Biomedical Engineering Reference
In-Depth Information
Fig. 11.5
Attachment points between the face and underlying bony structures. From Ref. [
10
].
Copyright 2013 by American Speech-Language-Hearing Association. Adapted with permission
11.2.1.5 Face-Jaw-Tongue Attachments
The insertion sites of the facial and lingual muscles define the primary attachments
between the face, jaw, and tongue models. Line-based mandibular muscles couple
the hyoid bone to the jaw and skull. These include the digastrics, stylohyoid, and
geniohyoid muscles. The tongue is coupled to the jaw and hyoid bone by node
attachments and by the end-points of the genioglossus andmylohyoidmuscles. These
attachments are implemented with the nodes of the muscle elements in the FEmodel.
The face muscles are attached to the underlying jaw and skull with node attach-
ments. In addition, a number of inner-surface nodes of the face are attached to the
jaw and maxilla to represent the zygomatic and mandibular ligaments. The nodes in
the region of the lips and cheeks are unattached. Adjacent surfaces of the tongue and
face models are attached near the region of the floor of the mouth. The attachment
points are illustrated in Fig.
11.5
.
Contact between the upper and lower lip, the lips and the teeth, the tongue and jaw,
and the tongue and hard-palate are also implemented in the model. Unlike attachment
constraints, which are always coupling the tissues together, contact constraints are
only active when the meshes of the structures are in contact. Contact handling is
described below.
11.2.2 Subject Specific Material Properties
In addition to subject specific morphology, material properties are also required for
a biomechanical model. Subject specific material properties are much more chal-
lenging to acquire than morphology because experimental techniques for measur-
