Anat Cell Biol.  2023 Jun;56(2):280-284. 10.5115/acb.23.004.

Pectorobrachioepicondylaris musculoaponeurotic band: case description with evidence of median nerve compression

• Carrera A
• Chaiyamoon A
• Reina F
• Iwanaga J
• Cateura A
• Reina MA
• Sañudo JR
• Tubbs RS

• KMID: 2544092
• DOI: http://doi.org/10.5115/acb.23.004

Abstract

Upper limb muscle variations can be encountered on imaging or at surgery. We report an unusual muscle and band found during routine dissection of the arm in a cadaver. This case is described and salient literature reviewed. A band was found that traveled from the insertion of the pectoralis major tendon distally and obliquely toward the medial intermuscular septum and medical epicondyle. Fibers of the brachialis were found to interdigitate into the band. A tunnel was formed that carried the median nerve and brachial vessels. Evidence of median nerve compression was observed. We considered this an example of a pectorobrachioepicondylaris muscle. However, some can lead to clinical presentations. Although the significance of the case reported herein is not certain, signs of median nerve compression were identified. We believe that the term pectorobrachioepicondylaris bests describes the muscle reported herein and that our case represents a previously unreported variant of this muscle.

Keyword

Anatomy; Muscle; Variations; Arm; Upper limb

Figure

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  Fig. 1 Anteromedial view of the arm showing the PBEb running from the inferior border of the pectoralis major muscle to the medial epicondyle of the humerus and the medial intermuscular septum. White dashed line, total length 23.5 cm; black dashed line, attachment in the fascia of epitrochlear muscles; (A) 5 cm form origin. Point of smaller width of the band; (B) 14 cm from origin. Division of the band in anterolateral and posteromedial layers; white arrow, proximal opening of the canal; Black arrow, distal opening of the canal; PBEb, pectorobrachioepicondylaris band; PMt, pectoralis major tendon; BBm, biceps brachii muscle; Bm, brachialis muscle; MACn, medial antebrachial cutaneous nerve.

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  Fig. 2 Anteromedial view of the distal third of the arm. (A) Formation of the musculotendinous arch for the median nerve and the brachial artery by the division of the band into anterolateral and posteromedial layers. (B) Layer of muscular fibers from the brachialis muscle fused with the anterolateral fibers of the band. (C) Distal opening of the canal between the medial border of the brachialis muscle and the posteromedial fibers of the band. White dashed line, anterolateral layer; black dashed line, posteromedial layer; black arrows, medial intermuscular septum; Bm, brachialis muscle; Mn, median nerve; Ba, brachial artery.

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  Fig. 3 (A) Demonstration of the opened musculotendinous canal by sectioning and reflecting the posteromedial fibers of the band. Superficial and deep fibers of the brachialis muscle can be observed. (B) Enlarged image showing evidence of possible median nerve compression. Bm-sf, brachialis muscle-superficial fibers; Bm-df, brachialis muscle-superficial fibers; Mn, Median nerve; Ba, Brachial artery.

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  Fig. 4 Anterior view of the proximal third of the arm showing the accessory head of biceps brachii muscle and the coracobrachialis muscle. PMt, pectoralis major tendon; BBm-sh, biceps brachii muscle-long head; BBm-lh, biceps brachii muscle -short head; BBm-th, biceps brachii muscle-third head; CBm, coracobrachialis muscle; Mn, median nerve; Ba, brachial artery.

Reference

References

1. Wood J. 1867; IV. Variations in human myology observed during the Winter session of 1866-67 at King's college, London. Proc R Soc Lond. 15:518–46. DOI: 10.1098/rspl.1866.0119.

2. Loukas M, Tubbs RS. 2009; Musculus dorsoepitrochlearis. Clin Anat. 22:782. DOI: 10.1002/ca.20826. PMID: 19637307.

3. Macalister A. 1867; Further notes on muscular anomalies in human anatomy, and their bearing upon homotypical myology. Proc R Irish Acad. 10:121–64.

4. Tubbs RS, Shoja MM, Loukas M. 2016. Bergman's comprehensive encyclopedia of human anatomic variation. John Wiley & Sons;DOI: 10.1002/9781118430309.

5. Georgiev GP, Landzhov B, Tubbs RS. 2017; A novel type of coracobrachialis muscle variation and a proposed new classification. Cureus. 9:e1466. DOI: 10.7759/cureus.1466.

6. Iwanaga J, Singh V, Takeda S, Ogeng'o J, Kim HJ, Moryś J, Ravi KS, Ribatti D, Trainor PA, Sañudo JR, Apaydin N, Sharma A, Smith HF, Walocha JA, Hegazy AMS, Duparc F, Paulsen F, Del Sol M, Adds P, Louryan S, Fazan VPS, Boddeti RK, Tubbs RS. 2022; Standardized statement for the ethical use of human cadaveric tissues in anatomy research papers: recommendations from anatomical journal editors-in-chief. Clin Anat. 35:526–8. DOI: 10.1002/ca.23849. PMID: 35218594.

7. Afroze MKH, Sangeeta M, Tiwari S. 2020; A case report of additional slip of pectoralis major- pectorotubero fascialis muscle. J Med Sci Health. 6:18–20. DOI: 10.46347/JMSH.2020.v06i01.004.

8. Hartman CG, Straus WL. 1971. The anatomy of the rhesus monkey, Macaca mulatta. Hafner;DOI: 10.1038/134047a0.

9. Palagama SP, Tedman RA, Barton MJ, Forwood MR. 2016; Bilateral chondroepitrochlearis muscle: case report, phylogenetic analysis, and clinical significance. Anat Res Int. 2016:5402081. DOI: 10.1155/2016/5402081. PMID: 27242928. PMCID: PMC4875967.

10. Loukas M, Louis RG Jr, Kwiatkowska M. 2005; Chondroepitrochlearis muscle, a case report and a suggested revision of the current nomenclature. Surg Radiol Anat. 27:354–6. DOI: 10.1007/s00276-005-0337-4. PMID: 15912263.

11. Kotian SR, Bhat KMR. 2013; Pectoro-epicondylaris: a rare extension of the pectoralis major muscle. Rev Argent Anat Clin. 5:29–32. DOI: 10.31051/1852.8023.v5.n1.14049. PMID: 5c2d606f1b1f4d548d21cffdc78310c0.

12. Horrocks P, Hale White W, Lane WA. 1884; An account of the abnormalities observed in the dissecting room during the winter session 1882-1883. Guys Hosp Rep. 42:39–48.

13. El-Naggar MM, Al-Saggaf S. 2004; Variant of the coracobrachialis muscle with a tunnel for the median nerve and brachial artery. Clin Anat. 17:139–43. DOI: 10.1002/ca.10213. PMID: 14974102.

14. Calori L. 1868; On important anomalies of bones, vessels, nerves and muscles observed in last two years doing human anatomy. Mem Acad Sci Bol. 8:417–82. Italian.

15. Iwanaga J, Singh V, Ohtsuka A, Hwang Y, Kim HJ, Moryś J, Ravi KS, Ribatti D, Trainor PA, Sañudo JR, Apaydin N, Şengül G, Albertine KH, Walocha JA, Loukas M, Duparc F, Paulsen F, Del Sol M, Adds P, Hegazy A, Tubbs RS. 2021; Acknowledging the use of human cadaveric tissues in research papers: recommendations from anatomical journal editors. Clin Anat. 34:2–4. DOI: 10.1002/ca.23671. PMID: 32808702.