25 - Inferior Trapezius Agenesis and Scapular Dyskinesis in a 58 Year-Old Black Male Donor

Poster Board Number: 25
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Abstract Body : INTRODUCTION & OBJECTIVE
The trapezius muscle is important for head and neck stabilization and shoulder movement, while the scapula is involved in arm movement. We hereby report a unilateral trapezius muscle abnormality with associated unilateral scapular dyskinesis. These findings have functional significance and implications for the other muscles in that region, such as the semispinalis capitis and splenius cervicis muscles.

MATERIALS & METHODS
We present a functionally significant abnormality observed in a 58 year-old Black male donor deceased from thyroid cancer. We encountered this finding during a routine human donor anatomical dissection in the 2021-2022 Medical and Nursing student gross anatomy course at the Uniformed Services University of the Health Sciences. The donor exhibited left inferior trapezius agenesis as well as scapular dyskinesis. The initial dissection was completed by medical students, and assistance was provided by anatomy faculty when the abnormality was found. Additionally, we performed a literature review in an effort to further characterize the incidence and implications of these findings.

RESULTS
In addition to left trapezius inferior potion agenesis, we extended the scope of the dissection to include left scapular dyskinesis and reveal the left scapula pressing into the adjacent C7 and T1 vertebral bodies, with resultant deviation in the left semispinalis capitis and splenius cervicis muscle location. This also resulted in compromise of the left levator scapulae muscle function.

CONCLUSION
This case report explores the possible implications and significance of left inferior trapezius agenesis in combination with scapular dyskinesis, the latter of which affected other muscles.

SIGNIFICANCE/IMPLICATION
The observed abnormalities suggest that the donor would have experienced functional limitations in arm movement, particularly in adduction. A literature review was performed to understand the significance of these abnormalities.