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Where do the internal carotid and external carotid arteries not anastamose?

A. Perinasal

B. Glabella

C. Mentum

D. Periorbital

C. Mentum. Blood supply to the head and neck is via the internal carotid artery (ICA) and external carotid artery (ECA) and their branches. Intimate anastamoses between ICA and ECA occur in the region of the upper central face (nose, glabella, periorbital, and forehead). These connections are important clinically in that: (1) infections in this area may extend intracranially via ICA; (2) steroid injections in the periorbital skin may embolize to the retinal artery and cause blindness.

Put the following items in order from least to most sensitive to cryogen exposure:

  1. Melanocytes

  2. Keratinocytes

  3. Fibroblasts

A. 1, 2, 3

B. 1, 3, 2

C. 2, 1, 3

D. 2, 3, 1

E. 3, 2, 1

F. 3, 1, 2

E. 3, 2, 1 (fibroblast, keratinocyte, melanocyte). Different cells and tissues demonstrate a range of temperature sensitivity. Melanocytes are more sensitive than keratinocytes, and with cold injury, dyspigmentation should be discussed as an adverse outcome when treating dark skinned individuals. Fibroblasts and other stromal structures are less sensitive to cold, which may contribute to the lack of scarring after superficial cold injury and/or cryosurgery.

How much will a scar lengthen with a 60-degree Z-plasty transposition?

A. 10%

B. 25%

C. 50%

D. 55%

E. 75%

E. 75%. The Z-plasty is a form of transposition flap that is often used for scar revision for scar length and changing scar orientation. It alters the change (redirection) of tension vectors of the original wound/scar, in addition to lengthening and breaking up of a scar into multiple zigzag lines. The extent of scar lengthening depends on the degree of transposition of the Z-plasty.

Which of the following in not a risk factor for a patient developing methhemoglobinemia while using topical EMLA?

A. Patient younger than 1 year old

B. Patient with G-6-PD deficiency

C. Patient with sickle cell anemia

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