L1: The Lungs

what are the margins of the thorax

the superior to inferior thoracic aperture.

what does the thorax contain

the heart

trachea

oesophagus

lungs

thoracic duct

great vessels

what protects the thorax

the thoracic wall

what is the mediastinum

the area between the R and L lungs

what are the superior and inferior thoracic apertures

the two openings at the bottom and top of the thorax.

they allow passage for structures such as: trachea, oesophagus, blood vessels and nerves.

what is a thoracotomy

surgical procedure where a surgeon makes an incision between the ribs to access the organs in the chest such as:

lungs, heart or oesophagus for treatment or diagnosis.

what are the 4 divisions of the mediastinum?

• superior mediastinum

• anterior mediastinum

• middle mediastinum

• posterior mediastinum

where is the superior mediastinum?

its above the heart from the thoracic aperture/inlet until T4-T5

what are the contents of the superior mediastinum?

• thymus

• aortic arch

• brachiocephalic veins

• trachea

• esophagus

• vagus and phrenic nerves

where is the anterior mediastinum

in front of the pericardium

what are the contents of the anterior mediastinum

• fat

• lymph nodes

• remnants of the thymus

• internal thoracic vessels

where is the middle mediastinum?

contains the heart and pericardium

what are the contents of the middle mediastinum

• heart

• ascending aorta

• pulmonary trunk

• superior vena cava

• phrenic nerves

where is the posterior mediastinum

behind the pericardium in front of the spine

what are the contents of the posterior mediastinum?

• esophagus

• descending aorta

• thoracic duct

• azygos system

• vagus nerves

where does the trachea run to and from?

from C6 to T4 and then it divides into the main R and L bronchi.

what is the trachea covered in?

15-20 U-shaped hyaline cartilages

what is the function of the oesophagus

fibro-muscular tube connecting the pharynx to the stomach

where does it exit the thorax?

at T10 and pierces the muscular right crus of the diaphragm through the oesophageal hiatus

what are the 3 narrowings of the oesophagus

• cricopharyngeus

• left bronchus

• gastro-oesophageal junction

describe lobes and fissures of the R lung

3 lobes

separated by horizontal and oblique fissures

describe the lobes and fissures of the L lung

2 lobes separated by an oblique fissure

what are the 3 surfaces of the lungs

costal - facing the ribs

mediastinal - faces the heart and mediastinum

diaphragmatic - rests on the diaphragm

what are boarders of the lungs

anterior, posterior and inferior

these are important for auscultation and imaging interpretation

what is auscultation

listening to sounds produced in the body

what are the 2 blood supply for the lungs

• pulmonary circulation: for gas exchange

• bronchial circulation: supplies lung tissue

what is the parasympathetic innervation to the lungs

vagus nerve - bronchoconstriction and increased secretion

what is the sympathetic innervation to the lungs?

thoracic sympathetic branch - bronchodilation

label the sternum

what are the true ribs and their features

ribs 1-7

they have costal cartilages which attach to the sternum

what are the false ribs and their features

ribs 8-10

have costal cartilages which attach to the CCs above

what are the floating ribs and their features

ribs 11 and 12

have no costal cartilages

what are the atypical ribs

1

2

11

12

why is rib 1 atypical

• only has one articulation with the vertebral body

• short, broad and most curved

why is rib 2 atypical

• less curved that 1

• has a rough tuberosity for serratus anterior

why are 11 and 12 atypical

• 1 articulation w the vertebral body

• no anterior articulation

• no tubercle for articulation with the transverse process

what are the typical features of a rib (3-10)

• head 2 articulations

• neck

• tubercle

• curve

• costal groove

what are the 3 sternal joints

• sternoclavicular

• manubriosternal joint

• xiphisternal joint

describe the sternocostal joints

• between the sternum and costal cartilages

• 1st costal joint - primary cartilaginous

• 2-7 are synovial

describe the costochondral joints

• between the rib and costal cartilage

• primary cartilaginous

• no ligaments

describe intercondral joints

• between costal cartilages

• synovial

• no ligaments

describe costovertebral joints

• synovial joints between ribs and thoracic vertebrae

• head articulates with the bodies of the vertebrae

• ribs 2-10 have 2 facets where as 1,11 and 12 only have one facet

• the tubercles articulate with the transverse process of the same vertebra (costotranverse joint)

what are the muscles of respiration

• diaphragm

• intercostal muscles

• accessory muscles

what is the structure and function of the diaphragm

• dome shaped musculotendinous structure

• separates the thoracic cavity from the abdominal cavity

• responsible for expiration

what is the nerve supply to the diaphragm

phrenic nerve

C3,4,5 keeps the diaphragm alive

what are the diaphragmatic aperatures?

T8 - IVC hiatus and (R phrenic nerve)

T10 - oesophageal hiatus

T12 - the aortic aperature: thoracic duct, azygos vein , hemiazyos vein

what is a diaphragmatic hernia?

condition where abdominal organs move into the chest cavity through a defect in the diaphragm - often requires surgery

what are the attachments of the diaphragm

• landmarks of the inferior thoracic aperture

• left and right crus

what are the 3 types of intercostal muscles

• external

• internal

• innermost

what are is the origin and insertion of the external intercostal muscles?

from the tubercles of ribs 1-11

to the cartilages of ribs 2-12

how do the external intercostals terminate?

as the external intercostal membranes

what is the orientation of the external intercostal muscles

infero-anteriorly

what is the action of the external intercostals?

they elevate the ribs for inhalation

what is the origin and insertion of the internal intercostal muscles

from the sternum between the costal cartilages of the true ribs

to the outer costal cartilages of the false ribs

what is the orientation of the internal intercostal muscles

fthey face infero-posteriorly

what do the internal intercostal muscles terminate as

the posterior intercostal membranes

what is the function of the internal intercostal muscles terminate as

they assist forced expiration

what is the function of the innermost intercostal muscles

they assist expiration by narrowing the intercostal spaces

where are the innermost intercostal muscles located

between the ribs

when do the accessory muscles of respiration act

exercise

respiratory distress

what are the 6 accessory muscles

1. scalene muscles

2. SCM

3. trapezius

4. pec major

5. pec minor

6. serratus anterior

what is the costal groove described as?

a neurovascular bundle

what is the groove van?

V- vein

A-artery

N-nerve

they lie between the innermost layer of the intercostal muscles in the groove

what is the blood supply and drainage of the thoracic wall

posteriorly: descending aorta

anteriorly: subclavian artery

what are the movements of the thorax

• lateral expansion

• anterior expansion

• descent of the diaphragm

which muscles partake in quiet, deep and very deep inspiration

• quiet - diaphragm

• deep - diaphragm and external intercostals

• very deep - accessory muscles

what muscles partake in quiet and forced expiration

• quiet - passive as the diaphragm releases

• forced - internal and innermost intercostal and abdominal muscles

what is the lingula

a unique, tongue-like projection of tissue found exclusively in the left lung,

representing a specific segment of the upper lobe

what is the function of the lingula

to facilitate gas exchange

what are the the types of lung pleura

• visceral

• parietal

between the two lies the pleural cavity

why would a chest drain be inserted

to remove unwanted substances from the pleural space such as air, blood or pus

where are they inserted and why

ypically inserted at the 4th or 5th intercostal space, just anterior to the

mid-axillary line, and always above the rib to avoid damaging the

neurovascular bundle that runs along the inferior border of each rib

what is the hilum of the lung

A triangular depression on the inner (mediastinal) surface of each lung.

Acts as the entry and exit point for structures connecting the lungs to the body (the "root of the lung").

what is the bronchial tree?

trachea - bronchi - lobar bronchi - segmental bronchi - bronchiole - alveolar duct - alveolus

the last 3 have no cartilage

what is the blood supply to the bronchi?

• bronchial arteries: arise from the descending thoracic aorta

• bronchial veins: usually two on each side, drain into the azygos system of the veins

what is the innervation of the bronchi

• pulmonary plexus

describe the innervation of the visceral pleura

• Sensitivity: Not sensitive to pain, temperature, or touch.

• Innervation: Autonomic only (i.e., no sensory); receives sympathetic and parasympathetic fibers from the pulmonary plexus (Vagus n.).

describe the innervation of the parietal pleura

• Sensitivity: Sensitive to pressure, pain, and temperature.

• Innervation: Sensory innervation from intercostal nerves and phrenic nerves.