S: http://www.medicinenet.com/script/main/art.asp?articlekey=15568 (last access: 12 July 2017); http://www.healthline.com/human-body-maps/thyroid-cartilage (last access: 12 July 2017).
N: 1. – thyroid (adj): 1690s (in reference to both the cartilage and the gland), from Greek thyreoiedes “shield-shaped” (in khondros thyreoiedes “shield-shaped cartilage,” used by Galen to describe the “Adam’s apple” in the throat), from thyreos “oblong, door-shaped shield” (from thyra “door,” from PIE root *dhwer- “door, doorway”) + -eides “form, shape”. The noun, short for thyroid gland, is recorded from 1849.
– cartilage (n): early 15c., from Middle French cartilage (16c.) and directly from Latin cartilaginem (nominative cartilago) “cartilage, gristle,” possibly related to Latin crates “wickerwork.”
2. The thyroid cartilage, which forms the Adam’s apple, is the largest and uppermost of nine cartilages within the larynx, or voice box. (Cartilage is a strong but flexible tissue.) It houses the vocal folds, also known as the vocal cords.
3. The thyroid cartilage is composed of two plates, called laminae, that join in the front at an angle of 90 to 120 degrees. The protrusion it creates, visible on the front of the neck, is generally more prominent in men because of a sharper angle in males. The thyroid cartilage typically grows larger during the teenage years, especially in boys, and is seen as a secondary sexual characteristic. Secondary sexual characteristics are indicators of a person’s sex, which develop as they age (usually around puberty). Others include facial hair in men and breasts in women.
4. Despite its name, the thyroid cartilage has nothing to do with the thyroid gland or its processes. It plays a role in the production of the human voice, providing protection and support for the vocal folds. The muscles of the larynx act on skeletal structures, including the thyroid cartilage, to produce the vibration of the vocal folds, which is necessary to produce vocalization.
S: 1. OED – http://www.etymonline.com/index.php?term=thyroid; http://www.etymonline.com/index.php?allowed_in_frame=0&search=cartilage (last access: 12 July 2017). 2 to 4. http://www.healthline.com/human-body-maps/thyroid-cartilage (last access: 12 July 2017).