Thorax/Lung Anatomy Flashcards
what protects the contents of the thoracic cavity?
thoracic wall
what are the 3 main functions of the thorax?
respiration
protection
conduit (passageway)
what does the thoracic wall consist of?
sternum, T1-12 vertebrae, 12 rib pairs + costal cartilages, intercostal muscles (in intercostal spaces), supplying arteries/nerves
what are the 3 types of intercostal muscles?
external, internal, innermost
what is the function of the thoracic cage?
provides rigidity and flexibility
what are the 3 types of ribs and how do they differ?
true ribs - costal cartilage attaches directly to sternum (sternocostal joints)
false ribs - costal cartilage attaches to cartilage above (interchondral joints)
floating ribs - dont attach to sternum
where does the head of the rib articulate?
superior demi-facet of corresponding vertebra and inferior demi-facet of vertebra superior to it
(costovertebral joints)
where does the tubercle of the rib articulate?
transverse process of corresponding vertebra
(costotransverse joints)
what are the 4 atypical ribs in terms of articulation?
1, 10, 11, 12
what separates the thoracic and abdominal cavities?
diaphragm
what does the inferior thoracic aperture do?
provides attachment for the diaphragm
what does the superior thoracic aperture separate?
the thoracic cavity and the neck/upper limb
name the 3 attachments of the diaphragm
L1-3 vertebrae
inferior costal cartilages and adjacent ribs
xiphoid process
what nerve is the diaphragm supplied by?
phrenic nerve (contributions from C3-5)
what is the purpose of diaphragmatic apertures?
permit structures to pass between thorax and abdomen
name the 3 diaphragmatic apertures and what structures pass through
canal opening - IVC
esophageal hiatus - oesophagus
aortic hiatus - aorta
describe external intercostal muscles in terms of where they occupy, muscle fibre direction and when they’re most active
occupy intercostal spaces from posterior to costochondral junction
fibres run anteroinferiorly
most active during inspiration
describe internal intercostal muscles in terms of where they occupy, muscle fibre direction and when they’re most active
occupy intercostal spaces from anterior to angle of ribs
fibres run anteroposteriorly
most active during expiration
where does the intercostal neurovascular bundle lie?
between internal and innermost intercostals
(innermost = deep internal layer)
what happens when ribs are elevated?
anteroposterior and lateral dimentions of the thorax increase
what happens to the dimentions of the thoracic wall when the diaphragm is contracted?
superoinferior dimentions increase
what are the accessory muscles of respiration and how do they assist?
arm/pectoral girdle allow neck/arm muscles to assist rib elevation in forced breathing
abdominal muscles assist forced expiration
what forms the intercostal nerves?
anterior rami of T1-11 spinal nerves
what forms the subcostal nerve?
anterior ramus of T12 spinal nerve
in what order are the major vessels found in the intercostal neurovascular bundle (from S -> I)
intercostal vein, intercostal artery, intercostal nerve
VAN
what are the originations of the intercostal arteries?
posterior - aorta
anterior - internal thoracic artery (branches)
both IC arteries anastomose
what does the internal thoracic artery originate from and what does it bifurcate into?
originates from subclavian artery
bifurcates into musculophrenic and superior epigastric arteries
what 2 blood vessels expand to maintain blood supply when there is a stricture of the proximal aorta?
internal thoracic and anterior IC arteries
what are the 3 compartments of the thoracic cavity?
pulmonary cavities (L and R)
mediastinum
what 2 layers of pleura surround each lung?
parietal (superficial)
visceral (deep)
what is the function of the serous fluid inbetween the serous membranes of the lung? (visceral/parietal pleura)
lubrication
what are pleural recesses?
potential spaces between costal and diaphragmatic pleura that the lungs can move into during inspiration
what is pectus excavatum?
chest wall indentation into thoracic space
what is pectus carinatum?
pigeon’s chest - chest wall protrusion
name 3 abnormailities that can occur in the pleural cavity
(tension) pneumothorax
hydrothorax/haemothorax
mesothelioma
what does tension pneumothorax limit?
ventilation and venous return
where would you insert a tube/train to decompress a pneumothorax?
midclavicular line, 2/3rd intercostal space, closer to lower rib
what is a flail segment?
3 (or more) consecutive ribs broken in 2 places each
what deformities are seen in a flail segment during inhalation?
un-coordinated movement, poor inflation (poor gas exchange), pain, wrong direction of movement
what is administered when in rib pain?
nerve block - image guidance (ultrasound) used to inject local anaesthetic to reduce pain and encourage normal breathing
what is lung contusion?
bruised lung
what comprises the upper respiratory tract?
nasal cavity, pharynx, larynx
what comprises the lower respiratory tract?
trachea, primary bronchi, lungs
what are paranasal sinuses?
air filled cavities beside the nose
what are the differences between the left and right bronchus?
right is more vertical, greater diameter and shorter than left
(foreign body more likely to go into right)
what are the 3 lobes of the lung?
superior (L/R)
middle (R)
inferior (L/R)
describe the structure of respiratory epithelium
pseudostratified, ciliated, columnar containing goblet cells for mucous secretion
what is surfactant and what does it do?
secreted by type 2 pneumocytes
increases lung compliance and prevents lung collapse
name the structures of the lung from superior to inferior
apex
hilum
bronchus
pulmonary artery
pulmonary vein
name the borders/surfaces of the lung from medial to lateral
mediastinal surface
inferior border
base
anterior border
costal surface
what separates the lung lobes?
oblique fissure - separates superior/middle from inferior (L/R)
horizontal fissure - separates inferior/middle from superior (R)
what does the pulmonary ligament do?
holds pulmonary arteries/veins in place
what is the function of the nasal cavities and paranasal sinuses in breathing?
filter/warm/humidify air and detect smells
what is the function of the pharynx in breathing?
conducts air to larynx (chamber shared with digestive tract)
what is the functions of the larynx in breathing?
protects opening to trachea
contains vocal chords
what is the function of the trachea/bronchi in breathing?
filters air
traps particles in mucous
(cartilages keep airway open)
what is the general function of the lungs in breathing?
air movement through volume changes during rib/diaphragm movements (in airways and alveoli)
what is the function of the alveoli in breathing?
acts as gas exchange sites between air and blood
what is the respiratory unit?
basic physiological lung unit consisting of respiratory bronchioles, alveolar ducts and alveoli
what are the functions of type 1 and 2 epithelial cells in alveoli?
type 1 - gas exchange site
type 2 - produce pulmonary surfactant to reduce surface tension
where are the apex and base of the lungs?
apex - above 1st rib and just above clavicle
base - ribs 8-12 (sits on diaphragm)
what is the lingula?
protruding aspect of the superior left lung
what is the cardiac notch?
a left lung indentation superior to the lingula protrusion
what structures are found in the root of the lung?
bronchi
pulmonary artery/vein
nerves
lymphatics
what is the hilum?
area of lung where each structure enters and leaves
what is the general arrangement of the hilum?
pulmonary artery superiorly
pulmonary vein inferiorly
bronchi posteriorly
explain the segmentation of the bronchi
primary bronchi branch into secondary (lobar) bronchi (L2, R3)
secondary bronchi branch into tertiary bronchi (L8, R10)
what do tertiary bronchi supply?
the bronchiopulmonary segment
explain the pulmonary circulation of the lung
pulmonary artery enters through hilum
segments into lobar then segmental arteries
goes through capillaries
moves into segmental then lobar veins
enters pulmonary vein then heart
explain the course of the left vagus nerve
branches into left recurrent laryngeal nerve
hooks around right subclavian artery before travelling to larynx
explain the course of the right vagus nerve
branches into right recurrent laryngeal nerve
hooks around aortic arch before travelling to larynx
explain the function of the recurrent laryngeal nerves and the consequences of damage to these nerves
innervate aortic arch
impairment to nerve, speech, breathing and coughing when damaged
how can a phrenic nerve injury be sustained?
medical harm - surgery, chiropractor
trauma - blunt, penetrating
central - spinal cord injury/compression
what are the 2 divisions of the respiratory system?
conducting - nasal cavities to terminal bronchioles
respiratory - respiratory bronchioles to alveoli
what is the trachea supported by and what are the structures composed of?
10-12 C-shaped hyaline cartilages
chondrocytes embedded in cartilage
smooth muscle joins ends of C-shape cartilage posteriorly
what is the function of seromucous glands?
found in trachea lumen
produce mucous secretions delivered to surface by ducts
supports goblet cell function
what changes are observed when bronchi segment from primary to tertiary?
size decrease
irregular cartilage plates on walls become smaller and fewer
seromucous glands decrease
what are bronchioles composed of?
mostly smooth muscle
larger broncioles lined with simple ciliated columnar epithelium with few goblet cells
what changes are observed in bronchiole structure as they decrease in size?
epithelium changes to simple cuboidal with few ciliated cells and more club cells
explain the branching of the terminal bronchioles
terminal bronchioles -> respiratory bronchioles (gas exchange begins here) -> alveolar ducts -> alveolar sacs -> 2-3 alveoli
explain the structure of type 1 pneumocytes
squamous with flat, dark, oval nuclei and very thin cytoplasm
mostly found on alveolar surface
explain the structure and additional function of type 2 pneumocytes
cuboidal cells mainly in alveolar space
progenitor cells that proliferate to replace pneumocytes after lung damage
what does the blood-air barrier contain?
type 1 pneumocytes
capillary endothelial cells
fused BM of these cells in the middle
what is found in the inferior mediastinum region?
anterior - fat, thymus
middle - heart
posterior - aorta, oesophagus
what is found in the superior mediastinum region?
upper - T1 posteriorly
lower - sternal angle (rib 2 landmark)
what are the physical characteristics of arteries in alveoli?
thin walled
highly compliant
larger diameter
lower resistance (than systemic)
