Trapezius 1
I would imagine that would be the trapezius muscles.
Upper fibres of the trapezius, rhomboid minor and major and levator scapulae.
Incorporating the levator scapulae exercise into your workout routine can help improve shoulder stability, reduce neck and shoulder pain, and enhance overall posture by strengthening the muscles in the upper back and neck.
The serratus anterior is one, and the lower trapezius muscles are the others. The SA muscles pull the scapulae downward and anteriorly while the lower traps pull downward and medially.
Levator scapulae
Levator scapulae and trapezius
The muscles involved in elevating the shoulder girdle (e.g. shrugging your shoulders) are the upper fibers of trapezius, levator scapulae, rhomboid major and rhomboid minor.
The most effective exercises for strengthening the levator scapulae muscle include shoulder shrugs, neck stretches, and scapular retraction exercises.
Trapezius and Levator Scapulae
levator scapulae
a combined contraction of the levator scapulae, rhomboid major and minor muscles and the latissimus dorsi muscle.I would narrow this answer down to the Rhomboid Muscles-Luceinrhomboids
The synergist of the trapezius in scapular elevation is the levator scapulae muscle. It works together with the trapezius to elevate the scapula and assist in movements like shrugging the shoulders.