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The sternocleidomastoid muscle variations: a mini literature review
Affiliations- Institute of Anatomy and Cell Biology, Paracelsus Medical University, Nuremberg and Salzburg, General Hospital Nuremberg, Nuremberg, Germany
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Abstract
The sternocleidomastoid muscles (SCM) are prominent paired muscles of the
neck connecting proximally the manubrium sterni and the clavicle to the mastoid
process and the occipital bone distally. Following their points of attachment
sternomastoid, sternooccipital, cleidomastoid and cleidooccipital portions of this
muscle have been described. Altogether 23 case reports from year 2000 till 2020
with 29 subjects related to the SCM supernumerary variations were searched
and analysed where parameters such as supernumerary proximal variation types
(sternal vs. clavicular), insertional variation, unilaterality/bilaterality of the variation,
study type, reported gender of the subjects and the country of research were
extracted. The research shows that 48.3% of the subjects had bilateral presentation
of SCM variations. If present unilaterally, three quarters of the cases were
on the left side. The most frequent variation is located at the clavicular side of
the proximal SCM head whereas isolated sternal sided proximal head variation
or an insertional variation alone are very rare. Interestingly, with 96.6%, most of
cases in the literature were discovered in cadavers during anatomical dissections.
Male gender represented with 82.8% higher prevalence than females. The higher
male prevalence in the body donor system, predominantly in the Asian continent
could play a decisive role in the outcome as more than half of the reported cases
stemmed from India in this period. Importantly, the knowledge of different anatomical
variations of the SCM is highly relevant for surgical, clinical or radiological
approaches in the neck.
Abstract
The sternocleidomastoid muscles (SCM) are prominent paired muscles of the
neck connecting proximally the manubrium sterni and the clavicle to the mastoid
process and the occipital bone distally. Following their points of attachment
sternomastoid, sternooccipital, cleidomastoid and cleidooccipital portions of this
muscle have been described. Altogether 23 case reports from year 2000 till 2020
with 29 subjects related to the SCM supernumerary variations were searched
and analysed where parameters such as supernumerary proximal variation types
(sternal vs. clavicular), insertional variation, unilaterality/bilaterality of the variation,
study type, reported gender of the subjects and the country of research were
extracted. The research shows that 48.3% of the subjects had bilateral presentation
of SCM variations. If present unilaterally, three quarters of the cases were
on the left side. The most frequent variation is located at the clavicular side of
the proximal SCM head whereas isolated sternal sided proximal head variation
or an insertional variation alone are very rare. Interestingly, with 96.6%, most of
cases in the literature were discovered in cadavers during anatomical dissections.
Male gender represented with 82.8% higher prevalence than females. The higher
male prevalence in the body donor system, predominantly in the Asian continent
could play a decisive role in the outcome as more than half of the reported cases
stemmed from India in this period. Importantly, the knowledge of different anatomical
variations of the SCM is highly relevant for surgical, clinical or radiological
approaches in the neck.
Keywords
sternocleidomastoid, sternocervical, sternopharyngeal, trapezius, variation
About this articleTitle
The sternocleidomastoid muscle variations: a mini literature review
Journal
Issue
Article type
Review article
Pages
507-512
Published online
2022-04-28
Page views
1488
Article views/downloads
1364
DOI
Pubmed
Bibliographic record
Folia Morphol 2023;82(3):507-512.
Keywords
sternocleidomastoid
sternocervical
sternopharyngeal
trapezius
variation
Authors
S. Silawal
G. Schulze-Tanzil
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