The thyroid cartilage consists of 2 hyaline cartilage lamina which fuse their lower 2/3rd's in the midline to form the adams apple and create the superior thyroid notch.
The base of the lamina is an oblique line which serves as a point of muscular attachment.
The cartilage has a superior cornu and an inferior cornu along its poterior borders.
The superior horns attach the thyrohyoid ligaments.
Inferior horn articulates with the cricothyroid joint! - allowing gliding of the thyroid cartilage for talking.
The thyroid cartilage is the cartilaginous component of the 4th arch - muscular component is the cricothyroid muscle + inferior constrictor (both attach to it!) - and superior largyneal nerve is the innervation - pierces the thyrohyoid membrane and that's the reason that the cricothyroid is the exception to the rule that intrinsic muscles of the larynx are supplied by the recurrant larynx arch.
Thyroid cartilage Ossification: Begins at puberty (other sources say commences at 25!) , at inferior margin, progressing cranially.
Thyroid attaches the inferior constrictor along its oblique line. (the inferior constrictor muscle has two parts, by which it is sometimes referred, cricopharyngeus and thyropharyngeus). )
Sternothyroid muscule is the only infrahyoid muscle to directly act on the thyroid cartilage (others act indirectly via hyoid bone).
Thyrohyoid muscle from oblique line to hyoid bone.
Medial and Lateral thyrohyoid ligaments along its superior notch and along superior cornu to attach to the hyoid bone.
- From the junction of the lower 2/3'ds of the laminae fusing extend the
vocal ligaments posteriorly. These form the submucosal skelton of the vocal fold.
- The thyroid cartilage is the anterior attachement for the
epiglottic petiole at the anterior commisure via the thyroepiglottic ligament.
intrinsic muscles of the larynx arise form the anterior interior surface of the thyroid cartilage.
Pathology of the thyroid cartilage drains into the superior deep cervical lymph nodes.
Upwards attachment of pretracheal fascia is limited by the attachement of muscles onto the thryoid cartilage.
Surgical Anatomy of the thyroid Cartilage
Oblique Line - demarcates the anterior projection of the pyriform sinus.
The cricothyroid joint (inferior cornu of thyroid cartilage) is the landmark for where the recurrant laryngeal nerve enters the larynx.
Gutman sign is associated with SLN paralysis. In the normal individual, lateral pressure over the thyroid cartilage causes an increased voice pitch, whereas anterior pressure causes a decrease. In SLN paralysis, the reverse is true (paralysis of the cricothyroid muscle).