Anatomy and Cell Biology

Korean Association of Anatomists (대한해부학회)
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Untrapped: bilateral hypoplasia of the trapezius muscle

  • BaileaSue R. Rounds (Department of Anatomy, Lake Erie College of Osteopathic Medicine) ;
  • Meredith F. Rasey (Department of Anatomy, Lake Erie College of Osteopathic Medicine) ;
  • Randy Kulesza (Department of Anatomy, Lake Erie College of Osteopathic Medicine)
  • Received : 2022.07.15
  • Accepted : 2022.10.01
  • Published : 2023.03.31
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Abstract

Agenesis or congenital hypoplasia of skeletal muscles occurs infrequently but may occur with specific conditions such as Poland syndrome. The trapezius muscle can vary in the extent of its bony attachments or may have additional slips, however congenital absence or hypoplasia is extremely rare. There are only a few reports of partial or complete absence of the trapezius muscle. Two cases of bilateral absence of the trapezius were both in males and were accompanied by the absence of additional muscle in the pectoral girdle. Herein, we describe a case of a 56-year-old male cadaver with bilateral hypoplasia of the trapezius. The muscle was largely represented by atrophied muscle fibers with an abundance of fibrotic or fatty connective tissue. This subject had very minor hypoplasia of the left pectoralis major muscle, but the remaining muscles of the pectoral girdle were normal. The spinal accessory nerve terminated in the sternocleidomastoid muscle on both sides, failing to reach the trapezius. We interpret these findings to be consistent with a minor variant of Poland syndrome.

Keywords

Acknowledgement

The authors are grateful to those who donated their bodies to medical education and anatomical research. Results from such anatomical research provides an important avenue to extend our understanding of human structure and function and improve patient care.

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