Oblique part of cricothyroid muscle
Pars obliqua musculi cricothyreoidei
The oblique part is the rear, more horizontal set of cricothyroid fibres, running from the cricoid arch to the thyroid cartilage's lower horn.
At a glance
- English
- Oblique part of cricothyroid muscle
- Latin (TA2)
- Pars obliqua musculi cricothyreoidei
- System
- Muscle
- Region
- Neck
- Side
- Paired, left and right
About the oblique part of cricothyroid muscle
The cricothyroid is the only intrinsic muscle of the larynx that lies on its outer surface. It sits on the front and side of the larynx, between the arch of the cricoid cartilage and the lower edge of the thyroid cartilage, and has two parts. The straight part in front runs steeply upwards to the lower border of the thyroid lamina. The oblique part lies behind it, and its fibres run backwards and outwards, much nearer the horizontal.
The oblique part arises from the outer surface of the cricoid arch, behind the straight part. Its fibres pass backwards and upwards to the front edge of the inferior horn of the thyroid cartilage, close to the cricothyroid joint, where the horn rests on the side of the cricoid. A small gap usually separates the two parts at their origin.
The two parts act together to lengthen and tense the vocal folds, which raises the pitch of the voice. The straight part mainly tilts the thyroid cartilage forwards and down on the cricoid, like closing a visor. The oblique part, because of its line of pull, mainly slides the thyroid cartilage forwards on the cricoid at the cricothyroid joint. Both movements increase the distance between the thyroid angle and the arytenoids, stretching the vocal ligaments between them.
Unlike the other intrinsic laryngeal muscles, the cricothyroid is supplied by the external branch of the superior laryngeal nerve, a branch of the vagus. Its blood comes from the cricothyroid branch of the superior thyroid artery. The external laryngeal nerve runs close to the superior thyroid vessels and can be damaged when they are tied during thyroid surgery; the result is a voice that tires quickly and cannot reach high notes.
Attachments, action and supply
- Origin
- Outer surface of the cricoid arch, behind the straight part.
- Insertion
- Front border of the inferior horn of the thyroid cartilage.
- Action
- Slides the thyroid cartilage forwards on the cricoid, tensing and lengthening the vocal folds and raising pitch.
- Nerve supply
- External branch of the superior laryngeal nerve (from the vagus, CN X).
- Blood supply
- Cricothyroid branch of the superior thyroid artery.
Anthromica
See the oblique part of cricothyroid muscle where it really sits, with every layer of the body around it.
- Every layer, one body. Peel from muscle to bone, nerve, vessel and organ, and turn it any way.
- English and Latin. Every structure named the way your exam names it.
- Quiz until it sticks. Short drills on the structures you keep missing.
Free to start. No card.
