11.05: Zone P3 – Inferior Anterior Cheek
YOUR ASSIGNMENT FOR THIS LESSON
✅ Step #1: Review all content below.
✅ Step #2: Image the P3 zone on your own with your ultrasound, and using the checklist provided on this page, check off all key structures to be identified in this location.
TRANSDUCER POSITION AT P3
STANDARD P3 ORIENTATION:
TRANSVERSE
Intersection of horizontal line from labial mental crease to midpupillary vertical line is the location of P3.
- Identify a hyperechoic linear band deeply which is the mandible. Adjust your depth of penetration to position this at the bottom of your screen.
- The hypoechoic linear band directly above the mandible is an accessory muscle to the obicularis oris muscle called the incisivus labii inferioris (ILI) muscle.
- The DAO muscle is a hypoechoic region just deep to the subcutaneous tissue in the lateral fields of the image.
- Deeply, and medial to the DAO muscle is the DLI muscle. These two muscles will overlap slightly.
EXAMPLE OF TRANSVERSE IMAGE ACQUIRED AT P3
ANATOMICAL LEGEND FOR P3 LOCATION IN TRANSVERSE
DOPPLER IMAGES ACQUIRED AT P3 OF KEY VESSELS
- The main vessel to be seen here is the inferior labial artery. The artery can be often seen branching from the facial artery just lateral to P3.
- This vessel will course deep to the DOA muscle and superficial to the DLI muscle.
- Angulating your probe slightly can help you visualize more of the artery simultaneously.