thorax 4 (gross anatomy)

Question 1

what sits on either side of the mediastinum?

Answer 1

right and left lung pleural cavities

Question 2

what does the mediastinum contain?

Answer 2

every thoracic structure besides the lungs and their associated pleura

Question 3

what is the mediastinum bound by superiorly?

Answer 3

superior thoracic aperture

Question 4

what is the superior thoracic aperture?

Answer 4

manubrium of sternum
left and right first ribs
thoracic vertebrae 1 (T1)

= aperture (hole) formed by the superior borders of the above structures

Question 5

what is the mediastinum bound by inferiorly?

Answer 5

diaphragm

Question 6

what is the mediastinum bound by anteriorly?

Answer 6

sternum

Question 7

what is the mediastinum bound by posteriorly?

Answer 7

twelve thoracic vertebrae

Question 8

what is the mediastinum bound by laterally?

Answer 8

the lungs enveloped in theri pleura

Question 9

how is the mediastinum a moveable structure?

Answer 9

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

Question 10

what happens to the mediastinum during a tension pneumothorax?

Answer 10

lung collapses

mediastinum pushed to opposite side = deviation of the trachea (pulled over to side opposite of the tension pneumothorax)

Question 11

how is a tension pneumothorax identified?

Answer 11

deviation of the trachea

away from the side of the pneumothorax

Question 12

what are the anatomical divisions of the mediastinum?

Answer 12

superior mediastinum

inferior mediastinum = anterior, middle and posterior mediastinum

Question 13

what is the most important plane that divides the mediastinum?

Answer 13

sternal angle

Question 14

what does the sternal angle divide the mediastinum into?

Answer 14

superior and inferior mediastinum

Question 15

what does the sternal angle also indicate?

Answer 15

indicates the division of thoracic mediastinal structures into either superior OR inferior mediastinal structures

Question 16

what are the borders of the anterior mediastinum?

Answer 16

anterior = sternum

posterior = anterior border of the pericardium

Question 17

what are the borders of the middle mediastinum?

Answer 17

anterior = anterior border of the pericardium

posterior = posterior border of the pericardium

Question 18

what are the borders of the posterior mediastinum?

Answer 18

anterior = posterior border of the pericardium

posterior = thoracic vertebrae

Question 19

how is the sternal angle formed?

Answer 19

articulation between manubrium and body of sternum

Question 20

what is in line with the sternal angle?

Answer 20

second costal cartilages of second ribs

= articulate on either side of sternal angle

Question 21

why is the sternal angle clinically important?

Answer 21

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)

Question 22

what spinal level is the sternal angle at?

Answer 22

T4 (maybe T5)

Question 23

what does the sternal angle divide?

Answer 23

1) mediastinum into superior and inferior portions

2) a number of thoracic and mediastinal structures

Question 24

how does the sternal angle divide the arch of the aorta?

Answer 24

superior mediastinum = arch of the aorta

inferior mediastinum = ascending aorta and descending thoracic aorta

Question 25

where can the bifurcation of the trachea be found?

Answer 25

sternal

Question 26

at which spinal level does the trachea bifurcate?

Answer 26

T4 (i.e. at the level f the sternal angle)

Question 27

what does the trachea bifurcate into?

Answer 27

the left and right primary bronchi

Question 28

what is left to right venous shunting?

Answer 28

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)

Question 29

why is left to right venous shunting important?

Answer 29

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

Question 30

where do the great vessels lie in the mediastinum?

Answer 30

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)

Question 31

what are the boundaries of the superior mediastinum?

Answer 31

anterior = manubrium of sternum

posterior = T1-T4

superior = superior thoracic aperture

inferior = sternal angle plane

Question 32

what is the thymus gland?

Answer 32

makes white blood cells (T lymphocytes) = part of the immune system + help fight infection

Question 33

when is the thymus gland most active?

Answer 33

only active until puberty

Question 34

how does the activity of the thymus gland vary with age?

Answer 34

after puberty, thymus starts to shrink and is replaced by fatty connective tissue = becomes a residual, inactive structure

Question 35

where is the thymus gland located in the mediastinum?

Answer 35

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