The Head and Neck at the Bedside: Landmarks, Levels and Needles
Everything difficult about the head and neck — the density of nerves and vessels packed into a hand's breadth, the airway and the great arteries lying a finger apart — is also what makes it the region where a clinician does the most with the least. A fingertip on a ring of cartilage locates an emergency airway. A pulse felt in front of a muscle marks the artery a needle must avoid. Three little dimples in a vertical line down the face are three doors into the same nerve. The person who has learned the anatomy carries an atlas under the skin: they can feel the larynx rise on a swallow, count the vertebral levels by the cartilages of the neck, and find — blind, by feel alone — the exact centimetre where a cannula belongs and the exact centimetre where it must never go. This is the chapter where the anatomy stops being a map and becomes something done with the hands.
The trauma call has gone the worst way it can go. The patient cannot be intubated — the airway is full of blood, the view is a red blur — and now the oxygen saturation is falling through the floor and a bag-mask is achieving nothing. This is "can't intubate, can't oxygenate", the corner from which there is only one way out. The anaesthetist stops trying to look and starts to feel. Two fingers run down the front of the neck: the hard shield of the thyroid cartilage, then a soft give just below it, then the firm arch of the cricoid. That soft give between the two is the cricothyroid membrane, and it is the one place on the whole airway where nothing important stands between skin and lumen — no thyroid, no great vessels, no thick muscle. A scalpel goes through it horizontally, a finger holds the hole open, a bougie slides down into the trachea, and a tube follows. Fifteen seconds of anatomy, done blind by touch, and the saturation begins to climb. Nobody scanned anything. A hand found a membrane a centimetre wide because the person attached to it knew exactly which two cartilages it lay between.
The landmarks you can feel
Run a finger from the back of the skull to the top of the sternum and you cross a dozen named points, each one useful. Begin behind. In the midline of the occiput the EXTERNAL OCCIPITAL PROTUBERANCE — the INION — is the bump under your thumb, the attachment of the ligamentum nuchae and the surface marker of the confluence of the dural venous sinuses inside. A hand's breadth forward and down, behind the ear, is the MASTOID PROCESS, the anchor of sternocleidomastoid and the bony guard over the mastoid air cells. On the side of the face the ZYGOMATIC ARCH runs as a palpable bar from the cheek to the ear, and just in front of the ear you can feel the head of the mandible move when the mouth opens — the temporomandibular joint. Follow the MANDIBLE forward along its lower border: at the ANGLE it turns up towards the ear, and about two-thirds of the way forward along the body, just in front of the masseter, a soft pulse crosses the bone — the FACIAL ARTERY, the reliable place to feel the facial pulse and the point a surgeon compresses to control facial bleeding. Now the front of the neck. High up, at the level of the third cervical vertebra, the HYOID BONE is a slender horseshoe you can pinch and rock. Below it the THYROID CARTILAGE forms the laryngeal prominence — the "Adam's apple" — its notch at C4-C5. A finger's width lower is the CRICOID CARTILAGE at C6: the only complete ring of the airway, the landmark for cricoid pressure, and the level that marks the lower limit of both the larynx and the pharynx and the beginning of the trachea and oesophagus. Below the cricoid the TRACHEAL RINGS step down to the SUPRASTERNAL (jugular) NOTCH between the two sternoclavicular joints. And one landmark that is felt rather than seen: the TRANSVERSE PROCESS OF THE ATLAS, palpable as a deep point midway between the tip of the mastoid and the angle of the mandible.
The vertebral levels a clinician counts
The cartilages of the neck are not just handholds; they are a vertical ruler calibrated to the spine, and a clinician uses them to locate structures that cannot be felt at all. The HYOID sits at C3. The THYROID CARTILAGE's upper border and notch mark C4. The common carotid artery divides into its internal and external branches at roughly the C3-C4 level — behind the tip of the greater cornu of the hyoid — which is where the CAROTID SINUS and CAROTID BODY lie and where atheroma clusters. The CRICOID CARTILAGE is the great fixed point at C6: it marks not only the narrowest part of the child's airway and the site of cricoid pressure, but also the level at which the larynx becomes trachea, the pharynx becomes oesophagus, the recurrent laryngeal nerve slips behind the larynx, and the middle thyroid vessels and the vertebral artery's entry into its canal all cluster. Learning these levels turns a neck into a labelled diagram: a lump felt at the thyroid notch, a pulse felt at the hyoid, a ring felt at C6 — each has an address, and the vessels and nerves that share that address are known even though they are invisible.
Think of the front of the neck as the spine of a book with the chapters marked on the outside. You cannot see the pages — the carotid, the recurrent laryngeal nerve, the oesophagus behind — but the raised bands on the spine tell you exactly where each chapter begins. The hyoid is the header at C3, the thyroid notch at C4, the cricoid ring at C6. Once you know that the cricoid is C6, you know without looking that below your fingertip the airway has just become a windpipe, the food tube has just begun, and the nerve to the voice box has just ducked behind the gland. The examiner who palpates a neck is not groping in the dark; they are reading the raised titles on a spine they have memorised, and every title names the hidden structures underneath.
The triangles, sternocleidomastoid, and Erb's point
One muscle divides the neck into two territories, and every landmark of the side of the neck is described relative to it. The STERNOCLEIDOMASTOID (SCM) is the great oblique strap that runs from the sternum and clavicle up to the mastoid process, and it splits the side of the neck into two triangles, mapped in full in the triangles and fasciae of the neck. IN FRONT of it is the ANTERIOR TRIANGLE — bounded by the midline, the lower border of the mandible and the anterior border of SCM — containing the carotid sheath, the larynx and thyroid, the submandibular gland and the anterior jugular veins. BEHIND it is the POSTERIOR TRIANGLE — bounded by the posterior border of SCM, the anterior border of trapezius and the middle third of the clavicle — a flatter, more superficial space crossed by the accessory nerve, the roots and trunks of the brachial plexus described in the same map, the external jugular vein and the cutaneous branches of the cervical plexus. The single most examined point on the whole side of the neck sits at the MIDPOINT OF THE POSTERIOR BORDER OF SCM: this is ERB'S POINT, where the four cutaneous branches of the cervical plexus (the lesser occipital, great auricular, transverse cervical and supraclavicular nerves) emerge together to fan out over the skin, and — a few millimetres deeper and higher — where the ACCESSORY NERVE (CN XI) crosses the posterior triangle superficially on its way from SCM to trapezius. That superficial course is the whole reason the accessory nerve is one of the most commonly injured nerves in minor surgery.
Drawing the vessels and nerves on the skin
The great vessels of the neck have surface markings precise enough to draw with a pen, and every procedure depends on them, as the full course is set out in the carotid and jugular. The COMMON CAROTID and the INTERNAL CAROTID above it are represented by a line from the STERNOCLAVICULAR JOINT running up under the anterior border of SCM to a point midway between the mastoid tip and the angle of the mandible; the bifurcation, at the upper border of the thyroid cartilage (C3-C4), is where the carotid pulse is best felt against the transverse process of C6 (the carotid tubercle). The INTERNAL JUGULAR VEIN runs a line from the EAR LOBE to the MEDIAL END OF THE CLAVICLE, lying first behind and then lateral to the carotid inside the carotid sheath, deep to SCM — invisible and impalpable, which is exactly why its central-line access is defined entirely by landmarks. The EXTERNAL JUGULAR VEIN, by contrast, is superficial and visible: it runs from the angle of the mandible obliquely DOWN AND BACK ACROSS SCM to the middle of the clavicle, and it is the vein whose distension you read as a rough gauge of central venous pressure. Two named arteries are palpable on the face: the FACIAL ARTERY at the lower border of the mandible in front of masseter, and the SUPERFICIAL TEMPORAL ARTERY immediately in front of the tragus of the ear — the vessel biopsied in suspected giant cell arteritis. And the ACCESSORY NERVE is drawn as a line from the point just below and behind the angle of the mandible, across the posterior triangle, to a point on the anterior border of trapezius about 5 cm above the clavicle.
Two hands, two absolute rules at the carotid. First: never palpate both carotid pulses at the same time. Firm bilateral pressure can occlude cerebral inflow and, worse, stimulate both carotid sinuses at once — the baroreceptor reflex answers with a plunge in heart rate and blood pressure that can drop an elderly patient to the floor. Feel one side, then the other. Second: what you read at the neck is not one signal but two. The carotid PULSE is arterial, palpable, single, and unaffected by posture or breathing. The jugular venous PRESSURE (JVP) is venous, impalpable, a double flicker you see rather than feel, that falls when the patient sits up and falls further on inspiration — and rises, tellingly, on pressing the liver. Confusing the two is the classic bedside error: the giveaway is that the JVP is obliterated by light pressure at the root of the neck and refills from above, while an arterial pulsation cannot be wiped out and comes from below. Read the vein for the state of the right heart; feel the artery for the pulse — and never both arteries together.
- Palpable landmarks, front to back: external occipital protuberance (inion) and mastoid process; zygomatic arch; the angle, body and lower border of the mandible (facial pulse crosses just in front of masseter); hyoid at C3; thyroid cartilage (laryngeal prominence, notch at C4-C5); cricoid at C6 (only complete ring); tracheal rings and the suprasternal notch; and the atlas transverse process between mastoid and mandibular angle.
- Vertebral levels a clinician uses: hyoid C3, thyroid notch C4, cricoid C6, carotid bifurcation ~C3-C4. The cricoid at C6 marks where larynx becomes trachea and pharynx becomes oesophagus.
- SCM divides the neck into the anterior triangle (carotid sheath, larynx, thyroid, submandibular gland) and the posterior triangle (accessory nerve, brachial plexus, external jugular vein, cervical plexus branches).
- ERB'S POINT at the midpoint of the posterior border of SCM: where the four cutaneous branches of the cervical plexus emerge, the target of the superficial cervical plexus block — and just deep to it the accessory nerve crosses, exposed and easily injured.
- Surface markings: common/internal carotid from the sternoclavicular joint to midway between mastoid and mandibular angle; internal jugular vein from the ear lobe to the medial clavicle (deep, impalpable); external jugular crossing SCM obliquely (superficial, a rough CVP gauge); facial and superficial temporal arteries palpable on the face.
Putting needles and blades where the anatomy allows
Four procedures, each one nothing more than an anatomical relationship exploited on purpose. INTERNAL JUGULAR CENTRAL VENOUS ACCESS. The vein lies within the carotid sheath, LATERAL to the common carotid artery, and its most reliable surface target is the APEX of the small triangle formed by the two heads of SCM (sternal and clavicular) with the clavicle as its base. The operator feels the carotid pulse, keeps a finger on it as the artery to be avoided, and directs the needle just lateral to that pulse, towards the ipsilateral nipple, at about 30-45 degrees. The reason ULTRASOUND GUIDANCE is now the standard of care is written into the anatomy: the vein overlaps the artery variably, the two are a few millimetres apart, and the dome of the pleura is only a little lower — landmark technique alone carries a real rate of arterial puncture and pneumothorax that direct vision removes. CRICOTHYROIDOTOMY, the emergency surgical airway: an incision through the CRICOTHYROID MEMBRANE between the thyroid and cricoid cartilages, chosen precisely because at that one level the airway is subcutaneous, the isthmus of the thyroid lies below it, and no major vessel crosses — which is why in a crisis it is quicker and safer than a formal tracheostomy, which cuts lower through the thyroid isthmus and its vascular bed. TRACHEOSTOMY proper is a planned procedure placed between the SECOND AND FOURTH TRACHEAL RINGS, usually dividing or retracting the ISTHMUS OF THE THYROID that overlies the second and third rings. And the humblest but commonest office procedure: FINE-NEEDLE ASPIRATION of a thyroid nodule or a neck node, in which the levels and drainage set out in the cervical lymph nodes tell you which node belongs to which primary before the needle even goes in.
Needles in the face: the nerve blocks
The face is exquisitely served by two cranial nerves whose exit points are predictable enough to anaesthetise by landmark. The three sensory exits of the TRIGEMINAL NERVE — the SUPRAORBITAL foramen or notch (V1), the INFRAORBITAL foramen (V2) and the MENTAL foramen (V3) — famously lie in a single VERTICAL LINE dropped through the pupil when the eyes look straight ahead, roughly along the mid-pupillary line, and each can be blocked with a small deposit of local anaesthetic to numb the forehead, the mid-face and cheek, or the lower lip and chin respectively; the divisions and their territories are laid out in the trigeminal nerve. The dentist's INFERIOR ALVEOLAR (dental) BLOCK targets the same nerve deeper, as V3 enters the mandibular foramen on the medial surface of the ramus, numbing the lower teeth of that side. Away from the face, the GREATER OCCIPITAL NERVE — the medial branch of the C2 dorsal ramus — is blocked at the back of the head, medial to the occipital artery and about a third of the way along a line from the mastoid to the inion, for occipital neuralgia. And at ERB'S POINT the SUPERFICIAL CERVICAL PLEXUS BLOCK, a single injection along the posterior border of SCM at its midpoint, anaesthetises the skin of the anterolateral neck, the angle of the jaw and the ear for procedures such as carotid surgery. The reason a small volume placed against a trunk silences a whole territory is the same pharmacology used everywhere in local anaesthetics.
A woman is referred with a swelling in the front of her neck. Before touching it, the examiner watches. She is asked to swallow a sip of water: the lump RISES with the larynx and falls again — the sign of a mass bound to the pretracheal fascia, which means thyroid, or something fixed to the larynx or trachea. Then she is asked to PROTRUDE HER TONGUE: this particular lump also moves upward on tongue protrusion, which points specifically to a THYROGLOSSAL CYST, tethered to the hyoid and the foramen caecum by the track down which the thyroid descended in the embryo. Had it moved on neither, it would more likely be a lymph node or a skin lesion. The examiner then palpates from BEHIND, both hands on the neck, walking through the nodal LEVELS in order — submental and submandibular, then down the jugular chain, then the posterior triangle, then the supraclavicular fossa, where a hard left-sided node (Virchow's node) would raise the spectre of an abdominal primary. If a discrete nodule or a suspicious node is found, the next step is FINE-NEEDLE ASPIRATION, and the whole approach to the neck mass — the questions to ask of the swelling and the differential by site — is what the neck lump is built around. Two questions asked before a hand even settles on the skin — does it move on swallowing, does it move on tongue protrusion — have already narrowed the diagnosis to a handful.
The danger zones to respect
Four nerves account for most of the avoidable harm done to the head and neck by a blade. Every surgical field in the head and neck is defined as much by the nerve you must not cut as by the target you mean to reach. The FACIAL NERVE (CN VII) runs THROUGH the substance of the PAROTID GLAND, dividing it into superficial and deep lobes, so that any parotid surgery is fundamentally an operation of nerve dissection — cut the trunk or a division and you paralyse a half of the face; its branches and the way an upper motor neuron stroke spares the forehead are the subject of the facial nerve. Its lowest branch, the MARGINAL MANDIBULAR NERVE, loops below the lower border of the mandible before turning up to the muscles of the lower lip, and is the classic casualty of a submandibular gland excision or a neck incision placed too high — the result is an asymmetrical smile. The ACCESSORY NERVE (CN XI), crossing the posterior triangle superficially at Erb's point, is injured with dispiriting ease during lymph node biopsy in that triangle, producing a dropped, winged shoulder and difficulty raising the arm above the head from trapezius palsy. And in the thyroid bed, two nerves are perpetually at risk: the RECURRENT LARYNGEAL NERVE in the tracheo-oesophageal groove behind the gland — one side injured gives a hoarse voice, both sides an airway emergency — and the EXTERNAL BRANCH of the SUPERIOR LARYNGEAL NERVE running with the superior thyroid vessels to cricothyroid, whose loss robs the voice of its high notes. This is why a thyroidectomy consent form names hoarseness explicitly, and why these nerves are the anatomy every head-and-neck surgeon learns first and forgets last.
- INTERNAL JUGULAR central line: target the apex of the triangle between the two heads of SCM, LATERAL to the palpated carotid pulse, aiming at the ipsilateral nipple. Ultrasound is now standard because the vein overlaps the artery and the pleural dome sits just below.
- CRICOTHYROIDOTOMY through the cricothyroid membrane between the thyroid and cricoid cartilages is the fastest, safest emergency surgical airway — subcutaneous, above the thyroid isthmus, no major vessel. A formal TRACHEOSTOMY is placed lower, between the 2nd and 4th tracheal rings, through or around the thyroid isthmus.
- A neck lump that RISES ON SWALLOWING is thyroid or fixed to the larynx/trachea; one that also rises on TONGUE PROTRUSION is a thyroglossal cyst. Neck nodes are examined from behind, level by level; a hard left supraclavicular node (Virchow's) suggests an abdominal primary. FNA characterises both.
- Landmark nerve blocks: the three trigeminal exits (supraorbital V1, infraorbital V2, mental V3) in a vertical mid-pupillary line; the inferior alveolar (dental) block at the mandibular foramen; the greater occipital nerve block for occipital neuralgia; and the superficial cervical plexus block at Erb's point.
- Danger nerves: the FACIAL nerve within the parotid; the MARGINAL MANDIBULAR nerve below the jaw (asymmetrical smile); the ACCESSORY nerve in the posterior triangle (winged shoulder); and the RECURRENT and external SUPERIOR LARYNGEAL nerves in thyroid surgery (hoarseness, loss of high notes, or bilateral airway obstruction).
- Placing an emergency surgical airway too low or reaching for a formal tracheostomy in a crisis. The cricothyroid membrane — between the thyroid and cricoid cartilages — is the correct site: it is subcutaneous, above the vascular thyroid isthmus and clear of major vessels. Cutting lower, through the thyroid isthmus, is what makes tracheostomy slower and bloodier and wrong for the "can't intubate, can't oxygenate" moment.
- Palpating both carotid pulses at once, or confusing the carotid pulse with the JVP. Bilateral carotid pressure can cause a reflex bradycardia and hypotension and reduce cerebral flow — always one side at a time. The JVP is impalpable, biphasic, obliterated by light pressure and rises on the hepatojugular reflux; the carotid pulse is palpable, single and cannot be wiped out.
- Doing a lymph node biopsy in the posterior triangle without regard for the accessory nerve. CN XI crosses that triangle superficially at Erb's point with almost nothing over it; a careless incision there denervates trapezius, giving a dropped, winged shoulder and a weak arm above the head. The posterior triangle is not a safe place to dissect blind.
In a "can't intubate, can't oxygenate" emergency, an anaesthetist palpates down the front of the neck and makes an incision through the soft membrane between the thyroid cartilage above and the cricoid cartilage below. Why is this the preferred site for an emergency surgical airway rather than an incision lower over the trachea?
- The neck is a labelled ruler: hyoid at C3, thyroid notch at C4, cricoid at C6 (the only complete ring, marking where larynx becomes trachea and pharynx becomes oesophagus), carotid bifurcation ~C3-C4. Palpable landmarks run from the inion and mastoid behind, through the zygomatic arch and mandible (facial pulse in front of masseter), to the hyoid, thyroid and cricoid cartilages, tracheal rings and suprasternal notch in front.
- SCM splits the neck into anterior and posterior triangles; ERB'S POINT at the midpoint of its posterior border is where the cervical plexus branches emerge and the accessory nerve crosses, exposed. Vessel surface lines: internal jugular from ear lobe to medial clavicle (deep), external jugular across SCM (superficial, a CVP gauge), carotid from sternoclavicular joint upward with its bifurcation and pulse at C3-C4.
- Procedures on the anatomy: internal jugular central access at the SCM triangle apex lateral to the carotid pulse (ultrasound now standard); cricothyroidotomy through the cricothyroid membrane for the emergency airway; tracheostomy between the 2nd-4th tracheal rings and the thyroid isthmus; thyroid/neck lump examination by swallowing and tongue protrusion; FNA of a nodule or node by level; and the landmark nerve blocks — the three trigeminal exits in a vertical line, inferior alveolar, greater occipital and superficial cervical plexus at Erb's point.
- Respect the danger nerves: the facial nerve within the parotid, the marginal mandibular nerve below the jaw, the accessory nerve in the posterior triangle, and the recurrent and external superior laryngeal nerves in thyroid surgery. And two carotid rules: never palpate both at once, and never confuse the arterial carotid pulse with the venous, biphasic, easily obliterated JVP.
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- Moore KL, Dalley AF, Agur AMR. Clinically Oriented Anatomy — Surface anatomy of the neck; cricothyroidotomy, tracheostomy and internal jugular access.
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- Snell RS. Clinical Anatomy by Regions — The neck: landmarks, the carotid sheath, nerve blocks and surgical approaches.
- Last RJ. Last's Anatomy: Regional and Applied — Head and neck: the larynx, thyroid gland and the laryngeal nerves at risk in surgery.
- TeachMeAnatomy — Surface anatomy of the neck; the cricothyroid membrane; the cervical plexus and Erb's point.
