Applied Anatomy of Airway

Airway? Pathway in which air passes Natural & artificial Natural airway = upper airway Nasal cavity, mouth, pharynx, larynx Trachea,bronchus, bronchial division

Anatomical airway

Nasal cavity Phylogeniticaly breathing occurs through nose Enables to smell danger, unconditional supply of air while feeding Resistance to air flow twice that of mouth breathing Exercise & respiratory distress mouth breathing is facilitated

Nasal Cavity

# cribriform plate of ethmoid  csf rhinorhoea Inadverdant placement of NPA, NTT, NG into anterior cranial fossa Chronic nasal intubation cause sinus sepsis

Floor of nose & Inferior turbinate Oriented perpendicular to fascial plane Nasal instrumentation should be done perpendicular to this plane Major air passage lies beneath inf. Turbinate Inf. Turbinate limits the size of NTT

Vasculature of nose Vasularized sub mucosa Branches of internal carotid artery Nasal packing only way to control bleeding Antero inferior septum- site of epistaxsis Orient leading edge of NTT away from septum

Nasal airway calibre change Prior to vasoconstrictorAfter vasoconstrictor

Innervation of nasal cavity

The Kratschmer reflex leads to bronchiolar constriction upon stimulation of the anterior nasal septum in animals. Similar reflex seen in the postop period when a pt becomes agitated when the nasal passage is packed

Mechanism of perforation & submucosal tunneling

Tonsils – possible cause of airway obstruction

Pharynx Musculofascial tube connects nasal and oral cavity with larynx and esophagus Lacks of bony / cartilagenous frame work Patency maintained by muscle tone only Common site of laceration during traumatic intubation Lead to hematoma, cellulites and total airway collapse

Pharynx

Sites of airway obstruction

Velopharynx – the site of airway obstruction

Laryngeal frame work

Direct layngoscopic view of larnyx

Intrinsic muscles of larynx

Normal vocal cord movement

Vocal cord Palsies Selmons law : nerve fibers to abductors are vulnerable to injury than adductors Partial b/l RLN palsy leads to stridor Pure adductor palsy, rare clinical entity

Cadaveric position of cord Combined b/l RLN & SLN palsy Use of musle relaxants

Cricothyroid membrane Extends from inf. border of thyroid cartilage to sup. border of cricoid 9 mm Ht / 22 mm width Sup. 1/3 traversed by sup. Cricoid vessel Laterally by ant. Jugular & inf thyroid veins Midline neck, low 1/3 of CTM – safe site for performing cricothyroidotomy

Appropriate position of ETT Endo tracheal tube tip follows tip of the nose position