lecture-4-mediastinum

Question 1

Superior Mediastinum

Answer 1

Thymus

Great vessels of the Heart

SVC

Arch of Aorta & major roots: Brachiocephalic Trunk, Left CC artery, Left SC artery

Phrenic N.

Vagus N.

Trachea

Superior part of the Esophagus

Question 2

The SVC is formed from the joining of the

Answer 2

R and L Brachiocephalic Veins

Question 3

Branching of Aortic Arch

(ascending –> descending)

Answer 3

Right common cartoid artery (RC)

Right Subclavian (RS)

Brachiocephalic Trunk (BT)

LC

LS

Question 4

Azygos vein

Answer 4

located in the posterior mediastinum

joins SVC

forms collateral circulation between SVC and IVC

e.g. if IVC is obstructed, blood can flow into SVC from abdominal area

Question 5

SVC

Answer 5

formed by the merger of the R. and L. Brachiocephalic Veins

Question 6

Aortic Arch Branches

Answer 6

BT, LC, LS

Question 7

Branches of BT

Answer 7

RC and RS

Question 8

Variations of the aortic arch:

Bovine arch

Answer 8

Bovine arch - LC branches off BT (12%)

Question 9

ductus arteriosus

Answer 9

connects PT to Aorta

Question 10

Coarctation of the aorta

Answer 10

defect during birth

narrows surrounding aorta (ductus arteriosus) ==> reduces bloodflow to the inferior aorta

Collateral system established ==> Subclavian A ==> internal thoracic a. ==> intercostals a. ==> inferior aorta

Question 11

Vagus N.

Answer 11

CN X

Posterior to the root of the lungs

activities: sensory, somatic and parasympathetic

Question 12

Branches of vagus also form _____

Answer 12

Branches of vagus also form __Cardiac and Pulmonary Plexus___

Question 13

Left and Right Vagues N. are ______

Answer 13

Left and Right Vagues N. are ___Asymmetrical___

Question 14

Left recurrent laryngeal n

Answer 14

Branch of Left Vagus N.

Somatic component of Vagus N.

goes underneath ligamentum arteriosum + back up toward the larynx to form the laryngeal plexus

Question 15

Right recurrent laryngeal n.

Answer 15

branch of the right vagus n.

travels underneath the RS a. to the Larynx

Question 16

The ____ recurrent laryngeal n. branches off the ___ vagus n. at a lower level than the ___

Answer 16

The __LEFT__ recurrent laryngeal n. branches off the __LEFT__ vagus n. at a lower level than the __RIGHT__

Question 17

Phrenic N.

Answer 17

Cervical plexus origin (C3,4,5 keeps diaphragm alive)

innervates diaphragm (somatic and senosry)

runs INFRONT of the root of the lung

Vagus n. rungs behind the root of the lung

Question 18

inferior mediastinum

Answer 18

anterior, middle, posterior

between sternal plane and vertebra

Question 19

Posterior Mediastinum location & contents

Answer 19

T5 - T12 + behind middle mediastinum

below sternal angle, behind heart, in front of vertebral column

“DATES”

Descending Aorta

Azygos (and hemiazygos) veins

Thoracic duct

Esophagus

Sympathetic trunk

+

Vagus nerves & splanchnic n.

Question 20

Thoracic Aorta Branches

Thoracic Aorta becomes abdominal aorta

Answer 20

tracheal

esophageal

intercostal

Thoracic Aorta crosses diaphragm via aortic hiatus @ T12 ==> abdominal aorta

Question 21

Azygos Vein

Answer 21

Right side

Collateral circulation for IVC (if obstructed) then blood can travel to SVC

drains blood from the posterior wall of the thorax and abdomen

Question 22

Hemiazygos Vein

Answer 22

Left Side

Ascends to T8 => crosses vertebra and joins azygos vein

drains blood from lower floor end of thoracic cavity

Question 23

accessory hemiazygos vein

Answer 23

Descends on Left side from T5-T8

crosses at T7/8 to join azygos vein

drains 4-8 ICS

Question 24

Thoracic Duct

Answer 24

largest lymphatic channel of the body

travels on the right side of the aorta (posterior to the esophagus)

Lymphatic drainage into LS and Jugular veins