Trachea and Lungs Flashcards
Trachea
- What is the origin and end point of the trachea?
- What are its borders/ Relations?
- Describe its structure.
- Inferior surface of the cricoid cartilage and terminated at the bifurcation into the Bronchi at the carina.
- Most superior structure is the cricotracheal ligament which connects the cricoid cartilage with the first tracheal ring.
Relations:
Cervical portion:
Anteriorly
- Thyroid isthmus
- Inferior thyroid veins
- Strap muscles (sternothyroid and sternohyoid)
- Cervical fascia
- Subcutaneous tissue and skin
Lateral
- The common carotid arteries (in the carotid sheaths with internal jugular vein and vagus nerve) on each side
- Right and left lobes of the thyroid gland
- Inferior thyroid arteries
The recurrent laryngeal nerves on each side run in the groove between the trachea and the oesophagus.
Thoracic:
In the thoracic portion of the trachea, the anterior relations (from the skin inwards) are:
- Skin
- Subcutaneous tissue
- Manubrium sterni
- Remains of the thymus
- Left innominate vein
- Aortic arch or great vessels arising from the arch
- Cardiac plexus
Lateral relations on the right are:
- Pleura
- Innominate artery
- Vagus nerve
Lateral relations on the left are:
- Recurrent laryngeal nerve
- Aortic arch
- Left common carotid and subclavian arteries
3.
There are 12-20 C shaped cartilaginous rings. The rings are incomplete and completed my the TRACHEALIS muscle at the posterior wall
Adults it is 12cm long 1.6-2cm diameter. Wider in males.
The length is increased during inspiration and diameter narrowed by contraction of the trachealis
The lining is pseudostratifed columnar epithelium with mucus glands.
It is divided into cervical and thoracic components which are equal lengths 5-6cm each.
- The cervical component extends from cricoid cartilage the sternal notch (C6-T2/3)
- The thoracic component extends from the sternal notch to the carina (T2/3-4/5)
- The trachea starts as a superficial midline structure in the neck and passes posteroinferiorly to become a deep structure
Trachea
- What are the functions of the trachea?
- Tube that allows passage of air
- Mucus layer traps particles and the cilia transport this out to the larynx to be swallowed of coughed out
- Mucus is warm and humidifies the gas
- Sensation is provided by Vagus nerve- provides afferent limb of the cough reflex
- motor response to particles is a vigourus cough with contraction of trachealis. The narrowed diameter of the trachea increases speed of the expulsive airflow. Exceeds the speed of sound
Oesophagus
What is its relation to the trachea and when my it effect the trachea?
This is posterior to the trachea for its entire length. If there is a tumour of it it may obstruct the trachea, long standing FBs may erode into the trachea and surgery on the oesophagus may damage the posterior wall of the trachea.
- What is the blood supply to the trachea?
- What is the nerve supply to the trachea?
- Inferior thyroid arteries, internal thorasic and branches of the bronchial a.s
Venous drainage into inferior thyroid veins
- PARASYMPATHETIC: supply to smooth muscle and glands is the vagus n either directly of from the recurrent laryngeal nerves.
SYMPATHETIC supply is sympathetic trunk
Right main bronchus
- Describe its course, characteristics and relation to surface markers
- What is the clinical significance of its characteristics
- It is the larger of the two Bronchi
Starts at T4/5 (angle of Louis) in supine patient- descends inferiorly in errect patient and on inspiration (T6/7).
- RMB is in a more direct line with the trachea- therefore FBs and ETs are more likely to go there
Carina
- Where does it lie?
- What are its relations?
- To the right of the midline and is more or less at the centre of the AP dimension of the chest a T4/5
2.
The main trunk of the pulmonary artery divides into right and left PAs anteriorly to the carina overlying the left main bronchus
The PAs then pass into the lungs close to the bronchi.
The ascending Aorta passes in front of the carina and PAs passing to the left of the trachea arching over the left main bronchus.
It is the presence of the aorta on the left, which determines that the lower trachea is slightly to the right of midline.
- What is the composition of a Bronchi and what do they divide into (inc all divisions)?
- Name the lobar bronchi in each lung and draw a diagram to illustrate the divisions.
- Bronchi have cartilaginous rings in their walls and divide into bronchioles with a diameter of <1mm abd walls of smooth muscle
These branch into terminal bronchioles before ending in respiratory bronchioles which connect to alveolar sacs.
- Right lung
Rt upper lobar bronchus
Rt Middle lobar bronchus
Rt Lower lobar bronchus
Left Lung
Lt upper lobar bronchus
Lt upper lower bronchus
With the exception of the right upper lobar bronchus arising from the right main bronchus, all origins of lobar and segmental bronchi are intrapulmonary
- What is a bronchopulmonary segement?
- What is the surgical significance of this?
- Describe the possible anatomical variation of the right lung.
- What is the relivance of this variation?
- It is a discrete anatomical and functional subdivision of a lobe of the lung. It consists of a segment of lung surrounded by connective tissue supplied by one seqmental bronchys and one segmental artery
- It may be removed without interfering with others
- Either the whole upper lobe of the rt lung, or a segment of it, may be supplied by a bronchus arising from the trachea. 0.2% in humans (normal in pigs), it is termed bronchus sui (latin for pig)
In a true tracheal bronchus, the right upper lobe comes directly from the trachea, usually within 2cm of the carina. The right main bronchus is strictly called the bronchus intermiedius.
- This variant, a normal right-sided double lumen tube (as used in thorasic anaesthesia) will not provide isolation/ventilation of the right upper lobe.
Left lung
- How many bronchopulmonary segments are there? Describe the arrangement of these.
- How are these arranged?
- 8-10 bronchopulmonary seqments in the two lobes of the left lung.
Commonly, the lower lobe has only four bronchopulmonary segments, the medial basal (or cardiac) segment being lost as a result of the “intrusion” of the heart into the space occupied by the left lung.
- A typical pattern of nine segments would be:
Upper lobe (including lingula of upper lobe)
- Apical segment of upper lobe of left lung
- Posterior segment of upper lobe of left lung
- Anterior segment of upper lobe of left lung
- Superior segment of lingula of upper lobe of left lung
- Inferior segment of lingula of upper lobe of left lung
Lower lobe
- Apical (or superior) segment of lower lobe of left lung
- Anterior basal segment of lower lobe of left lung
- Lateral basal segment of lower lobe of left lung
- Posterior basal segment of lower lobe of left lung
Right lung
- How many bronchopulmonary segments are there and in how many lobes?
- Detail them (with a diagram if possible).
- There are ten bronchopulmonary segments in the three lobes of the right lung.
- Upper lobe
Apical segment of upper lobe of right lung
Posterior segment of upper lobe of right lung
Anterior segment of upper lobe of right lung
Middle lobe
Lateral segment of middle lobe of right lung
Medial segment of middle lobe of right lung
Lower lobe
Apical segment of lower lobe of right lung
Medial basal segment of lower lobe of right lung
Anterior basal segment of lower lobe of right lung
Lateral basal segment of lower lobe of right lung
Posterior basal segment of lower lobe of right lung
A good mnemonic to help you remember the bronchopulmonary segments of the right lung is APALM AMALP
