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