Opening of the throat requires flexibility of the throat muscles

I often hear Vocal Coaches say, “try to open your throat when vocalizing.”
I’ll now explain what opening the throat means.
The throat has two layers, when referencing structure. One is inside of the larynx, where the vocal cord is located. The other one is outside of the larynx, where the thyroid cartilage is located. The inside is referred to as the interior, and the outside is the exterior layer.
I’ve asked a professional vocal coach to perform opening of the throat, so I could analyze this procedure, and what I found is as follows:
(1)The hyoid bone moves forward.
(2)The thyroid cartilage moves backwards
(3)The soft palate is then lifted up
(4)The position of the tongue is slightly downward

The above 4 conditions are required to open the throat, and the larynx needs to be in a softened state.
The infrahyoid muscles, suprahyoid muscles, and the pharyngeal muscle located in the throat are all being used when opening the throat.

Luciano Pavarotti opened the throat ideally as follows.e01

Note1: The preferred condition of the larynx to successfully perform the action of the throat opening has four points to keep in consideration. Those four key points are that the vocal cord can vibrate easily, the arytenoid cartilage can move smoothly, the epiglottis can stand up and the space of the piriform recess is large enough to handle the action.
The following photo displays the status of opening the throat.


Note2:The throat has muscles that can contract but not extend by themselves, that is the reason why if your muscles are not flexible the throat cannot open easily.