Lungs and Diaphragm

Question 1

Thoracic cavity

Answer 1

Region enclosed by the thoracic wall

Question 2

Pleurae

Answer 2

Serous sacs surround the lungs

Visceral pleura lines lung

Parietal pleura lines walls of thoracic cavity

Visceral and parietal pleurae are continuous with each other

Question 3

Visceral pleura

Answer 3

Lines surface of the lung

Closely adherent to the lungs and extends into lung fissures

Has visceral sensory innervation

Does NOT have somatic sensory (pain, temperature, touch) innervation

Question 4

Parietal pleura

Answer 4

Lines walls of the thoracic cavity

Does HAVE somatic sensory (pain, temperature, touch) innervation by intercostal nerves and phrenic nerves

Question 5

Pleuritis

Answer 5

Inflammation of the pleura

Can lead to adhesion of visceral and parietal layers, resulting in acute pain association with elevated activity

Question 6

Pleural cavity

Answer 6

Potential space between the visceral and parietal pleurae

Normally contains only a thin layer of serous fluid, which acts as a lubricant, facilitating movement of lungs during respiration

Right and left pleural cavities are independent

Question 7

Hydrothroax

Answer 7

Accumulation of fluid in pleural cavity

Question 8

Pneumothorax

Answer 8

Accumulation of air in pleural cavity

Question 9

Hemothorax

Answer 9

Accumulation of blood in pleural cavity

Question 10

Costodiaphragmatic recess

Answer 10

With inspiration, lungs expand and recess decreases in area

With expiration, recesses enlarge again

Question 11

Thoracentesis

Answer 11

Procedure to drain excess fluid or blood from pleural cavity

Following an intercostal nerve block, a needle is inserted into an intercostal space (avoiding the inferior border of the rib above and superior border of the rib below)

Good place to perform thoracentesis is the posterior aspect of 7-9 intercostal space. Needle will enter costodiaphragmatic recess, avoiding injury to lungs and abdominal organs

However, other locations can be targeted depending on the effusion

Question 12

Lungs

Answer 12

Organ of respiration - function is to oxygenate blood

Pink color darkens over time with exposure to particulates in air

Due to elasticity, if thoracic wall is breached (knife, GSW, etc), the lung will shrink to 1/3 of its normal size (as result of a pneumothorax)

Question 13

Anatomy of lung

Answer 13

Root - collection of structures entering and exiting the lung (pulmonary vessels and bronchi)

Apex - superior portion extending into the neck

Base - concave inferior portion adjacent to diaphragm

Question 14

Right lung

Answer 14

3 lobes - superior, inferior, and middle

Horizontal fissure separates superior and middle

Oblique fissure separates inferior

Question 15

Left lung

Answer 15

2 lobes - superior and inferior

Oblique fissure separates

Superior lobe has cardiac notch on anterior margin

Question 16

Organization of trachea and bronchi

Answer 16

Trachea
Right and left main bronchi
Lobar bronchi
Segmental bronchi

Question 17

Trachea

Answer 17

Inferior to larynx

Palpable at jugular notch due to cartilaginous rings

C shaped hyaline cartilages (open posteriorly because esophagus is there and will expand when eating)

Bifurcates at sternal angle (T4 / T5 level)

Carina - ridge of cartilage at the bifurcation

Question 18

Right and left main bronchi

Answer 18

Extrapulmonary (outside the lungs)

Also supported by C shaped rings of cartilage

Right main bronchus is wider, shorter, and more vertical than left

Therefore, aspirated foreign objects are more likely to lodge in the right bronchus

Question 19

Lobar bronchi

Answer 19

Each main bronchus divides into lobar bronchi

Intrapulmonary (within the lungs)

Right lung has 3 lobar bronchi

Left lung as 2 lobar bronchi

Question 20

Segmental bronchi

Answer 20

Each lobar bronchi divides into segmental bronchi, which each correspond to specific bronchopulmonary segment

Question 21

Bronchopulmonary segment

Answer 21

10 segments per lung

An area of the lung supplied by a segmental bronchus and a segmental branch of the pulmonary artery

Segments are separated by connective tissue, therefore a segment can be surgically resected if needed

Pulmonary veins are intersegmental - run within the connective tissue that separates the segments

Question 22

Pulmonary vessels

Answer 22

Pulmonary trunk
Pulmonary arteries
Pulmonary veins

Question 23

Pulmonary trunk

Answer 23

Exits right ventricle of heart and divides into right and left pulmonary arteries, when then enter lungs

Question 24

Pulmonary arteries

Answer 24

Carry O2 poor blood from heart to lungs for oxygenation

Each pulmonary artery divides into lobar and segmental arteries, running parallel with the bronchi

Question 25

Pulmonary veins

Answer 25

Carry O2 rich blood from the lungs to left atrium of the heart 2 pulmonary veins bilaterally (vs. 1 artery bilaterally) Lie in intersegmental connective tissue separating the bronchopulmonary segments and do NOT course with arteries and bronchi

Question 26

Bronchial arteries

Answer 26

Carry O2 rich blood to the tissues of the lung itself Most are branches off the thoracic aorta

Question 27

Bronchial veins

Answer 27

Return O2 poor blood from the tissues of the lung to the azygos system or intercostal veins

Question 28

Innervation of the lungs

Answer 28

Innervation of the lungs is via pulmonary plexus with contributions from vagus nerve (CN X) and pulmonary nerves All organs are innervated by the AUTONOMIC NS Remember: autonomic NS includes sympathetic (fight or flight) and parasympathic (rest and digest) Parasympathetic - bronchoconstriction Sympathetic - bronchodilation

Question 29

Parasympathetic innervation of lungs via vagus nerve (CN X)

Answer 29

Achieves bronchoconstriction of smooth muscle of bronchial tree Parasympathetic: Preganglionic cell bodies - brain Preganglionic fibers - vagus nerve Postganglionic cell bodies - wall of target organ (lung) Postganglionic fibers - wall of target organ (lung) and are very short in length

Question 30

Sympathetic innervation of lungs

Answer 30

Achieves bronchodilation of smooth muscle of bronchial tree Sympathetic: Preganglionic cell bodies - lateral horn of thoracic spinal cord Preganglionic fibers - ventral root, spinal nerve, ventral ramus, white ramus communicans, sympathetic trunk Postganglionic cell bodies - upper thoracic paravertebral ganglia Postganglionic fibers - pulmonary nerves

Question 31

Diaphragm

Answer 31

Separates the thoracic and abdominal cavities Composted of skeletal muscle surrounding C shaped central tendon Pericardium surrounding heart is attached to central tendon 2 domes - right sits higher than left due to liver

Question 32

Attachments to the diaphragm

Answer 32

All are peripheral - Xiphoid process Costal margin Ribs 11-12 Lumbar vertebrae (via right and left crura)

Question 33

Openings in the diaphragm

Answer 33

I ate 10 eggs at 12 Inferior vena cava (caval opening) at T8 - goes through central tendon Esophagael hiatus at T10 - for esophagus and vagus nerve (CN X) Aortic hiatus at T12 - for aorta, thoracic duct, and azygos vein

Question 34

Sensory innervation for diaphragm

Answer 34

Primary phrenic nerves Peripherally, via intercostal nerves

Question 35

Motor innervation for diaphragm

Answer 35

Phrenic nerves - ventral rami C3, 4, and 5 keep the diaphragm alive Primary muscle of inspiration

Question 36

Phrenic nerves

Answer 36

Phrenic nerves course along lateral mediastinum and anterior to roots of lungs Phrenic nerves independently innervate left and right domes

Question 37

Lesion of a phrenic nerve

Answer 37

This paralyzes the corresponding side of the diaphragm X-ray during inspiration will show a depressed (active side) and raised (paralyzed side) of the diaphragm

Question 38

Diaphragm is primary muscle of inspiration

Answer 38

When diaphragm contracts, the domes descend and flatten, increasing vertical dimension of thoracic cavity. This also decreases volume of abdominal cavity, which increases abdominal pressure. Diaphragm relaxes during expiration, allowing domes to rise.

Question 39

Basic principles of respiration

Answer 39

Inspiration - To draw air into lungs, thoracic pressure must be less than atmospheric pressure - An increase in the volume of the thoracic cavity will decrease the thoracic pressure Expiration - To expel air from the lungs, thoracic pressure must be higher than atmospheric pressure - A decrease in the volume of the thoracic cavity will increase the thoracic pressure

Question 40

Movements of thorax during inspiration

Answer 40

Contraction (flattening) of the diaphragm causes the abdominal contents to be forced down, thereby increasing the vertical dimension of the thorax Contraction of muscles that elevate the ribs (external intercostals) expands the thoracic cavity transversely (laterally) as a "bucket handle" movement and anteroposteriorly as a "pump handle" movement During forceful inspiration, may also use pectoral muscles

Question 41

Movements of thorax during expiration

Answer 41

Thoracic cavity reduces in size primarily due to relaxation of the diaphragm and elastic recoil of lungs During forceful expiration, abdominal muscles are recruited to compress abdominal viscera upward, expelling air from lungs