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Head and Neck 01 (General)


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Extracranial head and neck divisions
Suprahyoid neck

Infrahyoid neck

Oral cavity
What is oral cavity comprised of?
Sublingual and Submandibular spaces.
Where in head and neck is it most advantageous to use MRI versus CT?
Suprahyoid neck.
Because of paucity of fat. Infrahyoid neck has better fat planes.
What is advantage to imaging with MRI vs CT in suprahyoid neck?
1) delineate tumor-muscle interfaces.

2) Image skull base and intracranial invasion.

3) Evaluate perineural spread.
When a mass of the suprahyoid neck is suspected, what are the 3 questions posed to the radiologist at the time of CT or MRI?
1) Where is the mass (what space is it in)

2) What important neurovascular structures are in the vicinity of the mass?

3) What is the likely pathologic diagnosis?
What is the "old" way of defining the organization of the suprahyoid neck?
The suprahyoid neck was divided into three areas: Nasopharynx, oropharynx, and oral cavity.
When is this method of organization still considered effective?
In the case of SCCa.
Why are we still using the old way for SCCa?
Because SCCa in each of these regions has different route of spread, nodal dissemination patterns, and prognosis.
Why is this anatomic scheme ineffective when considering non-squamous lesions?
Because nonsquamous lesions spread within fascia-defined spaces.
Nasopharynx boundaries?
1) Anterior

2) Posterosuperior

3) Lateral

4) Inferior
Anterior boundary of nasopharynx?
Posteriormost aspect of nasal cavity.
What is this called?
Nasal choanae.
Posterosuperior boundary of nasopharynx?
Lower clivus

Upper cervical spine

Prevertebral muscles
Inferior boundary of nasopharynx?
A horizontal line drawn along the hard and soft palates.
Lateral boundary of nasopharynx?
Torus tubarius.

Eustachian tube orifice.

Mucosa of lateral pharyngeal recess.
What is the torus tubarius?
The cartilaginous portion of the eustachian tube.
What is another name of the lateral pharyngeal recess?
Fossa of Rosenmuller.
What is the most common malignant lesion seen in the nasopharynx?
Nasopharyngeal carcinoma.
What is the oropharynx?
The portion of the upper aerodigestive tract that is visible posteriorly through the open mouth.
What is the oropharynx not?
It is not the oral cavity. These are separate structures.
Boundaries of the oropharynx?
1) Anterior

2) Posterior

3) Inferior

4) Superior
Anterior boundary of oropharynx?
The oral cavity.
What structures separate the oropharynx from the oral cavity?
A ring of structures does.
What structures comprise the inferior aspect of this ring?
Circumvallate papillae
What structures comprise the lateral aspects of this ring?
The anterior tonsillar pillars.
What structures comprise the superior aspect of this ring?
The soft palate.
Posterior boundary of oropharynx?
Superior and middle constrictor muscles of pharyngeal wall.
What structures lie inferior to the oropharynx?
Larynx and hypopharynx.
What separates the oropharynx from the larynx?
1) Epiglottis

2) Glossoepiglottic fold.
What separates the oropharynx from the hypopharynx?
Pharyngoepiglottic fold.
Superior boundary of oropharynx?
Soft palate.
What is the new classification of suprahyoid neck anatomy defined by?
Compartments and spaces.
What are the compartments of the suprahyoid neck?


What spaces are in the medial compartment?
Pharyngeal mucosal space.
What spaces are in the lateral compartment?
1) Parapharyngeal space

2) Masticator space

3) Parotid space

4) Carotid space
What spaces are contained within the posterior compartment?
1) Retropharyngeal space

2) Danger space

3) Perivertebral space
What is used to define spaces in the suprahyoid neck?
Deep cervical fascial planes.
How many layers of deep cervical fascia are there in the suprahyoid neck?
What are the three layers?
Superficial layer

Middle layer

Deep layer
What is true of all but two of the spaces of the suprahyoid neck?
They are true fascia-enclosed spaces
What does that mean?
They are completely enclosed by the layers of deep cervical fascia.
Which two spaces are not completely enclosed?
Parapharyngeal space

Pharyngeal mucosal space (for obvious reasons)
What is different about the parapharyngeal space?
It has complex borders, unlike the other spaces, which simply are contained within a circle of fascia. The PPS is sort of constrained by other spaces (fig 1-3).
What forms the border of the PPS anteriorly and laterally?
The superficial layer of deep cervical fascia investing the medial side of the masticator and parotid spaces.
What is the superior boundary of the deep spaces of the suprahyoid neck?
The skull base
There are two very important interactions between the skull base and the spaces of the suprahyoid neck. What are they?
1) Parotid space--stylomastoid foramen--CN VII 2) Masticator space--foramen ovale--CN V3
What spaces of the suprahyoid neck extend inferiorly into the infrahyoid neck?
1) Carotid space 2) Retropharyngeal space 3) Perivertebral space (this certainly makes sense, as they are the only spaces that surround long tubular conduits, which extend all the way into the thorax)
When a mass is identified in the suprahyoid neck, what is the first question that must be answered?
What is the space of ORIGIN of the mass
What is the reference point in the suprahyoid neck for making this determination?
The parapharyngeal space
How many factors are considered in making this analysis?
What are these factors?

1) Position of the center of the mass (relative to the PPS)

2) Its pattern of displacement of the PPS.
What is the utility of this method?
1) Allows development of a space-specific differential diagnosis, which can be further narrowed by the imaging appearance of the lesion.

2) Provides awareness of the critical adjacent neurovascular structures.
How many spaces directly surround the parapharyngeal space?
Anterior to PPS?
Masticator space
What are the most common lesions in the masticator space?
Odontogenic abscess

Sarcomatous tumors
Medial to PPS?
Pharyngeal mucosal space
What is the most common lesion occurring in the PMS?
Posterior to PPS?
Carotid space
What are the most common tumors of the carotid space?
Paragangioma Schwannoma
Lateral to PPS?
Parotid space
What is the most common benign tumor of the parotid space?
Benign mixed tumor
What is the most common malignant tumor of the PS?
What about lesions within the PPS?
Almost no disease process begins in the PPS
What are the posterior midline spaces of the suprahyoid neck?

How many divisions of the perivertebral space?
What are the two divisions of the perivertebral space?

How are lesions in the posterior midline areas of the suprahyoid neck anatomically defined?
By their displacement pattern w/r/t the prevertebral muscles.
What spaces are we talking about here?
1) Retropharyngeal space

2) Prevertebral portion of the perivertebral space.
Where is the paraspinal division of the perivertebral space located w/r/t the prevertebral division?
Paraspinal is more posterior (i.e. adjacent to the posterior elements--spinous processes--paraspinal).
What does anterior deviation of the prevertebral musculature indicate?
A mass lesion in the prevertebral portion of the perivertebral space.
What does posterior deviation of the prevertebral musculature indicate?
A mass lesion filling the retropharyngeal space.
What can mimic a lesion of the carotid space?
A mass lesion in the lateral recess of the retropharyngeal space.
Where is the lateral recess of the retropharyngeal space located?
Just medial to the carotid space.
What is one way to differentiate mass in lateral recess of the retropharyngeal space from mass in the carotid space?
The center of the mass will always be medial to the ICA.
What is the most common pathology seen in the lateral recess of the retropharyngeal space.
How are lesions in the paraspinal portion of the perivertebral space recognized?
They either arise in the posterior elements, centrifugally displacing the paraspinal muscles, or arise in the paraspinal muscles themselves.

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