The oxygen molecules moves through the nostrils, pharynx, trachea, bronchus, smaller and smaller branches of the bronchial tree, and then into the alveolus.
The path of oxygen from the atmosphere to the lungs can be described from the nasal cavity to the alveoli. The oxygen is inhaled with air during the breathing process that travels from the nasal cavity to the pharynx that is tube or tract where mouth or oral cavity and nasal cavity combined. Oxygen moves from pharynx to the larynx and then to trachea or the windpipe.
The trachea is a tube that extended to the larynx to the 2 primary bronchi. Oxygen moves from the trachea to the bronchi. Bronchi are the main passage of oxygen to the lungs. Bronchi shuttle air to and from the lungs. These are of three types and oxygen travels into each in order first primary bronchi then secondary and in last to tertiary bronchi and bronchioles and ultimately to the site of gas exchange called alveoli.
