The larynx, commonly referred to as the voice box, plays a vital role in breathing, producing sound, and protecting the airway during swallowing. Structurally, the larynx is supported by a framework of cartilages that provide both rigidity and flexibility. These cartilages serve as anchoring points for muscles and ligaments involved in speech and respiration. Understanding the number of cartilage in the larynx and their individual characteristics helps to clarify how this structure functions as a central component of the upper respiratory tract.
How Many Cartilages Are in the Larynx?
The human larynx contains a total of nine cartilages. These cartilages are categorized based on their size and whether they occur as single or paired structures.
- Three unpaired cartilages
- Three pairs of smaller cartilages
This makes a total ofnine cartilages: three single (3) and three paired (2 x 3 = 6), adding up to 9 in total.
Unpaired Cartilages of the Larynx
The unpaired cartilages are larger and form the main framework of the larynx. These include the thyroid cartilage, cricoid cartilage, and epiglottis.
Thyroid Cartilage
The thyroid cartilage is the largest cartilage in the larynx. It forms the anterior wall of the larynx and is most noticeable as the Adam’s apple in males. This cartilage consists of two broad plates (laminae) that are joined at the front and diverge at the back.
Functions of the thyroid cartilage include:
- Protecting the vocal cords
- Providing attachment for laryngeal muscles and ligaments
- Helping maintain the open structure of the larynx
Cricoid Cartilage
Located just below the thyroid cartilage, the cricoid cartilage is shaped like a signet ring. It is the only complete ring of cartilage in the respiratory tract. The posterior portion of the cricoid cartilage is broader and taller than the anterior portion.
Key functions include:
- Serving as the base for the larynx
- Providing attachment for the arytenoid cartilages and several muscles
- Helping regulate tension of the vocal cords during speech
Epiglottis
The epiglottis is a leaf-shaped elastic cartilage located behind the tongue and in front of the laryngeal inlet. Its main function is to prevent food and liquids from entering the trachea during swallowing.
When swallowing occurs, the epiglottis folds downward to cover the laryngeal opening, directing food into the esophagus.
Paired Cartilages of the Larynx
The paired cartilages are smaller and more variable in shape. They play a crucial role in vocal fold movement and positioning. These include the arytenoid, corniculate, and cuneiform cartilages.
Arytenoid Cartilages
These pyramid-shaped cartilages sit atop the posterior portion of the cricoid cartilage. Each arytenoid has two projections: the vocal process and the muscular process.
The arytenoids are essential for voice production as they:
- Anchor the posterior ends of the vocal cords
- Move to adjust vocal cord tension and position
- Allow for opening and closing of the glottis
Corniculate Cartilages
These small, horn-shaped cartilages sit on top of the arytenoids. They are composed of elastic cartilage and assist in the function of the arytenoids by helping with the movement and stabilization of the vocal folds.
Although not as functionally prominent as the arytenoids, the corniculate cartilages contribute to:
- Shaping the laryngeal inlet
- Supporting the posterior part of the vocal fold structure
Cuneiform Cartilages
The cuneiform cartilages are small, elongated pieces of elastic cartilage located in the aryepiglottic folds, which extend from the arytenoids to the epiglottis. These cartilages are embedded within the soft tissue and are not directly attached to other laryngeal cartilages.
Their primary functions are:
- Supporting the aryepiglottic folds
- Maintaining the shape and patency of the laryngeal inlet
Composition and Types of Cartilage
Most laryngeal cartilages are composed of hyaline cartilage, which is firm and somewhat flexible. The epiglottis, corniculate, and cuneiform cartilages are made of elastic cartilage, which is more flexible and resilient, suitable for repetitive movement.
Over time, especially with age, hyaline cartilage may undergo calcification or ossification, becoming more rigid. This process is more common in the thyroid and cricoid cartilages and can affect vocal quality in older adults.
Anatomical Relationships and Attachments
The laryngeal cartilages are connected by joints, membranes, and ligaments. These connections allow for movement and support necessary functions like sound modulation and airway protection.
- Cricothyroid joint: Allows for tilting of the thyroid cartilage over the cricoid, adjusting vocal cord tension.
- Cricoarytenoid joint: Facilitates rotation and sliding of the arytenoid cartilages, which control the opening and closing of the vocal folds.
Ligaments such as the vocal ligaments and the thyrohyoid membrane also attach to the cartilages and play structural roles.
Clinical Relevance
Laryngitis and Swelling
Inflammation of the laryngeal cartilages or surrounding tissues can lead to laryngitis, resulting in hoarseness, loss of voice, or breathing difficulty. This is especially problematic if swelling affects the epiglottis or arytenoid region.
Cartilage Trauma
Injuries from blunt trauma or intubation may damage the cartilages, leading to vocal changes or airway obstruction. The cricoid cartilage is particularly important to assess in such cases, as it forms a complete ring around the airway.
Voice Disorders
Improper movement or misalignment of the arytenoid cartilages can result in voice disorders. Surgical or therapeutic interventions may target these structures to restore function.
Ossification in Aging
The natural calcification and ossification of laryngeal cartilage can affect vocal pitch and projection in elderly individuals. This age-related change is particularly evident in the thyroid and cricoid cartilages.
The larynx is supported by a framework of nine cartilages: three unpaired (thyroid, cricoid, epiglottis) and three paired (arytenoid, corniculate, cuneiform). Each cartilage plays a specific role in breathing, protecting the airway, and enabling vocalization. The interaction between these cartilages, along with associated muscles and ligaments, allows for complex and coordinated functions such as speech and swallowing. A solid understanding of the number and function of the cartilage in the larynx is essential for anyone studying anatomy, medicine, or voice physiology.