Anatomic variations of levator scapulae in a normal cohort: an MRI study

Purpose: Accessory attachments of the levator scapulae (LS) muscle have been described in the literature in previous cadaveric studies, but there is little knowledge about the incidence and distribution. Knowledge of LS accessory attachments is relevant to clinicians working in the fields of radiology, surgery, neurology, and musculoskeletal medicine. The purpose of this study was to explore the incidence and spectrum of LS caudal accessory attachments in vivo using magnetic resonance (MR) imaging in a young cohort. Methods: MR images of the cervical spine were obtained from 37 subjects (13 males and 24 females) aged 18–36 years using an axial T1-weighted spin echo sequence acquired from a 3-Tesla MR scanner. The LS muscle was identified, and the presence of caudal accessory attachments was recorded and described. Results: LS caudal accessory attachments were identified in 16 subjects (4 right, 6 left, and 6 bilateral; 12 female). Ten had unilateral accessory attachments to the serratus anterior, serratus posterior superior or the first/second rib. Four had bilateral accessory attachments to serratus anterior. One had bilateral accessory attachments to serratus posterior superior and unilateral accessory attachment to serratus anterior. One had bilateral attachments to both muscles. Conclusions: Both unilateral and bilateral LS caudal accessory attachments were present in nearly half of the subjects examined. They were relatively more frequent in females than males. The findings indicate that these accessory attachments are common, and in some cases, those accessory attachments can occur bilaterally and to more than one site.