Muscle · Neck

Inferior pharyngeal constrictor

Musculus constrictor pharyngis inferior

The lowest and thickest of the three overlapping muscular sheets that make up the back and sides of the throat, wrapping from the larynx round to a midline seam behind. It comes in two parts with different fibre directions and different jobs: the upper, oblique part sweeps up over the middle constrictor and squeezes a swallowed bolus downwards, while the lower part runs horizontally around the junction with the oesophagus and stays contracted at rest, holding that junction shut between swallows and relaxing to let each one through. The whole sheet works as a circular squeezer rather than a mover of bones, so no joint action is listed for it.