Chapter 50: The Larynx

Anatomy

The larynx is an anatomical structure bridging the upper aerodigestive tract and the lower airways. Within the larynx, the vocal folds act as the principle valve dynamically controlling the aperture.

Laryngeal Cartilages

1. Hyoid bone is the cranial-most component.

   1. U-shaped bone with a central body and superiorly projecting greater and lesser cornua

   2. Suspended from the mandible by muscular attachments and from base of the skull by stylohyoid ligaments

   3. Provides stability to the larynx and pharynx

   4. Site of attachment for cervical strap, extrinsic tongue, middle pharyngeal constrictor, and hyolaryngeal elevator muscles

2. Thyroid cartilage is the largest component of the laryngeal skeleton.

   1. Shield-shaped structure, formed from two alae fused anteriorly with an opening posteriorly.

   2. Forms the protuberance known as Adam’s apple, larger in males.

   3. Provides anterior support and protection for the larynx.

   4. Posteriorly, each ala has superior and inferior cornua.

   5. Thyrohyoid ligament connects the superior cornua to the hyoid bone.

   6. Inferior cornua articulate with the cricoid cartilage.

3. Cricoid cartilage is the strongest of the laryngeal cartilages.

   1. The only complete and rigid ring in the airway

   2. Shaped like a signet ring with a lower height anteriorly than posteriorly

4. Epiglottic cartilage is leaf shaped.

   1. Attaches to the inside of the thyroid cartilage anteriorly and projects superiorly and posteriorly above the glottic aperture.

   2. The petiole is the point of attachment to the thyroid cartilage.

   3. The inferior aspect of the epiglottis has fenestra that allows blood vessels to cross through the cartilage.

5. Arytenoid cartilages are the primary moving parts of the larynx.

   1. Muscles that open and close the glottis act by moving the arytenoids.

   2. Pyramidal shaped, with broad bases that articulate with the posterior superior surface of the cricoid cartilage via shallow ball and socket joints.

   3. Vocal process:

      1. Anterior projection of each arytenoid

      2. Site of attachment for thyroarytenoid muscle

   4. Muscular process:

      1. Lateral projection of arytenoid, adjacent to medial aspect of piriform sinus

      2. Site of insertion of the lateral and posterior cricoarytenoid muscles

   5. The medial surfaces of the arytenoids are the site of insertion of the interarytenoid muscle, which acts as the primary adductor of the vocal folds

6. Sesamoid cartilages: small cartilages above the arytenoid within the aryepiglottic fold

   1. Corniculate cartilages (also called cartilages of Santorini)

   2. Cuneiform cartilages (also called cartilages of Wrisberg)

   3. Triticeous cartilage (variably present)—small elastic cartilage in thyrohyoid ligament; sometimes mistaken for a foreign body on soft tissue x-ray

Laryngeal Joints

1. Cricoarytenoid joint

   1. Motion is primarily rotational about a variable vertical axis, with minor gliding/sliding motion secondarily.

   2. Synovial joint

   3. Arytenoid rotates externally to move vocal process upward and outward.

   4. Arytenoid rotates internally to move the vocal process medially and inferiorly.

2. Cricothyroid joints

   1. Primary motion is rotational, akin to a bucket (cricoid) on a handle (inferior cornua), with minimal sliding.

Extrinsic Ligaments

1. Thyrohyoid membrane

   1. Connects thyroid cartilage and hyoid bone

   2. Pierced on lateral surface by superior laryngeal vessels and internal branch of ...