parasympathetic 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 regulates homeostasis. Trait.ontology VT:0001033 cholinergic system morphology trait craniosacral system morphology trait somatic parasympathetic system morphology trait autonomic nervous system morphology trait