Anatomy of the oral cavity, pharynx,larynx and infrahyoid neck

Bernhard Schuknecht Medical Radiological Institutes Zurich

Switzerlandbschuknecht@mri-roentgen.ch

ECNR Dubrovnik 22.10. 2018

Order of „business“

Anatomy and imaging issuesThe space based approach• Oral cavity• Hypopharynx • Larynx • Thyroid/ parathyroid gland

How to approach neck lesions?space based approach

Deep cervical fasciasuperficial

deep layer

separate spaces: suprahyoid infrahyoid

Fig.Harnsberger Ed. Diagnostic Imaging Head and neck 2nd ed. I1 4,6; Amirsys 2011

Supra- and infrahyoid neck continuation:

Carotid spaceRetropharyngeal & danger spacePerivertebral (prevertebral, paraspinal)

Posterior cervical space

Harnsberger ED. Diagnostic Imaging Head and neck 2nd edition Amirsys 2011

continuity w suprahyoid neck :

Infrahyoid only: Visceral space suprahyoid pharyngeal mucosal

Anterior cervical space

Infrahyoid levelVisceral space = unpaired infrahyoid spacemiddle layer of deep cervical fascia

spatial relationshipretropharyngeal spacecarotid space anterior cervical space

contents:larynx, hypopharynxtrachea, esophagusthyroid, parathyroid- thymusrecurrent laryngeal nerve, paratracheal LN

LN level-classification in the neck Level I: superior to hyoidIA: submental, IB: submandibular

Level II: internal jugular -superior to hyoidIIA: anteror to SCM, IIB: medial to SCM

Level III: int. jugular (inferior hyoid-inf. cricoid)midthird vascular chain – SCM

Level IV: internal jug- inf cricoid- supraclavicularlower vascular chain – SCM

Level V: posterior cervical space – supraclavicularVA : above inf. cricoid level VB: below inf. cricoid

Level VI: prelaryngeal:hyoid- jugulum

Level: VII: jugulum -aortic archupper mediastinum

+ retropharyngeal, parotid, facial LN

from Harnsberger Diagnostic Imaging Head and Neck, Amirsys 2004

Oropharynx

Subsites • post. 1/3 of tongue, • lingual tonsils,

• palatine tonsils,

• soft palate,

• post. pharyngeal wall

squamous epithelium within the oropharynx derives from endoderm

Oral cavity

Subsites• lips,

• 2/3 of the tongue,

• buccal mucosa,

• gingiva,

• retromolar trigone,

• hard palate,

• floor of the mouth

squamous epithelium of the oral cavity derived from ectoderm

Oropharynx + oral cavity cancer : incidence 8.5 : 100000oral cavity to oropharynx 2:1

Floor of mouthRoot of tongueGeniohyoid-genioglossus complex and lingual septum

Tongue musclesIntrinsic: slong., ilong., transverse, verticalExtrinsic: genioglossus 1, hyoglossus 2,

styloglossus 3, palatoglossus 4

1 2

3

4

Sublingual space: not fascia linedSublingual gland, + minor salivary glandssubmandibular, sublingual ductlingual, glossopharyngeal, hypoglossal n.

Submandibular space : fascia linedSubmandibular gland superficial lobe (deep lobe = partly within SLS)Facial artery, vein, digastric muscle (ant. belly)LN: submental IA, submandibular IBBoth spaces : extend from side to side

Sublingual & submandibular space: content

submandibular & sublingual spaces

superficial lobe

deep lobe

Sm gland: Superficial lobe in Sm space deep lobe = partly within SLSsl+ sm above midlinesm parapharyngeal space

Anatomic variations

Herniation of sl gand

Unilateral agenesis of sm gland Staphne cyst

Oral cavity neoplasmsoral tongue ca

floor of the mouth ca

buccal mucosa casquamous cell neoplasms glandular neoplasms

oral tongue mucoepidermoid ca

retreomolar adenoidcystic ca

Oral cavity congenital lesions

• Vascular malformations: venous, lymphatic, mixed• Germ cell tumours: epi-, dermoid, teratoma

venous / lymphatic vascular malformation

dermoid, epidermoid,

paSobotta Becher 2nd ed. U&S 1972

nasopharynxSkull base

Soft palate

oropharynxsoft palate

pharyngo-epiglottic fold

hypopharynxcricopharyngeus m.

Anatomical subdivision of the pharynx:naso-, oro-, and hypopharynx

Anatomic division of the pharynx: naso-, oro-, and hypopharynx

lateral

nasopharynxskull base

soft palate

oropharynxsoft palate

pharyngo-epiglottic fold

hypopharynxcricopharyngeus m.

• aryepiglottic fold anteromedially

• thyroid cartilage laterally

• paraglottic space anteriorly

• hypopharynx esoph. junction@ level of inf. cricoid lamina

Hypopharynx subsites:piriform sinus, postcricoid region, posterior wall

Hypopharynx subsites:piriform sinus, postcricoid region, posterior wall

• aryepiglottic fold anteromedially

• thyroid cartilage laterally

• paraglottic space

• hypopharynx esophagus junction

@ level of inf. cricoid lamina

Anatomic subdivision of the larynx

supraglottis

glottis

subglottis

5

5

M arytenoideus transversus + obliquus

Supraglottisderived from buccopharyngeal anlage

rich lymphatic drainage !

laryngeal vestibule

epiglottis

pre-epiglottic fat

false vocal cords

ventriculus laryngis

paraglottic space

arytenoid cartilage

epiglottis

pre-epiglottic fat

false vocal cords

laryngeal ventricle

arytenoid cartilage

true vocal cord

paraglottic space

cricoid cartilage

false cord

true cordarytenoid c

cricoid c

thyroid c

Larynx

cricoid c

Glottis and subglottisderived from tracheo-bronchial bud

sparse lymphatic drainage !

Glottis level: Vocal cord = medial fibres of thyroarytenoid m.anterior posterior commissure+ 5mm belowSubglottis : mucosal surface close to cricoidconus elasticus fibroelastic membrane

betw. vocal lig. - cricoid cartilageLN prelaryngeal = Delphian lymph node (s) (VI)

Level VI

Hyoid

Cricoid c

Thyroid c

Glottis-levelHow to identify ?

thyroid c

arytenoid c

cricoid c

3 levels !

false vocal cordplica vestibularis

arytenoid c.true vocal cordvocal ligament= glottis + 5mm

cricoid c. subglottisconus elasticus

Embryology: thyroid- parathyroid

• Thyroid lobesand superior parathyroid

4th branchial pouch

• Isthmus thyroidand inferior parathyroid

3rd branchial pouchInferior parathyroid (35% ectopichyoid, carotid, intrathyroid, mediastinal)longer course of 3rd branchial pouch

Embryology• Thyroid descent via thyroglossal duct

from foramen cecum suprahoid midline

infrahyoid off midline to visceral space• thyroglossal duct involutes at 5-6 gest. weeksThyroglossal duct cyst: 25% suprahyoid,

50% level of hyoid, 25% infrahyoid

Lingual thyroid Thyroglossal duct cyst

Thyroglossal duct cystfistula continuation thyroid isthmus

Thyroid/visceral space anatomy

VIBE Gd

Thyroid anatomic variation: Zuckerkandl tubercle

Posterior thyroid tubercle “ Zuckerkandl tubercle”• surgical landmark (proximity to recurrent laryngeal nerve)

• extension of thyroid to tracheo-esophageal sulcus in 87%,

• nodular configuration of ZT in 42.1% of patients.

• DD: Parathyroid adenoma

Posterior view: two different cases

Lee TC et al. Zuckerkandl Tubercle of the Thyroid: A Common Imaging Finding That May Mimic Pathology.AJNR 2012 33: 1134-1138

Black dots = parathyroid glands

Parathyroid gland anatomy

Dynamic CT Dynamic MR

Parathyroid adenomaAdenoma > 5mm (10-30mm),

Upper: posterior to upper midpole

Lower: 65% lateral/posterior to lower pole

20 % ectopic (intrathyroid, carotid, mediastinum..)

2-3% multiple<1% parathyroid carcinoma

Tc 99m sestamibi: early + delayed focal enhancementCholin PET: under investigationUS: homogenous, well defined hypoechoic, hypervascularDynamic CT/ and – dyn. MR: early enhancement !

Dynamic ceCT or ceMR arterial phase!!

CT

VIBE Gd

Twist dynamic

Specialized examinationDynamic ceMR sequence (10s intervall)

baseline 10s 20s 60s

Work in progress: improved detection of parathyroid adenoma (?)

bschuknecht@mri-roentgen.ch

- thank you

MR Imaging protocol neck Coverage: orbital roof - below aortic arch

• sagittal T2 TSE 3 mm • coronal STIR 4 mm • axial T2 TSE fs Dixon 3 mm • axial T1 TSE localized 3 mm• axial DWI b 0, b 800-1000; ADC 5mm• axial VIBE Dixon Gd 3D 0.9 mm (T1 TSE Gd fs Dixon, T2 Space 0.8-1.0mm)

CT Imaging protocol neckMDCT (64/128)

Coverage Orbital roof – below aortic arch

• Collimation : 0.6mm

• Table feed per rot : pitch 1.0

• Rot. time, duration : 0.3s /16s

• Reconstruction slice: thickness/ increm. 1.0/0.7 mm, Fov 180

• MPR 3mm contig. : W/C soft tissue 270 -300/100

W/C HR bone 2mm 3200/700(1700/600 cartilage)

• 80ml nonionic contrast + 20ml saline 2ml/s; => 50s delay