sympathetic nervous system morphology trait Any measurable or observable characteristic related to the shape, structure, color, or pattern of the part of the autonomic nervous system that innervates smooth muscle, cardiac muscle and glands and mediates the body's response to stressful situations. Trait.ontology VT:0001007 adrenergic system morphology trait somatic sympathetic system morphology trait thoracolumbar system morphology trait autonomic nervous system morphology trait