Neck anatomy

Why this matters

A tooth is the commonest single source of the deep neck infections that fill head-and-neck emergency lists. In a 2023 systematic review of deep neck space infection in adults — 60 included studies, 103,320 patients — 28 studies reported aetiology at all, 26 of those reported dental infection, and dental infection was the commonest cause at 47.7%.

The big picture

The neck is a set of soft-tissue compartments wrapped around a bony column, an airway and a great-vessel bundle. Loose areolar planes between those compartments are not cavities — they are potential clefts that open only when something pushes them apart. Pus from a tooth is exactly such a thing. Everything else in the lesson — triangles, carotid sheath, thyroid, nerves — is the map of what those planes contain and what gets damaged when they fill.

The 15 cards in this lesson

1. 01Why the neck is a dental subject
2. 02The fascial layers in cross-section — and what the standard actually says
3. 03Does the investing layer exist? Two good studies disagree
4. 04The triangles: boundaries, contents and the nodal levels that replaced them
5. 05The carotid sheath: two structures, not one, and no fixed map inside it
6. 06Thyroid and parathyroid: the glands, their vessels and the nerves at risk
7. 07Clinical alert — in the lesson
8. 08Four nerves you must be able to place: XI, XII, X and the phrenic
9. 09The cervical plexus, and the raphe that may not be a raphe
10. 10Four compartments a lower molar can open: sublingual, submandibular, pterygomandibular, parapharyngeal
11. 11Where dental infection actually goes — and whether the corridor to the mediastinum is real
12. 12A swollen neck is not always a tooth: differential, examination and the no-red-flag branch
13. 13Clinical alert — in the lesson
14. 14What the numbers really say about Ludwig's angina
15. 15Clinical alert — in the lesson

You have got it when

You can name what each named cervical fascia encloses and say honestly which of them the primary evidence supports; you can locate a neck lump by triangle and by nodal level; you can give the walls and the contents of the sublingual, submandibular, pterygomandibular and parapharyngeal compartments, explain how a lower molar reaches each one and name the neighbour each one opens into; and you can list, without…