Thyroid Cartilage

The thyroid cartilage is the uppermost and the biggest amongst the 8 other cartilages that constitute the laryngeal skeleton, which in turn is a cartilaginous structure present in and around the wind pipe or the trachea that contains the larynx or the voice box. It may be noted that cartilages are not bones, but partially to fully flexible, yet firm and strong, tissues. The thyroid cartilage is home to the vocal folds or vocal cords.

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The thyroid cartilage is made of up of 2 plates known as laminae which connect anteriorly at an angle of 90 degrees to 120 degrees. The cartilage tends to jut out from the neck area and this protrusion is more visible in males due to a more prominent and sharp angle occurring in men. The cartilage normally grows bigger during teens and particularly in boys. It is regarded as one of the secondary sexual characteristics in men.

Even though the structure is named as the thyroid cartilage, it has no connections or association with the processes of the thyroid gland or the gland itself. The cartilage is instrumental in helping produce the voice in humans. The laryngeal muscles act on the skeletal tissues, which includes the thyroid cartilage, and facilitate the vibration of the vocal cords, which in turn triggers the occurrence of vocalization. The thyroid cartilage also offers support to and protects the vocal folds. Most parts of the anterior wall of the larynx consists of the structures of the thyroid cartilage. The vocal cords are located directly behind it which offers protection from any kind of damage. The thyroid cartilage also acts as a point of connection for many muscles of the larynx.

At the cricothyroid joint, both the laminae of the thyroid cartilage move in conjunction with the cricoid cartilage. The trachea is surrounded by the cricoid cartilage, which is the only completely ring-shaped cartilaginous structure present in the region. The cricothyroid joint, which links the cricoid and thyroid cartilage, assists in changing the tension and pressure occurring in the vocal chords thereby helping adjust the pitch of the human voice.

Thyroid cartilage-  Anatomy,  functions, and pain

thyroid cartilage picture diagram

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  • Anatomy: The thyroid cartilage is located just anterior to the larynx and superior to the thyroid gland. It occurs between the levels of the C5 and C4 vertebrae.
    • The cartilaginous structure is made up of 2 halves which connect at the center at the laryngeal prominence which is a peaked formation and commonly known as the Adam’s apple. The superior thyroid notch is situated just above the Adam’s apple, bang in its center. The base of the cartilage features the complementary notch and is known as the inferior thyroid notch.
    • The exterior surfaces of the thyroid cartilage are made up of its two halves. Each of them extend in an oblique fashion and enclose the sides of the windpipe or the trachea. Also, the back border of each half of the cartilage communicates inferiorly with the cricoid cartilage at a joint known as the cricothyroid joint. The back section of the cartilage that is the farthest also features 2 projections in the downwards and upward directions. The lower projection is known as the inferior horn while the upper one is known as cornu or the superior horn. The latter is narrow and long, medialward and backward, and finishes in a cone-shaped extremity, which is the connection point of the lateral thyrohyoid ligament. The inferior horn is thick and short, and with a downward direction, a medialward and forward minor inclination. The medial section of its apex features an oval and tiny articular facet that articulates with the cricoid cartilage’s side portion.
    • The complete upper border of the thyroid cartilage is connected by the thyrohyoid membrane to the hyoid bone. The thyroid cartilage also features a line known as the oblique line. It acts as the superior side margins of the thyroid gland. The inferior pharyngeal constrictor and the thyrohyoid muscle are two different muscles that begin along this line, while the sternothyroid inserts in it.
  • Functions: When the thyroid cartilage moves at the joint, it brings about a change in the levels of tension affecting the vocal cords, which then creates the variations in human voice. Change in thyroid cartilage angle in relation to the cricoid cartilage also help bring about variations in the pitch of the voice.
    • In combination with the cricothyroid joint, the cartilage thyroid cartilage also affects the quality of the voice. Males have a bigger thyroid cartilage. Hence, men have a voice that is normally deeper than women. During the teen years the cartilage tends to grow and hence boys who once had a mild squeaky quality to the voice elicit changes in the voice quality as the growth of the cartilage continues. Once the growth stops, the voice quality changes tend to level out.
    • The thyroid cartilage acts an attachment point for many muscles.
    • Most of the anterior wall of the larynx is formed by the thyroid cartilage. It thus offers protection to the vocal cords which are situated just behind it.
  • Pain: Pain in the thyroid cartilage can occur due to varied causes such as sore throat, fracture of the cartilage, and increased tension or stress on the muscles that surround the cartilage, etc. It is also possible that the pain may not be associated with the thyroid cartilage, but may have spread to the area from other tissues with different conditions.

Treatment of thyroid cartilage conditions

The thyroid cartilage may suffer from a variety of adverse signs and symptoms and each of them may be associated with some different kind of health problem. It is therefore best to consult a doctor for proper diagnosis and relevant treatment whenever patients experience pain in the thyroid cartilage or other thyroid cartilage abnormalities.

Thyroid cartilage fracture can be classified into 3 categories, i.e., non-displaced with minor laryngeal injuries, moderately displaced with intra-laryngeal injuries and defects, and severe or major fractures with intra-laryngeal damage and avulsion injuries. In each of these cases, doctors will access the severity of the associated damage and then treat it via conservative, non-surgical, or surgical therapies.

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