Lecture 2: Skin, scars and invisible lines of force

Question 1

Recount the 4 layers in normal skin structure from superficial to deep

Answer 1

• epidermis made of epithelial cells.
• Dermis that has an upper border of dermal papillae to provide friction against top layer being sloughed off, and made of reticular collagen and elastic fibres.
• hypodermis (subcutaneous layer) which contains adipose cells
• Investing fascia

Question 2

Describe the structural features given to skin from the dermis and the special term given to this

Answer 2

fibroblasts make collagen (tensile) and elastin (elastic) which are woven together in an irregular way. this means skin has different physical properties in different directions- ability to stretch.
Term: anisotropic

Question 3

Describe the 6 stages of wound healing for 12+ months

Answer 3

1. Bleeding control (haemostasis) and clot formation: make scab
2. Inflammation including: redness, swelling, heat and pain
3. Matrix formation: fibroblast migration producing collagen and elastin
4. Neovascularisation
5. Re- epithelialisation: epithelial cell migration underneath scab
6. Wound contraction and remodelling

Question 4

How long does it take for wound strength (force to reopen a wound) to get back to 90%

Answer 4

A year- so it is a long process

Question 5

What is a scar

Answer 5

Scar is a collagen patch that forms over a wound as part of healing process. collagen align along lines of stress during scar formation

Question 6

Compare Hypertrophic and Keloid scars

Answer 6

Both are red, itchy and raised and are raised because of the disorganised collagen within the reticular dermis that align themselves to fight an external pressure, not the natural line of tension in the skin. However hypertrophic scars remain in the confines of the wound and may contract, remaining for an indefinite period and then maybe regressing over time while Keloid scars invade surrounding tissues, do not contract or regress and often recur and can happen long after the injury.

Question 7

How do you find skin tension (langers) lines?

Answer 7

Circles are applied on the patients back in flexed fetal position. When extended in the anatomical position, the circles deform into ellipses and the long axes of the ellipses align with the skin tension lines

Question 8

How can knowing skin tension lines help in surgery

Answer 8

Wounds will heal better if made parallel to skin tension lines because there is no external force keeping the edges of the wound away from each other and so we can avoid abnormal scaring when doing surgical procedures