Upper limb
Trapezius, transverse part (middle fibers)
Musculus trapezius (pars transversa)
- Origin
- Spinous processes of Th1–Th4
- Insertion
- Acromion and the crest of the scapular spine
- Function
- Retracts the scapula (pulling the shoulder blades together) and assists upward rotation of the glenoid cavity
- Innervation
- Accessory nerve (CN XI) + cervical plexus (C3–C4)
- Movement & chain
- Retracts the scapula toward the spine; works together with the descending and ascending parts in upwardly rotating the glenoid cavity during arm elevation above 90°.
- Palpation
- Felt between the medial border of the scapular spine and the upper thoracic spinous processes when the shoulder blades are squeezed together.
- Clinical
- A common site of myofascial complaints in a prolonged forward-flexed (protracted) posture.
- Segmental innervation
- Accessory nerve (XI) motor; proprioception via the cervical plexus C3–C4.
- In clinical practice
- Safe transfer techniques avoiding arm traction (prevents shoulder subluxation in stroke patients); monitor injection sites and offload scapular pressure.
- Region in the model
- Upper limb