posterior mediastinum

Question 1

prominent vessels in posterior mediastinum

Answer 1

descending aorta, oesophagus, vagus nerve

Question 2

ligamentum arteriosum - remnant left over of foetal pulmonary bypass

Answer 2

vagus to left recurrent laryngeal nerve - control most skeletal muscles of larynx

Question 3

recognise

Answer 3

phrenic, vagus nerves, hylem (bronchus, pulmonary veins, pulmonary arteries), trachea, oseophagus, thoracic duct

Question 4

pulmonary ligament

Answer 4

part of hylem allowing expansion of right lung

Question 5

right lung

Answer 5

azygos veins (more R than L)

Question 6

hylem

Answer 6

phrenic anterior, alongside pericardium, vagi posterior

Question 7

entire diagram at T3 from A

Answer 7

slide 5; no subclavian artery so only braciocephalic trunk; left winds around aorta; right winds around subclavian so right recurrent laryngeal nerve not present at T3; left recurrent laryngeal nerve winding around ligamentum arteriosum

Question 8

contents of posterior mediastinum

Answer 8

remove pericardium; oesophagus, (larynx top of airway, pharynx top of GIT); descending aorta, thoracic duct, Azygos venous system
Posterior mediastinal lymph nodes
Thoracic sympathetic trunks
Splanchnic nerves

Question 9

oesophagus

Answer 9

Begins at level of C7 vertebra
Ends at stomach, level of T11 vertebra
Bends more anteriorly at T7
Is right of aorta above T7
Deviates to left at T7
Progressively anterior to aorta below T7
Passes through diaphragm at T10
Has constrictions at four locations

Question 10

trachea

Answer 10

C6

Question 11

constrictions of oesophagus

Answer 11

at C7 (junction of oesophagus with pharynx), where arch of aorta becomes descending aorta, where compressed by L main bronchus, where passes through diaphragm

Question 12

arteries of oesophagus

Answer 12

intercostal spaces at top have different supply to bottom (aorta doesn’t ascend as high as ICS 1 and 2 - posterior intercostal arteries receive supply from subclavian arteries - supreme intercostal artery); others supplied by descending aorta

Question 13

azygos

Answer 13

thoracic duct; left and right brachioceophalic merge to form SVC; left to right side, ascends and drains into SVC; azygos smaller than aorta; on left: accessory hemiazygos and hemiazygos

Question 14

azygos venous system

Answer 14

variable; Drains posterior wall of chest and upper abdomen + posterior mediastinal organs
Usually accessory hemiazygos (upper) and hemiazygos (lower) veins on left cross thoracic vertebral bodies to join single axygos vein on right
Azygos vein arches over right lung root to enter SVC just above right atrium

Question 15

nerves in inferior mediastinum

Answer 15

phrenics (anterior to lung roots), vagi (posterior to lung roots - plexus - follow oesophagus to abdomen), sympathetic trunks (each side of posterior mediastinum)

Question 16

vagus nerves

Answer 16

chest and abdomen are parasympathetic; large sensory from gut and airways, recurrent laryngeal nerve not parasympathetic - runs back up neck to supply most skeletal muscles of larynx

Question 17

left vagus becomes anterior vagal trunk

Answer 17

right vagus becomes posterior vagal trunk

Question 18

sympathetic trunks - none for preaortic ganglia which serve heart

Answer 18

Receive branches from spinal nerves T1 - L2
Distribute sympathetic nerves to smooth muscle and glands throughout body
Nerves to body wall synapse in ganglia of trunks
Nerves to internal organs (viscera) synapse in local ganglia
Also bring pain fibres back to CNS from viscera
Fibres from lower T5 - T12 reach abdomen in bundles called splanchnic nerves

Question 19

stellate ganglion

Answer 19

trunk associated with T1 spinal cord segment

Question 20

T5-T9

Answer 20

greater splanchnic nerve

Question 21

T10-T11

Answer 21

lesser splanchnic nerve

Question 22

T12

Answer 22

least splanchnic nerve

Question 23

thoracic duct

Answer 23

Lymph duct returning lymph from lower limbs, pelvis, abdomen & left thoracic wall to blood
Begins below diaphragm at cisterna chyli
Starts between oesophagus and aorta on right, runs along spinal column
Crosses behind oesophagus to left side between T7 and T4
Drains into junction of left subclavian and left internal jugular veins (to form left brachiocephalic vein)