Fig 1.
The original neck musculoskeletal model.
(A) Skeletal joints are shown as axes and the head COM is shown as a sphere; (B) different views of the 84 neck muscles including the hyoid muscles.
Fig 2.
The adjusted 50th percentile musculoskeletal model fitted within the mean ANSUR II Skin.
(A) Male; (B) Female.
Fig 3.
Body segmentation of the ANSUR II average (A) male and (B) female. The segmentation is done based on the anatomical structures contained in each body part and limited manual adjustment. The different shades of red and blue identify the different body parts.
Fig 4.
Zoom-in view of the head and neck segmentation for (A) male and (B) female. The balls are the COMs of the head and neck. The local rotational axes for head and neck are also shown. Planes of separation of the neck from the torso and the head are based on the rules by Walker et al. [18].
Table 1.
Peak forces and moments that can be resisted by the 50th percentile male and female for extension, flexion, lateral bending and axial rotation.
The male and female target data from literature [19–22] are the targets used for optimization, and the male and female optimized are the forces and moment that can be resisted by the optimized models.
Table 2.
Muscle volume distributions (calculated from isometric muscle strength and optimal fiber length) by Zheng et al. [8,9], with total muscle volume in the bottom row.
Fig 5.
Exemplary anthropometry body models generated based on neck width, depth and length.
Fig 6.
Anthropometrically scaled percentile models (5th, 50th, 95th) for (A) males and (B) females.
Table 3.
Mass and inertia properties of the head and neck of the 50th percentile male and female models.
x, y, z are the anterior-posterior, media-lateral, and top-bottom directions, respectively. Inertia properties (unit: 10−4 kgm2) are relative to the segment’s COM.
Fig 7.
Placement of (A) the rectus capitis anterior and(B) lateralis in the model.
Table 4.
Maximum isometric muscle forces of the original model and the final optimized and scaled male and female models.
Table 5.
Body height, mass, neck circumference and length of the 12 percentile male models that have been created together with data for the 50th percentile male.
These data are reproduced from the ANSUR II database [36].
Table 6.
Body height, mass, neck circumference and length of the 12 percentile female models that have been created together with data for the 50th percentile female.
These data are reproduced from the ANSUR II database [36].
Fig 8.
Comparison of the peak resistible forces and moments for the 13 (A) male percentile models and (B) female percentile models.