31/05/2025
Trapezius Muscle:
The trapezius is a large, flat, triangular muscle that extends across the back of the neck and shoulders, covering the upper back.
Origin:
Upper fibers: External occipital protuberance, nuchal ligament
Middle fibers: Spinous processes of C7 to T3
Lower fibers: Spinous processes of T4 to T12
Insertion:
Lateral third of the clavicle (collarbone)
Acromion
Spine of the scapula (shoulder blade)
Nerve Supply:
Motor: Accessory nerve (Cranial Nerve XI)
Sensory: C3 and C4 spinal nerves (for proprioception and pain)
Blood Supply:
Transverse cervical artery
Dorsal scapular artery
Function:
The trapezius muscle is divided into three parts, each with different functions:
Upper fibers: Elevate the scapula (e.g., shrugging the shoulders)
Middle fibers: Retract the scapula (pull the shoulder blades together)
Lower fibers: Depress the scapula (pull the shoulder blades down)
Together: They help in rotating the scapula and stabilizing the shoulder.
