Which statement best describes the outermost layer composition?

Which statement best describes the outermost layer composition?

• A. Elastic collagen fibers and connective tissue
• B. Smooth muscle and elastin only
• C. Endothelium and basement membrane
• D. Muscle and nerve fibers

Answer: (A)

The outermost layer of a vessel wall is the adventitia, a sheath of dense connective tissue that contains collagen fibers with some elastic fibers. This arrangement provides structural support and anchors the vessel to surrounding tissues, which is why describing it as elastic collagen fibers and connective tissue fits best. The middle layer is mainly smooth muscle with elastic fibers, and the innermost layer is the endothelium sitting on a basement membrane. While nerves can be present in the outer layer, they aren’t the defining component, making that option less appropriate.

The outermost layer of a vessel wall is the adventitia, a sheath of dense connective tissue that contains collagen fibers with some elastic fibers. This arrangement provides structural support and anchors the vessel to surrounding tissues, which is why describing it as elastic collagen fibers and connective tissue fits best. The middle layer is mainly smooth muscle with elastic fibers, and the innermost layer is the endothelium sitting on a basement membrane. While nerves can be present in the outer layer, they aren’t the defining component, making that option less appropriate.