11.04: Zone P2 – Lateral Commissure of Lips Region
YOUR ASSIGNMENT FOR THIS LESSON
✅ Step #1: Review all content below.
✅ Step #2: Image the P2 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 P2
STANDARD P2 ORIENTATION:
TRANSVERSE & LONGITUDINAL
Intersection of horizontal line from lateral commissure of lips to midpupillary vertical line is the location of P2.
- IN TRANSVERSE:
- Medially identify a hypoechoic structure with is subcutaneous, this is the orbicularis oris muscle. Deep and lateral to this is another linear hypoechoic structure the buccinator muscle. Directly superficial to the buccinator muscle is. the buccal fat pad
- IN LONGITUDINAL:
- Identify a hypoechoic linear band like structure, the orbicularis oris muscle. Scan until you find a hypoechoic structure just deep and in continuity to the orbicularis oris muscle, this is the modiolar region, where 5 muscles are converging (see figure below).
EXAMPLE OF TRANSVERSE IMAGE ACQUIRED AT P2
ANATOMICAL LEGEND FOR P2 LOCATION IN TRANSVERSE
EXAMPLE OF LONGITUDINAL IMAGE ACQUIRED AT P2
ANATOMICAL LEGEND FOR P2 LOCATION IN LONGITUDINAL
DOPPLER IMAGES ACQUIRED AT P2 OF KEY VESSELS
- IN TRANSVERSE:
- You will be transecting the facial artery in this short axis in this plane, so it will appear circular. You will find this vessel within the buccal fat pad.
- IN TRANSVERSE:
- You will be transecting the facial artery in this long axis in this plane, so it will appear linear, or as a bead of high flow regions (due to a torturous course).
- Slightly angulate the probe with the marker more anterior to often see more of the facial artery simultaneously.
- If you scan just anterior to the facial artery from P2, you will often encounter the superior labial artery with will be transected in the short axis, and appear circular.