Posterior CricoArytenoid Muscle (PCA)

The PCA muscle is the only muscle that opens (ABducts) the vocal cords for breathing. Located on the back of the larynx, it is strongly activated by sniffing and can sometimes be seen directly bulging behind the arytenoids.

The Posterior CricoArytenoid (PCA) Muscle

The PCA muscle is located on the back of the larynx, behind and lateral to the arytenoid cartilage. It pulls on the arytenoid cartilage to open the vocal cords for breathing. The effect of contraction of this muscle can be visualized as the opposing effect of contraction of the LCA muscle.

The PCA muscle is strongly activated by sniffing. During a brisk inhale through the nose, the PCA muscle contracts and each vocal process moves laterally, increasing the size of the opening of the glottis.

The PCA is the only abductor of the vocal cords — and its actual bulk can sometimes be seen bulging behind the arytenoids during excess tension phonation.

Additionally, contraction of the PCA muscle can be viewed when a person initiates sound with excess tension. The LCA muscle brings the vocal cords together but then the PCA muscle also contracts and pulls the vocal processes slightly apart. The actual belly of the muscle can be seen bulging behind or posterior to the arytenoids.

PCA indirect effect — vocal processes abducting on brisk inhalation
Indirect Effects: During a brisk breath in, particularly through the nose, the PCA muscles contract and the vocal processes (arrows) move far laterally, opening the airway to its maximum size. This is the configuration when the LCA muscles are at rest.
PCA direct visibility — muscle bulk increases on contraction
Direct Visibility: Left: the relaxed right PCA muscle's bulk between the left arrows is small. Right: the right PCA muscle has contracted, (pulling the vocal cords slightly apart) and the increased thickness of the right PCA muscle is visible between the right arrows.

What You Learned

  • The PCA is the sole abductor — it is the only muscle that opens the vocal cords for breathing.
  • Sniffing activates it strongly — a brisk nasal inhale drives the PCA to open the glottis to its maximum.
  • Its bulk can be directly seen — when the PCA contracts during excess-tension phonation, the muscle belly visibly bulges behind the arytenoids.
  • It opposes the LCA — understanding PCA action is best appreciated as the mirror image of LCA contraction.