Main Model
Muscles : 50 Trapezius
Muscle: Trapezius
Superior Attachment: Medial third of
superior nuchal
line, external occipital protuberance, nuchal ligament,
spinous processes
of C7-T12 vertebrae, and lumbar
and sacral spinous processes
Inferior Attachment: Lateral third of clavicle, acromion, and
spine of scapula
Innervation: Spinal accessory
nerve (CN XI;
motor fibers); C2 and C3 spinal nerves (pain and proprioceptive fibers)
Main Action(s):
A. Elevates, retracts, and rotates scapulae superiorly
B. Descending (superior) fibers - elevate scapulae/
shoulders, maintain level of shoulders against
gravity or resistance
C. Transverse (middle) fibers - retract scapulae
D. Ascending (inferior) fibers - depress scapulae/
shoulders
E. Descending and ascending fibers together - rotate spinous process of scapulae superiorly
F. With shoulders fixed, bilateral contraction
extends neck; unilateral contraction produces lateral flexion to same side