Module 2 Respiratory Flashcards
Skull osteology
Ethmoid bone - Superior midline nasal septum
Frontal bone - Front of head
Mandible - Jaw
Maxilla - Lower mouth and Above mouth
Sphenoid bone - Behind the eyes and nose
Nasal bones - Top of nose
Occipital bone - Back of head
Palatine bones - Back of mouth
Parietal bones - Top of head
Temporal bones - Bottom of skull
Vomer - inferior midline nasal septum
Zygomatic bones - outside cheeks
GEM Upper Respiratory Tract - Part 1
Anatomy of the nasal cavities
The anterior openings (the nares) are formed by the two nostrils.
The posterior openings (called the choanae) open into the nasopharynx
The floor of the nasal cavity is formed by the maxillary bone and the palatine bone, which form the hard palate (ie, roof of the oral cavity)
The medial walls are formed by a midline nasal septum made of ethmoid and vomer bone(inferior to ethmoid) (posteriorly) and septal cartilage (anteriorly).
The lateral walls are formed by a number of the bones of the skull, by cartilage and soft tissues.
Three nasal conchae (curled shelves of bone – also called the ‘turbinates’) protrude from lateral walls – superior, middle and inferior.
The conchae create 4 air channels/meatuses, which are contained within the respiratory regions of the nasal cavity.
What is the function of the Conchae/Turbinates?
increase the surface area of contact between tissues of the lateral wall of the nasal cavity and the respired air.
This improves the filtration, heating and humidification of inspired air
What covers the nasal cavity?
thick, vascular, glandular mucosal layer with pseudostratified ciliated columnar respiratory epithelium. This contains erectile tissue with venous sinusoids which will intermittently fill with blood.
What are the paranasal sinuses?
Frontal, Ethmoidal, Maxillary, Sphenoidal
What are the function of the sinuses?
Lighten the weight of the head, humidify and heat inhaled air, increase the resonance of speech.
What can cause the spread of disease from sinuses?
The close anatomical relations of the sinuses to the orbit, the meninges (linings of the brain) and the brain and the thin bony walls do make this possible.
What epithelium lines the sinuses?
Ciliated, mucous secreting respiratory epithelium
How are Pituitary adenomas removed?
Most pituitary tumours can be removed trans-sphenoidally.
The approach is through the sphenoid sinus.
What blood supplies the nasal cavities and the air sinuses
The arterial blood supply to the nasal cavities and paranasal sinuses come from branches of the facial, maxillary and ophthalmic arteries (from the internal and external carotid arteries)
What blood supplies the ethmoidal and frontal sinuses
Branches from the ophthalmic artery (a branch of the ICA) – also supply the ethmoidal and frontal sinuses
What blood supply supplies the lip and anterior nasal cavity?
Branches from the facial artery (a branch of the ECA) – supply lip and anterior nasal cavity
What blood supply supplies the nasal mucosa and also supplies the maxillary and sphenoidal sinuses?
Branches from the maxillary artery (a branch of the ECA) – form the main supply to nasal mucosa and also supplies the maxillary and sphenoidal sinuses
Where is a common site of nose bleeds?
An anastomotic plexus of arteries, lies on the anterior cartilaginous septum – this is a common site for nosebleeds (epistaxis)
Sensory nerve supply to the paranasal air sinuses?
The trigeminal nerve (CN V) is the major general sensory cranial nerve of the head and it has 3 major divisions.
The ophthalmic division provides the sensory supply to the upper part of the face, the maxillary division the middle part and the mandibular division to the lower part of the face.
The frontal sinuses are, therefore, supplied by the ophthalmic (V1) division
The ethmoidal and sphenoidal sinuses and nasal cavity are supplied by both the ophthalmic (V1) and maxillary (V2) divisions
The maxillary sinuses are supplied solely by the maxillary (V2) division
Nerve supply to the nasal cavities
Olfactory nerve (CN I) which is responsible for olfaction (our sense of smell)
The mucous producing cells of the nasal mucosa are supplied by parasympathetic neurons and the smooth muscle walls of blood vessel in the respiratory epithelium are supplied by sympathetic neurons which are both carried in the maxillary (CN V2) division of the trigeminal nerves (CN V).
General sensation - touch, pain and temperature from the nasal mucosa is carried by branches of the ophthalmic (CN V1) and maxillary (CN V2) divisions of the trigeminal nerve (CN V).
Describe apertures in the nasal cavity
Blood vessels, nerves and drainage enter and exit the nasal cavity via apertures in the bones of the skull.
List the main apertures in the nasal cavity
Cribriform plate – fibres of the olfactory nerve (CN I) and the branches from the ophthalmic vessels pass through here
Sphenoid sinus drains into the sphenoethmoidal recess above the superior concha
Maxillary, ethmoidal and frontal sinuses mainly drain into the middle meatus
Maxillary, ethmoidal and frontal sinuses mainly drain into the middle meatus
Why might an infection persist in the maxillary sinus?
The sinuses also drain into the nasal cavity.
All will drain assisted by gravity (except for the maxillary sinuses – this makes these sinuses more prone to infections).
Infections result in swollen mucosa, blocked drainage holes and subsequent pressure (and pain) on the nearby structures.
Explain the patterns of pain referral from the paranasal air sinuses.
Irritation of sensory nerves by inflammatory mediators, pressure changes, and a blocked non-draining sinus may present with pain which is felt away from the site of the actual pathology.
What is Sinusitis?
Pain over the site of an infected sinus is common in sinusitis (inflammation of the lining of the nasal cavity and the sinuses).
The infection may be viral or bacterial.
Symptoms of sinusitis
Nasal blockage, congestion, obstruction—essential for diagnosis
Nasal discharge (anterior rhinorrhoea or post-nasal drip)—essential for diagnosis
Reduced sense of smell (hyposmia)
Describe two pain patterns of sinusitis - referred pain.
The headache may result from frontal sinusitis due to compression/irritation of branches from the ophthalmic (CN V1) division of the trigeminal nerve (CN V).
Toothache may occur with acute maxillary sinusitis due to compression/irritation of branches from the maxillary (CN V2) division of the trigeminal nerve (CN V).
What does the pharynx do?
Conducts air to the larynx, trachea, and lungs
In breathing, air may flow through either the nose or the mouth but it always flows through the pharynx
Directs food to the oesophagus
During swallowing, the pharynx changes from an airway to a food channel
What is the pharynx?
Thepharynxis a Musculo membranous tube - extends from the choanae (posterior openings of the nasal cavity) to the oesophagus, which starts at the cricoid cartilage (vertebral level C6)
What are the subdivisions of the pharynx
Nasopharynx – the nasal cavities open into here
Oropharynx – the oral cavity opens into here
Laryngopharynx – the laryngeal inlet opens into here
What are the muscles of the pharynx and their innervation?
3 circular constrictors
Superior - Vagus
Middle - Vagus
Inferior - Vagus
3 longitudinal elevators
Salpingopharyngeus - Vagus
Palatopharyngeus - Vagus
Stylopharyngeus - Glossopharyngeal
Tensor veli palatini - Mandibular division of trigeminal nerve (CN V3)
Levator veli palatini - Vagus
^^^Two other muscles shown here attach to the soft palate – one tenses the soft palate and one elevates the soft palate.
Structures of the Nasophayrnx
Pharyngotympanic tube (auditory tube)
Salpingopharyngeus, palatopharyngeus, stylopharyngeus muscles
Superior, middle and inferior pharyngeal constrictor muscles
Pharyngeal (adenoid) tonsil
The floor of the nasopharynx (soft palate) can raise and lower
Structures of the Oropharynx
Begins at the pharyngeal isthmus
The posterior tongue forms the anterior oropharynx
Palatoglossal arch
Palatopharyngeal arch
Palatine tonsil
Structures of the Laryngopharynx
The laryngeal inlet opens into the anterior laryngopharynx
Epiglottis
Laryngeal inlet
Opening of oesophagus
Nerve supply to the Pharynx: Sensory
Nasopharynx – the maxillary (V2) division of the trigeminal nerve (CN V)
Oropharynx - glossopharyngeal nerve (CN IX) + Stylopharyngeus muscle
Laryngopharynx – the vagus nerve (CN X) + taste sensation from the pharynx
Motor supply to the pharynx?
Motor supply to the pharynx is mostly by the Vagus nerve (CN X). However, each region of the pharynx has a different sensory innervation
Referred pain from the Pharynx examples
A lesion in the pharynx but the pain may be felt around the external ear.
This happens because part of the skin of the outer ear is supplied by a branch of the Vagus nerve (CN X) (the auricular branch).
The laryngopharynx is also supplied by a branch of the Vagus nerve (CN X) – the superior laryngeal nerve
Sensory neurons from both the vagal nerve branches synapse in the same place in the medulla of the brain – the brain can get ‘confused’ as to where the pain is coming from and interprets that it is coming from a lesion of the skin of the ear rather than from the laryngopharynx.
Loss of the sensory or motor nerve supply to half of the pharynx (e.g. as a result of stroke) results in:
Diminished gag reflex – Due to glossopharyngeal nerve (CN IX) sensory loss & Vagus nerve (CN X) motor loss
Poor swallowing reflex – because of pharyngeal and laryngeal muscle paralysis due to Vagus nerve (CN X) loss
What is the larynx responsible for?
An air passage – part of the respiratory viscera
A sphincter – to prevent aspiration (inhalation) of foods and liquids
An organ of phonation - Production of sounds / voice
Raises intra-abdominal pressure - Valsalva manoeuvre
What is the larynx?
It is a hollow tube formed by a series of nine cartilages interconnected by the ligaments and fibrous membranes.
It moves up and down during swallowing under the action of a number of extrinsic muscles (i.e., the muscles that originate from neighbouring structures and insert into the larynx)
Intrinsic muscles (which have their origin and insertion within larynx) move the vocal folds and modify the laryngeal inlet.
Where is the larynx?
The larynx is suspended from the hyoid bone
Describe the hyoid bone?
The hyoid bone is attached to the:
Floor of the oral cavity above
The larynx below
The pharynx posteriorly
The hyoid bone is suspended from the styloid process of the temporal bone of the skull by the stylohyoid ligament
A number of muscles attach to the hyoid, such as the middle pharyngeal constrictor.
Describe the larynx membranes
The larynx is joined to surrounding structures by a number of membranes:
The thyrohyoid membrane is a broad, fibroelastic membrane attached to the thyroid cartilage and hyoid bone
The cricothyroid membrane attaches to the thyroid and cricoid cartilage and to the vocal processes of the arytenoid cartilages
The upper free margin of the cricothyroid membrane forms the vocal ligaments
Describe the larynx cartilages
The laryngeal skeleton is nine cartilages: the thyroid cartilage, cricoid cartilage, epiglottis, arytenoid cartilages, corniculate cartilages, and cuneiform cartilages.
The first three are unpaired cartilages, and the latter three are paired cartilages.
The thyroid cartilage pivots forward and backwards at the cricoids synovial joints.
What forms the true vocal folds
The vocal ligaments (which are elastic) form the skeleton of the true vocal folds (they extend from the vocal process of the arytenoid cartilage to the thyroid cartilage).
The true vocal folds are formed by the mucosal covering and the underlying vocal ligaments.
The vocal folds can be abducted and adducted by the intrinsic muscles of the larynx.
Moving vocal folds opens and closes the rima glottidis
What is unique about the vocal ligaments?
The vocal ligaments are covered with a non-keratinized, stratified squamous epithelial mucosa (ie NOT the usual respiratory mucosa usually found in the larynx) - this protects the tissue from the effects of the considerable mechanical stresses that act on the surfaces of the vocal folds.
What controls the glottis movements?
The primary muscle which opens the glottis (by Abducting the vocal folds) is the posterior cricoarytenoids – if these are paralysed then asphyxiation can result as the airway will be unable to open!
The Larynx: Motor supply to the intrinsic muscles
Motor supply: All the intrinsic muscles of the larynx are supplied by the Vagus nerve (CN X)
BUT - by the different branches of it.
All the muscles EXCEPT CRICOTHYROID are supplied by the recurrent laryngeal branch of the Vagus nerve (CN X)
At the arch of the aorta (on the left side only) the Vagus nerve (CNX) gives off the recurrent laryngeal branch which then ascends back up the left side of the neck to innervate the intrinsic muscles of the larynx
At the right sub-clavian artery (on the right side only) the Vagus nerve (CN X) gives off the recurrent laryngeal branch which then ascends back up the right side of the neck to innervate the intrinsic muscles of the larynx
Clinical example of the Recurrent Laryngeal Nerve pathology (RLNs)
Tumours of the apex of the right lung (Pancoast Tumours) may compress the right recurrent laryngeal nerve (as it is given off at the sub-clavian artery)
Results in a hoarse voice and right vocal cord palsy
Surgery to the left lung (lobectomy or pneumonectomy) or tumours involving the hilum of the lung may result in injury/compression to the left recurrent laryngeal nerve (as it is given off at the aortic arch)
Results in a hoarse voice and left vocal cord palsy
Bilateral lesions of RLNs:
Thyroid surgery
Cervical spinal surgery
Viral infection
The patient may have a near normal voice because the vocal cords will lie close to the midline (see image)
The voice will be minimally affected
HOWEVER, the airway will be very compromised, because abduction of the vocal cords will not be possible on either side
Patients can present with respiratory distress resulting in hypoxia, respiratory arrest and death!
They may require urgent tracheotomy
Three regions of the temporal bone
Squamous part
Petro-mastoid part
Tympanic part
What are the auditory ossicles? and where are they found?
Malleus, incus, stapes
Middle ear - Found in the petrous portion of the temporal bone
Key features of the the ossicle structures and how they interact.
Malleus - head and handle - head has the incus articulation, handle attaches to tympanic membrane
Incus - Body and long limb - Body has the malleus articulation
Stapes - Base articulates with oval window, head articulates with long limb of incus
state and descrive the type of joint found between the auditory ossicles
Synovial joints:
Outer fibrous articular capsule surrounds the joint
Synovial membrane lines articular capsule
Synovial fluid-filled cavity lies within the joint
Articular (hyaline) cartilage lines articular surfaces
What is Conductive Hearing Loss
When there is a problem conducting sound waves anywhere along the route through the outerear, tympanic membrane or middleearauditory ossicles
State 4 examples of conductive hearing loss
Autoimmune conditions (i.e. rheumatoid arthritis) leading to inflammation of synovial membrane -> joint stiffness and eventually damage
Head trauma can lead to joint dislocation
Repeated acute otitis media -> joint scarring and stiffness
Otitis media with effusion -> mild conductive hearing loss
What are the portions of the external ear
Outer portion: auricle (pinna)
Inner portion: external acoustic meatus (or external auditory canal)
What kind of epithelium in the external ear?
keratinised stratified squamous epithelium
What is the Sensory Innervation to the Pinna:
Cranial nerves
Trigeminal nerve, mandibular division (CN V3) - Anteriorly
Facial nerve (CN VII) - Around concha
Vagus nerve (CN X) - Whole ear
Spinal nerves
Lesser occipital nerve (C2) - Posterior
Greater auricular nerve (C2, C3) - Inferior
How could pain in the external ear be caused by osteoarthritis (degenerative processes) in the neck region
Pain in the external ear may result from compression of one or more of the spinal nerves that supply the ear, as a result of osteoarthritis (degenerative processes) in the neck region
Anatomy, Histology & Nerve Supply of the External Acoustic Meatus
Anatomy:
S- shaped
Histology:
thin, adherent to cartilage and bone
contains ceruminous glands
Nerve Supply:
Cranial nerves V, VII & X
Key observable features of the tympanic membrane
Handle of malleus, Cone of light, Membrane, Incus
What should a healthy tympanic membrane look like?
The healthy tympanic membrane is a pale, grey, ovoid semi-transparent membrane situated obliquely at the end of the bony external auditory canal
The handle of the malleus is seen extending downwards and backwards, ending at the apex of the triangular “cone of reflected light”
The long process of the incus may be seen too
What is the function of the Pharyngotympanic Tube
Connects the middle ear with the nasopharynx.
Equalizes pressure on both sides of the tympanic membrane.
During swallowing the salpingopharyngeus muscle (one of the longitudinal pharyngeal muscles) opens the pharyngeal orifice of the pharyngotympanic tube
CN X (vagus) nerve supply
Allows mucociliary clearance and drainage of the middle ear
Dampens loud sounds (as it is closed at rest – most of it is cartilaginous)
How do infections in the nasopharynx move into the ear?
The mucosa of the pharyngotympanic tube is continuous with the nasopharyngeal mucosae infections from the nasopharynx can track up to the middle ear.
What is acute otitis media?
infection involving the middle ear space and is a common complication of viral respiratory illnesses
Viruses can infect the nasal passages, pharyngotympanic tube, and middle ear, causing inflammation and impairing the mucociliary action and ventilatory function of the pharyngotympanic tube to clear nasopharyngeal flora that enter the middle ear.
A middle ear effusion develops, and nasopharyngeal bacteria contaminate the effusion resulting in a purulent effusion
What is otitis media with effusion? And potential causes of persistent OME.
non-purulent effusion within the middle ear without signs of acute inflammation (also known as ‘glue ear’)
Persistence of OME may occur because of one or more of the following:
Impaired pharyngotympanic/eustachian tube function causing poor aeration of the middle ear
Low-grade viral or bacterial infection
Persistent local inflammatory reaction
Adenoidal infection or hypertrophy
Why are children more susceptible to ear infections?
In children, the pharyngotympanic tube is more horizontal and slightly narrower than in adults - this predisposes them to middle ear infections and the clearance mechanism is not as efficient
What is Sensorineural Hearing Loss
injury or pathology affecting the inner ear structures
Muscles of the middle ear
Tensor tympani muscle – attaches to the malleus and tenses the tympanic membrane when we hear loud noises.
Nerve supply: mandibular (V3) division of the trigeminal nerve (CN V)
Stapedius muscle – attaches to the stapes. It contracts during loud noises and prevents excessive oscillation of the stapes
Nerve supply: facial nerve (CN VII)
Both for acoustic reflex
What is hyperacusis
The experience of inordinate loudness of sound that most people tolerate well, associated with a component of distress. This experience has a physiologic basis - but it also has a psychological component.
Middle ear innervation
Tympanic plexus of nerves:
From glossopharyngeal nerve (CN IX)
Innervates mucous membrane of the middle ear
Sympathetic fibres from the sympathetic chain in the cervical region join this plexus
The plexus sits on the promontory which is formed by the cochlea in the inner ear
Chorda tympani - Facial nerve (CN VII)
Innervates the salivary glands.
Carries taste sensory fibres from the anterior 2/3 of the tongue back to the brain.
Types of upper respiratory viruses
Rhinoviruses (>100 serotypes)
Parainfluenza viruses 1-4
Coronaviruses
RSV
Adenoviruses
Enteroviruses (coxsackie, echo)
What causes Pharyngitis/Tonsillitis
Viruses (adenoviruses)
Bacteria – Strep pyogenes
What is Infectious mononucleosis?
Glandular fever
Constellation of symptoms and signs, not an aetiological diagnosis
Pharyngitis, lymphadenopathy (cervical, generalised), fever, malaise
Atypical mononuclear cells in peripheral blood
Epstein-Barr virus, cytomegalovirus, toxoplasmosis, HIV seroconversion
Lower respiratory tract viruses
Influenza viruses
Respiratory syncytial virus
SARS-CoV-2
Rare:
Varicella zoster virus (adults)
Measles virus (giant cell pneumonia)
Cytomegalovirus (immunocompromised)
SARS and MERS coronaviruses
How are influenzas typed?
TYPES – A, B, or C
On basis of internal proteins NP, matrix
SUBTYPES – A only
On basis of surface proteins, HA, NA
16 HA, 9NA known
Pathogenesis of influenza
Pneumotropic and lytic ie strips off respiratory epithelium
Removes 2 innate defence mechanisms – mucous secreting cells and cilia
Interferon production – circulates in blood (virus doesn’t)
What are potential complications of influenza
Pneumonia
myocarditis
Encephalitis
What is antigenic shift?
Occurs only in influenza A viruses
Genetic reassortment between human and non-human viruses leading to new subtypes
Describe respiratory Syncytial virus epidemiology
Enveloped paramyxovirus
–ve ssRNA encodes 9 polypeptides incl 2 surface proteins F,G
Causes LRTI in infants – bronchiolitis, pneumonia
High hospitalisation rates
Low mortality
Extremely common - global infection by age 2
How many recurrent episodes of upper respiratory tract infections are common in children
Six to eight per year
Risk factors of otitis media with effusion
Exposure to cigarette smoke
Bottle feeding
Older siblings or contact with older children such as in day care
Atopic rhinitis
Cleft palate
Down’s syndrome
Cystic fibrosis
Glue ear
Signs
hearing difficulty (for example, mishearing when not looking at speaker, difficulty in a group, asking for things to be repeated)
poor educational and language progress
When is surgical intervention necessary for otitis media with effusion
Persistent bilateral glue ear documented over 3 months with hearing loss in the better ear of 25-30 dBHL
What is a treatment for otits media with effusion?
A temporary grommet (a tympanostomy tube) is placed in the tympanic membrane.
This ventilates the middle ear, maintains normal middle ear pressures and reduces the risk of fluid building up in the middle ear.
Routine hearing tests for children in the UK
Newborn hearing screening
9months to 2.5 years of age – routine enquires about parental concerns with hearing tests arranged if necessary
4 to 5 years of age – preschool hearing test
typical speech and language development milestones
By 6 months: Turn towards a sound when they hear it
1 year: Listen carefully, and turn to someone talking on the other side of the room.
Babble strings of sounds, like ‘no-no’ and ‘go-go
18 months : Start to understand a few simple words, like ‘drink’, ‘shoe’ and ‘car’. Also simple instructions
2 years: Understand between 200 and 500 words and simple questions and instructions. E.g. ‘where is your shoe?’ and ‘show me your nose’.
3 years: Listen to and remember simple stories with pictures.
Understand longer instructions, such as ‘make teddy jump’ or ‘where’s mummy’s coat?’
Understand simple ‘who’, ‘what’ and ‘where’ questions
Describe the larynx epithelia
Lined by pseudostratified columnar ciliated epithelium, except epiglottis & vocal cords – Stratified Squamous Non Keratinising
Trachea histology
Interior to exterior:
PSCC
Connective tissue
Seromucous acinar glands
Perichondrium
Hyaline cartilage
Horse-shoe shaped rings of cartilage – ends connected posteriorly by the trachealis muscle (smooth)
Bronchi structure
Seromucous glands
Cartilage: complete rings (extrapulmonary)
Cartilage: incomplete rings (intrapulmonary)
Spirally arranged smooth muscle
Bronchioles structure
1mm in diameter
Simple columnar/cuboidal epithelium
NO glands
NO cartilage
Prominent smooth muscle
Gradual decrease in goblet cells & cilia
Alveoli structure
Thin walls lined by simple squamous epithelium
Type I pneumocytes (gas exchange)
Type II pneumocytes (surfactant production) - reduces surface tension, preventing collapse
Capillaries in mid-wall
Elastic and reticular fibres
Alveolar macrophages (no cilia or mucus for defence
Lung (pulmonary) interstitium
Basement membrane and surrounding interstitium, which separates the endothelial cells from the alveolar lining epithelial cells.
Interstitial space (pulmonary interstitium) contains fine elastic fibers, small bundles of collagen plus some fibroblast-like interstitial cells, smooth muscle cells, mast cells, and rare lymphocytes or monocytes.
Describe the alveolar air blood barrier
Endothelium - Fused basement membrane - epithelium
Describe the pleura
2 layers of opposing mesothelium
Visceral pleura
Parietal pleura
Pleural “cavity” in-between
What is the conducting aspect of the respiratory tract?
Trachea > Primary bronchi > Lobar (secondary) bronchi > Segmental (tertiary) bronchi
What is the respiratory aspect of the RT?
Branching of terminal bronchioles to respiratory bronchioles and alveolar sacs
Features of the trachea. Vertebral levels, features, innervation
Trachea starts at cricoid cartilage (C6) is palpable superior to suprasternal notch
Trachea bifurcates at T4 (sternal angle) into right and left main bronchi. Main bronchi enter lung hilum at T5/6 vertebral level
Incomplete ring of hyaline cartilage
Trachealis muscle
Left main bronchus passes under arch of the aorta and is longer and narrower than right. Right is more vertical
Tracheobronchial innervation = vagus nerve (CNX), sympathetic nerves
What is relevant about the bronchial tree surgically?
Each segment is functionally independent - can be surgically resected
Right lung lobes and segments
Superior lobe
Apical segment (1)
Posterior segment (2)
Anterior segment (3)
Middle lobe
Lateral segment (4)
Medial segment (5)
Inferior lobe
Apical segment (6)
Medial basal segment (7)
Anterior basal segment (8)
Lateral basal segment (9)
Posterior basal segment (10)
What segments of the lung are usually affected in supine patients?
Apical basal and posterior basal dependent
Fluid / secretions can collect– postural drainage)
Left lung lobes and segments
Left lung has 9 segments
No middle lobe – lingula instead
Apical and posterior segments of superior lobe may be combined
Inferior lobe – medial basal segment is smaller, shares bronchus with anterior basal segment
What are the fissures of the lungs?
Oblique on both
Horizontal on the right
What is the Hilum? and what is its structure?
Hilum of the lung – connects lung to mediastinal structures
Pulmonary artery
Bronchi
Pulmonary veins
Mediastinal relations of the left lung
Aortic Arch
Cardiac impression
Subclavian artery
Brachiocephalic vein
Stomach (diaphragm)
Mediastinal relations of the right lung
Vena cava S and I
Oesophagus
Azygos vein
Brachiocephalic vein
Liver (diaphragm)
What is the innervation of the diaphragm?
Phrenic nerve - C3,4,5
Major structures passing through the diaphragm (+vertebral levels)
Inferior vena cava (T8 vertebral level)
Oesophagus (T10)
Aorta (T12)
Layers of the intercostal muscles (out to in) and their function
Externals = inspiration
Internals + innermost = expiration
Describe the Neurovascular bundle in costal groove of superior rib
Intercostal vein
artery
nerve
Found superiorly
Collateral branches found inferiorly
What is the External intercostal muscle action on the thoracic cage
Upper ribs = Increase anteroposterior diameter
Lower ribs = Increase transverse diameter
Describe the pleura
Visceral pleura: covers lung
Parietal pleura: covers internal surface of chest wall, mediastinum, diaphragm
Pleural “cavity” in-between
Lined with serous fluid
What is a pneumothorax
collapsed lung
What is the nerve supply of the parietal pleura?
Nerve supply of parietal pleura is the phrenic nerve (C3,4,5) for mediastinal and diaphragmatic pleura
Intercostal nerves for costal pleura
Describe how a collapsed lung could be resolved.
A chest drain is inserted in mid-axilliary line, 5th or 6th IC space, to remove air (point upwards) or fluid (point downwards).
Describe the complications of a tension pneumothorax
In a tension pneumothorax, air that continues to enter the pleural cavity can’t escape. The trachea deviates towards the contralateral side and can form a “valve” that prevents air entering the unaffected lung.
Where are the surface markings of the lung?
Oblique fissure T4 to 6th costal cartilage
Horizontal – follows 4th intercostal space from sternum to meet oblique fissure at 5th rib
Apex is 2 cm above medial 1/3 of clavicle
Cardiac notch of left lung below T4
Where is the Pleural surface exposed?
Exposed above clavicle
Pleura is at 12th rib or lower, exposed here at the renal angle
Describe biology behind a cough
From trachea to alveoli sensitive to irritants.
Afferents utilize primarily CN X (Thevagus nerve).
Process
2.5 L of air rapidly inspired
Epiglottis closes and vocal chords close tightly
muscles of expiration contract forcefully which causes pressure in lungs to rise to 100 mm Hg
Epiglottis and vocal chords open widely which results in explosive outpouring of air to clear larger airways at speeds of 75 – 100 MPH
Sneeze
Associated with nasal passages
Irritation sends signal over CN V (The trigeminal nerve) to the medulla:
Response similar to cough, but in addition uvula is depressed so large amounts of air pass rapidly through the nose to clear nasal passages
What can depress respiratory defence mechanisms
Chronic alcohol is associated with an increase incidence of bacterial infections.
Cigarette smoke and air pollutants is associated with an increase incidence of chronic bronchitis and emphysema.
Occupational irritants is associated with and increased incidence of hyperactive airways or interstitial pulmonary fibrosis
Common cold
Viral disease of the upper respiratory system.
Caused by a variety of viruses;
rhinoviruses and coronaviruses are the most common.
Symptoms are sneezing, runny nose, and congestion.
Viruses prefer a slightly cooler temperature hence the upper respiratory system.
Self-limiting, 7days or so
Sinusitis
Inflammation of the mucosal lining of paranasal sinuses.
Characterised by:
Facial pain
Nasal obstruction
Nasal discharge
Post-nasal drip from sinusitis is irritating to the larynx and may cause a persistent cough.
What bacteria most commonly cause sinusitis
Streptococcus pneumoniae
Haemophilus influenzae
Staphylococcus aureus
Streptococcus pyogenes (Group A) – less common
Otitis externa
Otitis externa
Aka Swimmer’s ear
Outer ear exposed to water lowering acidity
Microbes accumulate and colonise
Bacterial
Staph aureus
Enteric bacteria
Malignant OE in immunocompromised:
Pseudomonas – multi-drug resistant
Fugal
Aspergillus
Candida
Symptoms of malignant otitis media
persistent and foul-smelling yellow or green drainage from the ear
ear pain that gets worse when moving the head
hearing loss
persistent itching in the ear canal
fever
difficulty swallowing
weakness in the facial muscles
loss of voice, or laryngitis
swollen and red skin around the ear
Otitis media pathogens
Haemophilus influenzae
Strep pneumoniae
Moraxella catarrhalis – Gram neg cocci
Also anaerobes such as Prevotella
Pharyngitis, laryngitis, tonsillitis
Most commonly of viral causes
Bacterial – Strep Group A (Strep pyogenes)
Sore throat
Erythema of the pharynx
Often enlargement of the tonsils (Tonsillitis)
Scarlet fever
Caused by Strep pyogenes through inhalation, skin contact or oral route
Leading cause of death in children in the early 20th century
Most commonly affects children between 5 to 15 y.o.
Fever followed by rough red rash over trunk and abdomen then spreads to entire body
Accompanied by pyrexia, lymphadenopathy, aches and nausea
Diphtheria
Caused by Corynebacterium diphtheriae
Gram-positive, rod-shaped bacteria
Irregular, club-shaped or V-shaped arrangements
Toxin induces epithelial necrosis embedded in fibrin and white cell infiltrates forming pseudomembrane in trachea
Can be fatal - multisystem toxaemia and myocarditis
Tracheitis
Rarely occurring in adults, affects primarily infants and children
Symptoms:
Severe coughing
Nasal flaring
Breathing difficulties
Cyanosis
Viral or bacterial
Bacterial causes:
Most common Staph aureus including MRSA
Strep pyogenes
Strep pneumoniae
Haemophilus influenzae
Moraxella catarrhalis
Enteric bacteria
Bronchitis
Symptoms:
coughing up mucus
wheezing
shortness of breath
chest discomfort
Cough lasting few weeks
Primarily viral
Occasionally bacterial
Strep pneumoniae
Haemophilus influenzae Moraxella catarrhalis
Bronchiolitis
Viral causes (RSV – most common, Influenza, parainfluenza, Rhinovirus)
Affecting infants up to 2 y.o.
Preceded by viral URTIs
Cough, wheezing followed by respiratory distress
Pneumonia
Inflammation of the lung affecting primarily the alveoli but also the bronchioles and bronchi
Pathology includes build up of fluid in the form of mucus and / or blood in the alveoli
Symptoms: Productive or dry cough, chest pain, fever, and troubles during breathing
Streptococcus pneumoniae is the most commonly identified bacterial cause of CAP in all age groups worldwide.
Whooping cough - Pertussis
Caused by Gram negative coccobacilli Bordetella pertussis
Re-emergent as a serious respiratory illness affecting infants and children but also occasionally young adults
Toxin similar to cholera toxin
Explosive cough as disease develops into paroxysmal stage (series of consecutive bursts of cough with increasing intensity)
Rapid exhaustion
Cyanosis and Convulsion
Anatomical Dead Space
Morphological
Volume of conducting airways
Air flushed out with each new breath
~ 150ml
Determined by:
Anatomy/radial traction
Subject size and posture,
Size of breath (tidal volume)
Physiological Dead Space
anatomical dead space and alveoli not perfused/diseased
Describe Single breath method
Measures rate of gas transfer across the
Air-blood barrier
patient inhales test gas (with known v. small concentration of CO) and holds breath for 10 sec
Rate of CO disappearance from alveolar air is measured by comparing expired air with inspired air (infrared analyser)
25mL/min/mmHg
What is VQ mismatch
VQ mismatching is the most common cause for a fall in PaO2 in resp. disease
VQ mismatch increases the area that is not used for gas exchange.
PaO2 falls, the PA-PaO2 gradient increases
Breathing rate may increase
Range of pathologies :
Alveolar structural problems
Lack of inspired oxygen
Respiratory failure,
Lack of circulation/ blood flow
Causes of type I respiratory failure
Decreased PaO2
Hypoventilation; Low O2 in inspired air; V/Q mismatch
Decreased mixed venous O2 content
Increased metabolic rate (e.g. fever) ; Decreased cardiac output (cardiac failure); Decreased arterial O2 content (e.g. Diffusion problem?)
Anatomical intrapulmonary shunts
Congenital cardiac lesions (Fallor’s tetralogy) section of lung is unventilated and blood bypasses the lungs
