The posterior cricoarytenoid muscles are small, paired intrinsic muscles of the larynx that extend between

cricoid cartilage The cricoid cartilage , or simply cricoid (from the Greek ''krikoeides'' meaning "ring-shaped") or cricoid ring, is the only complete ring of cartilage around the trachea. It forms the back part of the voice box and functions as an attachment sit ...

to the

arytenoid cartilage The arytenoid cartilages () are a pair of small three-sided pyramids which form part of the larynx. They are the site of attachment of the vocal cords. Each is pyramidal or ladle-shaped and has three surfaces, a base, and an apex. The arytenoid ...

s in the

larynx The larynx (), commonly called the voice box, is an organ in the top of the neck involved in breathing, producing sound and protecting the trachea against food aspiration. The opening of larynx into pharynx known as the laryngeal inlet is abo ...

Structure

Origin and insertion

The posterior cricoarytenoid originates from the posterior surface of the posterior quadrate lamina of the

. It inserts onto the muscular process of the

. Its distinct medial and lateral bellies insert onto opposite surfaces of the muscular process.

Nerve supply

The posterior cricoarytenoid muscles are supplied by the anterior division of the

recurrent laryngeal nerve The recurrent laryngeal nerve (RLN) is a branch of the vagus nerve (cranial nerve X) that supplies all the intrinsic muscles of the larynx, with the exception of the cricothyroid muscles. There are two recurrent laryngeal nerves, right and l ...

, a branch of the

vagus nerve The vagus nerve, also known as the tenth cranial nerve, cranial nerve X, or simply CN X, is a cranial nerve that interfaces with the parasympathetic control of the heart, lungs, and digestive tract. It comprises two nerves—the left and right ...

(CN X). Sometimes, different parts of the muscle (such as the medial and lateral muscle bellies) are supplied by separate branches. This may vary between 1 and 6 branches, usually 2 or 3. These may connect within the muscle.

Function

The posterior cricoarytenoid muscles are the only muscles to open the

vocal cords In humans, vocal cords, also known as vocal folds or voice reeds, are folds of throat tissues that are key in creating sounds through vocalization. The size of vocal cords affects the pitch of voice. Open when breathing and vibrating for speech ...

. By rotating the arytenoid cartilages laterally, these muscles abduct the

vocal cord In humans, vocal cords, also known as vocal folds or voice reeds, are folds of throat tissues that are key in creating sounds through vocalization. The size of vocal cords affects the pitch of voice. Open when breathing and vibrating for speec ...

s. This opens the

rima glottidis The rima glottidis is the opening between the two true vocal cords anteriorly, and the two arytenoid cartilages posteriorly. It is part of the larynx. Anatomy The rima glottidis is the narrowest part of larynx. It is longer (~23 mm) in males ...

. This is important in

breathing Breathing (or ventilation) is the process of moving air into and from the lungs to facilitate gas exchange with the internal environment, mostly to flush out carbon dioxide and bring in oxygen. All aerobic creatures need oxygen for cell ...

and

speech Speech is a human vocal communication using language. Each language uses phonetic combinations of vowel and consonant sounds that form the sound of its words (that is, all English words sound different from all French words, even if they ar ...

. Their action opposes the

lateral cricoarytenoid muscle The lateral cricoarytenoid (also anterior cricoarytenoid) muscles extend from the lateral cricoid cartilage to the muscular process of the arytenoid cartilage. By rotating the arytenoid cartilages medially, these muscles adduct the vocal cords and ...

Clinical significance

Paralysis of the posterior cricoarytenoid muscles may lead to

asphyxia Asphyxia or asphyxiation is a condition of deficient supply of oxygen to the body which arises from abnormal breathing. Asphyxia causes generalized hypoxia, which affects primarily the tissues and organs. There are many circumstances that ca ...

, as they are the only laryngeal muscles to open the

(allowing

Denervation Denervation is any loss of nerve supply regardless of the cause. If the nerves lost to denervation are part of the neuronal communication to a specific function in the body then altered or a loss of physiological functioning can occur. Denervati ...

leads to a slow

fibrosis Fibrosis, also known as fibrotic scarring, is a pathological wound healing in which connective tissue replaces normal parenchymal tissue to the extent that it goes unchecked, leading to considerable tissue remodelling and the formation of perm ...

that worsens over many months.

Additional images

File:Gray950.png, The cartilages of the larynx. Posterior view. File:Gray958.png, Muscles of larynx. Posterior view. File:Gray960.png, Muscles of the larynx, seen from above. File:Gray1028.png, Dissection of the muscles of the palate from behind. File:Slide6sss.JPG, Posterior cricoarytenoid muscle File:Slide13sss.JPG, Posterior cricoarytenoid muscle File:Slide4kkkk.JPG, Posterior cricoarytenoid muscle

References

External links

* * () {{Authority control Muscles of the head and neck