key facts

Origin

Vertebral part: Spinous processes of vertebrae T7-T12, Thoracolumbar fascia

Iliac part: Posterior third of crest of ilium

Costal part: Ribs 9-12

Scapular part: Inferior angle of scapula

Insertion

Intertubercular sulcus of the humerus, between pectoralis major and teres major muscles

Mnemonic: Lady between two majors (lady refers to latissimus dorsi)

Innervation Thoracodorsal nerve (C6-C8)

Blood supply

Thoracodorsal artery, perforating arteries of the 9th-11th posterior intercostal arteries, and 1st-3rd lumbar arteries

Functions

Shoulder joint: Arm internal rotation, Arm adduction, Arm extension; Assists in respiration