Extrinsic Back Muscles: Origins, Insertions, Actions, Innervations

Trapezius purposeful activity

Reaching for an object overhead (upper/lower trapezius), rowing a kayak or canoe (middle trapezius)

Trapezius Orgin

superior nuchal line, external occipital protuberance, nuchal

ligament (ligamentum nuchae), spinous processes of C7 and all

thoracic vertebrae

Trapezius Insertion

lateral clavicle, acromion, spine of scapula

Trapezius Actions

Upper fibers elevate, middle fibers retract (adduct), and lower fibers depress scapula; Assists in rotating the scapula

Trapezius primary innervations

CN XI

Latissimus Dorsi purposeful activity

Wheelchair mobility (propelling a manual

wheelchair forward), standing from sitting

(pushing downward on the arms of a chair

Latissimus Dosi Orgin

Spinous processes of lower thoracic and all lumbar vertebrae,

sacrum, iliac crest, lower ribs

Latissimus Dorsi Insertion

Intertubercular sulcus of humerus

Latissimus Dorsi primary actions

Extends, adducts, & medially rotates humerus

Latissimus Dorsi Primary Innervations

Thoracodorsal

levator scapulae purposeful activity

Shrugging shoulders (nonverbal

communication) or carrying a briefcase

levator scapulae orgin

Transverse processes of upper cervical vertebrae

levator scapulae insertion

Superior angle of scapula

levator scapulae primary actions

Elevates scapula, downward rotation of scapula

Rhomboid major & minor purposeful activity

reaching into a back pocket

Rhomboid major & minor orgin

Lower portion of nuchal ligament (ligamentum nuchae), spinous

processes of upper thoracic vertebrae

rhomboid major and minor insertion

Medial border of the scapula

rhomboid major and minor primary actions

Retracts (adducts) and elevates scapula

rhomboid major and minor primary innervation

dorsal scapular

Serratus posterior superior orgin

Nuchal ligament, spinous processes of lower cervical and upper

thoracic region

Serratus posterior superior insertion

upper ribs

serratus posterior inferior primary actions

elevate upper ribs

Serratus posterior inferior orgin

Spinous processes of lower thoracic and upper lumbar region

serratus posterior inferior insertion

lower ribs

serratus posterior inferior primary innervations

depress lower ribs