H&N Larynx Anatomy Flashcards
Describe the boundaries of the larynx according to
the AJCC.
● Superior: Oropharynx; tip and lateral borders of the
epiglottis
● Inferior: Trachea; plane passing through the inferior limit
of the cricoid cartilage
● Posterior/lateral: Hypopharynx; laryngeal surface of the
aryepiglottic folds, arytenoid region, interarytenoid
space, mucous membrane covering the posterior surface
of the cricoid cartilage
● Anterior: Anterior/lingual surface of the suprahyoid
epiglottis, thyrohyoid membrane, anterior commissure,
thyroid cartilage, cricothyroid membrane, anterior arch of
the thyroid cartilage
What are the subsites of the larynx according to
the AJCC?
● Supraglottis: Lingual and laryngeal surfaces of the epiglottis, laryngeal surface of aryepiglottic folds, aryte-
noids, false vocal folds; divided from glottis by a
horizontal plane passing through the lateral margin of the
ventricle at its junction with the superior surface of the vocal cord.
● Glottis: Superior and inferior surface of the true vocal fold,
anterior and posterior commissure; extends 1 cm below the plane dividing supraglottis and glottis; lateral margin
defined by the junction of the lateral aspect of the ventricle at its junction with the superior surface of the
true vocal fold.
● Subglottis: inferior margin of the glottis to inferior border
of the cricoid cartilage.
What subsite of the larynx arises from the
buccopharyngeal primordium (third or fourth
branchial arches) and therefore derives its arterial
supply from the superior laryngeal arteries and
lymphatic drainage is to levels II and III?
Supraglottis
What subsites of the larynx arise from the
tracheobronchial primordium (sixth branchial
arch) and therefore derives its arterial supply from
the inferior laryngeal arteries and lymphatic
drainage is to levels IV and VI?
Glottis and subglottis
What branchial arch structures give rise to the
hyoid bone?
● Second branchial arch: Lesser horn and upper portion of
the hyoid bone
● Third branchial arch: Greater horn and lower portion of
the hyoid bone
What are the five subsites of the supraglottis?
● Suprahyoid epiglottis ● Infrahyoid epiglottis ● Aryepiglottic fold (laryngeal surface) ● False vocal fold (also called the ventricular bands) ● Arytenoid
What are the subsites of the glottis?
True vocal folds (superior and inferior surface), including the anterior and posterior commissures
What are the subsites of the subglottis?
None
What is the normal histology of the supraglottis?
● Pseudostratified columnar respiratory epithelium. The
lateral surface of the aryepiglottic folds and epiglottis are
stratified squamous epithelium.
● Numerous mucous glands
What is the normal histologic structure of the glottis, proceeding medial to lateral through the true vocal fold?
● Stratified squamous epithelium
● Superficial lamina propria (Reinke space)
● Vocal ligament (intermediate and deep lamina propria)
● Thyroarytenoid muscle
● Paraglottic fat
● Thyroid cartilage
What is the normal histology of the subglottis?
Pseudostratified columnar epithelium
What are the natural barriers to spread of
laryngeal cancer?
● Quadrangular membrane* ● Conus elasticus* ● Thyrohyoid membrane* (aperture for superior laryngeal neurovascular bundle allows spread) ● Laryngeal cartilages ● Hyoepiglottic ligament ● Anterior commissure tendon ● Cricothyroid membrane *Most commonly considered
What sheet of fibroelastic tissue stretches from
the epiglottis to the arytenoid and corniculate
cartilages, contributes to the aryepiglottic fold
superiorly, and defines the free margin of the false
cord inferiorly?
Quadrangular membrane
What sheet of fibroelastic tissue stretches from
the vocal ligament to the superior margin of the
cricoid laterally and inferior margin of the thyroid cartilage anteriorly (where it forms the cricothyroid membrane)?
Conus elasticus
What 1 × 10-mm fibrous tissue band connects the vocal ligaments to the midline of the thyroid
cartilage, is associated with a lack of perichon-
drium at the insertion point, and serves as a strong barrier to spread of laryngeal cancer (Kirchner,
1987)?
Anterior commissure tendon (the Broyles ligament)
Broyles ligament, or the anterior commissure
tendon, is often sited as a pathway for spread of
laryngeal cancer through the thyroid cartilage.
However, studies have shown that this structure
actually serves as a strong barrier to spread in the
absence of what tumor characteristics?
Significant supraglottic (petiole, pre-epiglottic space) or subglottic extension (ossified thyroid cartilage, lymphatics, cricothyroid membrane)
Name the funnel-shaped space formed by the thyrohyoid membrane and thyroid cartilage anteriorly; the epiglottis posteriorly; the hyoepiglottic ligament, vallecula, and hyoid bone superiorly; and
the thyroepiglottic ligament inferiorly. The space communicates laterally with the paraglottic space
and acts as an avenue for tumor spread.
Pre-epiglottic space.
Name the paired spaces that are defined by the
thyroid cartilage laterally, the conus elasticus inferomedially, the ventricle medially, the quadrangular membrane superomedially, and the pyriform sinus mucosa posteriorly. It is an avenue for spread of laryngeal cancer and communicates
anteriorly with the pre-epiglottic space.
Paraglottic space
What important feature of the infrahyoid epiglottic cartilage allows easy tumor growth into the pre-epiglottic space?
Fenestrations
Transglottic tumors by definition cross the ven-
tricle and involve the supraglottis and glottis and may involve the subglottis. Define the theoretical methods by which a laryngeal tumor can become transglottic.
● Directly crossing the ventricle
● Crossing at the anterior commissure
● Via the paraglottic space (all three subsites of the larynx
are accessible)
● Spread along the arytenoid cartilage to the posterior
ventricle
Why do lateralized supraglottic tumors drain
bilaterally?
The supraglottis is formed embryologically from a single
structure (i.e., no midline fusion), and therefore its
lymphatics cross midline, allowing for bilateral spread of
disease.
What is the inferior limit of the supraglottic
lymphatic system within the larynx?
Inferior false vocal fold (barrier is the quadrangular
membrane)
What nodal levels are most commonly involved by supraglottic tumors?
Levels II, III, and IV. Bilateral disease is common, especially
with midline tumors.
What is the pathway for nodal spread from a
supraglottic tumor to level II?
Along the superior laryngeal neurovascular bundle
What supraglottic subsite presents a high risk for
aggressive behavior and early nodal metastases?
The “marginal zone”: suprahyoid epiglottis and superior
aspect of the aryepiglottic folds
What is the rate of occult nodal disease in supraglottic malignancies (considering all stages)?
Up to 40%. Increases with increasing T stage (10% T1 to 57%
T4)
Why do lateralized glottic tumors drain unilaterally?
They are formed embryologically by paired structures that
fuse in the midline. Lymphatics within this subsite are
minimal and do not communicate across midline.
What is the risk of occult nodal metastases in
glottic carcinoma?
18%. Increases with T stage
What nodal levels are at risk for disease in glottic
carcinoma?
Levels II, III, IV, and VI (prelaryngeal, pretracheal, and
paratracheal nodes)
What nodal levels are at highest risk for disease in subglottic carcinoma?
Level VI. Commonly present with contralateral or bilateral
disease and mediastinal lymphadenopathy below level VII
(distant metastases)
