Certified Wound Ostomy Nurse (CWON) Practice Test

Which tissue layer is most vulnerable to ischemic damage?

1. Dermal layer

2. Epidermal layer

3. Muscle/fascia layer

4. Subcutaneous layer

The correct answer is: Muscle/fascia layer

The muscle/fascia layer is the most vulnerable to ischemic damage primarily due to its high metabolic demand and sensitivity to oxygen deprivation. This layer has a greater need for blood supply to support its metabolic activities, especially during periods of reduced blood flow. When ischemia occurs, tissues that require a consistent and adequate blood supply, such as muscle, can suffer more significant and quicker damage compared to other layers. In contrast, the epidermal layer is relatively avascular and can survive temporarily without a direct blood supply; it relies on diffusion from underlying layers for nutrients. The dermal layer, while it contains blood vessels, has a more considerable ability to withstand some degree of ischemia before permanent damage occurs. The subcutaneous layer, primarily composed of fat and connective tissue, is also more resilient under ischemic conditions and does not have the same metabolic demands as the muscle/fascia layer. Thus, the muscle/fascia layer’s vulnerability to ischemic injury is a reflection of its critical dependence on a robust blood supply to maintain cellular function.