In order to understand the placements of articulation, we need to name every part of the supra-glottal part of the vocal tract:
Trachea: Leads air to and from the lungs.
Larynx: Above trachea, opens into Pharynx. Its most prominent cartilage is the thyroid cartilage, especially prominent in men's throats (so-called Adam's Apple)
Vocal Folds: A pair of membranes with the ability to vibrate. The space between them is called Glottis. Glottis is V-shaped, as the vocal folds are connected in the front, while their back ends are attached to the Corniculate cartilages, which can abduct them apart for breathing and adduct back together for the phonation position. See the video "A Phoniatrist's View" on the left, towards the bottom of the page.
Oesophagus: Leads into the stomach.
Pharynx: Part of the vocal/gastrointestinal/respiratory tract where all lines (from the oral & nasal cavities and leading to lungs & stomach) meet. Divides into Nasopharynx, Oropharynx and Laryngopharynx.
Epiglottis: A lid preventing food from falling into the wrong pipe. In resting (breathing) position is rised, only covers the larynx when swallowing.
Uvula: The most disgusting part of mouth :-); the lobe hanging from the back of the oral cavity.
Velum: Or Soft Palate. Very important for speaking, because it has the ability to rise itself, thus preventing the air to escape through the nose.
Tongue: Is said to be the strongest muscle of the body. A set of many muscles, can be divided into:
Apex (Tip) - The fastest and most precise part, that is why so relatively many consonants are pronounced on the Alveolar Ridge
A vast majority of speechsounds are lingual (pronounced with the tongue)
Lips: Can be used as primary articulatory organs. E.g. the bilabial p, b, m or labio-dental f, v), or can modify the existing sound by getting rounder or sharper (rounder e.g. for "sh", sharper for "s", but not always, both coarticulation (the surrounding sounds, e.g. in "usu", the [s] will have lips rounded) and individual style of the speaker can play a role.