Undermining Planes in Dermatologic Surgery Part 2
In the cheek, undermining is performed in the mid subcutaneous plane to reduce risk of transecting the parotid duct, branches of the facial nerve including the buccal and zygomatic branches of cranial nerve VII, and regional vascular structures. In the lateral neck, undermining is performed in the superficial subcutaneous plane to remain superficial to the spinal accessory nerve at Erb point. In the lip, the correct plane is immediately above the orbicularis oris muscle to avoid injury to the vascular orbicularis muscle and branches of the labial arteries. In the eyelids, undermining occurs immediately above the orbicularis oculi muscle because the eyelids contain minimal subcutaneous tissue. In the eyebrows, undermining is performed in the subcutis deep to hair bulbs to reduce postoperative eyebrow alopecia. In the temple, undermining occurs in the superficial subcutaneous plane to protect the temporal branch of the facial nerve and the temporal artery.
Cheek
- Woman Applying Blush = Undermining plane of cheek in mid subcutaneous plane
- Sub On Middle Of Shirt = Mid subcutaneous plane middle layer
- Parrot On Shoulder Near Parotid Duct = Avoid parotid duct
- Belt Buckle And Passport To Zanzibar = Avoid buccal and zygomatic branches of cranial nerve VII
- Red Tail On Parrot = Avoid vascular structures
Lateral Neck
- Kid Eating A Wrap = Undermining plane of lateral neck in superficial subcutaneous plane
- Wrap Bread = Superficial subcutaneous tissue
- Necklace Labeled ERB = Avoid spinal accessory nerve at Erb point
Lip
- Woman Applying Lipstick With Orbiting Cloud = Undermining plane of lip above orbicularis oris muscle
- Blood Vessel Strands And Purse Resembling Orbicularis Oris = Avoid vascular orbicularis muscle and labial artery branches
Eyelids
- Woman With Wide Open Eyelids And Orbiting Clouds = Undermining plane of eyelids immediately above orbicularis oculi muscle minimal subcutaneous tissue
Eyebrows
- Man With Bushy Eyebrows Digging Through Bulbs = Undermining plane of eyebrows in subcutis deep to hair bulbs to minimize hair loss
Temple
- Priest Eating Superficial Sandwich Wrap = Superficial subcutaneous plane in temple
- High Tempo Speedometer = Avoid temporal branch of facial nerve and artery
Quiz
Question 1
Which undermining plane is recommended for surgical dissection of the cheek?
A. Deep subcutaneous plane
B. Mid subcutaneous plane
C. Submuscular plane
D. Dermal plane
Question 2
Undermining in the lateral neck should remain superficial to which nerve?
A. Marginal mandibular nerve
B. Greater auricular nerve
C. Spinal accessory nerve
D. Hypoglossal nerve
Question 3
The appropriate undermining plane of the lip lies immediately above which muscle?
A. Orbicularis oculi
B. Orbicularis oris
C. Buccinator
D. Levator labii superioris
Question 4
Which arterial branches are at risk when undermining the lip too deeply?
A. Angular arteries
B. Labial arteries
C. Temporal arteries
D. Supraorbital arteries
Question 5
Why must eyelid undermining remain immediately above the orbicularis oculi muscle?
A. The eyelid contains minimal subcutaneous tissue
B. The levator palpebrae lies superficially
C. The supraorbital nerve lies within the dermis
D. The tarsal plate is superficial
Question 6
Undermining the eyebrow deep to which structure helps prevent eyebrow hair loss?
A. Hair shaft
B. Hair bulbs
C. Sebaceous glands
D. Dermal papilla
Question 7
Which nerve must be avoided when undermining the temple in the superficial subcutaneous plane?
A. Infraorbital nerve
B. Temporal branch of the facial nerve
C. Zygomatic nerve
D. Buccal nerve
Answers:
1 B. Mid subcutaneous plane
2 C. Spinal accessory nerve
3 B. Orbicularis oris
4 B. Labial arteries
5 A. The eyelid contains minimal subcutaneous tissue
6 B. Hair bulbs
7 B. Temporal branch of the facial nerve