[TA] thoracoappendicular muscle (superficial muscle of back); origin, spinous processes of lower five or six thoracic and the lumbar vertebrae, median ridge of sacrum, and outer lip of iliac crest; insertion, with teres major into posterior lip of bicipital groove of humerus; action, adducts arm, rotates it medially, and extends it; nerve supply, thoracodorsal. SYN: musculus latissimus dorsi [TA], broadest muscle of back.
