Trapezius M. function Elevation, retraction, and rotation of scapula. Helps in adduction and slight elevation of arm. Trapezius M. innervation Accessory N. (CNXI) and C3-C4 (propioception and pain) Rhomboid Minor/Major M. function Press the scapula to the thoracic wall. Retraction of scapula medially. Rhomboid Minor/Major M. innervation Dorsal scapular N. (C4-C5) Leavtor Scapulae M. function Elevates the scapula. Levator Scapulae M. innervation Dorsal scapular N. (C4-C5) Latissimus dorsi M. function Adduction and lowering the arm. Medial rotation and extension of the arm. Raises the body toward the arm when climbing. Latissimus dorsi M. innervation Thoracodorsal (C6, C7, C8) Serratus posterior inferior/superior M. function Rib elevation *May function as accessory muscles of respiration (in COPD). Serratus posterior inferior/superior M. innervation Intercoastal N. (T9-T12) Erector Spinae lateral M. function Erect posture of the body. Splenii rotate the head. Extensors when both sides contract. Flexion when one side contracts. Erector Spinae lateral M. innervation Primary spinal dorsal rami. Erector Spinae medial M. function Extensors when both sides contract. Flexors when one side contracts. Some stabilize and some rotate the vertebral column. Erector Spinae medial M. innervation Primary dorsal rami. Suboccipital triangle function Turning the head backward or laterally. Suboccipital triangle innervation Sensory: Greater occipital N (C2) Suboccipital N (C1) innervates all 3 muscles Suboccipital triangle contents Third part of vertebral artery. Suboccipital N (C1) innervating all 3 muscles. Suboccipital plexus of veins.