Back and Spinal Cord - LO 1

1. Identify the trapezius muscle. Understand the muscle’s attachments, functions, innervation, blood supply, anatomical relationships, and clinical considerations.

Trapezius m.

• Proximal attachments:

  • Superior nuchal line & external occipital protuberance of the occipital bone

  • Ligamentum nuchae & spinous processes of C7-T12

• Distal attachments:

  • Clavicle

  • Spine of the scapula

• Action(s):

  • Retraction of scapula (all fibers); 

  • Depression of scapula (ascending fibers); 

  • Elevation of scapula (descending fibers); 

  • Superiorly rotates glenoid cavity (ascending & descending fibers)

• Innervation:

  • Efferent: Accessory n. (CN XI)

  • Afferent: Branches of VPR of C3-C4

• Dominant arterial supply:

  • Transverse cervical a. [thyrocervical trunk]

• Anatomical relationships:

  • Three collections of fibers:

    • Descending (superior)

    • Transverse (middle)

    • Ascending (inferior)

  • Most superficial and superior-most muscle of the neck, shoulders, & back

  • Ascending fibers form the medial border of the triangle of auscultation