Organization of the thorax: Thoracic cavities and mediastinum

Question 1

what are the three compartments of the thoracic cavity

Answer 1

2 lateral pulmonary cavities

central mediastinum

Question 2

what are the borders of the mediastinum
5 boundaries (S, L, I, A, P)

Answer 2

1. Superior: superior thoracic aperture
2. Lateral: mediastinal parietal pleura
3. Inferior: diaphragm
4. Anterior: sternum and costal cartilages
5. Posterior: bodies of thoracic vertebrae

Question 3

what are the divisions of the mediastinum

Answer 3

superior

inferior

• anterior
• middle–> heart and pericardial cavity
• posterior

Question 4

what are the boundaries of the superior mediastinum

Answer 4

1. Superior: superior thoracic aperture
2. Inferior: transverse plane passing from sternal angle to the disk between TV4-TV5, (transverse thoracic plane).
3. Anterior: manubrium
4. Posterior: anterior surface of vertebral bodies of TV1-TV4

Question 5

what is the transverse thoracic plane and what structures are right on it (3)

Answer 5

transverse plane passing from sternal angle to the disk between TV4 and TV5

structures:
concavity of arch of aorta
ligamentum arteriosum
left pulmonary artery

vagus splits up and becomes a plexus around esophagus
trachea bifurcates (carina) 
azygous vein dumping into superior vena cava

Question 6

what is the clavicle a landmark for?

Answer 6

internal jugular joins the subclavian to form the brachiocephalic L and R

Question 7

1st rib is a landmark for what?

Answer 7

two brachiocephalics come together

Question 8

3rd rib is a landmark for what

Answer 8

where the superior vena cava drains into the right atrium

Question 9

What are the major structures in the superior mediastinum (8)

Answer 9

thymus
brachiocephalic veins
superior vena cava
aortic arch and main branches
trachea
esophagus
thoracic duct
sympathetic trunk

Question 10

where is the thymus located?
in infants what is the significance?  adults?
what is its vascular supply?
lympathic drainage?
innervation?

Answer 10

a. Located directly posterior to manubrium.
b. Primary lymphatic organ in infants, in adults mostly replaced with fatty tissue.
c. Vascular supply – internal thoracic and inferior thyroid vessels.
d. Lymphatic drainage – parasternal and tracheobronchial nodes.
e. Innervation is mainly from the vagus nerve and sympathetic trunk (vasomotor).

Question 11

where are the brachiocephalic veins formed and from what veins?
which side is longer and where does this particular vein travel

Answer 11

a. Formed posterior to sternoclavicular joint from union of subclavian and internal jugular veins (called venous angle or jugulovenous angle).
b. Left brachiocephalic v. is longer than right and travels transversely across superior mediastinum; right brachiocephalic v. descends just right of manubrium.

Question 12

what is the superior vena cava formed from?

where does it descend

Answer 12

a. Formed from the union of the left and right brachiocephalic veins.
b. Descends to the right of the sternum from the level of the first costal cartilage to the third costal cartilage (third rib) (where it then enters the right atrium).

Question 13

where does the aorta begin?
where does it course?
when does it become the descending thoracic aortic?

Answer 13

a. Begins at TV4/TV5 intervertebral space as a continuation of ascending aorta.
b. Arches posteriorly and to the left over the root of the left lung.
c. Ends posteriorly and to the left of midline at the TV4/TV5 intervertebral disc, becoming the descending (thoracic) aorta.

Question 14

what are the 3 main branches of the aorta?

Answer 14

brachiocephalic trunk (right)–> becomes right common carotid and right subclavian

left common carotid artery
left subclavian artery

Question 15

where is the ligamentum arteriosum

what is the significance of the ligamentum arteriosum

Answer 15

passes from the origin of the left pulmonary artery to the arch of the aorta

represents remnant of the fetal ductus arteriosus which shunted blood from the pulmonary trunk to aorta in order to bypass the fetal lungs.

Question 16

what is the origin of the phrenic nerve?
what does the phrenic nerve supply motor innervation to?
what does the phrenic nerve supply sensory innervation to?

Answer 16

a. Derived from spinal segments C3, C4, C5 (keeps the diaphragmn alive)
b. Motor innervation to the thoracic diaphragm.
c. Sensory innervation to the diaphragm, mediastinal pleura, and pericardium.

Question 17

where does the phrenic nerve enter the thorax?

where does it sit in relation to the root of the lung

Answer 17

d. Enters thorax from neck by passing anterior to the subclavian artery.
e. Pass anterior to the root of the lungs

Question 18

what is origin of the vagus nerve

where does it enter the superior mediastinum? and where does it sit in relation to the root of the lung?

Answer 18

cranial nerve 10

a. Enter the superior mediastinum along lateral border of common carotid arteries.
b. Pass posterior to the root of the lung.

Question 19

what type of nerve cell processes does the vagus nerve carry?

what branch does the left vagus nerve give off and where does this branch course?

Answer 19

c. Carry preganglionic parasympathetic nerve cell processes to thoracic autonomic plexuses.

gives off a left recurrent laryngeal nerve which loops underneath the arch of the aorta just lateral to the ligamentum arteriosum, then courses superiorly in the tracheo-esophageal groove to supply laryngeal muscles.

Question 20

as the left and right vagus nerves approach the esophagus in the posterior mediastinum what do they become

Answer 20

left–> anterior vagal trunk

right–> posterior vagal trunk

Question 21

what is the cause of hoarseness?

Answer 21

due to loss of innervation to laryngeal muscles).

Due to its position in the superior mediastinum, aortic aneurysm, bronchogenic or esophageal cancer, and/or enlargement of mediastinal lymph nodes can impinge on the recurrent laryngeal nerve

Question 22

what are the structures of the anterior mediastinum

Answer 22

thymus, sternopericardial ligaments, fat, lymphatics, connective tissue

bunch of shit

Question 23

what are the borders of the anterior mediastinum

Answer 23

a. Superior: transverse thoracic plane
b. Inferior: diaphragm
c. Lateral: mediastinal parietal pleura
d. Anterior: sternum
e. Posterior: anterior surface of pericardium

Question 24

what are the 5 boundaries of the posterior mediastinum

Answer 24

a. Superior: transverse thoracic plane
b. Inferior: diaphragm
c. Lateral: mediastinal parietal pleura
d. Anterior: sternum
e. Posterior: anterior surface of pericardium

Question 25

what are the major contents of the posterior mediastinum (6)

Answer 25

1) Thoracic (descending) aorta 2) Esophagus 3) Azygous venous system 4) Vagus nerves 5) Thoracic duct and lymph nodes 6) Sympathetic trunk (sympathetic chain ganglia) and splanchnic nerves

Question 26

where does the esophagus originate where does it travel in the superior mediastinum and in the posterior mediastinum?

Answer 26

at the CV6 level as a continuation of the pharynx b. Travels through superior mediastinum posterior and slightly left of trachea. c. Travels right along midline through the posterior mediastinum.

Question 27

where does the esophagus exit the thorax? what is the landmark

Answer 27

exits through the esophageal hiatus of the diaphragm at TV10

Question 28

what are the landmarks of the Cervical, Thoracic and Diaphragmatic Constrictions

Answer 28

cervical- CV6 pharyngoesophageal thoracic- TV4-5 broncho-aortic diaphgragmatic - TV10

Question 29

what is the vascular supply of the esophagus

Answer 29

esophageal and bronchial arteries and veins.

Question 30

what is the lymphatic drainage of the esophagus

Answer 30

posterior mediastinal lymph nodes

Question 31

what is the sympathetic innervation of the esophagus

Answer 31

i. Preganglionic nerve cell bodies at T2-T6 and processes enter sympathetic chain. ii. Postganglionic nerve cell bodies in sympathetic chain ganglia.

Question 32

why does esophageal pain sometimes present similarly to MI pain

Answer 32

Many of the postganglionic nerve cell processes travel with the cardiopulmonary splanchnic nerves ; thus esophageal pain and pain from myocardial infact can present very similarly.

Question 33

what is the parasympathetic innervation of the esophagus

Answer 33

a. Preganglionic nerve cell bodies in brainstem, processes travel with vagus nerve. b. Vagus nerve provides numerous esophageal branches. c. Postganglionic cell bodies in the wall*** of esophagus.

Question 34

what are the functions of the parasympathetic innervation to the esophagus

Answer 34

vasodilation increased gland secretion increased peristalsis

Question 35

what are the functions of the sympathetic innervation to the esophagus

Answer 35

vasoconstriction | decreased gland secretion

Question 36

where does the descending aorta travel in the posterior mediastinum? where does it exit?

Answer 36

left of the midline exits thorax at TV12 through aortic hiatus of thoracic diaphragm

Question 37

what are the branches of the descending aorta ?

Answer 37

Posterior intercostal (9 pair) and subcostal arteries Bronchial artery (usually 2 on left and 1 on right) 4. Esophageal artery (3-5 unpaired branches) 5. Pericardial and mediastinal arteries (unpaired) 6. Superior phrenic arteries (1 pair)

Question 38

what is the landmark for when the azygos arches anteriorly over the root of the right lung to enter the SVC?

Answer 38

TV4

Question 39

what is the landmark for when the hemiazygos (more left in the posterior mediastinum) crosses the midline and joins the azygos vein

Answer 39

TV9

Question 40

where is the landmark for when the accessory hemiazygos crosses the midline and joins the azygos vein

Answer 40

TV8

Question 41

where does the thoracic duct begin? where does it travel and enter the thorax

Answer 41

at LV2 from the dilated sac called the cisterna chyli enters the thorax with the aorta and ascends along the midline posterior to the esophagus

Question 42

at what point does the thoracic duct cross to the left of midline and travel in the superior mediastinum to the left of the esophagus

Answer 42

TV5

Question 43

what is the path of the thoracic duct in the neck

Answer 43

passes posterior to the left common carotid and internal jugular vein to enter the VENOUS ANGLE the venous angle is the junction of the left subclavian and the left jugular veins

Question 44

from what structures does the thoracic duct receive drainage before emptying into the venous angle ?

Answer 44

left bronchomediastinal left jugular left subclavian trunk

Question 45

what does the right lympathic duct drain?

Answer 45

right side of head, right neck | right arm

Question 46

ultimately, what does the thoracic duct receive ?

Answer 46

both lower extremities the entire pelvis abdomen left upper extremity 3/4 of body!!

Question 47

what does an autonomic pelxus contain

Answer 47

both sympathetic and parasympathetic components

Question 48

where are thoracic splanchnic nerves headed

Answer 48

going to prevertebral ganglia in the abdomen

Question 49

what are thoracic splanchnic nerves composed of?

Answer 49

PREGANGLIONIC sympathetic nerve cell process

Question 50

greater splanchnic

Answer 50

T5-T9

Question 51

lesser splanchnic

Answer 51

T10-T11

Question 52

least splanchnic

Answer 52

T12

Question 53

where does the inferior vena cava enter the heart? what landmark?

Answer 53

6th costal cartilage

Question 54

where does the right brachiocephalic vein end up in the neck?

Answer 54

ends at level of 1st costal cartilage

Question 55

in the thorax what does the vagus nerve give branches of? x4

Answer 55

recurrent laryngeal cardiac pulmonary esophageal

Question 56

what does the azygos drain and communicate with

Answer 56

drains both thoracic and abdominal walls and communicates with the vertebral plexus of veins

Question 57

what might an aortic aneurysm cause?

Answer 57

dysphagia (difficulty swallowing) | hoarseness

Question 58

what is a hiatal hernia and what is it usually accompanied by?

Answer 58

protrusion of the abdominal viscera or the omentum through the esophageal hiatus into the thoracic cavity usually has gastritis and epigastric pain too

Question 59

The thoracic vertebral level of structures traversing the diaphragm is .... (esophagus, aorta, inferior vena cava)

Answer 59

T8 for the inferior vena cava, T10 for the esophagus, and T12 for the aorta. The anteroposterior position is inferior vena cava, esophagus, and aorta.