[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Anatomy](https://durgical.com/en/anatomy/) › [Spine](https://durgical.com/en/anatomy/region/spine/) › Latissimus dorsi [Muscular system](https://durgical.com/en/anatomy/system/muscular-system/) · [Spine](https://durgical.com/en/anatomy/region/spine/) # Latissimus dorsi The latissimus dorsi is the broad back muscle from the lower [spine](https://durgical.com/en/anatomy/region/spine/) and [pelvis](https://durgical.com/en/anatomy/region/pelvis/) to the upper arm; it pulls the arm down and back. Official name: Latissimus dorsi muscle [See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=spine&select=latissimus_dorsi&side=r) Opens in the Durgical app, no sign-up needed. ## What it is The broad back muscle from the lower spine, thoracolumbar fascia and pelvis to the upper arm. ## What it does Pulls the arm down and back (climbing, rowing) and, through the fascia, helps stiffen the lower back. ## Key points - The [thoracodorsal nerve](https://durgical.com/en/anatomy/thoracodorsal-nerve/) and artery run on its deep surface along the posterior wall of the axilla, and are kept safe in axillary lymph node dissection - Wraps around teres major to form the posterior axillary fold - Bounds the inferior lumbar triangle (with the external oblique and iliac crest) and roofs the superior lumbar triangle ## Key facts **Origin** Spinous processes of T7–T12, thoracolumbar fascia, iliac crest, lower 3–4 ribs (often inferior angle of scapula) **Insertion** Floor of the intertubercular sulcus of the [humerus](https://durgical.com/en/anatomy/humerus/) **Action** Extends, adducts and medially rotates the humerus; raises the trunk when climbing **Nerve** Thoracodorsal nerve (C6–C8) **Blood supply** Thoracodorsal artery (from subscapular); posterior intercostal and lumbar perforators ## Relations **Superficial** [Skin](https://durgical.com/en/anatomy/skin/) and fat over most of it; [trapezius](https://durgical.com/en/anatomy/trapezius-muscle/) overlaps its upper medial part **Deep** Erector spinae and [serratus posterior](https://durgical.com/en/anatomy/serratus-posterior-superior-muscle/) inferior (through the [thoracolumbar fascia](https://durgical.com/en/anatomy/thoracolumbar-fascia/)), the lower [ribs](https://durgical.com/en/anatomy/ribs/), the inferior angle of the [scapula](https://durgical.com/en/anatomy/scapula/) and [teres major](https://durgical.com/en/anatomy/teres-major/) **Lateral** Its free border forms the posterior axillary fold with teres major; its rib slips interlock with the [external oblique](https://durgical.com/en/anatomy/external-abdominal-oblique-muscle/) **Below** Iliac crest; the inferior lumbar triangle (of Petit) lies between its lateral border, the external oblique and the crest ## How to find it Grasping the posterior axillary fold between thumb and fingers holds it with teres major; the fold hardens when the person presses the arm down against resistance or coughs. ## Examination - Manual test: the person pulls the raised arm down and back against resistance, or coughs, while the examiner feels the posterior axillary fold; absent or weak contraction points to a thoracodorsal nerve lesion ## On imaging MRI shows it best: a broad, thin muscle wrapping the lower back and forming the posterior axillary fold with teres major. A tear of its tendon near the intertubercular groove of the humerus is rare and mostly seen in throwing athletes; MRI shows a retracted tendon with oedema. CT angiography can map the thoracodorsal artery before a flap, and ultrasound checks for a seroma at the donor site. ## Clinical notes - Latissimus dorsi flap on the thoracodorsal artery: a standard option to rebuild the breast and [chest](https://durgical.com/en/anatomy/region/chest/) wall or to cover large defects - Tendon transfer to restore external rotation in massive irreparable rotator cuff tears and in [brachial plexus](https://durgical.com/en/anatomy/roots-of-brachial-plexus/) birth palsy - A lumbar hernia can come through the inferior lumbar triangle at its lateral border ## Anatomical variants - Axillary arch (of Langer): a muscle slip from its edge crossing the axilla to [pectoralis major](https://durgical.com/en/anatomy/pectoralis-major-muscle/), present in some people; it can press on axillary vessels or nerves and confuse axillary surgery ## Development A classic migrating muscle: it starts with the limb bud muscles in the lower neck and spreads down over the back, carrying its nerve with it. That is why a muscle of the lower back is supplied by the thoracodorsal nerve (C6–C8) from the brachial plexus. ## Memory aid The lady between two majors: latissimus dorsi inserts in the floor of the intertubercular sulcus, between pectoralis major (lateral lip) and teres major (medial lip). ## Test yourself Think of the answer, then tap the question to see it. ## Where does the latissimus dorsi insert? The floor of the intertubercular sulcus of the humerus, between pectoralis major and teres major («the lady between two majors»). ## What are the action and nerve supply of the latissimus dorsi? It extends, adducts and medially rotates the humerus; supplied by the thoracodorsal nerve (C6–C8). ## How is the latissimus dorsi tested at the bedside? Feeling the posterior axillary fold while the person pulls the raised arm down against resistance or coughs; weakness points to the thoracodorsal nerve. ## Which triangle does the latissimus dorsi bound with the external oblique and iliac crest? The inferior lumbar triangle (of Petit), a site of lumbar hernia. ## On which vessel is a latissimus dorsi flap based? The thoracodorsal artery; used to rebuild the breast and chest wall. [Add to my cards (5)](https://durgical.app/estudiar/?add=/en/anatomy/latissimus-dorsi-muscle/) Educational information, not medical advice. For any symptom, see a health professional. ## Its names **Official Latin (TA2)** musculus latissimus dorsi TA2 2231 **Official Spanish (DeCS)** Músculo dorsal ancho DeCS D064171 **English (TA2)** Latissimus dorsi muscle ## Related - [Thoracolumbar fascia](https://durgical.com/en/anatomy/thoracolumbar-fascia/) - [Hip bone](https://durgical.com/en/anatomy/hip-bone/) Sources: Terminologia Anatomica (TA2); [DeCS](https://decs.bvsalud.org/es/ths/resource/?id=55180&filter=ths_termall&q=M%C3%BAsculos%20Superficiales%20de%20la%20Espalda); [Anatomy, Back, Latissimus Dorsi](https://www.ncbi.nlm.nih.gov/books/NBK448120/); Anatomy of the Human Body (20th ed.): Development of the Muscles (Lea & Febiger (Gray's Anatomy, 1918), 1918) · adapted, Public domain. ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/anatomy/latissimus-dorsi-muscle/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/latissimus-dorsi-muscle/