Arytenoid Cartilage

The arytenoid cartilages are a pair of small, pyramid-shaped cartilages located in the posterior aspect of the larynx. They play a central role in the mechanics of phonation by anchoring and moving the vocal cords. Each arytenoid serves as a point of attachment for multiple muscles and ligaments that control tension, position, and movement of the vocal folds.

Location

The arytenoid cartilages are situated on the superior border of the posterior cricoid cartilage lamina. They lie within the posterior part of the larynx, at the level of the C6 vertebra, and are located just posterior to the glottis and vocal folds.

Structure

Each arytenoid cartilage has a three-sided pyramidal shape with a base and apex, and three surfaces. The base articulates with the cricoid cartilage, forming the cricoarytenoid joint.

Key Landmarks

• Apex: The pointed superior part, which supports the corniculate cartilage and is part of the aryepiglottic fold.
• Base: Articulates with the cricoid cartilage and contains important processes.
• Vocal process: Projects anteriorly and serves as the attachment point for the vocal ligament (true vocal cord).
• Muscular process: Projects laterally; serves as the attachment for several intrinsic laryngeal muscles, including the posterior and lateral cricoarytenoid muscles.

Articulations

The arytenoid cartilages articulate with the cricoid cartilage at the cricoarytenoid joints. These synovial joints permit both sliding and rotation, which are essential for opening and closing the vocal folds.

Muscle Attachments

The arytenoid cartilages serve as the origin or insertion for multiple intrinsic laryngeal muscles:

• Posterior cricoarytenoid muscle: Inserts on the muscular process; abducts (opens) the vocal folds.
• Lateral cricoarytenoid muscle: Inserts on the muscular process; adducts (closes) the vocal folds.
• Thyroarytenoid muscle: Inserts into the anterolateral surface; relaxes the vocal folds.
• Transverse and oblique arytenoid muscles: Attach between the two arytenoid cartilages; adduct the vocal folds.
• Vocalis muscle: Inserts into the vocal process; fine-tunes pitch during phonation.

Ligament Attachments

• Vocal ligament: Extends from the vocal process to the thyroid cartilage; forms the core of the true vocal fold.
• Vestibular ligament: Extends superiorly from the arytenoid cartilage to the epiglottis; forms the core of the false vocal fold.

Function

The arytenoid cartilages are critical for:

• Regulating tension and position of the vocal cords for sound production.
• Opening the vocal folds during breathing.
• Closing the vocal folds during swallowing and phonation.
• Fine motor control of the glottis via intrinsic muscle action.

Vascular Supply

Blood is supplied by the:

• Superior laryngeal artery (branch of the superior thyroid artery).
• Inferior laryngeal artery (branch of the inferior thyroid artery).

Innervation

The intrinsic muscles controlling arytenoid movement are innervated by:

• Recurrent laryngeal nerve (branch of the vagus nerve, CN X): motor innervation to most intrinsic laryngeal muscles.
• External branch of superior laryngeal nerve: Innervates the cricothyroid but does not affect the arytenoid directly.

Clinical Significance

• Arytenoid dislocation: Can result from trauma or intubation, leading to hoarseness or vocal cord immobility.
• Recurrent laryngeal nerve damage: Affects arytenoid movement and can cause vocal fold paralysis.
• Vocal cord paralysis: May involve impaired arytenoid function, affecting speech and breathing.
• Cricoarytenoid arthritis: Inflammatory conditions such as rheumatoid arthritis can affect the mobility of arytenoid cartilages.