PMC7365184_01
Parts (a) and (b) depict the chin-down posture. (a) NF: The thin black line
connecting the upper margins of the C5 and C6 anterior vertebral bodies forms a 40 
neck flexion (NF) from the bold black line showing a 60  reclining posture. The dashed
black line connecting the lower margins of the C1 and C2 anterior vertebral bodies
creates a 15  extension (physiological cervical lordosis) from the thin black line.
(b) CHNF: The thin black line depicts a 45  NF from the bold black line. The dashed
black line is parallel (straight neck) in reference to the thin black line due to a
15  HF. Parts (c) and (d) show the VFSS results. Chronological changes in swallowing
(3 ml barium paste) are shown from 1 to 5. (c) NF: Residue at the epiglottic
valleculae and pyriform sinuses. (d) CHNF: No residue at the epiglottic valleculae and
pyriform sinuses.
prm-5-20200002-g001.jpg
PMC7365184_01_prm-5-20200002-g001.jpg
fig_001
As shown in Fig. 1, the patient sat in a comfortable 60  reclining position to stabilize the chin-down posture.
(a) Distance between the origin and insertion of the SM, and (b) and (c) distance
between the origin and insertion of the GM. (b) Hyoid in the anterior displacement
start position, and (c) hyoid in the anterior displacement end position.
prm-5-20200002-g002.jpg
PMC7365184_01_prm-5-20200002-g002.jpg
fig_002
The DOI of the SM (DOI-SM) was measured as the distance between the upper end of the manubrium of the sternum and the central portion of the hyoid bone [Fig. 2(a)]. This distance was measured with the hyoid in the anterior displacement start position (b) and the anterior displacement end position (c) [Fig. 2(b), (c)].