AS4.2 | Airway Anatomy Relevant to General Anaesthesia — Summary & Reflection

KEY TAKEAWAYS

The anaesthetic airway extends from the nares and lips to the carina. The nasal route runs along the inferior turbinate — angulate posteriorly, not superiorly, to avoid haemorrhage. The tongue is the most common cause of unconscious airway obstruction and the epiglottis is the biological valve protecting against aspiration — both are lost under general anaesthesia. The vallecula is the landmark for the curved (Macintosh) laryngoscope blade; the straight (Miller) blade directly lifts the epiglottis. The glottis (vocal folds) is the narrowest point in adults; the subglottis (cricoid ring) is the narrowest fixed point in young children. The sniffing position aligns the three airway axes (oral, pharyngeal, laryngeal). Airway assessment uses Mallampati I–IV (oropharyngeal view), thyromental distance (≥6 cm normal), neck mobility, and inter-incisor distance; Cormack–Lehane I–IV grades the laryngoscopic view. The cricothyroid membrane — between thyroid and cricoid cartilages, midline — is the emergency surgical airway access site. Paediatric differences (anterior/high larynx, omega-shaped epiglottis, subglottic narrowest point, short trachea) require modified equipment and technique.

REFLECT

You are seeing a 28-year-old woman for pre-anaesthetic evaluation before an elective laparoscopic cholecystectomy. Her Mallampati score is Class IV, her thyromental distance is 4 cm, and she is 162 cm tall and weighs 96 kg (BMI 37). She has no prior anaesthetic history. How would you classify her airway risk? Write out your complete airway management plan — including your primary technique, your first backup, your second backup, and your plan for a cannot-intubate-cannot-oxygenate scenario. At each step, state the anatomical reason why the technique you have chosen is preferred over the alternatives. Reflect on how the anatomy learned in this SDL underpins every decision in your plan.