It seemed to suggest a significant redundancy in growth rate of the laryngeal structures.Ībberant origin Cricothyroideus Human fetus Inferior pharyngeal constrictor Laryngeal cartilage Thyrohyoideus Upper esophageal sphincter.Ĭopyright © 2019 Elsevier GmbH. In addition, a final or adult-like morphology was found in two of the present 37 fetal specimens. Such a discrepancy in growth seems to resemble the IPC wrapping around the superior cornu of thyroid cartilage. The aberrant or transient origin of the IPC seemed to result from a discrepancy in growth of the cartilage and muscles. Therefore, these aberrant origins were, even if developed, most likely to be 'corrected' to the adult morphology during midterm or late prenatal period. The inferior pharyngeal constrictor expiratory EMG activity was quantified by averaging the maximal voltage of the integrated signal over the same 15-s epochs. These aberrant connections with nearby muscles seemed to become separated by a growing protrusion of the thyroid cartilage. In four of the latter six specimens, a tendinous band from the IPC inferior end connected to the cricothyroideus muscle to provide a digastric muscle-like appearance. These aberrant connections were most likely to be transient origins of the IPC not from a hard tissue but nearby striated muscles. In serial sagittal sections of 37 embryos and fetuses at 6-15 weeks (crown rump length 15-115mm), we found (1) the IPC connecting to the sternothyroideus and thyrohyoideus muscles (16 fetuses at 6-11 weeks) or (2) the cricothyroideus muscle (6 fetuses at 12-15 weeks) in addition to the usual cricoid origin. The inferior pharyngeal constrictor (IPC) originates from the thyroid and cricoid cartilages and inserts to the pharyngeal raphe.

Inferiror pharyngeal constrictor