Cricothyroid muscle

The cricothyroid notch is the anatomic reference for the needle insertion.

The needle pierces the skin 5 mm lateral to the midline on the level of the center of the cricothyroid notch at an angle of around 50° to the midline. After insertion, the needle should be moved tangentially to the cricothyroid membrane until entering the muscle after 15–20 mm.

EMG Activity

  • If no activity is recorded, the needle should be withdrawn a few millimeters and aimed more laterally.
  • If the needle is inserted too laterally, the needle will pierce the sternohyoid muscle.
  • To confirm the position of the electrode, the patient is asked to phonate /i:/ at a low pitch and then to raise the pitch. If the electrode is in a normal cricothyroid muscle, the EMG activity will increase sharply.
  • The activity of the sternohyoid muscle can be tested by elevating the head.

Click here to go back to Transcutaneous LEMG.