Imaging of the neck part i

IMAGING OF THE NECK

DR/ Wafik Ebrahim, MDAssistant Professor of Rradiodiagnosis

Faculty of MedicineAlazhar University

For proper studying of the neck it is divided into compartments and spaces:

Suprahyoid neck: From skull base to the hyoid bone

Infrahyoid neck:Below hyoid bone to thoracocervical junction. Some spaces continue to mediastinum.

Suprahyoid neck spaces: Parapharyngeal space (PPS). Pharyngeal mucosal space (PMS). Masticator space (MS). Parotid space (PS). Carotid space (CS). Buccal space (BS). Retropharyngeal space (RPS). Perivertebral space (PVS).

Infrahyoid neck spaces: Visceral space (VS). Posterior cervical space (PCS). Anterior cervical space (ACS). CS. RPS. PVS.

Skull base relation to SHN

Skull base interaction with SHN spaces:

Neck spaces:are They true spaces

?

Deep cervical fascia: Superficial layer:

SHN: Around MS, PS and contributes to CS. IHN: surrounding strap, sternocleidomastoid and

trapezius muscles.

Middle layer: SHN: defines PMS and contributes to CS. IHN: defines VS and contributes to CS.

Deep layer: SHN and IHN: surrounds PVS and contributes to CS. Alar fascia is a slip within the deep fascia.

Deep cervical fascia: three layers cleave neck into spaces .

Axial Coronal

Suprahyoid neck

Infrahyoid neck

Deep fascia

Neck spaces

Suprahyoid neck:

Suprahyoid neck

Hyoid bone level

Infrahyoid neck

Lower level of infrahyoid neck

Parapharyngeal space (PPS): It is fat filled space (easily identified even with

large neck masses). Extends from the skull base to the cornue of

hyoid bone (SHN). According to direction of displacement, the

origin of a mass can be identified. Superiorly, interacts with skull base with no

foramina. Inferiorly, communicates with submand. space.

Mass in PPS can present at angle of mandible

Parapharyngeal space (PPS) Contents:

Fat, minor salivary glands and vessels (internal maxillary and ascending pharyngeal arteries and ptrygoid plexus of veins).

No mucosa, muscles, nodes, bones. Pathology:

Rarely diseases can originate within. Minor salivary gland tumors, lipoma may be.

To say it is from PPS, it should be completely surrounded by fat.

Pharyngeal Mucosal Space (PMS) Nasopharyngeal, oropharyngeal and

hypopharyngeal surface structures on the air way side of the middle layer of deep cervical fascia.

Superiorly, interacts with the skull (basisphenoid and basiocciput). Foramen lacerum is here (perivascular spread of tumors around ICA ).

PMS: Contents Mucosal surface of the pharynx. Lymphatic (Waldeyer) ring:

Nasopharynx Adenoid.Oropharynx Palatine tonsils.

Lingual tonsils. Minor salivary glands. Fascia: Muscles: Cartilage:

PMS: Diseases Mass should:

Be medial to PPS.Push PPS laterally.Disrupts mucosal and submucosal architecture.

Pathology:Mucosa: SCC.Lymphatic: NHL.Salivary glands: Minor salivary glands tumors

(uncommon).Muscles: Rabdomyosracoma (rare).

PMS: Ba. swallow

صورة إلضافة الرمز فوق The hypopharynx extends from•انقرthe level of vallecula and glossoepiglottic fold down to the inferior margin of the pyriform fossa.• Three important subsites in hypopharynx to be identified; Postcricoid hypopharynx, posterior wall of hypopharynx and pyriform sinus.• Remember The lower margin of vallecula is the landmark where hypopharynx starts. •The lingual tonsil has irregular outline resulting in irregularity of contrast column.

PMS: MRI T1

Nasopharynx Oropharynx

PMS: MRI T2

Nasopharynx Oropharynx

PMS Coronal (graphic & MRI Postcontrast T1)

Masticator space (MS) Large anterolateral space of the suprahyodid neck

containing muscles of mastication. Included within the superficial layer of deep cervical

fascia. Extends from high parietal calvarium to mandibular

angle. Surgical terms:

Temporal fossa (Suprazygomatic MS). Infratemporal fossa (Infrazygomatic MS).

Skull: MS abuts skull base including: Foramen ovale (CN V3). Foramen spinosum (middle meningeal A.).

MS: Contents: Muscles of mastications:

Masseter, Tempralis, Medial ptrygoid and lateral prygoid muscles.

Nerves: Mandibular division of trigeminal N: Masticator: Motor to Msc of mastication. Mylohyoid: Motor to mylohyoid and diagastric m.Inferior alveolar: Sensory to chin and mandible.Lingual: Sensory to anterior 2/3 tongue and mouth floor. Auriculotemporal: Sensory to EAC and TMJ

Bones:Ramus and posterior body of the mandible, coronoid process

and condylar process as well as TMJ. Vessels:

Ptrygoid plexus of veins.

MS:

Important note: tumors may spread along CN V3 intracranially. So the course of the nerve should be assessed.

Pitfalls: Ptrygoid venous plexus enhancement

(misinterpreted as a mass).CN V3 motor atrophy of muscles

(misinterpreted as a contralateral mass)

MS: MRI

MS: Coronal MRI T1 post-contrast

Mass in MS

Parotid space (PS): It extends from the EAC and mastoid tip

down to below the angle of the mandible.

Skull interaction: stylomastoid foramen is related to this space transmitting the facial nerve.

The space is enclosed within the superficial layer of the deep cervical fascia.

PS: Contents: Parotid gland:

Superficial lobe (2/3 of the space). Deep lobe.

Extracranial facial nerve: Ramifies within the PS. Forms a surgical plane between Superficial and deep lobes. It is not detected by CT. It is plane is estimated between just

medial to mastoid process to just lateral to the retromandibular vein.

Vessels (just behind mandibular ramus): Retromandibular vein (lateral and larger) External carotid artery (medial and smaller).

PS: Contents: Lymph nodes:

Late embryonic encapsulation results in intraparotid nodes.

About 20 in each PS.1st order drinage of EAC, pinna and adjacent scalp.

Parotid duct:Runs on the surface of masseter muscle. Enters the buccal space and pierce the buccinator

to open opposiet 2nd premolar tooth. Accessory parotid gland:

20% of population. Along the surface of masseter muscle.

PS: Important notes:

If inflammation is suspected: CECT with angulations of the gantry to avoid artifacts from dental filling.

If tumors are suspected: MRI+C and assess for perineural spread (facial nerve).

Parotid tail mass should be identified as intraparotid to avoid facial nerve injury during excision. (tail is between platysma and sternomastoid ms inferiorly).

Pitfalls:It is more fatty in elderly.It is soft tissue like in children.

PS:MRI T1

PS:MRI T2 FS

Carotid space CS: Travels from the skull base (jagular

foramen and carotid canal) to aortic arch (SHN and IHN)

Contents: SHN: IJV, ICA and cranial nerves (9-12). IHN: IJV, CCA, and cranial nerve 10 (only).Sympathetic chanin (between CS and RPS).Internal jagular lymph node chain (closely

related).

CS

SHN IHN

Retropharyngeal space (RPS) Starts at the skull base and extends

down to mediastinum (T3 level). (SHN and IHN)

Contents: SHN:

FatLNs: lateral (Nodes of Rouviere ) group and

medial group (rarely seen):IHN:

only fat.

RPS: Fascia:

Anterior wall: middle layer DCF.Posterior wall: deep layer DCF:

Two slips present with Danger space in between.Lateral wall: (Alar fascia).

Danger space: Infection or tumor can extend to diaphragm

(hence the name). The RPS is locked inferiorly by trap door at level

of T3. Lesion that opens the door reaches DS and down to diaphragm.

RPS: Imaging issues:

Nodal disease: localized.Extranodal disease (infection or tumor) with

fill the space (reactangular lesion). Mass here may mimic CS mass so look

carefully to the CS structures and their displacement.

RPS and DS are indistinguishable from each other by CT. just you have to consider the danger.

RPS :

SHN IHN

Perivertebral space PVS: Perivertebral space: term dropped to

include all structures under the deep layer of deep cervical fascia.

Supra-infrahyoid neck. Down to T4 and some authors consider it one space down to coccyx.

Divisions: by dipping of the deep facia laterally toward transverse processes. Prevertebral compartment.Paraspinal compartment.

PVS Contents: Prevertebral space:

Bones: vertebral body.Muscles: longus colis and capits and scalene MusclesNerves: Brachial plexus roots and phrenic nerveVessels: vertebral A&V

Paraspinal space:Paraspinal muscles.Posterior elements of the vertebrae.

Brachial plexus roots: Pass between ant. and mid. Scalenei, to posterior

cervical space to axilla.

Posterior cervical space (PCS) Posterolateral fat filled space. Triangular wit its tip at mastoid process

and base at clavicle. Contents:

Fat.Spinal accessory nerve.Spinal accessory nodes (group V). Brachial plexus: Roots pass in way to axilla. Dorsal scapular nerve.

PCS: How to differentiate spinal accessory

nodes from jagular nodes. Infrahyoid neck:

IJ nodes Abut the carotid sheath. SA node has surrounding fat separating it from CS.

Suprahyoid neck: IJ nodes are anterior and lateral to CS. May be

posterior but should abut the CS. SA nodes are posterior to CS only separated from it

by fat.

Visceral space (VS): Midline cylindrical space in IHN. Enclosed in

DL-DCF. Contents:

Thyroid and parathyroid (4) glands. Cervical trachea and esophagus.Lymph nodes: level VI (prelaryngeal and

pretrachesal) Recurrent laryngeal nerve:

Left: recurs at level of aortic arch. Right: recurs around right subclavian A. (low IHN).

Pass to larynx in tracheoesophageal groove.Recurrent laryngeal nerve:

VS: Important notes: MRI is preferred in staging thyroid

malignancy to prevent iodine load delaying iodine based nuclear therapy.

VS imaging should include upper mediastinum (to carina):Group VII lymph nodes drain VS malignancy.Left distal vagal neuropathy requires examination

down to carina. Ectopic thyroid may be seen in superior

mediastinum.

Hypopharynx-Larynx: Hypopharynx: is continuation of PMS. Larynx: junction between upper and

lower airways. From glossoepiglottic and

pharyngoepiglottic folds to level of cricoid cartilage. Hypopharynx to esophagus.Larynx to traches.

Hypopharynx-Larynx: Larynx: is the organ of phonation.

It consists of cartilagenous skeleton and mucosal curtains. Ligaments and muscles fix structures in place and produce movements responsible for sound production.

Larynx: cartilagenous skeleton :

Is the supporting framework of the larynx. Epiglottis, thyroid cartilages, cricoid cartilages, arytenoid cartilages, corniculate and cuniform cartilages. Thyroid cartilages: two lamina meeting anteriorly at

acute angle. Cricoid cartilage: the only complete ring (signet ring

appearance). Arytenoid (paired) cartilages: set on posterior aspect

of cricoid. Vocal process gives attachment to TVC and is landmark in CT.

The interval between cartilages is closed by ligaments(thyrohyoid and cricothyroid ligaments.

Larynx: mucosal foldsTwo main mucosal folds are seen in the

endolarynx sweeping from front to back along the lateral surface of larynx. (true and false vocal cords). In between is the Laryngeal ventricle.

Consequntly the three compartments form; supraglottis, glottic region and infraglottis.

Hypopharynx-Larynx: contents: Supraglottis: Extends from the tip of epiglottis above to the

laryngeal ventricle below. Epiglottis: laryngeal lid. Has free edge (suprahyoid) and

attached portion (infrahyoid). It is attached to the thyhroid lamina below by the

thyroepiglottic ligament.The free edge is connected to the hyoid bone by the

hyoepiglottic ligament that is covered by glossepiglottic midline mucosal fold.

Valleculae are air spaces formed between the base of tongue and free part of epiglottis on both sides of glossoepiglottic fold.

Preepiglottic space: fat filled space anterior to epiglottis.

Hypopharynx-Larynx

Hypopharynx-Larynx: contents : Aryepiglottic fold: Extends from the tip of

arytenoid cartilage to inferolateral margin of epiglottis. It is the superolateral wall of the supraglottis

separating the supraglottis from the pyriform sinus.

Paraglottic space: paired spaces beneath the false and true vocal cords. Filled with fat in supraglottis and occupied by muscle at the glottis (landmark)

Larynx: Glottis: True vocal cord, anterior

commissure and posterior commissure. True vocal cord (TVC): the only soft tisue

structure in the larynx: comprised of thyroarytenoid muscle (medial fibers are the vocalis muscle).

Anterior and posterior commissures are the midline meeting of both cords.

Conus elasticus: fibroelastic membrane extending from medial aspect of TVC to the cricoid cartilage.

Larynx: Subglottis: from the under surface of

TVC to inferior border of cricoid cartilage. Its mucosa is closely applied and merges

with the mucosal covering of trachea.

Hypopharynx :

Pyriform sinus: (2) between the inner surface of thyroid cartilage and thyrohyoid ligment laterally and posterolateral surface of the AE fold. Its apex is at level of TVC.

Posterior wall: is the posterior continuation of the posterior wall of oropharynx.

Postcricoid space: interface between larynx and hypopharynx (from level of cricoarytenoid joint to lower margin of cricoid cartilage.

Larynx- Hypopharynx CT

Larynx- Hypopharynx CT (breath holding)

Larynx- Hypopharynx CT

Larynx: MRI

Thyroid and parathyroid glands

oThyroid glands: Two lobes connected by the isthmus wrapped around the trachea.Accessory pyramidal lobe may be seen. It is located in the visceral space enclosed within the middle layer of deep cervical fascia.o parathyroid gland: Four lobes at the posterior surface of thyroid gland. .

Thyroid gland:

صورة إلضافة الرمز فوق انقر

Imaging with CT scan and isotope scan should be coordinated. The iodinated contrast media in CT scan interferes with the iodine uptake of isotope scan postponing the study for 4-6 weeks.

Thyroid gland

US is the first line of imaging because the gland is superficial.

Thyroid gland•Thyroglossal duct cyst.•Lymph drainage of thyroid malignancy./

Cervical trachea and esophagus: Trachea (10-13cm): starts opposite C6

vertebra (continuation of larynx). And ends at T5 vertebra (carina).

Esophagus (25cm): starts opposite C6 (continuation of hypopharynx) down to T11 vertebra. Its upper limit is identified by the cricophryngeus muscle.

Tracheoesophageal groove: Contains parathyroid gland, recurrent laryngeal artery and lymph nodes.

BA swallow :

Trachea and esophagus :

Imaging of the neck part i

Health & Medicine

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