Final answer:
The term 'trachealis' pertains to the trachea and refers to the muscle that aids in regulating the diameter of the trachea during respiration.
Step-by-step explanation:
The term that means pertaining to the trachea is trachealis.
This term refers to the trachealis muscle, which is a band of smooth muscle that extends longitudinally between the ends of the C-shaped cartilages at the posterior part of the trachea, connecting them.
The trachealis muscle is important because it allows the diameter of the trachea to change slightly during breathing, facilitating the passage of air and playing a role in the cough reflex.