H&N Larynx Anatomy

Question 1

Describe the boundaries of the larynx according to

the AJCC.

Answer 1

● 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

Question 2

What are the subsites of the larynx according to

the AJCC?

Answer 2

● 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.

Question 3

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?

Answer 3

Supraglottis

Question 4

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?

Answer 4

Glottis and subglottis

Question 5

What branchial arch structures give rise to the

hyoid bone?

Answer 5

● Second branchial arch: Lesser horn and upper portion of
the hyoid bone
● Third branchial arch: Greater horn and lower portion of
the hyoid bone

Question 6

What are the five subsites of the supraglottis?

Answer 6

● Suprahyoid epiglottis
● Infrahyoid epiglottis
● Aryepiglottic fold (laryngeal surface)
● False vocal fold (also called the ventricular bands)
● Arytenoid

Question 7

What are the subsites of the glottis?

Answer 7

True vocal folds (superior and inferior surface), including the anterior and posterior commissures

Question 8

What are the subsites of the subglottis?

Answer 8

None

Question 9

What is the normal histology of the supraglottis?

Answer 9

● Pseudostratified columnar respiratory epithelium. The
lateral surface of the aryepiglottic folds and epiglottis are
stratified squamous epithelium.
● Numerous mucous glands

Question 10

What is the normal histologic structure of the glottis, proceeding medial to lateral through the true vocal fold?

Answer 10

● Stratified squamous epithelium
● Superficial lamina propria (Reinke space)
● Vocal ligament (intermediate and deep lamina propria)
● Thyroarytenoid muscle
● Paraglottic fat
● Thyroid cartilage

Question 11

What is the normal histology of the subglottis?

Answer 11

Pseudostratified columnar epithelium

Question 12

What are the natural barriers to spread of

laryngeal cancer?

Answer 12

● 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

Question 13

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?

Answer 13

Quadrangular membrane

Question 14

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)?

Answer 14

Conus elasticus

Question 15

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)?

Answer 15

Anterior commissure tendon (the Broyles ligament)

Question 16

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?

Answer 16

Significant supraglottic (petiole, pre-epiglottic space) or
subglottic extension (ossified thyroid cartilage, lymphatics,
cricothyroid membrane)

Question 17

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.

Answer 17

Pre-epiglottic space.

Question 18

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.

Answer 18

Paraglottic space

Question 19

What important feature of the infrahyoid epiglottic cartilage allows easy tumor growth into the pre-epiglottic space?

Answer 19

Fenestrations

Question 20

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.

Answer 20

● 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

Question 21

Why do lateralized supraglottic tumors drain

bilaterally?

Answer 21

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.

Question 22

What is the inferior limit of the supraglottic

lymphatic system within the larynx?

Answer 22

Inferior false vocal fold (barrier is the quadrangular

membrane)

Question 23

What nodal levels are most commonly involved by supraglottic tumors?

Answer 23

Levels II, III, and IV. Bilateral disease is common, especially
with midline tumors.

Question 24

What is the pathway for nodal spread from a

supraglottic tumor to level II?

Answer 24

Along the superior laryngeal neurovascular bundle

Question 25

What supraglottic subsite presents a high risk for

aggressive behavior and early nodal metastases?

Answer 25

The “marginal zone”: suprahyoid epiglottis and superior

aspect of the aryepiglottic folds

Question 26

What is the rate of occult nodal disease in
supraglottic malignancies (considering all stages)?

Answer 26

Up to 40%. Increases with increasing T stage (10% T1 to 57%

T4)

Question 27

Why do lateralized glottic tumors drain unilaterally?

Answer 27

They are formed embryologically by paired structures that
fuse in the midline. Lymphatics within this subsite are
minimal and do not communicate across midline.

Question 28

What is the risk of occult nodal metastases in

glottic carcinoma?

Answer 28

18%. Increases with T stage

Question 29

What nodal levels are at risk for disease in glottic

carcinoma?

Answer 29

Levels II, III, IV, and VI (prelaryngeal, pretracheal, and

paratracheal nodes)

Question 30

What nodal levels are at highest risk for disease in subglottic carcinoma?

Answer 30

Level VI. Commonly present with contralateral or bilateral
disease and mediastinal lymphadenopathy below level VII
(distant metastases)