ICU · Anatomy
Functional Anatomy for ICU Procedures
Also known as Procedure anatomy · Cricothyroidotomy · Cricothyroid membrane · Tracheostomy · Chest drain safe triangle · Lumbar puncture · Intraosseous access · Pericardiocentesis · Central venous catheter anatomy · Internal jugular vein · Radial artery cannulation · Allen test · Intercostal neurovascular bundle · Cauda equina · Ligamentum flavum
Functional anatomy for common ICU procedures: the cricothyroid membrane (cricothyroidotomy), the tracheal rings and thyroid isthmus (tracheostomy), the chest-drain safe triangle (5th intercostal space, anterior axillary line), the lumbar-puncture ligament layers (L3-L4, below the conus), the internal jugular vein and carotid sheath (central venous catheter), the radial artery and palmar arches (arterial line, Allen test), the intraosseous sites (proximal tibia), and the subxiphoid route for pericardiocentesis.
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Meet the patient
A 58-year-old septic, obese man with a beard and a receded mandible is in arrest on the ward; the registrar has tried twice to intubate and cannot ventilate with a bag mask. The saturation is falling through the 70s. This is the can't-intubate-can't-oxygenate moment, and the scalpel is already in your hand.[3]
The question that decides whether this patient lives is the question that decides every ICU procedure: what is the superficial, avascular, midline target — and what lies behind it that I must not injure? For front-of-neck access the answer is the cricothyroid membrane, a flat fibroelastic sheet stretched between the thyroid cartilage above and the cricoid below, with the oesophagus immediately posterior. That one triplet — landmark, target, danger — is the whole of procedural anatomy, and it applies to every line, drain, and puncture you will ever do.[3]
References9ShowHide
- [1]Parienti JJ, Mongardon N, Mégarbane B, et al. Intravascular Complications of Central Venous Catheterization by Insertion Site. N Engl J Med, 2015.PMID 26398070
- [2]Havelock T, Teoh R, Laws D, et al. Pleural procedures and thoracic ultrasound: British Thoracic Society Pleural Disease Guideline 2010. Thorax, 2010.PMID 20696688
- [3]Cook TM, Woodall N, Harper J, et al. Major complications of airway management in the UK: results of the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society. Part 2: intensive care and emergency departments. Br J Anaesth, 2011.PMID 21447489
- [4]Marchese RM, Launico MV, Geiger Z. Anatomy, Shoulder and Upper Limb, Forearm Radial Artery. StatPearls, 2026.PMID 31536233
- [5]Brzezinski M, Luisetti T, London MJ. Radial artery cannulation: a comprehensive review of recent anatomic and physiologic investigations. Anesth Analg, 2009.PMID 19923502
- [6]Slogoff S, Keats AS, Arlund C. On the safety of radial artery cannulation. Anesthesiology, 1983.PMID 6859611
- [7]Doherty CM, Forbes RB. Diagnostic Lumbar Puncture. Ulster Med J, 2014.PMID 25075138
- [8]Patolia S, Farhat R, Subramaniyam R. Bronchoscopy in intubated and non-intubated intensive care unit patients with respiratory failure. J Thorac Dis, 2021.PMID 34527353
- [9]Nakashima H, Ito K, Katayama Y, et al. The Level of Conus Medullaris in 629 Healthy Japanese Individuals. J Clin Med, 2021.PMID 34300348