INTRODUCTION
Initial studies on the lower portion of the trapezius muscle (TM) in the 1980s gave
importance to irrigation by the transverse cervical artery (TCA) 1,2. In the following decade, new studies considered possible variations in the blood
supply of TM through the dorsal scapular artery (DSAA) 3. Although underutilized by the conventional way for repairing the head and neck,
the applicability of the lower third of the TM has been recommended by applications
in the proximity or by free transfer4. The variations in the origin of the pedicle of the DSAA are not important and do
not interfere with the procedures in the proximity5. Yet, studies have warned of the importance of preserving DSAA even in flaps based
on TCA, for the safety of the lower extremity of these flaps6 The constancy of DSAA branches for the lower third of the TM was found, as well as
anastomoses between arterial branches on opposite sides 7,8. However, considering new knowledge about the role of DSAA and its musculocutaneous
perforators in the blood supply to the descending portion of the TM and the description
of two patterns of irrigation9, the authors felt the need for greater safety for surgical dissections and flap dimensions.
OBJECTIVE
Obtain familiarity with the anatomy of irrigation of the lower third of the TM by
anatomical dissections and doppler echo examination.
METHODS
The research protocol was submitted to the research ethics committee of the University
of Vale do Sapucaí and approved under number 169/02 on August 20, 2002. The study
was carried out from 2002 to 2012. The two sides of four fresh corpses with no injuries
or scars on their backs have been studied. A U-shaped incision from the skin to the
muscular fascia of the latissimus dorsi muscle was performed from a posterior axillary
line to the opposite side, contouring the back at the level of the third lumbar vertebra.
This large patch of skin was raised along with the TM on both sides. On each side,
the muscle’s origin was carefully separated from the vertebrae and the underlying
muscles; the DSAA was identified and preserved. The vessels that ran through the fascia
on the deep surface of the flap, outside the limits of the TM and those that emerged
from the DSAA were identified and preserved. The flap elevation was conducted to the
level of the scapular spine (Figure 1).
Figure 1 - Flap of the high back with TM and DSAA variations.
Figure 1 - Flap of the high back with TM and DSAA variations.
Alternatively, in each corpse, one of the DSAA was catheterized and, by the catheter,
injected 20 ml of vital dye (Patent Blue V, Guerbet) to better register and documentation
the vessels. Simultaneously, after examining four volunteers by eco-Doppler searching
for DSAA as a pilot study, thirty adult volunteers were examined bilaterally. DSAA
was studied by a collaborating examiner who specializes in imaging. The equipment
used was the Envisor model (Phillips, Bothell, WA, United States) with multifrequency
linear transducer (3-12MHz) adjusted for visualization of superficial peripheral vessels.
The volunteers were placed in the prone position with the arm on the side being examined
along the trunk and with the palmar face of the hand oriented dorsally. The opposite
arm was positioned with the hand at the level of the head, and the head was kept with
the face turned to the opposite side. The transducer was positioned just below the
spine of the scapula and directed medially to search the artery.
RESULTS
About the anatomical study
ADE was present on all eight sides of the corpses studied. Variation in the course
of the artery was found. Its emergence from the deep plane to the rhomboid (MR) muscles
occurred in two locations: on four sides on the auscultation triangle (triangular
space delimited by the lateral margin of the TM, inferior medial margin of the scapula
and the medial margin Great Dorsal Muscle GDM), with cephalocaudal course and dimension
that varied from 3.5 to 4 cm from the emergency until penetration in the TM, emitting
direct branches to the overlying skin, always more than 5 cm caudally to the lower
scapular angle ). On the other four sides, in the upper portion of the RM, perforating
it at the height of the scapula spine and running caudally along the deep face of
the TM, up to the lower third of the muscle. In this conformation, no direct branches
to the skin were observed (Figure 3).
Figure 2 - Emergence in the trigone of auscultation with direct branches to the skin.
Figure 2 - Emergence in the trigone of auscultation with direct branches to the skin.
Figure 3 - Emergency at the level of the spine of the scapula by piercing the RM.
Figure 3 - Emergency at the level of the spine of the scapula by piercing the RM.
About image study
The 8-sided pilot exam of 4 volunteers was sufficient to familiarize the examiner
with the findings, and the average exam duration was 20 minutes. On 56 sides, DSAA
was found and well described. On two sides (from different volunteers), the artery
was visualized on only one side. In a volunteer, the artery was not seen anywhere.
In all views, it was present at the level of the scapular spine, medially distant
from 0.3 to 2 cm with an average of 1.1 cm, varying in depth, always accompanied by
a vein, in a caudal course in the topography of the TM (Figure 4).
Figure 4 - Image of DSAA piercing the TM at the level of the spine of the scapula.
Figure 4 - Image of DSAA piercing the TM at the level of the spine of the scapula.
DISCUSSION
About the anatomical study
The DSAA irrigates the middle and lower portion of the TM. For some authors, its applicability
as a pedicle for flaps in the lower portion of the TM is unlikely due to the reported
inconsistency. Some publications do not guarantee its use or limit the dimensions
of its skin territory 1,2,8. Other authors describe DSAA as dominant for the lower third of the TM on one third
of the sides with a constant path of branches that pierce the RM and enter the deep
surface of the TM, supplying its middle and lower portions9. In another study with 15 corpses, through classification based on size, DSAA was
the dominant vessel on half of the sides5. It was also the dominant vessel in 15 of 30 dissections3. According to another publication, there are branches of DSAA constant for TM supplying
the skin up to more than 10 cm below the lower margin of the muscle7. In a more recent publication, secured by a previous study with portable eco-Doppler,
the authors treated ten patients with a flap based on DSAA perforators and TM preservation,
six of which were pedicled flaps and four were free4. The present study identified the presence of DSAA on the eight sides studied, with
variations that allow the planning of flaps in the lower third of the TM. The variation
of the emergence on the auscultation trine offered evidence of the existence of branches
for the skin that seems to ensure a cutaneous territory that exceeds the limits of
TM. The variation of the emergency through the perforation of the RM makes intimacy
with the deep surface of the TM in a caudal course. It emits branches to the muscle
that also irrigates the skin. The dye injection allowed the identification of the
vessels and their path but did not allow the determination of the cutaneous territory.
Both variations irrigate the lower third of the TM.
About image study
The image examination by eco-Doppler is harmless, has low cost, agility, and high
sensitivity for detecting arterial vessels 4,10. The DSAA exam required a quick familiarization with the characteristics of the route.
The path was constant from the axial plane of the scapular spine, varying the course
in depth, which is consistent with the anatomical findings, being able to reach the
muscle by emergency in the middle of the RM and go through the deep face of the TM
or travel deep to RM and emerge at the auscultation trine. According to the study,
there is a possibility of not being identified on some sides. On these sides, there
was no way to establish the real absence of the vessel. Still, considering publications
that suggest its inconstancy, it is recommended the preoperative examination by echo-Doppler
in the flap planning based on DSAA 1,2,8,9.
CONCLUSION
The DSAA was constant on the eight sides studied in cadaver dissections and presented
two course variations in the irrigation of the lower portion of the trapezius muscle
through penetration at the level of the scapula spine on four sides and the level
of the auscultation trigone on four sides. The variation can occur in the same individual.
The echo-Doppler examination proved to be feasible and recommended to describe the
presence and path of the DSAA. Visualization was possible in 56 of the 60 sides studied.
ACKNOWLEDGMENT
To the then academics Danielle M. Moura and Natali A. Rodrigues and the imagologist
Prof. Sizenildo Silva Figueirêdo of the Medicine Course at the Federal University
of Rondônia, for his dedication to the study.
REFERENCES
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flap. Surg Radiol Anat. 1996;18(4):257-61.
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1998 Jul;41(1):52-7.
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1. Federal University of Rondônia, Laboratory of Operative Technique, Department of
Medicine, Porto Velho, RO, Brazil.
2. Hospital de Clínicas, Rehabilitation and Assistance Program for the Fissured Face,
Rio Branco, AC, Brazil.
3. Clínica Paiva & Rocha, Surgery, Pouso Alegre, MG, Brazil.
Corresponding author: João Lorenzo Bidart Sampaio Rocha, Avenida Alberto de Barros Cobra, 717, Nova Pouso Alegre, Pouso Alegre, MG, Brazil.
Zip Code: 37553-459 E-mail: joaolorenzorocha@gmail.com
Article received: August 10, 2020.
Article accepted: April 23, 2021.
Conflicts of interest: none
COLLABORATIONS
JLBSR Conception and design study, Investigation, Methodology, Realization of operations
and/or trials, Writing - Original Draft Preparation
GRP Analysis and/or data interpretation, Data Curation, Investigation, Realization of
operations and/or trials, Writing - Review & Editing
LCSR Analysis and/or data interpretation, Investigation, Writing - Review & Editing
