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Variations of accessory thoracic muscles identified in the ethnically diverse whole-body donation population in Northern California
, 1, 1
Affiliations- Department of Cell Biology and Human Anatomy, University of California, School of Medicine, Davis, California, United States
open access
Abstract
Accessory thoracic muscles in humans are relatively common and it is important
to draw awareness to their variable presentations and potential clinical implications
owing to their close association with the axilla. Here we report four cases
of accessory thoracic muscle variations identified in the ethnically diverse whole-
-body donation population in Northern California (4 out of 48 donors, 8.3%). Of
these, combined presentations of thoracic accessory muscles were observed in
two of the donors, one involving bilateral axillary arches and a pectoralis quartus
on the left and the other a unilateral axillary arch on the left and bilateral pairs
of pectoral fascicles. In the former, the proximal ends of the left axillary arch and
pectoralis quartus joined to form a common aponeurosis which inserted onto the
deep tendon of the pectoralis major; in the latter, the pectoral fascicles originated
from the surface of the ribs and inserted into the deep surface of the pectoralis
major muscle. In the other two donors, unilateral axillary arches were observed.
Our observations illustrate that accessory thoracic muscles, in isolated as well as
combined forms, are commonplace in the general population. We also describe
the proposed embryonic origins of these accessory muscles, which may reflect
their frequent occurrence, and potential clinical implications of these muscles, as
discussed in literature.
Abstract
Accessory thoracic muscles in humans are relatively common and it is important
to draw awareness to their variable presentations and potential clinical implications
owing to their close association with the axilla. Here we report four cases
of accessory thoracic muscle variations identified in the ethnically diverse whole-
-body donation population in Northern California (4 out of 48 donors, 8.3%). Of
these, combined presentations of thoracic accessory muscles were observed in
two of the donors, one involving bilateral axillary arches and a pectoralis quartus
on the left and the other a unilateral axillary arch on the left and bilateral pairs
of pectoral fascicles. In the former, the proximal ends of the left axillary arch and
pectoralis quartus joined to form a common aponeurosis which inserted onto the
deep tendon of the pectoralis major; in the latter, the pectoral fascicles originated
from the surface of the ribs and inserted into the deep surface of the pectoralis
major muscle. In the other two donors, unilateral axillary arches were observed.
Our observations illustrate that accessory thoracic muscles, in isolated as well as
combined forms, are commonplace in the general population. We also describe
the proposed embryonic origins of these accessory muscles, which may reflect
their frequent occurrence, and potential clinical implications of these muscles, as
discussed in literature.
Keywords
accessory thoracic muscle, axillary arch, pectoralis quartus, latissimus dorsi, pectoralis major, cadaver, gross anatomy laboratory
About this articleTitle
Variations of accessory thoracic muscles identified in the ethnically diverse whole-body donation population in Northern California
Journal
Issue
Article type
Case report
Pages
957-962
Published online
2022-12-23
Page views
657
Article views/downloads
395
DOI
Pubmed
Bibliographic record
Folia Morphol 2023;82(4):957-962.
Keywords
accessory thoracic muscle
axillary arch
pectoralis quartus
latissimus dorsi
pectoralis major
cadaver
gross anatomy laboratory
Authors
H. Anderson
J. A. Weil
R. P. Tucker
References (28)- Bergman RA. Doubled pectoralis quartus, axillary arch, chondroepitrochlearis, and the twist of the tendon of pectoralis major. Anat Anz. 1991; 173(1): 23–26.
- Besana-Ciani I, Greenall MJ. Langer's axillary arch: anatomy, embryological features and surgical implications. Surgeon. 2005; 3(5): 325–327.
- Birmingham A. Homology and innervation of the achselbogen and pectoralis quartus, and the nature of the lateral cutaneous nerve of the thorax. J Anat Physiol. 1889; 23(Pt 2): 206–223.
- Bonastre V, Rodríguez-Niedenführ M, Choi D, et al. Coexistence of a pectoralis quartus muscle and an unusual axillary arch: case report and review. Clin Anat. 2002; 15(5): 366–370.
- Clarys JP, Barbaix E, Van Rompaey H, et al. The muscular arch of the axilla revisited: its possible role in the thoracic outlet and shoulder instability syndromes. Man Ther. 1996; 1(3): 133–139.
- Douvetzemis S, Natsis K, Piagkou M, et al. Accessory muscles of the anterior thoracic wall and axilla. Cadaveric, surgical and radiological incidence and clinical significance during breast and axillary surgery. Folia Morphol. 2019; 78(3): 606–616.
- Humphry GM. Lectures on human myology. Br Med J. 1872; 2(601): 4–5.
- Huntington GS. The derivation and significance of certain supernumerary muscles of the pectoral region. J Anat Physiol. 1904; 39(Pt 1): 1–54.27.
- Jelev L, Georgiev GP, Surchev L. Axillary arch in human: common morphology and variety. Definition of "clinical" axillary arch and its classification. Ann Anat. 2007; 189(5): 473–481.
- Karanlik H, Fathalizadeh A, Ilhan B, et al. Axillary arch may affect axillary lymphadenectomy. Breast Care. 2013; 8(6): 424–427.
- Langworthy O. The panniculus carnosus in cat and dog and its genetical relation to the pectoral musculature. J Mammal. 1924; 5(1): 49–63.
- Langworthy O. A morphological study of the panniculus carnosus and its genetical relationship to the pectoral musculature in rodents. Am J Anat. 1925; 35(2): 283–302.
- Loukas M, South G, Louis RG, et al. Jr, A case of an anomalous pectoralis major muscle. Folia Morphol. 2006; 65(1): 100–103.
- Lhuaire M, Wehbe K, Garrido I, et al. Anatomy of the axillary arch: from its incidence in human to an embryologic and a phylogenetic explanation of its origins. Surg Radiol Anat. 2021; 43(5): 619–630.
- Magee C, Jones C, McIntosh S, et al. Upper limb deep vein thrombosis due to Langer's axillary arch. J Vasc Surg. 2012; 55(1): 234–236.
- Naldaiz-Gastesi N, Bahri OA, López de Munain A, et al. The panniculus carnosus muscle: an evolutionary enigma at the intersection of distinct research fields. J Anat. 2018 [Epub ahead of print]; 233(3): 275–288.
- Natsis K, Vlasis K, Totlis T, et al. Abnormal muscles that may affect axillary lymphadenectomy: surgical anatomy. Breast Cancer Res Treat. 2010; 120(1): 77–82.
- Potau JM, Arias-Martorell J, Bello-Hellegouarch G, et al. Inter- and intraspecific variations in the pectoral muscles of common chimpanzees, bonobos, and humans . Biomed Res Int. 2018; 2018: 9404508.
- Pu Q, Huang R, Brand-Saberi B. Development of the shoulder girdle musculature. Dev Dyn. 2016; 245(3): 342–350.
- Ramsay A. Account of unusual conformations of some muscles and vessels. Edinb Med Surg J. 1812; 8(31): 281–283.
- Scrimgeour GE, St John ER, Leff DR. Langer's arch: A rare but important consideration for axillary surgery with implications for training. Breast J. 2020; 26(11): 2226–2228.
- Snosek M, Loukas M. Thoracic wall muscles. In: Bergman’s comprehensive encyclopedia of human anatomic variation. John Wiley & Sons, Ltd 2016: 335–368.
- Taterra D, Henry BM, Zarzecki MP, et al. Prevalence and anatomy of the axillary arch and its implications in surgical practice: A meta-analysis. Surgeon. 2019; 17(1): 43–51.
- Testut L. Les anomalies musculaires chez l'homme expliquées par l'anatomie comparée, leur importance en anthropologie par L. Testut: Précédé d'une préface par M. le professeur Mathias Duval. G. Masson 1884: 107–116.
- Theriault E, Diamond J. Nociceptive cutaneous stimuli evoke localized contractions in a skeletal muscle. J Neurophysiol. 1988; 60(2): 446–462.
- Turner WM. On the Musculus Sternalis. J Anat Physiol. 1867; 1(2): 246–378.25.
- Valasek P, Theis S, DeLaurier A, et al. Cellular and molecular investigations into the development of the pectoral girdle. Dev Biol. 2011; 357(1): 108–116.
- Wilson JT. The innervation of the Achselbogen muscle. J Anat Physiol. 1912; 47(Pt 1): 8–17.
