mediastinum

Question 1

subdivisions of mediastinum

Answer 1

sternum -> vertebral column
sternal angle –> T4
- superior (sup, mid, deep)
- inferior (ant, med, post)

Question 2

structures found in the superior, middle division of mediastinum

Answer 2

aortic arch, ligamentum arteriosum, vagus nerve, phrenic nerve

Question 3

structures found in the superior, deep division of the mediastinum

Answer 3

trachea, oesophagus, left recurrent laryngeal nerve, thoracic duct, azygos system, sympathetic trunk

Question 4

structures found in the inferior middle division of the mediastinum

Answer 4

pericardium + heart

Question 5

structures found in the inferior posterior division in the mediastinum (6)

Answer 5

oesophagus, vagus nerve, thoracic aorta, sympathetic trunk, thoracic duct, azygous system

Question 6

innervation of middle mediastinum

Answer 6

heart + visceral pericardium = vagus nerve (cardiac plexus) + sympathetic trunk

Parietal and fibrous pericardium = phrenic nerve

Question 7

arch of aorta

Answer 7

superior-middle mediastinum
emerges from pericardial sac as ascending aorta

sternal angle = arch

courses: superior (mid-mediastinum), posterolateral (left)

3 main branches

continues into the inferior, posterior mediastinum

Question 8

branches off the arch of the aorta (ABC’S)

Answer 8

part of superior-middle mediastinum

Arch
Brachiocephalic trunk
(left) Common carotid a.
(left) Subclavian a.

Question 9

thoracic aorta + branches

Answer 9

part of inferior-posterior mediastinum

branches:
- T4, anterior and left of vertebral column
- pericardial, bronchial, esophageal, mediastinal, posterior intercostal, superior phrenic, subcostal

Question 10

abdomen and what part of the mediastinum is it from

Answer 10

abdominal aorta - part of inferior-posterior mediastinum

Question 11

vagus nerve (general)

Answer 11

part of both superior-middle and inferior-posterior mediastinum

10th cranial nerve - brainstem
parasympathetic innervations to thoracic + abdominal organs (rest + digest)

Question 12

vagus nerve in the superior-middle mediastinum

Answer 12

left: lateral to arch of aorta
- left recurrent laryngeal nerve

passes behind lung roots into inferior-posterior mediastinum

Question 13

vagus nerve in the inferior-posterior mediastinum

Answer 13

contributes to many plexuses
- cardiac, left + right pulmonary, ant + post esophageal plexus

anterior + posterior vagal trunks travel through esophageal hiatus in diaphragm

Question 14

trachea

Answer 14

part of superior-deep mediastinum

larynx–> primary bronchi
- carina (~T4/T5 level standing)

16-20 C-shaped rings
- hyaline cartilage, prevents collapse, “open” posteriorly - esophagus

trachealis muscle
- smoother muslce
- runs longitudinally
- decreases diameter

does not leave superior-deep mediastinum

Question 15

bronchii

Answer 15

superior-deep and inferior-posterior mediastinum

left/right primary (main) bronchi
part of lung root
enter lung at hilum

2° bronchi = lobar
- each lobe

3° bronchi = segmental
- each lobe segment
- clinical importance - bronchopulmonary segments

extensive branching

Question 16

esophagus (general)

Answer 16

superior-deep + inferior-posterior mediastinum

straight, muscular tube
joints pharynx to stomach (cervical skeletal m., thoracic, abdominal smooth m.)
starts at C6 - upper esophageal sphincter - narrowing

becomes abdominal esophagus

Question 17

esophagus in superior deep mediastinum

Answer 17

narrowing behind aortic arch
behind left main bronchus

Question 18

esophagus in inferior-posterior mediastinum

Answer 18

midline anterior to vertebral bodies (posterior to mediastinum)
aorta on left (SVC/IVC on the right)
esophageal hiatus - diaphragm (narrowing)

Question 19

left recurrent laryngeal nerve

Answer 19

superior-deep mediastinum

branch of vagus nerve
left + right
different anatomy - non-symmetrical
- left = superior mediastinum, ligamentum arteriosum, arch of aorta
- trachea + esophagus –>larynx

Question 20

left recurrent laryngeal nerve is susceptible to compression as is passes under…..

+symptoms, diagnostics

Answer 20

under aortic arch

symptoms: vocal chord paralysis, hoarseness of voice

diagnostics: chest radiography

Question 21

thoracic duct

Answer 21

superior-deep and inferior-posterior mediastinum

drains body of lymph (except right upper limb, right half of thorax, head and neck)
drainage -> back to venous system

starts at cisterna chyli - L1-L2

Question 22

thoracic duct in inferior-posterior mediastinum is located…

Answer 22

between aorta + azygous vein
moves to teh left (alongside aorta) behind esophagus

Question 23

thoracic duct in superior-deep mediastinum

Answer 23

continuous on the left
drains into the left brachiocephalic vein

Question 24

azygous system (general)

Answer 24

superior-deep and inferior-posterior

anastomic pathway to drain blood from posterior body wall to superior vena cava

main components: - Azygous vein (main drainage on right)
- hemiazygos vein + accessory hemiazygos vein (main drainage on left, drain into azygos vein

abdominal

Question 25

azygos system in inferior-posterior mediastinum

Answer 25

posterior intercostal vein leftL hemiazygous vein + accessory hemiazygous right: azygous vein

Question 26

azygos system in superior-deep mediastinum

Answer 26

differences between left and right

Question 27

left and right azygos vein

Answer 27

left: superior intercostal vein - drains into left brachiocephalic vein -->SVC right: connection to the heart arches over esophagus + right main bronchus (T4) enters: superior vena cava

Question 28

sympathetic trunk

Answer 28

superior-deep and inferior-posterior mediastinum parallel chains of nerves ganglia (lateral to vertebral column, necks of ribs) sympathetic innervations thoracic + abdominal viscera (fight/flight)

Question 29

sympathetic trunk in superior-deep mediastinum

Answer 29

superior (4-5 ganglia) - thoracic viscera - pulmonary, esophageal + cardiac plexuses

Question 30

sympathetic trunk in inferior-posterior mediastinum

Answer 30

splanchnic nerves abdominal + pelvic viscera pass through diaphragm prevertebral plexuses