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Cricoid Cartilage Definition
Thyroid cartilage and cricoid cartilage are located in the larynx immediately behind the thyroid gland (just below the pharynx). It is a level plane that is part of the larynx (just below the pharynx). It’s a circular piece of hyaline cartilage that wraps completely around the trachea and serves as a connection point for ligaments, muscles, and other cartilage.
What is Cricoid Cartilage?
While the bulk of the cartilaginous rings that surround the trachea are semi-circular, the cricoid cartilage ring is a full circle with a small arch prior to the airway and a large lamina posterior to it. This shape is frequently compared to a signet ring. The widest side (the cricoid plate) is in front of the esophagus in the picture below, and the arch is facing the front.
The larynx may be a complex structure that serves three purposes. It has a valve (the epiglottis) that shields the airway from debris, especially while swallowing, as well as providing structure to the otherwise soft tissue of the airway and housing the vocalization apparatus. The cricoid cartilage lies just below the vocal chords and within touching distance of the thyroid cartilage.
Because it is placed just beneath the structure known as the Adam’s apple, cricoid cartilage serves as more than a tracheal buttress (thyroid cartilage). It’s connected to the thyroid and arytenoid cartilages by synovial joints, and it’s strong enough to support a number of ligaments and muscles. The vocal folds are linked to a tiny portion of arytenoid cartilage that is connected to the cricoid cartilage through a ball and socket connection. The cricoid cartilage is linked to the thyroid cartilage as well.
The three muscles that attach to the cricoid cartilage are the lateral cricoarytenoid, posterior cricoarytenoid, and cricothyroid. All of these factors contribute to the opening, shutting, and elongation of the vocal chords, as well as the pitch and quality of the voice. In the larynx, there are nine cartilages altogether. These are either single (cricoid, thyroid, epiglottis) or in pairs (arytenoids, comiculates, cuneiforms) and are mentioned because the ‘visceral skeleton’ of the neck, along side the hyoid.
Cricoid Cartilage Function
The cricothyroid, posterior cricoarytenoid, and lateral cricoarytenoid muscles, cartilages, and ligaments involved in voice tone and quality attach to the cricoid cartilage. In addition, cricoid cartilage, along with other semi-circular cartilage bands that traverse the length of the trachea, supports the soft connective tissue.
In emergency situations, cricoid cartilage is also utilized as an anatomical marker for surgical cricothyrotomy (temporary) and tracheostomy (permanent) operations to establish a functional airway. The Adam’s apple (1), cricothyroid ligament (2), cricoid cartilage (3), and trachea are shown within the diagram below (4). Locations A and B correspond to the incision points for cricothyrotomy and tracheostomy, respectively.
When there is a risk of stomach contents rising up through the esophagus and into the trachea (and lungs) owing to a paralyzed epiglottis, cricoid pressure (Sellick’s technique) is used during intubation. A small amount of pressure is applied to the cricoid just before a patient falls asleep to flatten the soft tube of the esophagus behind it and, in principle, prevent stomach contents from entering the airway.
Because the cricoid ring is a full circle with a larger plate facing the esophagus, any pressure applied to it will, in theory, seal off the esophagus, which is not protected by cartilaginous structures. This is a contentious procedure that is still employed during rapid-sequence anesthesia induction (RSI). Cricoid cartilage can shatter under strain only rarely.
Cricoid Cartilage Structure
Cricoid cartilage is made entirely of hyaline cartilage, with the extracellular matrix containing type II collagen and chondroitin sulphate. Because of its smooth, glass-like surface, this form of cartilage is long-lasting and has low friction. A perichondrial membrane surrounds cricoid cartilage.
Cricoid cartilage grows in a pattern of circumferential (cell proliferation) and interstitial (extracellular matrix formation) development, although this is a delayed process since it is a cartilaginous tissue with no direct blood supply.
Cricoid cartilage, like other cartilage, is aneural and avascular. The density of blood vessels in its immediate proximity, on the other hand, supplies nutrients and oxygen to the perichondrium, which eventually diffuse into the cartilage tissue. The larynx, as well as the muscles connected to the cricoid cartilage, are considerably innervated, despite the fact that cartilage tissue contains no nerves.
When an endotracheal tube is needed in an adult patient under general anesthesia, the narrowest portion of the trachea through which the tube may be passed is between the vocal chords. In older children and adults, the trachea maintains a consistent diameter throughout its length. The trachea is funnel-shaped in newborns and really quite young children, with the narrowest part being the cricoid cartilage itself, rather than just the voice chords.
The relative narrowness of the portion of the trachea enclosed by the cricoid cartilage makes tube insertion more difficult in a young kid. At the highest of the screen, notice the relaxed epiglottis.
Osteoarthritis can affect the cricoarytenoid and cricothyroid joints, very similar to the other joint. This causes cartilage tissue to crack or fissure, loosening of collagen structures, and therefore the loss of proteoglycans. Degeneration of the cricoid cartilage causes voice quality to deteriorate and pitch to shift.
Cricoid Cartilage Citations
- Low-grade chondrosarcoma of the cricoid cartilage: a case report and review of the literature. Skeletal Radiol . 2017 Nov;46(11):1597-1601.
- Anatomy, Head and Neck, Cricoid Cartilage. PMID: 30969643
- The problem of pediatric laryngotracheal stenosis: a clinical and experimental study on the efficacy of autogenous cartilaginous grafts placed between the vertically divided halves of the posterior lamina of the cricoid cartilage. Laryngoscope . 1991 Dec;101(12 Pt 2 Suppl 56):1-34.
- Figures are created with BioRender.com