ANATOMICAL STUDY

Assembling Facial Muscles in a Skull Model for Plastic
Surgery Trainees
Seon Mi Yun, BHS, Kun Hwang, MD, PhD, and Chan Yong Park, MD, PhDy
Abstract: The aim of this study was to report the results of a
training workshop on assembling facial muscles in a skull model,
with a focus on the depth and intermingling of the muscles.
A commercially available model with facial and masticatory
muscles was used and this has 33 muscle pieces removable andattachable by magnets. Seven participants were recruited for workshop. At first stage, they were asked to assemble 33 detached pieces.
Atlases of facial anatomy and Google searches except scientificarticles were available. The time required to complete the assembly
was measured. At second stage, a review article on facial anatomy
was provided and they were again asked to assemble the pieces andthe time was also measured. They were asked to rate their satisfaction with the outcomes on a Likert scale.
In the second stage, the time was significantly shortened (from66.9  22.2 to 27.9  15.0 minutes, P ¼ 0.002). The reasons for thisimprovement we think are: first, repeating an activity itself shortens
time, and second, reading a review article about the anatomy of theface, especially the depth and relationship of each muscle, provided
participants with deeper anatomical knowledge. Upon finishing the2-stage workshop, the participants’ knowledge of the name(P ¼ 0.019), origin and insertion of each muscle (P ¼ 0.017), as
well as the relationships of all neighboring muscles (including theirdepth) increased significantly (P ¼ 0.002).
This model would be useful for anatomy classes at the undergraduate level in medical schools or developing a station as part ofthe objective structured clinical examination for board certification.
Key Words: Anatomy, education, facial muscles, medical,regional(J Craniofac Surg 2022;33: 939–941)
From the Department of Plastic Surgery, Inha University College ofMedicine, Incheon; and yDivision of Trauma Surgery, Department ofSurgery, Seoul National University Hospital, Seoul, South Korea.
Received December 3, 2020.
Accepted for publication July 4, 2021.
Address correspondence and reprint requests to Kun Hwang, MD, PhD,
Department of Plastic Surgery, Inha University College of Medicine, 27
Inhang-ro, Jung-gu, Incheon, 22332, South Korea;
E-mail: jokerhg@inha.ac.kr; Chan Yong Park, MD, PhD, Division ofTrauma Surgery, Department of Surgery, Seoul National University
Hospital, 101 Daehak-ro, Jongno-gu, Seoul 03080, South Korea;
E-mail: wkafyddl@hanmail.net
This study was supported by a grant from Inha University Hospital.
The authors report no conflict of interest.
Supplemental digital contents are available for this article. Direct URL
citations appear in the printed text and are provided in the HTML andPDF versions of this article on the journal’s web site (www.jcraniofacialsurgery.com).
Copyright # 2021 by Mutaz B. Habal, MD
ISSN: 1049-2275
DOI: 10.1097/SCS.0000000000008014

An individual’s appearance and facial expression are based on
the musculoskeletal system of the face. The facial muscles orskin muscles generally originate from underlying bone surfaces andinsert to the skin of the face or intermingle with other facialmuscles. This complex musculature orchestrates the functions of
the eye, nose, ear, and mouth, as well as the facial expressions ofemotional and affective states.1In facelift surgery, the facial muscles are important landmarks inthe dissection of the superficial fascia in different planes foravoiding injuries of the facial nerve. Since the facial nerve branches
are not all present in the same plane, a three-dimensional anatomical
knowledge of the facial musculature is essential for young plastic
surgeons, especially trainees.
There have been several computer models of facial soft tissues,2,3 as well as a body painting model.4 However, these models
were made available through a computer interface. We thoughtthat assembling facial muscles in a physical skull model could
help plastic surgery trainees to learn the facial muscles and theirrelationships.
The aim of this study was to report the results of a training
workshop on assembling facial muscles in a skull model, with afocus on the depth and intermingling of the muscles.

MATERIALS AND METHODSModel
We used a commercially available model with facial and masticatory muscles (J-01, Bikin Lab/Iyashikuukan-fuu, MMI Co,Niigata, Japan). This model has 33 muscle pieces that are removable
and attachable by magnets (Figs. 1–2).

Participants
Seven participants (4 plastic surgery residents and 3 graduate
students enrolled in the PhD program in plastic surgery) wererecruited for the facial muscle assembly workshop.

Selection of an Article to Read Between Stage 1
and Stage 2
In PubMed, a search was made using the terms (facial muscles)
AND (anatomy) AND (superficial) AND (deep), resulting in 124
titles. Among the 124 abstracts, 2 full papers were reviewed,1,5 andfinally 1 review paper was selected.1
First stage: The participants were asked to assemble 33 muscle
pieces, which were all detached. Atlases of facial anatomy andGoogle searches were made available to the participants, whereas
they assembled the models; however, scientific articles were prohibited during the workshop. The time required to complete theassembly was measured.
Second stage: A selected review article on facial anatomy wasprovided.1 At least 1 week later, the participants were again asked toassemble the 33 muscle pieces, which were all detached as before.
The time required to complete the assembly was measured.
The participants were asked to rate their satisfaction with theoutcomes on a Likert scale (5: definitely satisfied, 4: satisfied, 3:The Journal of Craniofacial Surgery  Volume 33, Number 3, May 2022

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Copyright © 2022 by Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.

The Journal of Craniofacial Surgery  Volume 33, Number 3, May 2022

Yun et al

FIGURE 1. Model with facial and masticatory muscles, with 33 muscle pieces
removed.

neutral, 2: not satisfied, 1: definitely not satisfied) (SupplementaryDigital Content, Assessment Form 1, http://links.lww.com/SCS/
D27, Supplementary Digital Content, Assessment Form 2, http://links.lww.com/SCS/D28).

RESULTS

The time required to complete the assembly was 66.9  22.2 minminutes in the first stage and 27.9  15.0 minutes in the second
stage. The required time was significantly shorter in the second
stage (P ¼ 0.002 [independent 2-samples t test]) (SupplementaryDigital Content, Table 1, http://links.lww.com/SCS/D29).
After completing the 2-stage workshop, the participants’ knowledge of the name of each muscle (3.1  0.7 to 4.1  0.7) and their
origin and insertion (2.6  0.8 to 3.6  0.5) increased significantly(P ¼ 0.019 and P ¼ 0.017, respectively [independent 2-samples ttest]). The participants’ knowledge of the relationships of allneighboring muscles, including their depth (2.0  0.6 to 3.7
 1.0), increased significantly (P ¼ 0.002 [independent 2-samplest test]). However, there was no significant difference in the participants’ knowledge of the function of each muscle (3.3  0.8 to 3.7
 1.0) (P ¼ 0.369 [independent 2-samples t test]) (SupplementaryDigital Content, Table 1, http://links.lww.com/SCS/D29).
The satisfaction score for whether the participants found theworkshop interesting or boring was 4.7  0.5. The satisfaction score
for whether the workshop was helpful practically was 4.7  0.5. A
high satisfaction score (4.9  0.4) was also found for whether thetechnical process was helpful from a practical standpoint as a doctor
or anatomist. The satisfaction score for whether the workshop
improved the participants’ knowledge of the configuration of thefacial muscles was 4.4  1.0. The satisfaction score for participationin the workshop was 4.7  0.5, whereas that for whether theworkshop should be included in the objective structured clinicalexamination for board certification was 4.4  0.8. The satisfaction
score for whether the participants would recommend the workshop

940

FIGURE 2. Assembled model in which the muscles are attached by magnets.

to others was 4.9  0.4 (Supplementary Digital Content, Table 2,
http://links.lww.com/SCS/D30).

DISCUSSION
The muscles of the face include all the mimetic muscles innervatedby the facial nerve (VII). Two masticatory muscles (the masseterand temporalis) supplied by the motor portion of the trigeminal
nerve (V3) also contribute to the facial contour.1
Mazza developed a computer model of the face that included thesuperficial layers of the face (skin, superficial musculoaponeurotic
system, and fat), and most facial muscles.2 Nowinski created athree-dimensional interactive, stereotactic atlas, which provided
spatial relationships among the head muscles, glands, and cranial
nerves.3 Boggio used the body painting technique to represent themajor muscle groups of botulinum toxin A targets.4 These models
showed the anatomy of the face well, but were only accessible onflat computer monitors.
On the contrary, our model was composed of a plastic skull modelthat had 33 pieces of muscles that were removable and attachable by amagnet. When the participants were assembling the pieces, theyengaged in a trial-and-error process because the pieces could not
be assembled if the deeper muscle had not been attached first.
In the second stage, the time required to complete the assembly
was significantly shortened (from 66.9 to 27.9 minutes). We thinkthat the reasons for this improvement were as follows: first,
repeating an activity itself shortens the required time, and second,reading a review article about the anatomy of the face, especially#2021 Mutaz B. Habal, MD

Copyright © 2022 by Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.

The Journal of Craniofacial Surgery  Volume 33, Number 3, May 2022

the depth and relationship of each muscle, provided participants
with deeper anatomical knowledge. Upon finishing the 2-stage
workshop, the participants’ knowledge of the name, origin, andinsertion of each muscle, as well as the relationships of all neighboring muscles (including their depth) increased significantly.
The difference between the groups was significant and showed
an improving trend between the first and second activity and this is
more likely due to repeated action on the same model. The fact thatthe second attempt was after reading relevant articles cannot sorely
indicate an improvement in knowledge and this cannot be proven by
this experimental method. Further study, which compare control
group with experimental group who received academic articles
before the first attempt might be followed.
This model would be useful for anatomy classes at the undergraduate level in medical schools. It is suggested to hold workshops
for larger groups in plastic surgery residency programs or todevelop a station using this model as part of the objective structured
clinical examination for board certification.

Assembling Facial Muscles in a Skull

ACKNOWLEDGMENTS
The authors thank to Hun Kim, PhD, Department of Plastic Surgery,
Inha University College of Medicine, for making figures.

REFERENCES
1. von Arx T, Nakashima MJ, Lozanoff S. The face – a musculoskeletal
perspective: a literature review. Swiss Dent J 2018;128:678–688
2. Mazza E, Barbarino GG. 3D mechanical modeling of facial soft tissue forsurgery simulation. Facial Plast Surg Clin North Am 2011;19:623–637
3. Nowinski WL, Chua BC, Johnson A, et al. Three-dimensional interactive
and stereotactic atlas of head muscles and glands correlated with cranial
nerves and surface and sectional neuroanatomy. J Neurosci Methods
2013;215:12–18
4. Boggio RF. Dynamic model of applied facial anatomy with emphasis onteaching of botulinum toxin A. Plast Reconstr Surg Glob Open 2017;5:e1525
5. Westbrook KE, Nessel TA, Varacallo M. Anatomy, Head and Neck, FacialMuscles. Treasure Island, FL: StatPearls Publishing; 2020

Gone forever.

#2021 Mutaz B. Habal, MD

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Copyright © 2022 by Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.