The thyrohyoid membrane is a wide and fibrous layer of tissue that connects the thyroid cartilage to the hyoid bone. The thyroid cartilage is the largest cartilage — a type of strong, flexible tissue — in the neck, part of which forms the Adam’s apple. The hyoid is located in the neck, just below the lower jawbone, or mandible. The thyrohyoid membrane creates the conditions necessary for the upward movement of the larynx during deglutition, or swallowing.
The thyrohyoid membrane covers the area below the origin point of the middle constrictor muscle, which lies near the lower jawline. The thinner, lateral (side) portions of the thyrohyoid membrane are pierced by the internal laryngeal artery and the internal laryngeal nerve, which is a branch of the superior laryngeal nerve. This nerve helps sense the presence of mucus in the larynx, or voice box, and is part of the coughing reflex.
The middle, thicker part of the thyrohyoid membrane is called the middle hypothyroid ligament.
The membrane's anterior (front) surface is near the omohyoid, thyrohyoid, and sternohyoid muscles.
If a neck cancer affects the thyroid cartilage or the thyrohyoid membrane, it may result in a spreading of the tumor from the laryngeal area into the soft neck tissues. If a cancer deeply invades the area known as the paraglottic space after passing through the thyrohyoid membrane, it will not face any more barriers to vertically spreading through the larynx, which may drastically reduce the effectiveness of horizontal supraglottic laryngectomy. Horizontal supraglottic laryngectomy is a surgical removal of the epiglottis, false vocal cords, and the top half of the thyroid cartilage.