Anatomy of lower respiratory tract II Flashcards
What kind of stimuli are the pleura sensitive to?
Pain, pressure, temperature, and touch
What nerves supply the costal pleura?
Costal pleura is supplied by intercostal nerves (anterior rami of T1 - T11) and sucostal nerve (T12)
What nerves supply the mediastinal pleura?
Mediastinal pleura is supplied by phrenic nerves (C3 - C5 spinal segments)
What nerves supply the diaphragmatic pleura?
Diaphragmatic pleura (phrenic nerves, lower 5 iintercostal nerves and subcostal nerve)
What structures are supplied by the same nerves as parietal pleura?
The muscles and bones of the same area.
What supplies sensory innervation for visceral pleura?
It is sensitive only to stretch and so only has visceral reflexive afferent fibers which follow the parasympathetic fibers.
Not sensitive to pain
How long and wide is the trachea?
12.5cm long and 2.5cm wide
How long is the trachea?
Extends from lower border of cricoid cartilage (C5/C6) to the sternal angle at T4/5
Does trachea descend directly at the middle?
No, it descends through superior mediastinum a little to the right of the median plane.
What is the carina?
A keel-like ridge between at the bifurcation of the trachea into bronchi. It represents a cartilaginous projection of the last tracheal ring.
What is the importance of the carina in clinical practice?
It acts as a landmark for bronchoscopy.
Mucosa that lines carina is rich in sensory nerve endings and if mucous reaches carina it causes cough reflex.
Morphological changes in the carina assists with differential diagnosis of diseases. This is because tumours or growths can modify the shape of the carina.
What are the differences between right and left primary bronchi?
Right bronchus is shorter (2.5cm compared to 5). wider, shorter, and runs more vertically than left main bronchus
Descends more vertically than left lung.
What direction does the right bronchus descend?
Vertically, posterior to the right pulmonary artery and ascending aorta, anterior to the oesophagus and right vagus nerve
What direction does the left main bronchus descend?
Passes inferolaterally inferior to the arch of the aorta, posterior to the pulmonary artery and anterior to the thoracic aorta
What structures is the right main bronchus related to?
Posterior to right pulmonary artery and ascending aorta, anterior to the oesophagus and right vagus nerve
What structures is the left main bronchus related to?
Inferior to the arch of the aorta, posterior to left pulmonary artery and anterior to the thoracic aorta
What is the clinical significance of the morphology of the lungs?
Right main bronchus is more likely to be occluded by foreign body than left main bronchus
What artery runs anterior initially to the trachea then lateral to the trachea?
Carotid artery
What structures run anterolaterally to the trachea?
Brachiocephalic veins and arteries.
Vagus nerve (still runs posterior to hilum)
What are the branches of the right primary bronchus?
Superior lobar bronchus (braches before entering the lung)
Middle lobar bronchus
Inferior lobar bronchus
What are the branches of the left primary bronchus?
Superior lobar bronchus
Inferior lobar bronchus
What do lobar bronchi divide into?
Tertiary/segmental bronchi
How many segmental bronchi does each lung have?
Right lung = 10
Left lung = 8 - 10
What is a bronchopulmonary segment?
The segmental bronchus and surrounding lung parenchyma.
What is the division of segmental bronchi?
Bronchioles
Do bronchioles have cartilage plates?
No they are self supporting and have smooth muscle
What do bronchioles divide bronchopulmonary segments into?
Pulmonary lobules
What is the diameter of bronchioles?
1mm
What do bronchioles further divide into?
Terminal and respiratory bronchioles
What do respiratory bronchioles terminate in that terminal bronchioles don’t?
Alveolar sacs
What is the smallest functional unit of pulmonary system?
Pulmonary acini
What are the parts of the bronchopulmonary segments?
Bronchopulmonary segments are the anatomical, functional, and surgical units of the lungs
What is the shape of bronchopulmonary segments?
Pyramidal shaped; apex towards the lung root
What is each bronchopulmonary segment surrounded by?
Connective tissue septa
What is the clinical significance of bronchopulmonary segments?
Surgeons can resect these segments easily without threatening the life of the patient
What does each bronchopulmonary segment contain?
Connective tissue septa
Segmental bronchus
Segmental artery
Bronchial vessels, lymphatics and autonomic nerves.
Where do segmental veins lie?
In the intersegmental fibrous septa between the segments.
Are bronchopulmonary segments considered vascular segments?
No veins aren’t included in them so they are only surgical segments
What is pleural effusion?
Abnormal accumulation of pleural fluid in the costodiaphragmatic recess
What causes pleural effusion?
Causes include:
Pneumonia
Pulmonary tubercolosis
Malignancy
What is the consequence of pleural effusion?
The lung becomes compressed, bronchi are narrowed
Auscultation would reveal decreased breathing sounds over collapsed lung lobe.
Dullness on percussion over the area of pleural effusion
What is pneumothorax?
Presence of air in pleural cavity.
Who gets pneumothorax due to injury most often?
Children and infants because their necks are shorter.
What is hemothorax?
Blood in pleural cavity
What is the long term result of pneumothorax?
Presence of air causes lung to collapse resulting in what is known as atelectasis
How is accumulated air, blood, serous fluid, and pus treated?
By insertion of a chest tube
An incision is made between 5th and 6th ribs in mid axillary line.
Tube is directed superiorly (towards cervical pleura) for air removal and inferiorly for fluid removal.
The other side of the tube is inserted into an underwater drainage system
Why is tube put into superior border instead of inferior border of the rib (inferior aspect of the intercostal space)?
Because The intercostal vessels are located in this space.
How is ascultation of the base of the lung performed?
Stethoscope is applied to inferoposterior part of the thorax (on the lower part of the chest wall from behind at the level of T10.
The front part of the chest is occupied mostly by the superior lobe.
Which bronchopulmonary segment is most affected by a foreign body being lodged in the right bronchus?
The inferior bronchopulmonary segments (The superior segment of the lower lobe and inferior lobar bronchus)
The superior segment of the lower lobe is typically most affected by aspiration pneumonia.
What are the 3 itnercostal muscles?
External
Internal
Innermost
What direction do external intercostal muscles run?
Front pocket muscles
List vessels of the intercostal space in order from most superior to most inferior:
IC Vein
IC Artery
IC Nerve
IC lymphatics
Where do the vessels and nerves run?
Between Internal and innermost IC muscles in the intercostal groove
Where do Ext IC muscles originate and insert?
Origin: Upper and posterior border of intercostal space
Insertion: superiolaterally
What happens to external intercostal muscles at the costochondral junction?
They are replaced by a fibrous external intercostal membrane (posterior end of intercostal space to costochondral junction)
What do external intercostal muscles do?
Elevate ribs during inspiration
Where do internal IC muscles end?
At the angle of the rib
What do internal IC muscles do?
Opposite of External IC
What do innermost IC muscles do?
Act with internal IC
What are the parts of the diaphragm?
Sternal part (posterior surface of xiphoid process)
Costal part (Arise from inner surface of lower 6 ribs near their costal cartilage)
Vertebral part (right and left crura of diaphragm and the median, medial and arcuate ligaments)
Where does the median arcuate ligament extend?
Between upper ends of the 2 crura
Where does the medial arcuate ligament extend?
Thickened upper margin of psoas sheath
Where does the lateralarcuate ligament extend?
Thickened upper end of quadratus lumborum fascia
Where do the diaphragm muscles insert?
Central tendon
Which crus attaches lower?
The right crus inserts on L as opposed to
Which ligament connects the 2 crura of the diaphragm?
Median ligament
What is the medial arcuate ligmaent?
Thickened fascia covering origin of psoas major
What pleura covers the diaphragm?
All by phrenicopleural fascia except the middle which is covered by pericardium where it fuses to diaphragm
What nerve provides motor supply the diaphragm?
Only the phrenic nerve (C3 - C5)
What nerve provides sensory supply to diaphragm?
Centrally phrenic peripherally (T5-T11) IC nerves (T12)
What does the right crus of the diaphragm?
Forms a sphincter around the oesophagus
What happens to ribcage during inspiration?
External intercostal muscles contract which increase transverse and anteroposterior diameter by moving sternum upward
The overall shape of the ribcage is more rounded and short
What happens to the ribcage during expiration?
Internal intercostal muscles contract while the external intercostal muscles are relaxed leading to a flatter and longer shape.
How is the pump handle movement of the sternum possible?
Articular surfaces on the tubercles of the upper 6 ribs are convex and fit into concave transverse processes resulting in rotation of the rib around transverse axis.
This leads to elevation and depression of the sternal ends of the ribs
Flat articular surfaces of 7th to 10th ribs and vertebral transverse processes allow gliding
When does the respiratory system start developing?
Around the 4th week of embryonic period
What is the first step to develepment of respiration?
First a ventral outgrowth called respiratory/laryngotracheal diverticulum appears in the floor of the caudal end of the primordial pharynx.
Where is the respiratory diverticulum derived from?
Anterior part of the digestive system
What does the tracheoesophageal septum do?
Divides the respiratory diverticulum into a dorsal and ventral portion.
The dorsal portion is the primordium of the pharynx and oesophagus.
The ventral portion is the primordium of the larynx trachea bronchi and lungs
What does the dorsal portion of the tracheoesophageal septum form?
Pharynx and oesophagus
What does the ventral portion of the tracheoesophageal septum form?
Larynx, Trachea, lungs, and bronchi
What germ layer gives rise to the respiratory system?
The splanchnic mesoderm and endoderm.
Splanchnic mesoderm forms cartilage, smooth muscle and connective tissue.
Endoderm forms epithelium and submucosal gland
What are the 4 stages of lung maturation?
Pseudoglandular (6 - 16 weeks)
Canalicular (16 - 20 weeks)
Terminal sac (26 weeks - birth)
Alveolar (32 weeks until 8 years)
