â– DEFINITION: A flat, triangular muscle located on the external surface of the larynx. It is the only intrinsic laryngeal muscle that does not lie inside the cartilaginous framework.
â– ORIGIN & INSERTION:
- Origin: Anterolateral arch of the cricoid cartilage.
- Insertion: Inferior border and inferior horn of the thyroid cartilage.
â– INNERVATION EXCEPTION:
Unlike all other intrinsic muscles of the larynx (which are supplied by the recurrent laryngeal nerve), the cricothyroid is supplied by the External Laryngeal Nerve (a branch of the superior laryngeal nerve, CN X), reflecting its 4th pharyngeal arch origin.
â– ACTION MECHANISM:
When it contracts, it tilts the thyroid cartilage forward and downward around the cricothyroid joint. This action pulls the vocalis cords tautly, elongating and tensing them.
â– SURGICAL LANDMARKS & ANATOMICAL BOUNDARIES:
Intraoperative access requires meticulous dissection along defined tissue planes. Avoid excessive traction near neurovascular bundles and look for key bony landmarks or fascial reflections to secure margins.
â– SECONDARY PREVENTION METRICS:
Implementing long-term dietary adaptations, physical therapy, and compliance aids reduces the rate of recurring acute crises by more than half.
[HY-BOARD-1233]
🌟 Dynamic Clinical Key:
Known as the 'singer's muscle' because it raises vocal pitch by tensing the vocal cords. Ligation of the superior thyroid artery during thyroid dissection can sever the adjacent External Laryngeal Nerve, causing a weak, hoarse voice that fatigues quickly. Never divide or ligate any vessel before clearly isolating and confirming its origin and termination. Patient education regarding warning signs and therapy adherence is the cornerstone of secondary prevention.