Superior Mediastinum

Question 1

Superior mediastinum: location + contents

Answer 1

Btw. manubrium + bodies of T1-T4

Contents:

• thymus
• R + L brachiocephalic v.
• Left sup. IC v.
• SVC
• aortic arch = brachiocephalic trunk, LCCA + LSCA
• trachea
• oesophagus
• vagus
• phrenic
• LRL n.
• thoracic duct

Question 2

Trachea: structure + location

Answer 2

Cylindrical tube
Flattened post.
16-20 U-shaped rings
Below cricoid (C6) - T4/5
Bifurcates - primary bronchi
Carina = last ring

Question 3

Trachea: important relationships

Answer 3

Ant. = aortic arch
Post. = oesophagus
Lat. (R) = vagus + azygous arch
Lat. (L) = LRL n.

Question 4

Aortic arch: branches

Answer 4

3 Major:
*brachiocephalic trunk (R)
*LCCA
*LSCA
Brachiocephalic trunk = RCCA + RSCA
Ascending aorta = R + L coronary a.

Question 5

Left recurrent laryngeal nerve: origin + course

Answer 5

Branches off L vagus n.
Inf. margin of arch, lat. to ligamentum
Passes inf. to arch, ascends med. surface
Groove btw. trachea + oesophagus, sup. to neck + terminates in larynx

Question 6

Ligamentum arteriosum

Answer 6

Remnant of ductus arteriosus
Connects pulmonary trunk + arch = bypass lungs
1st breath - closes + ligamentum remains

Question 7

Right recurrent laryngeal nerve: origin + course

Answer 7

Branches off R vagus n.

Hooks around RSCA + ascends

Question 8

Horizontal section: 14 occurrences at sternal angle

Answer 8

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Manubriosternal joint
Rib 2
Pulmonary trunk bifurcation
Pericardium
Pleura (ant.)
Aortic arch
Ligamentum arteriosum
Recurrent laryngeal nerve (left)
Cardiac plexus
Tracheobronchial lymph nodes
Carina (tracheal bifurcation)
Azygous arch
Thoracic duct crossing over
Mediastinal division into superior + inferior

Question 9

Surface anatomy: trachea + bifurcation

Answer 9

C6-T4/5

Bifurcation = T4/5

Question 10

Surface anatomy: ascending aorta

Answer 10

3rd cartilage

Behind sternum in midline to sternal angle

Question 11

Surface anatomy: aortic arch

Answer 11

Sternal angle = level of T4/5

Question 12

Surface anatomy: pulmonary trunk

Answer 12

Left of sternum

From 2nd rib down

Question 13

Surface anatomy: SVC

Answer 13

Right of sternum

From middle of manubrium down

Question 14

Surface anatomy: IVC

Answer 14

Right border of heart

Question 15

Entrance to thorax: bones, blood, structures + nerves

Answer 15

Bones:

• manubrium
• 1st cartilage
• rib 1
• T1

Blood:

• brachiocephalic trunk
• brachiocephalic veins
• subclavian a. + v.

Structures:

• oesophagus
• trachea
• apices of lungs

Nerves:

• vagus
• phrenic
• sympathetic trunk