Muscle
Latissimus dorsi
Broad climbing/swimming muscle
High-yield
Powerful arm adductor/extensor/medial rotator — "handcuff muscle." Innervated by the thoracodorsal nerve (C6–C8).
Overview
The largest muscle of the back, spanning from the lower trunk to the humerus. It is the prime extensor and adductor of the arm from a flexed position.
Reference facts
- Origin
Spinous processes of T7–L5, thoracolumbar fascia, iliac crest, and inferior 3–4 ribs
- Insertion
Floor of the intertubercular (bicipital) groove of the humerus
- Action
Extends, adducts, and medially rotates the humerus; raises the body toward the arms in climbing
- Innervation
Thoracodorsal nerve (C6, C7, C8)
- Blood supply
Thoracodorsal artery
Mnemonic
Thoracodorsal: "ladies between two majors" (latissimus dorsi between teres major and pectoralis major functionally).