Cricothyroid (Oblique Part)
Larynx · Head & Neck
The oblique part is the more posterior division of the cricothyroid muscle. Like the straight part it arises from the anterolateral arch of the cricoid cartilage, but its fibres slant upward and backward to insert on the anterior border of the inferior horn of the thyroid cartilage. Acting with the straight part, it draws the thyroid cartilage and cricoid together at the cricothyroid joint, tensing and elongating the vocal folds to raise vocal pitch. It shares the distinctive supply of cricothyroid: the external laryngeal branch of the superior laryngeal nerve (vagus, CN X). Together the two parts are the principal tensors of the vocal folds.
Origin, Insertion, Action & Nerve
Origin
Anterolateral arch of the cricoid cartilage
Insertion
Anterior border of the inferior horn of the thyroid cartilage
Action
Tenses and elongates the vocal folds, raising vocal pitch
Nerve
External laryngeal branch of the superior laryngeal nerve (vagus, CN X)
Attachments explained
The Cricothyroid (Oblique Part) is defined first by where it attaches. Its origin is the more fixed anchor, usually the proximal or more stable end that stays put during contraction, while its insertion is the more mobile point that is pulled toward the origin when the muscle shortens.
Origin
Anterolateral arch of the cricoid cartilage
Insertion
Anterior border of the inferior horn of the thyroid cartilage
Action & function
When the Cricothyroid (Oblique Part) contracts, it produces the following movement: Tenses and elongates the vocal folds, raising vocal pitch.
As part of the Larynx group of the Head & Neck, it works alongside neighbouring muscles to generate smooth, coordinated movement and to stabilise the structures it acts on.
Nerve supply & clinical relevance
The Cricothyroid (Oblique Part) receives its nerve supply from the External laryngeal branch of the superior laryngeal nerve (vagus, CN X).
Because a muscle can only contract when its nerve is intact, injury to the External laryngeal branch of the superior laryngeal nerve can weaken or paralyse the Cricothyroid (Oblique Part), impairing the movements it normally produces (tenses and elongates the vocal folds, raising vocal pitch). This is why knowing the innervation is central to localising nerve lesions in clinical practice.
How to study the Cricothyroid (Oblique Part) (the OIANS method)
Contrast the oblique part with the straight part by their insertions: both start on the cricoid arch, but the oblique fibres slope backward to the inferior horn of the thyroid cartilage, so they rock the thyroid cartilage rather than simply pulling it forward. Seeing the two directions of pull as complementary explains how they combine to tense the folds.
Bundle its innervation with the straight part and remember the whole cricothyroid answers to the external laryngeal nerve, unlike every recurrent-laryngeal muscle. Because both parts raise pitch by elongating the folds, treat cricothyroid as the pitch-raising tensor of the larynx, and hold the oblique part as its posterior, rocking half.
Frequently asked questions
Where is the Cricothyroid (Oblique Part) located?
The Cricothyroid (Oblique Part) is a muscle of the Larynx group, located in the Head & Neck.
What is the origin of the Cricothyroid (Oblique Part)?
Anterolateral arch of the cricoid cartilage
What is the insertion of the Cricothyroid (Oblique Part)?
Anterior border of the inferior horn of the thyroid cartilage
What movements does the Cricothyroid (Oblique Part) produce?
Tenses and elongates the vocal folds, raising vocal pitch
What nerve supplies the Cricothyroid (Oblique Part)?
External laryngeal branch of the superior laryngeal nerve (vagus, CN X)
Is the Cricothyroid (Oblique Part) free to study in OIANS?
The Cricothyroid (Oblique Part) is always free to browse. Its full origin, insertion, action and nerve details are open to everyone in the Muscle Directory. Quiz and Flashcard practice for the Head & Neck is part of the one-time Lifetime upgrade, though; only the Upper Limb decks are free to test yourself on.
Related muscles
Study the Cricothyroid (Oblique Part)
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