Cavity of the Larynx

Cavity of the Larynx.

The cavity of the larynx extends from the laryngeal inlet, where it opens into the pharynx, to the lower border of the cricoid cartilage, continuing into the trachea.

1. Inlet of the Larynx: The laryngeal inlet is an oblique opening that faces backwards and upwards, and opens into the laryngopharynx. The inlet is bounded anteriorly by the free edge of the epiglottis, on each side by the aryepiglottic folds, and posteriorly by the interarytenoid fold.
2. Divisions of larynx. The larynx is divided anatomically into the supraglottis, glottis and subglottis by the false and true folds.

• • Supraglottis (vestibule) – The space above the vestibular folds (false vocal cords) and below the laryngeal inlet is called the supraglottis. Craniocaudally, it commences at the epiglottis and aryepiglottic folds to the arytenoids. Its lower border is defined by a horizontal line through the laryngeal ventricle. Its anterior wall is formed by the posterior surface of the epiglottis, while the sides by the aryepiglottic folds, and the posterior wall by the mucous membrane covering the front of the arytenoid cartilages.
  • Glottis (rima glottidis) – The elongated space between the two true vocal cords is known as the glottis. It includes the true vocal cords as well as the anterior commissure and posterior commissure. Craniocaudally, this space lies between the lower border of the supraglottis to a line drawn 1 cm below the free edge of the true vocal cords. In men, the glottis measures approximately 24 mm anteroposteriorly, while in women, it is around 16 mm. The narrowest part of the laryngeal cavity, the glottis, has two functional areas: the front two-thirds, made up of membranous vocal cords for sound production (phonatory glottis), and the back third, formed by the arytenoid vocal processes for respiratory function (respiratory glottis). Transglottic space is glottis + ventricle + false vocal cords.
  • Subglottis – The part below the glottis is called the subglottis. Craniocaudally, it commences from the lower border of the supraglottis to the lower border of the cricoid cartilage, connecting the larynx to the trachea.

3. Vestibular and Vocal folds. Within the cavity of the larynx, there are two sets of mucous membrane folds on each side. The upper fold is the vestibular fold (false vocal cords), and the lower fold is the vocal fold (true vocal cords).

• • Vestibular Folds (False Vocal Cords): The vestibular folds are two mucous membrane folds that run anteroposteriorly across the laryngeal cavity. Each contains the vestibular ligament, a few fibres of the thyroarytenoid muscle, and several mucous glands. The vestibular ligament is comprised of thickening of the inferior edge of the quadrangular membrane.
  • Vocal Folds (True Vocal Cords): The vocal folds appear as two sharp, pearly white bands that are attached anteriorly to the middle of the angle of the thyroid cartilage on its posterior aspect and posteriorly to the vocal process of the arytenoid cartilage. Each vocal fold is comprised of a vocal ligament, the vocalis muscle and a mucous membrane covering. The vocal ligament is comprised of thickening of the superior edges of the conus elasticus. The vocal folds act as the oscillator or voice source (noisemaker) of the vocal tract.

4. Ventricle (Sinus of the Larynx or Sinus of Morgagni): The ventricle is a narrow, deep, elliptical space situated between the vestibular and vocal folds. A small pouch known as the saccule branches from the ventricle’s anterior portion, ascending between the vestibular folds and thyroid cartilage lamina. The saccule houses numerous mucous glands that help to lubricate the vocal cords that is why it is often called as oil can of the larynx. When enlarged, this saccule may form an air-filled sac called a laryngocele, which may be visible externally on the neck.

——– End of the chapter ——–

Reference Textbooks.

• Scott-Brown, Textbook of Otorhinolaryngology-Head and Neck Surgery.
• Cummings, Otolaryngology-Head and Neck Surgery.
• Stell and Maran’s, Textbook of Head and Neck Surgery and Oncology.
• Ballenger’s, Otorhinolaryngology Head And Neck Surgery
• Susan Standring, Gray’s Anatomy.
• Frank H. Netter, Atlas of Human Anatomy.
• B.D. Chaurasiya, Human Anatomy.
• P L Dhingra, Textbook of Diseases of Ear, Nose and Throat.
• Hazarika P, Textbook of Ear Nose Throat And Head Neck Surgery Clinical Practical.
• Mohan Bansal, Textbook of Diseases of Ear, Nose and Throat Head and Neck Surgery.
• Hans Behrbohm, Textbook of Ear, Nose, and Throat Diseases With Head and Neck Surgery.
• Logan Turner, Textbook of Diseases of The Nose, Throat and Ear Head And Neck Surgery.
• Arnold, U. Ganzer, Textbook of  Otorhinolaryngology, Head and Neck Surgery.

Author:

Dr. Rahul Bagla
MBBS (MAMC, Delhi) MS ENT (UCMS, Delhi)
Fellow Rhinoplasty & Facial Plastic Surgery.
Renowned Teaching Faculty
Mail: msrahulbagla@gmail.com
India

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