Neck nodes and temporal bone
Neck vessels and lymph node levels; ear and temporal bone
Neck CT and MRI are read by tracing the carotid and jugular vessels and assigning each node to a level; thin-section CT and MRI show the small spaces of the temporal bone. CPSP asks about vessel relations, level boundaries, middle ear walls and classic temporal bone lesions.
Carotid arteries
- The common carotid divides at the upper border of the thyroid cartilage (about C3–C4). It can be compressed against the anterior (carotid) tubercle of C6.
- The internal carotid gives no branches in the neck; this identifies it at endarterectomy. The external carotid gives superior thyroid, lingual (opposite the tip of the greater horn of the hyoid, its loop crossed by XII), facial, ascending pharyngeal, occipital, posterior auricular, maxillary and superficial temporal.
- The carotid sheath holds the carotid artery, internal jugular vein (IJV) and vagus.
- Dissection: painful partial Horner syndrome with normal facial sweating (sweat fibres follow the external carotid). Fat-suppressed T1 MRI shows a bright crescent of intramural haematoma around a narrowed lumen (may not be bright in the first day or two).
| Carotid space mass | Displacement | Origin |
|---|---|---|
| Carotid body paraganglioma | Splays the ICA and ECA apart at the bifurcation; intense enhancement | Neural crest chief cells |
| Vagal schwannoma or paraganglioma | Pushes the ICA anteromedially and the IJV posterolaterally, separating them | Vagus nerve |
Vertebral and subclavian arteries
- The vertebral artery climbs through the foramina transversaria of C6 to C1 and runs on the posterior arch of the atlas in the suboccipital triangle.
- Subclavian steal: proximal subclavian stenosis gives reversed flow in the ipsilateral vertebral artery on arm exercise.
- Scalenus anterior separates the subclavian vein (in front) from the artery (behind) at the first rib.
Veins
- The IJV lies lateral and slightly anterior to the common carotid at the cricoid level; strong head rotation moves it over the artery. The right IJV runs straight to the right atrium, so it is used for the JVP.
- The external jugular vein is formed by the posterior division of the retromandibular vein and the posterior auricular vein, and drains into the subclavian. Where it pierces the deep fascia above the clavicle, the fascia holds it open, so a cut there can cause air embolism.
Imaging-based nodal levels
| Level | Boundaries on CT | Typical primary |
|---|---|---|
| IA | Submental, between the anterior bellies of digastric | Lip, floor of mouth, tongue tip |
| IB | Submandibular, around the gland, lateral to anterior digastric | Oral cavity, lateral tongue |
| II | Skull base to lower border of the hyoid, around the IJV | Oropharynx, tonsil (jugulodigastric node) |
| III | Hyoid to lower border of the cricoid | Larynx, hypopharynx |
| IV | Cricoid to clavicle, beside the IJV | Larynx, thyroid, oesophagus |
| V | Posterior triangle, behind sternocleidomastoid, in front of trapezius | Nasopharynx, skin of scalp |
| VI | Central, between the carotids, hyoid to manubrium | Thyroid (papillary), larynx |
- Imaging levels use the hyoid and cricoid, not the variable carotid bifurcation.
- Retropharyngeal nodes (medial to the ICA, in front of longus capitis) are outside levels I–VI and are a first station for nasopharyngeal carcinoma.
- Level V biopsy endangers the spinal accessory nerve. A cystic node in an adult suggests HPV-related oropharyngeal or papillary thyroid metastasis.
External and middle ear
- External canal from the first pharyngeal cleft; cerumen from modified apocrine glands; sensation from the auriculotemporal and vagus nerves. The tympanic membrane has all three germ layers; the cone of light is anteroinferior.
- In children the Eustachian tube is short, wide and horizontal.
| Middle ear wall | Relation | Clinical or imaging point |
|---|---|---|
| Roof | Tegmen tympani | Spread to the temporal lobe (abscess) |
| Floor | Jugular bulb | A dehiscent high bulb is a blue mass behind the drum; do not biopsy |
| Medial | Promontory (cochlea), oval window | Glomus tympanicum on the tympanic branch of IX with an intact floor |
| Posterior | Aditus to the mastoid antrum | Antrum found deep to the suprameatal triangle |
- Ossicles: malleus and incus from the first arch, stapes (smallest bone) from the second. Tensor tympani is supplied by V3, stapedius by VII (paralysis gives hyperacusis).
- Cholesteatoma of the pars flaccida fills Prussak space lateral to the malleus and erodes the scutum. Recurrence after surgery is bright on diffusion-weighted MRI; granulation tissue is not.
Temporal bone lesions
| Lesion | Imaging and clinical clue |
|---|---|
| Longitudinal fracture | Parallel to the petrous ridge through the ear canal roof and middle ear; conductive loss; facial palsy less common |
| Transverse fracture | Across the petrous ridge through the otic capsule; sensorineural loss and facial palsy more common |
| Petrous apicitis | Otorrhoea, retro-orbital pain (V) and VI palsy |
| Bezold abscess | Mastoiditis eroding the medial mastoid tip into the neck below sternocleidomastoid |
| Cholesterol granuloma | Expanded petrous apex, bright on T1 and T2, no enhancement |
| Superior canal dehiscence | No bone over the canal roof; sound-induced vertigo |
| Enlarged vestibular aqueduct | Wider than the posterior canal; Pendred syndrome with goitre |
| Otosclerosis | Lucent focus at the fissula ante fenestram in front of the oval window |
| Glomus jugulare | Pulsatile tinnitus with IX, X, XI palsy; adding XII means hypoglossal canal spread |
- Facial nerve: internal acoustic meatus, labyrinthine segment (narrowest; should not enhance; enhances in Bell palsy), geniculate ganglion, tympanic and mastoid segments, stylomastoid foramen. A cut at the foramen paralyses the face with taste and tears normal.
- Referred otalgia: TMJ via V3, tonsil via IX, piriform fossa via X.
Remember Hyoid and cricoid divide levels II, III and IV; the carotid artery separates level VI from the jugular chain.
Exam trap The external jugular drains into the subclavian vein, not the internal jugular.
Exam trap A carotid body tumour splays the ICA and ECA; a vagal tumour separates the ICA from the IJV.
Test yourself on this topic
5 of the 59 questions in our bank on this topic. Choose an answer to see why every option is right or wrong.
A 28-year-old woman has progressive conductive hearing loss in both ears, worse since her last pregnancy, with normal drums. At which site does this disease most commonly begin?
Answer: Fissula ante fenestram
Otosclerosis (otospongiosis) replaces dense enchondral bone of the otic capsule with spongy, vascular bone. The commonest site is the fissula ante fenestram, a small cleft just anterior to the oval window. Spread onto the stapes footplate fixes it and causes conductive hearing loss, with a Carhart notch on audiometry. Involvement around the cochlea (retrofenestral disease) adds sensorineural loss.
Fenestral otosclerosis
- Spongy bone in otic capsule
- First site: fissula ante fenestram
- Fixes the stapes footplate
- Worse in pregnancy
Remember Otosclerosis starts in front of the oval window.
Exam trap The drum is normal, but an active focus may show a pink flush through it (Schwartze sign).
Why the other options are wrong
- Round window niche Can be involved in advanced disease but is not the usual first site.
- Sinus tympani A posterior middle ear recess relevant to cholesteatoma.
- Facial recess A posterior recess used in cochlear implant surgery.
- Cochlear aqueduct Connects the inner ear to the subarachnoid space; not the site of otosclerosis.
A 19-year-old man with blocked nose and epistaxis has a nasopharyngeal mass and a hard node felt behind the posterior border of sternocleidomastoid, in front of trapezius. Which level does this node belong to?
Answer: Level V
Level V is the posterior triangle group, lying behind the posterior border of sternocleidomastoid and in front of the anterior border of trapezius. Levels II to IV lie along the internal jugular vein, deep to or in front of the posterior edge of sternocleidomastoid. Nasopharyngeal carcinoma typically spreads to retropharyngeal nodes and to levels II and V, so posterior triangle nodes are an important clue to a nasopharyngeal primary.
Level V nodes
- Behind posterior border of SCM
- In front of trapezius
- Posterior triangle group
- Typical of nasopharyngeal cancer
Remember Posterior triangle node in a young adult: look at the nasopharynx.
Exam trap Biopsy of level V nodes risks the spinal accessory nerve running through the posterior triangle.
Why the other options are wrong
- Level II Level II lies along the upper IJV, in front of the posterior edge of SCM.
- Level III Level III lies along the middle IJV.
- Level IV Level IV lies along the lower IJV.
- Level VI Level VI is the central compartment beside the trachea.
A 28-year-old woman with mild tinnitus has a bluish mass behind the inferior part of the right drum. At myringotomy there is brisk venous bleeding, and the bony plate between the jugular bulb and the floor of the middle ear is found to be absent. What is the diagnosis?
Answer: Dehiscent high jugular bulb
The jugular bulb normally lies below the floor of the middle ear, separated by a thin plate of bone. When the bulb is high and this plate is missing, the bulb bulges into the hypotympanum and shows through the drum as a blue mass. It is a normal variant but must be recognised, because a myringotomy or biopsy can cause heavy venous bleeding. Glomus tympanicum looks red and sits on the cochlear promontory with an intact jugular plate.
Dehiscent jugular bulb
- Blue mass behind the inferior drum
- Absent jugular plate
- Venous bleeding at myringotomy
- A normal variant
Remember Blue mass low behind the drum: think of the jugular bulb.
Exam trap Never biopsy a vascular-looking middle ear mass until a vascular variant has been excluded.
Why the other options are wrong
- Glomus tympanicum A red mass on the promontory with an intact jugular plate.
- Aberrant internal carotid artery A red pulsatile mass in the anterior middle ear; bleeding would be arterial.
- Cholesterol granuloma Causes a blue drum but the jugular plate is intact.
- Acquired cholesteatoma White debris, usually from the attic, eroding the scutum.
A 14-year-old boy with untreated acute otitis media for two weeks has fever and a tender swelling in the upper neck deep to sternocleidomastoid. Pus from the mastoid air cells has broken through the medial side of the mastoid tip. What is this collection called?
Answer: Bezold abscess
In a well-pneumatised mastoid, pus in the tip air cells can break through the thin medial cortex of the tip, where the digastric groove lies. Because sternocleidomastoid inserts on the lateral surface of the tip, the pus tracks down beneath this muscle into the neck, forming a Bezold abscess. A postauricular subperiosteal abscess results from erosion of the lateral cortex and pushes the ear forward. A Luc abscess lies beneath temporalis after spread through the external canal roof.
Bezold abscess
- Erosion of medial mastoid tip
- Pus tracks deep to SCM
- Needs a pneumatised tip
- Seen in older children and adults
Remember Neck abscess under SCM after otitis: Bezold.
Exam trap Young infants rarely get a Bezold abscess because the mastoid tip is not yet pneumatised.
Why the other options are wrong
- Citelli abscess Spreads back along the posterior belly of digastric towards the occiput.
- Luc abscess Lies beneath temporalis, from spread through the canal roof.
- Postauricular subperiosteal abscess From lateral cortex erosion; lies behind the ear, not deep to SCM.
- Parapharyngeal abscess May follow a Bezold abscess but begins from tonsils or teeth.
A 9-year-old girl has bilateral sensorineural hearing loss that worsened after minor head knocks, and a diffuse goitre although she is euthyroid. A perchlorate discharge test is positive. Which condition links these findings?
Answer: Pendred syndrome
Pendred syndrome is caused by mutations in SLC26A4, which encodes pendrin, an anion exchanger in the inner ear and thyroid. Faulty iodide transport into the thyroid follicle impairs organification, so trapped iodide is discharged by perchlorate, and a goitre develops, usually with normal thyroid function. In the inner ear the vestibular aqueduct is enlarged, and hearing often drops after minor head trauma. Alport syndrome links hearing loss with nephritis, not goitre.
Pendred syndrome
- Sensorineural loss, worse after head knocks
- Goitre, often euthyroid
- Positive perchlorate discharge
- Gene: SLC26A4 (pendrin)
Remember Deaf child with a goitre: Pendred.
Exam trap Thyroid function is often normal, so a normal TSH does not exclude Pendred syndrome.
Why the other options are wrong
- Waardenburg syndrome Links hearing loss with pigment changes such as a white forelock.
- Alport syndrome Links hearing loss with haematuria and nephritis.
- Usher syndrome Links hearing loss with retinitis pigmentosa.
- Treacher Collins syndrome Causes conductive loss from external and middle ear malformation.
Where this sits in the CPSP syllabus
- Diagnostic Radiology, Paper 2: Head and neck, Neck vessels and lymph node levels; ear and temporal bone