Joints of the larynx
In this article, all of the joints, ligaments, and membranes that make up this essential and astounding anatomical structure will be discussed, along with a small overview of the pathological disorders that may be inflicted upon the larynx.
- Ligaments and membranes
- Clinical notes
- Related diagrams and images
There are two sets of paired joints which aid the movement of the vocal cords in the larynx.
In this joint the thyroid cartilage glides and rotates laterally and either superiorly or inferiorly, which in turn changes the length of the vocal chords. When this movement occurs, the tension on the vocal chords changes, resulting in a different pitch of sound in the human voice.
The second pair of joints are the cricoarytenoid articulations which create the movement of the arytenoid cartilage upon the lamina of the cricoid cartilage.
The arytenoid cartilages slide both towards and away from each other, they rotate upon their own axis and they tilt forwards and backwards, gaging on the whole a very wide range of movement.
Ligaments and membranes
The ligaments and membranes of the larynx are classified according to their position, which is either intrinsic or extrinsic.
The major intrinsic ligaments include the quadrangular membrane, vocal ligament, and conus elasticus, which is comprised of the median and lateral cricothyroid ligaments. Together they both help form the true vocal cord.
The quadrangular membrane is comprised of nonelastic connective tissue which is attached to the lateral margins of the arytenoid cartilages and the epiglottis. At its inferior edge the border is mobile and is known as the vestibular ligament or false vocal cord. It is covered by the vestibular fold and is just above the vocal fold and it extends between the thyroid cartilage and the arytenoid cartilages. The superior border is also mobile and forms the aryepiglottic ligament which is covered by mucosa and is named the aryepiglottic fold.
The vocal ligament is located between the arytenoid and the thyroid cartilages.
The conus elasticus stretches superiorly from the thyroid cartilage, the vocal ligament and the arytenoid cartilage inferiorly to the upper border of the cricoid cartilage.
The major extrinsic ligaments and membranes include the thyrohyoid membrane (which contains the median and lateral thyrohyoid ligaments), the thyroepiglottic ligament and cricotracheal ligament.
The thyrohyoid membrane is a wide, fibroelastic sheet which reaches from the superior border of the thyroid cartilage lamina and the front of its superior cornua, to the the superior border of the body and greater cornua of the hyoid bone. It is pierced by the laryngeal vessels and the internal laryngeal nerve which innervates the intrinsic parts of the larynx.
Its median portion is thickened to form the median thyrohyoid ligament, while it lateral portions form the lateral thyrohyoid ligaments which connect the tips of the thyroid cornua to the greater cornua of the hyoid bone.
The thyroepiglottic ligament connects the inferior part or stem of the epiglottis to the thyroid angle which is formed by the laminae of the thyroid cartilage. It attaches just inferior to the superior thyroid notch.
Finally, the cricotracheal ligament that runs from the inferior border of the cricoid cartilage down to the first tracheal ring.
Acute laryngotracheobronchitis, which is simply known as croup, is an inflammation of the larynx, the trachea and the epiglottis. It is potentially life threatening and is usually seen in infants.
Chronic forms also exist that can ensue for months at a time, weakening the respiratory tract and exposing it to the risk of infestation by other microbes. The most common form of infection is by viral means and the most obvious clinical symptoms are a harsh cough and an audible inspiratory stridor.