Clinical Anatomy of mediastinum (A8)

Question 1

subdivisions of the mediastinum

Answer 1

1. superior (above level of sternal angle at T4/T5 vertebrae, and rises above rib 1)
2. inferior (below the level of the sternal angle) - splits into anterior, middle, and posterior divisions

Question 2

what subdivision of the mediastinum is the thymus gland contained

Answer 2

anterior

Question 3

important structures of posterior mediastinum

Answer 3

descending aorta(on left hand side) oesophagus, trachea and bronchi, thoracic duct, azygous vein, sympathetic chain (x2), vagus nerve (x2)

Question 4

descending aorta

Answer 4

arterial blood to intercostal spaces and lower half of the body (travels posterior to lung root on left lateral view)

Question 5

divisions of aorta

Answer 5

ascending -> arch -> descending -> abdominal (after passing through the diaphragm)

Question 6

oesophagus

Answer 6

carries food and liquid from pharynx (throat) to stomach, role in swallowing

Question 7

trachea and bronchi

Answer 7

respiratory gases between larynx (voice box) and lungs, trachea has a role in speech

Question 8

position of trachea, bronchi, aorta and oesophagus in relation to each other (on anterior view)

Answer 8

trachea sits anterior to oesophagus and posterior to the ascending aorta and arch of the aorta however the descending aorta loops behind the oesophagus before entering the diaphragm and becoming the abdominal aorta. The two main bronchi sit anterior to the descending aorta

Question 9

thoracic duct

Answer 9

major lymphatic vessel of the body, returns lymph to the venous system in the root of the neck, extends from within diaphragm and travels posterior to oesophagus (?)

Question 10

origin of lymph

Answer 10

fluid squeezed out of the capillaries is mainly reabsorbed before it reaches the venules, excess fluid left in the tissues is called tissue fluid and when taken up by the lymphatic vessels it is then called lymph

Question 11

tracheobronchial lymph nodes

Answer 11

at bifurcation of trachea into two main bronchi

Question 12

pulmonary lymph nodes

Answer 12

at bifurcation of primary (main) bronchi into secondary bronchi

Question 13

azygous vein

Answer 13

drains venous blood from intercostal spaces to superior vena cava

Question 14

sympathetic chain (x2)

Answer 14

sympathetic nerves to skin (of intercostal spaces) and organs of the body, the trunk of the sympathetic chain link the ganglion and the intercostal nerves together and have sympathetic branches to the heart and lungs (cardiopulmonary splanchic nerves) and descending branches to the abdomen (abdominopelvic)

Question 15

vagus nerve (x2)

Answer 15

parasympathetic nerves to internal organs of thorax and abdomen (not to skin), right vagus nerve runs lateral to the trachea; the left vagus nerve loops under the arch of the aorta

Question 16

right and left phrenic nerves

Answer 16

right runs posterior to right atrium, left runs across left ventricle

Question 17

ligamentum arteriosum

Answer 17

remnant of ductus arteriosum (The ductus arteriosus is a blood vessel that allows blood to go around the baby’s lungs before birth. Soon after the infant is born and the lungs fill with air, the ductus arteriosus is no longer needed. It usually closes in a couple of days after birth)

Question 18

thoracic aorta

Answer 18

descending aorta

Question 19

structures present in superior mediastinum

Answer 19

arteries to head and upper limbs, veins from head and upper limbs, scalenus anterior muscles, nerves (phrenic, vagus and recurrant laryngeal branches of vagus) - phrenic nerve lies on top of scalenus anterior muscle

Question 20

groove for subclavian artery and vein on rib 1

Answer 20

groove for subclavian artery sits posterior to the groove for subclavian vein and attachment of the scalenus anterior muscle to the scalene tubercle separates these two structures

Question 21

arch of the aorta

Answer 21

supplies oxygenated blood from left ventricle to the whole body

Question 22

branches of arch of aorta

Answer 22

(from my left to right)

1. brachiocephalic trunk/artery which splits into right subclavian artery (to supply right arm) and right common carotid artery (to supply right side of head/neck)
2. left common carotid artery (supplies left side of head/neck)
3. left subclavian artery (supplies left arm)
   - > arch then descends and becomes descending aorta/thoracic aorta

Question 23

veins from head and upper limbs

Answer 23

carry deoxygenated blood from upper limbs and head to right atrium via brachiocephalic veins into the superior vena cava (internal jugular veins and subclavian veins are branches of the brachiocephalic veins)

Question 24

location nerves present in superior mediastinum from lateral to medial

Answer 24

1. right and left phrenic
2. right and left vagus
3. right and left recurrent laryngeal

Question 25

right and left recurrent laryngeal nerves

Answer 25

branches of the vagus nerves that supply the larynx (voice box)

Question 26

hilum/hilar/hilus

Answer 26

sac that the lung sits within

Question 27

how can the spread of lung cancer, difficulty swallowing and a hoarse voice be linked anatomically

Answer 27

swelling of tracheobronchial nodes can compress adjacent structures; compression of oesophagus causes difficulty swallowing and compression of recurrant laryngeal nerve which supplies voice box can prevent action potentials reaching the muscles of the larynx/voice box that makes the vocal cords move to produce normal speech