic aperture
what is the superior thoracic aperture?
manubrium of sternum
left and right first ribs
thoracic vertebrae 1 (T1)
= aperture (hole) formed by the superior borders of the above structures
what is the mediastinum bound by inferiorly?
diaphragm
what is the mediastinum bound by anteriorly?
sternum
what is the mediastinum bound by posteriorly?
twelve thoracic vertebrae
what is the mediastinum bound by laterally?
the lungs enveloped in theri pleura
how is the mediastinum a moveable structure?
parts of the mediastinum (e.g. pericardium enveloping the heart) = anchored to diaphragm
during breathing, when diaphragm either contracts or relaxes = attached dynamic structures also move (w their attachments)
- maybe also during times of pathology
what happens to the mediastinum during a tension pneumothorax?
lung collapses
mediastinum pushed to opposite side = deviation of the trachea (pulled over to side opposite of the tension pneumothorax)
how is a tension pneumothorax identified?
deviation of the trachea
away from the side of the pneumothorax
what are the anatomical divisions of the mediastinum?
superior mediastinum
inferior mediastinum = anterior, middle and posterior mediastinum
what is the most important plane that divides the mediastinum?
sternal angle
what does the sternal angle divide the mediastinum into?
superior and inferior mediastinum
what does the sternal angle also indicate?
indicates the division of thoracic mediastinal structures into either superior OR inferior mediastinal structures
what are the borders of the anterior mediastinum?
anterior = sternum
posterior = anterior border of the pericardium
what are the borders of the middle mediastinum?
anterior = anterior border of the pericardium
posterior = posterior border of the pericardium
what are the borders of the posterior mediastinum?
anterior = posterior border of the pericardium
posterior = thoracic vertebrae
how is the sternal angle formed?
articulation between manubrium and body of sternum
what is in line with the sternal angle?
second costal cartilages of second ribs
= articulate on either side of sternal angle
why is the sternal angle clinically important?
once palpated it
1) can locate the intercostal surfaces (below and above second costal cartilages)
2) from 1, can palpate other intercostal spaces (essential for heart valve and lung lobe auscultation)
what spinal level is the sternal angle at?
T4 (maybe T5)
what does the sternal angle divide?
1) mediastinum into superior and inferior portions
2) a number of thoracic and mediastinal structures
how does the sternal angle divide the arch of the aorta?
superior mediastinum = arch of the aorta
inferior mediastinum = ascending aorta and descending thoracic aorta
where can the bifurcation of the trachea be found?
sternal
at which spinal level does the trachea bifurcate?
T4 (i.e. at the level f the sternal angle)
what does the trachea bifurcate into?
the left and right primary bronchi
what is left to right venous shunting?
right atrium of heart lies on the right side of thorax
venous structures form the left side of the thorax need to cross the midline to drain into the superior vena cava
(e.g. brachiocephalic vein)
why is left to right venous shunting important?
to enable venous structures from the left side of the thorax to drain into the superior vena cava on the right side, into the right atrium
where do the great vessels lie in the mediastinum?
emerge from the superior thoracic aperture and cross over the left and right first rib
subclavian veins are anterolateral to the subclavian arteries (positioned on the right)
what are the boundaries of the superior mediastinum?
anterior = manubrium of sternum
posterior = T1-T4
superior = superior thoracic aperture
inferior = sternal angle plane
what is the thymus gland?
makes white blood cells (T lymphocytes) = part of the immune system + help fight infection
when is the thymus gland most active?
only active until puberty
how does the activity of the thymus gland vary with age?
after puberty, thymus starts to shrink and is replaced by fatty connective tissue = becomes a residual, inactive structure
where is the thymus gland located in the mediastinum?
located behind your sternum and between your lungs, is only active until puberty
inferior portion projects downwards and sits in the anterior part of the inferior mediastinum
