Thoracic Cavity and Mediastinum

Question 1

What are the 3 parts of the sternum

Answer 1

Manubrium, body, xipoid process

Question 2

What is the sternal angle

Answer 2

junction of the manubium and steral body

most reliable surface landmark of chest

Question 3

Where is the sternal angle located relatively

Answer 3

2nd costal cartilage

Question 4

What articulates with the manubrium

Answer 4

clavicle and 1st costal cartilage

Question 5

Which ribs are true and why

Answer 5

Ribs 1-7

articulate diretly with the sternum

Question 6

Which ribs are false and why

Answer 6

Ribs 8-10

articulate with costal cartilages just above them

Question 7

Which are the floating ribs and where do they end

Answer 7

Ribs 11-12

Terminate in abdominal musculature

Question 8

How do upper thoracic vertebraes transverse processes articulate with ribs

Answer 8

Have cup shamed facets which allow rotational movements

Question 9

How do lower thoracic vertebraes transverse processes articulate with ribs

Answer 9

Have flat processes allowing gliding of tubercles

Question 10

What makes up the boundaries of the thoracic inlet

Answer 10

Anteriorly: manubrium
Latteraly: first pair of ribs
Posteriorly: first thoracic vertebra

Question 11

What makes up the boundaries of the thoracic outlet

Answer 11

Anteriorly: xiphoid process
Laterally: costal arch from costal cartilages 7to 10 and twelfth rib
Posteriorly: 12th vertetbrae

Question 12

What is the superficial later of the muscles of the thoracic wall and how do they run

Answer 12

External intercostals: run inferiorly and medialy and extend from tubercles to costal cartilage

Question 13

What is the middle later of the muscles of the thoracic wall and how do they run

Answer 13

Internal intercostals run at right angles to the superficial layers and extend from sternum to angels of the ribs

Question 14

What is the Deep later of the muscles of the thoracic wall and how do they run

Answer 14

Represented by transversus thoracis and innermost intercostal

Transversus thoracis: 4 or 5 slips of muscle from posterior surface of lower sternum to superior costal cartilages

Innermost: deep to internal and on most lateral portion of intercostal space (those that span 2 or more intercostal spaces are called subcostal

Question 15

What is the converrgence in the center of the diaphram called

Answer 15

central tendon or aponeurosis

Question 16

Where do the nerves and vessels of the thoracic wall run and what is their order

Answer 16

Run between middle and deep layers along costal groove (inferior border

Vein superior to artery that is superior to nerve

Question 17

What innervates the skin and muscles of the thoracic WALL

Answer 17

anterior rami of thoracic spinal nerves

T1-T11: intercostal
t12: Subcostal

Question 18

What muscle in the thoracic area do the costal nerves not motor innervate

Answer 18

Diaphram (phrenic)

They do give sensory information to peripheral area of diaphram

Question 19

Where do posterior intercostal arterires arise

Answer 19

first 2 off costocervical

rest off thoracic aorta

Question 20

Where do the anterior intercostal arteries arise

Answer 20

internal thoracic artery or the musculophrenic terminal branch of the internal thoracic

Question 21

Where do the anterior and posterior intercostal veins drain

Answer 21

Posterior: azygos venous system
(right side azygous)

(left side top 1/3 superior vena cava middle 1/3 accessory hemizygous lower 1.3 hemizygous)

Anterior: internal thoracic veins

Question 22

What changes in space cause a change in pressure of thoracic cavity

Answer 22

Superoinferior change: Diaphram contraction (primary means of increasing thoracic capacity)

anteroposterior change: elevation of the upper 6 ribs by the intercostal muscles ( caused by articulation of tubercles sternum pused forward)

lateral change: caused by elevation of lower ribs which swing up and out laterally`

Question 23

What maintains intercostal spacing

Answer 23

Contraction of intercostal muscles

Question 24

How is the mediastinum divided

Answer 24

Superior: continuous with retropharyngeal space and ends at sternal angle and disk between t4t5
Inferior: Anterior, Middle, Posterior

Question 25

What 7 things contained in the Superior Mediastinum

Answer 25

Thymus: (often just fat pad in adults)

Brachiocephalic veins:

Superior vena cava:

Arch of the aorta:

Vagus and Phrenic nerves:

Trachea:

Esophagus:

Question 26

What is contained in anterior mediastiunum

Answer 26

In front of pericardial cavity

Internal thoracic vessels: descend posterior to costal cartilages and slightly lateral to sterunum
In children: inferior part of thymus

Question 27

What 4 things are in the middle mediastiunum

Answer 27

Pericardium
Heart
Roots of great vessels

Phrenic nerve and pericardiacophrenic vessels run between pericardium and meiastinal pleurae

Question 28

What 7 things are in the posterior mediastiunum

Answer 28

Behind pericardial cavity
Descending aorta:initially left then centers

Esophagus: initially middline and shifts left, anterior to descending aorta before passing diaphram (t10)

Azygous vein:

Acessory Hemiazygous veins:

Thoracic duct: acscend through aortic haitus pass between azzygous vein and descending aorta

Vagus nerves: Posterior to root of lungs (reforms clost to diaphram to make anterior and posterior vagal trunks

Splanchnic nerves: Preganglionic sympathetic fibers pass through crura of diahpram

Question 29

Why arent inferior vena cava and sypathetic trunks part of mediastinum list

Answer 29

Inferior vena cave immediately enters heart and sympathetic trunks are not between mediastinal pleurae

Question 30

What vertebrae level do the, Aorta, Esophagus, and inferior vena cava pass through the diaphram

Answer 30

Aorta: t12: through aortic Haitus to become abdominal aorta

Esophagus: shifts to left and enters at T10

Inferior vena cava: Enters at T8

Question 31

What is the most likely fracture site for a rib crushing injury

Answer 31

Sternal angle

Question 32

What ribs are most commonly fractured

Answer 32

Middle ribs

Question 33

Where is a needle placed in thoracentesis or anestisia

Answer 33

On superior border of rib (to avoid nerves arteries and veins)

Question 34

Why is early diagnosis ssentiol in high speed decelerating injuries

Answer 34

likely trauma to superior mediastinum (ie large vessels)

Question 35

what would provide collateral cirucation in the event of carctation of the descending aorta

Answer 35

Anastomosation of anterior and posterior intercostal arteries