The Muscles That Make a Lip and Palate Work
Take the reading one piece at a time. For each piece: read it once, underline the sentence that says what happens, then look up any word in the list. Tap a word to see its definition.
Piece 1 of 2
The core muscle of the lips is the orbicularis oris. Imagine a ring of muscle that circles all the way around the mouth, like a drawstring around the opening of a bag. In a normal lip the fibers run continuously and cross the midline of the upper lip, so when the muscle tightens it closes and purses the lips evenly. A muscle that closes an opening by squeezing in a ring is a sphincter. Because its fibers are continuous across the midline, a baby can seal the lips to hold milk and later to make sounds like p, b, and m.
Piece 2 of 2
The most important muscle of the soft palate is the levator veli palatini. There are two of them, one on each side. Each starts up near the base of the skull (close to the Eustachian tube, which drains the middle ear) and sweeps down, forward, and toward the midline. The key detail: the fibers from the left and right muscles meet in the middle of the soft palate and join, forming a transverse sling (a band running side to side, like a hammock). When this sling contracts it lifts the soft palate up and back to touch the back wall of the throat, sealing the velopharynx. MRI studies confirm that in a normally formed palate the levator forms exactly this transverse, midline-continuous sling.
Reading the Research
- Skim the title and abstract first to get the gist.
- Circle the one sentence that states the main claim.
- Box the evidence the authors give for that claim.
- Mark one sentence that confuses you, and move on.
Now put it together: In one or two sentences, say what this whole reading is telling you about Mateo. Then go back to the lesson and fill in the guided notes.