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9.07: Zone C5 – Inferior Mid-Pupillary Region

YOUR ASSIGNMENT FOR THIS LESSON

✅ Step #1: Review all content below.

✅ Step #2: Image the C5 zone on your own with your ultrasond, and using the checklist provided on this page, check off all key structures to be identified in this location

TRANSDUCER POSITION AT C5

Note: Clip is sped up.

STANDARD C5 ORIENTATION:
TRANSVERSE

The intersection of the vertical line from mid-pupil to the horizontal line from the inferior alar groove is the location of C5.

QUICK TIP
  • In most patients you will need to increase your depth of penetration here to about 2cm.
  • It can be very hard to identify the zygomaticus minor and LLS muscles from the surrounding fatty tissue. Having the patient smile while imaging C5 can help identify which hypoechoic regions are involved in contracting and this can be used to differentiate fatty tissue from muscles.

EXAMPLE OF TRANSVERSE IMAGE ACQUIRED AT C5

Standard image acquired at C5. (Transverse | Left side is patient's left). See key below for lables.*

ANATOMICAL LEGEND FOR C5 LOCATION IN TRANSVERSE

*Standard image acquired at C5 labeled with key anatomical structures.
Superficial Fat Compartments
Deep Fat Compartments

KEY VESSELS IN THE REGION

There is variability in the course of the facial / angular vein. It usually is deep to the zygomatic muscles and superfical to the LLS muscle, but in a minority of cases it can be superficial to the zygomatic muscles.

DOPPLER IMAGES ACQUIRED AT C5 OF KEY VESSELS

Play Video
QUICK TIP
  • In this area you will most commonly identify the facial vein it's course is very variable. You may need to scan inferiorly or superiorly from C5 to detect it.
    • The course of the vein at C5 is large;y determined by how far superiorly it travels along the margin of masseter muscle. The longer it travels along this muscle the more superior it will usually be from C5. The inverse of this is also true.
    • The facial vein is usually but not always deep to the zygomatic muscles, and it will be superficial to the LLS muscle.

DO IT YOURSELF CHECKLIST

Structures to Identify on Ultrasound for C5

Once you have completed this checklist, mark this part of the lesson as complete.