Unilateral Levator Scapulae Anatomical Variant in Female Cadaver




Frangenberg, Alexander
Fisher, Cara L.


0000-0003-4394-2850 (Frangenberg, Alexander)
0000-0003-0257-3614 (Fisher, Cara L.)

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Background The levator scapulae (LS) muscle is a superficial extrinsic muscle of the back, most commonly originating on the posterior aspect of the transverse processes of the first through fourth cervical vertebrae and inserting on the superior aspect of the medial border of the scapula. These attachment sites further indicate the action of the LS, which along with the trapezius and rhomboid muscles, function to elevate the scapula during overhead upper extremity movements and shrugging of the shoulders. This elevation of the scapula also causes the scapula to rotate clockwise, thus tilting the glenoid cavity inferiorly. If the scapula is fixed, the LS may also function to rotate the neck laterally at the cervical attachment points. The most common pathology of the LS is termed "levator scapulae syndrome" and is commonly due to poor posture, resulting in chronically achy, tight, and tender neck muscles that may impede movement and illicit excess pain. Case Information Dissection of the posterior cervical region and deep upper back on an embalmed 41-year-old female cadaver revealed a unilateral accessory muscle of the left LS muscle. This accessory slip inserted perpendicularly onto the broad aponeurotic fibers of the serratus posterior superior muscle, deep to the rhomboid major muscle. This anatomical variant is present in the literature and is a common site of accessory muscle attachment for the LS. Conclusions This case report describes the anatomical findings in-depth and discusses their prevalence in the literature. Interestingly, the literature indicates a higher predominance of unilateral LS accessory muscles in women compared to men, and this case report further supports this finding. Damage to the LS may be caused by high-velocity injuries, however, the most frequent presentation is implicated in cases of chronic neck pain due to poor posture. Due to the high rates of neck pain diagnosis in U.S. adults from an increasingly sedentary and technology-prevalent lifestyle, variations in muscular anatomy to the LS should not be overlooked. Such variations could play a role in the presence of chronic neck pain through the interaction with vascular and neurologic factors and should be considered during diagnosis and surgery of the region.