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Page 4 of 5 Muñoz-Jimenez et al. Plast Aesthet Res 2018;5:14 I http://dx.doi.org/10.20517/2347-9264.2018.04

Table 1. Anatomic characteristics of the inferior belly of the omohyoid muscle
Model # 1 # 2 # 3 # 4 # 5 Mean
Left Right Left Right Left Right Left Right Left Right
Vascular pedicle length 15 17 28 - 13 21 23 - 20 42 22.3
Nerve length 46 17 37 - 26 21 31 - 25 20 27.8
Flap length 67 90 85 - 110 100 84 - 100 110 93.2
Flap width 20 16 16 - 6 11 11 - 12 11 12.8
Flap thickness 8 7 6 - 6 7 7 - 9 12 7.7
Tendon-Pedicle distance 19 19 27 - No central tendon 25 - 75 53 27.2
Source vessel SC SC SC - SC SC SC - TC TC
Main nerve AC AC AC - AC AC AC - AC AC
All measurements are expressed in millimeters (mm). SC: subclavian artery; TC: transverse cervical artery; AC: ansa cervicalis

DISCUSSION
Our work represents the first time an anatomical study focused on the morphology of the inferior belly of
the omohyoid muscle and its potential use as a free flap has been performed.

Our results show that the inferior belly is a small and thin muscle, with average measures of 93 mm × 12 mm
× 7.5 mm, a trait that could prove to be advantageous, especially in facial reconstruction. The short length
of the muscle’s belly might raise concern about its contractile capacity and usefulness as a functional flap;
however the senior author of this paper has observed that the muscle presents a nice range of motion when
subjected to transoperatory neurostimulation during procedures for brachial plexus injury [Video 1].

Previous anatomical studies have described that the strap muscles present high morphological variability ,
[2]
and we found that the inferior belly of the omohyoid muscle is no exception: a minor pedicle from the
transverse cervical vessels was found in 2 cases, and 1 case in which the main pedicle came from the
transverse cervical artery, in lieu of the subclavian artery.

The vascular pedicle of the inferior belly presents anatomical characteristics that may hinder its widespread
use, mainly the presence of a short and narrow pedicle (22.3 mm × 0.8 mm), nevertheless, the use of vein
grafts and supermicrosurgery might help overcome the problem. Our results show that the inferior belly of
the omohyoid muscle is innervated by the ansa cervicalis, and that it is relatively short as well, with a mean
length of 27.8 mm, however this limitation could be solved in a simple manner by using nerve autografts.

In conclusion, as microsurgical techniques and anatomical understanding of our body have expanded in
the last decade, multiple new flaps have been described; the use of supermicrosurgery has further pushed
boundaries and now vascular anastomosis in structures with a diameter minor to 0.8 mm are possible. This
anatomical study of the inferior belly of the omohyoid muscle proposes its use in reconstructive procedures
that require a small myofunctional flap such as facial reanimation surgery, sphincter reconstruction, vocal
cord reconstruction, and blink restoration surgery.

DECLARATIONS
Authors’ contributions
Anatomical model dissection, data acquisition and analysis: Muñoz-Jimenez G
Data analysis, paper writing, editing and translation: Telich-Tarriba JE, Palafox-Vidal D
Project supervisor and anatomical model dissection: Cardenas-Mejia A

Data source and availability
Anatomical models were obtained from the “Institute de Ciencias Forenses” in Mexico City. Raw data on
measurements can be obtained by contacting Dr. Alexander Cardenas-Mejia directly.