4- Superior Mediastinum

Question 1

2 pericardial sinuses

Answer 1

Transverse

Oblique

Question 2

How pericardial sinuses form

Answer 2

Transverse- venous and arterial ends of heart brought together
Oblique- reflection onto the pulmonary of heart

Question 3

Features of right atrium

Answer 3

Crista terminalis
Pectinate 
Fossa ovalis
Opening of coronary sinus
Right auricle

Question 4

Features of left atrium

Answer 4

Valve of fossa ovalis

Left auricle

Question 5

Intercostal nerves

Answer 5

11 pairs (+ 1 subcostal)
Mixed (= motor + sensory)
Spinal or segmental nerves
(anterior primary rami)
Supply the intercostal spaces
Lateral cutaneous branch - anterior and posterior
Anterior cutaneous branch - medial and lateral

Question 6

Where do sympathetic trunks receive nerves from

Answer 6

T1- l2

Question 7

Which fibres form splancnic nerves

Answer 7

T5-t12

Question 8

Course of vagus nerves

Answer 8

Cranial nerve X – arise from medulla and leave skull through jugular foramina
Descend neck posterolateral to common carotid artery
Left vagus crosses anterior to aortic arch then posterior to left lung root
Right vagus passes posterior to right lung root
Both vagi form a plexus round the oesophagus

Question 9

What does recurrantLarangeal supply

Answer 9

Recurrent laryngeal branch of vagus nerve is not parasympathetic – runs back up neck to supply most skeletal muscles of larynx

Question 10

Divisions of mediastinum

Answer 10

Superior: above sternal angle
Inferior: below sternal angle
Anterior: anterior to heart in pericardial sac
Middle: pericardial sac & heart
Posterior: posterior to pericardial sac and diaphragm

Question 11

Phrenic nerves give sensory innervation to the

Answer 11

central tendon of the diaphragm
–mediastinal pleura
–pericardium
–peritoneum of central diaphragm

Question 12

Where do l phrenic and vagus nerves run

Answer 12

Cross arch of aorta
Left phrenic descends in front of root lung
Left vagus crosses behind root lung gives off left recurrent laryngeal nerve – recurs (=turns back) around ligamentum arteriosum and aortic arch
Breaks up into many branches round oesophagus

Question 13

Where does right vagus nerve run

Answer 13

Lies on the trachea

• Crosses behind the root lung
• Recurrent laryngeal branch – recurs (turns back) around right subclavian artery