The document describes the different levels and boundaries of the larynx. It defines the supraglottic region as extending from the tip of the epiglottis to the laryngeal ventricle. The glottis extends from the ventricle to 1 cm below the true vocal cords. The subglottic region extends from the true vocal cords to the inferior portion of the cricoid cartilage. It also provides details on the structures within each region such as the false vocal cords in the supraglottis and the true vocal cords in the glottis.
1. LEVELS OF THE LARYNX AND THEIR BOUNDARIES
The supraglottic division:
From the superior-most tip of the epiglottis -to a
transverse plane through the laryngeal ventricle.
The glottis:
From this transverse plane to 1 cm inferiorly and
includes the true vocal cords.
The subglottic region
From the inferior-most plane of the true cords -to the
inferior portion of the cricoid cartilage.
2.
3. Supraglottis
• Extends from tip of epiglottis above to
laryngeal ventricle below.
• Contains vestibule, epiglottis, pre-epiglottic
fat, AE folds, FVC, paraglottic space, arytenoid
cartilages
4. • Pre-epiglottic space: Fat-filled space between
hyoid bone anteriorly & epiglottis posteriorly
• AE folds: Projects from cephalad tip of
arytenoid cartilages to inferolateral margin of
epiglottis
• Represents superolateral margin of
supraglottis, dividing it from pyriform sinus
(hypopharynx)
5. • False vocal cords: Mucosal surfaces of laryngeal
vestibule of supraglottis.
• Beneath FVC are paired paraglottic spaces
• Paraglottic spaces: Paired fatty regions beneath
false & true vocal cords
• Superiorly they merge into pre-epiglottic space
• Terminates inferiorly at under surface of TVC
6.
7.
8.
9. Glottis
• TVC & anterior & posterior commissures
• Comprised of thyroarytenoid muscle (medial
fibers are "vocalis muscle")
• Anterior commissure: Midline, anterior
meeting point of TVC
10.
11.
12. Subglottis
• Subglottis extends from under surface of TVC
to inferior surface of cricoid cartilage
• Mucosal surface of subglottic area is closely
applied to cricoid cartilage
• Conus elasticus: Fibroelastic membrane
extends from medial margin of TVC above to
cricoid below
33. NAME : Mr. Harnapallu Baburao Abbanna Req No : 330
Patient Code : 140102135 CT No:330
AGE/SEX : 74 Yr(s) / Male Date: 09/05/2014
MSCT NECK WITH CONTRAST
HISTORY :
K/C/O CA hypopharynx.
Post radiotherapy status,
34. soft tissue density mass involving hypopharynx, larynx & upper oesophagus which is occluding
the laryngeal airway (supra-glottic space) as well as upper end of oesophagus.
40. NAME : Mr. Khan Ibrahim Amir Req No : 339
Patient Code : 140403479 / IPD CT No:339
AGE/SEX : 72 Yr(s) / Male Date: 10/05/2014
MSCT NECK /LARYNX
Clinical Profile: H/o change in voice.
41. Small mildly heterogeneously enhancing polypoidal mass lesion is noted involving right vocal
cord and right para-glottic space, protruding into the laryngeal lumen
Plain Post-contrast
42. There is small non enhancing hypodense area noted within the lesion s/o necrosis.
43. Anteriorly the lesion is extending upto the anterior commissure with minimal extension to
contralateral side. Thyroid cartilage appears normal.
44. There is minimal extension of the enhancing soft tissue into the subglottic region noted at
the anterior commissure. No obvious mass or thickening noted in posterior commissure.
48. Supraglottic SCC
Approximately 30% of all laryngeal cancers arise in the supraglottis.
They often present in advanced stages, because symptoms
(hoarseness, due to vocal cord involvement) do not occur until late.
Due to the rich lymphatic network of the supraglottis, nodal
disease (level II and III) is a frequent finding in these patients.
Supraglottic SCC may arise in the
• anterior compartment (epiglottis) or
• the postero-lateral compartment (aryepiglottic fold and false
cords).
49. a. Epiglottic SCC
Spread:
PES (Pre-epiglottic space)
Vallecula
base of tongue
PGS (Paraglottic space)
PES glottis or subglottis
53. Glottic SCC
Glottic SCCs represent about 65% of all laryngeal cancers.
Hoarseness of voice due to vocal cord involvement is the primary presenting
symptom in these patients.
Metastatic nodal disease is rare in glottic carcinomas due to the sparse lymphatic
drainage of the glottis.
Glottic SCCs commonly arise from the anterior half of the vocal cord and spread
into the anterior commissure.
Anterior commissural disease is seen on CT or MRI as soft tissue thickening of
more than 1-2 mm.
54. Spread to :
• contralateral cord
• thyroid cartilage
• posterior commissure
• Arytenoids
• cricoarytenoid joint and the cricoid cartilage
• superiorly to access the PES and the PGS
• inferiorly to reach the subglottis
55.
56. Subglottic SCC
These cancers are rare, accounting for only 5% of all laryngeal cancers, clinically
silent and present late in the course.
Subglottic cancer is diagnosed if any tissue thickening is noted between the airway
and the cricoid ring.
57.
58. Transglottic SCC
Laryngeal SCC encroaching on both, the glottis and supraglottis, with or without
subglottic component and when the site of origin is unclear, is termed as
transglottic tumor.
Free edge of epiglottis is attached to hyoid bone via hyoepiglottic ligament which is covered by glossoepiglottic fold, a ridge of mucous membrane.
Graphic at mid-supraglottic level shows hyoepiglottic ligament dividing lower pre-epiglottic space. No fascia separates pre-epiglottic space from paraglottic space. These two endolaryngeal spaces are submucosal locations where tumors hide from clinical detection. Aryepiglottic fold represents junction between larynx & hypopharynx.
Graphic at low supraglottic level shows false vocal cords (FVC) formed by mucosal surfaces of laryngeal vestibule. Paraglottic space is beneath FVC, a common location for submucosal tumor spread.
(Top) Graphic at glottic, true vocal cord level shows thyroarytenoid. Medial fibers of thyroarytenoid muscle are known as vocalis muscle. Pyriform sinus apex is seen at glottic level. Thyroarytenoid gap is location where tumors may spread between larynx & hypopharynx.
Graphic at level of undersurface of true vocal cord shows posterior lamina of cricoid cartilage. Post-cricoid hypopharynx represents anterior wall of lower hypopharynx & extends from cricoarytenoid joints to lower edge of cricoid cartilage at cricopharyngeus muscle. Posterior wall of hypopharynx represents inferior continuation of posterior oropharyngeal wall & extends to cervical esophagus.
Graphic at subglottic level shows cricothyroid joint immediately adjacent to recurrent laryngeal nerve, located in tracheoesophageal groove.
Coronal graphic posterior view shows false & true vocal cords separated by laryngeal ventricle. Quadrangular membrane is a fibrous membrane which extends from upper arytenoid & corniculate cartilages to lateral epiglottis. Conus elasticus is a fibroelastic membrane which extends from vocal ligament of true vocal cord to cricoid. There membranes represent a relative barrier to tumor spread but are not seen on conventional imaging.
Sagittal graphic of midline larynx shows laryngeal ventricle, air-space which separates false vocal cords above with true vocal cords below. Aryepiglottic folds project from tip of arytenoid cartilage to inferolateral margin of epiglottis. Aryepiglottic folds represent junction between supraglottis & hypopharynx. Medial wall of aryepiglottic fold is endolaryngeal while posterolateral wall is anteromedial margin of pyriform sinus.
(Top) First of nine axial CECT images presented from superior to inferior of larynx & hypopharynx with patient in quiet respiration. Hyoid bone represents the level of the roof of larynx & hypopharynx Glossoepiglottic & pharyngoepiglottic folds represent transition from oropharynx above to larynx & hypopharynx below.
(Middle) Image of high supraglottic level of larynx shows C-shaped pre-epiglottic space, a common location for tumors to hide. If supraglottic tumor extends to pre-epiglottic space, it becomes a T3 tumor
(Bottom) Image of high supraglottic level shows pre-epiglottic & paraglottic spaces are continuous, with no intervening fascia. This allows tumors to spread submucosally in these locations.
Posterolateralwall of aryepiglottic fold is anteromedial margin of pyriform sinus.
(Top) Image of mid-supraglottic level shows thyroepiglottic ligament dividing the pre-epiglottic space. Aryepiglottic folds are at margin of pyriform sinus & larynx & a tumor primary to aryepiglottic fold is considered a "marginal supraglottic" tumor.. II
(Middle) Image of low supraglottic level shows false vocal cord level. Paraglottic space represents deep fatty space beneath false vocal cords. Tumors that cross laryngeal ventricle & involve false & true vocal cords are considered transglottic
. (Bottom) Image at glottic level shows true vocal cords in abduction in quiet respiration. True vocal cord level is identified on CT when arytenoid and cricoid cartilages are seen and muscle fills inferior paraglottic space.
Anterior and posterior commissures of true vocal cords should be less than 1 mm in normal patients.
Post-cricoid hypopharynx is typically collapsed.
In this image through the undersurface of true cord level the cricothyroid space is seen. Lack of arytenoid cartilage identifies undersurface of true cord level.
(Middle) Image more inferior shows subglottic level with cricoid ring nearly complete. Cricoid is only complete cartilage ring in larynx & provides structural integrity. Dislocations of cricothyroid joint may result in vocal cord paralysis secondary to recurrent laryngeal nerve injury. There may be associated atrophy of posterior cricoarytenoid muscle on involved side of vocal cord paralysis
(Bottom) At the level of the inferior cricoid cartilage the inferior margin of larynx & hypopharynx are transitioning to the trachea & cervical esophagus.
First of three axial CECT images from superior to inferior in patient with breath holding shows adduction of false & true vocal cords as well as aryepiglottic folds.
(Middle) Image at low supraglottic level shows level of false vocal cords in adduction. Note mucosa of aryepiglottic folds contacts posterior hypopharyngeal wall
(Bottom) Image at glottic level shows adduction of true vocal cords. With breath holding, true vocal cords oppose in midline. A cord that remains paramedian is either paralyzed or mechanically fixed. Vocal cord paralysis typically results in a paramedian true vocal cords with associated abnormal location of arytenoid cartilage which is fixed in an anterior-medial position. With breath holding, paralyzed cord remains fixed while opposite normal cord crosses midline in attempt to close glottis. There may be an associated patulous pyriform sinus.
In this image the laryngeal ventricle is visible as an air space between false vocal cords above & true vocal cords below. When a tumor crosses laryngeal ventricle to involve true & false cords it is transglottic, which has important treatment implications. Coronal imaging is particularly useful for evaluation of transglottic disease.
This image reveals pre-epiglottic fat to be continuous with paraglottic fat. These are the most important spaces of endolarynx as they allow submucosal spread of tumors which is undetectable by clinical exam.
Pre-epiglottic fat is seen at midline posterior & inferior to hyoid bone. Diseases of posterior hypopharyngeal wall are well seen on sagittal imaging. Sagittal imaging also helps define cranial to caudal extent of lesions.