Latissimus Dorsi
Back
The widest muscle in the body — gives you that V-shaped back. It's the 'pull-up' muscle.
Function
Extends, adducts, and internally rotates arm
Origin
Spinous processes of T7-T12, thoracolumbar fascia, iliac crest, lower 3-4 ribs
Insertion
Floor of intertubercular groove of humerus
Innervation
Thoracodorsal nerve (C6-C8)