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Thoracodorsal artery

The thoracodorsal artery is a terminal branch of the subscapular artery, which itself arises from the third part of the axillary artery, and it primarily supplies the latissimus dorsi muscle along with adjacent structures in the posterior thoracic wall.^[1]^[2]^[3] Originating in the axillary region near the inferior border of the subscapularis muscle, the artery courses inferomedially along the posterior axillary wall, following the lateral border of the scapula toward its inferior angle, where it pierces the deep surface of the latissimus dorsi muscle near its inferior angle.^[1]^[2]^[3] It travels in close association with the thoracodorsal nerve (a branch of the posterior cord of the brachial plexus) and is typically 8.5 cm in length with a diameter of about 3 mm, though variations exist where it may arise directly from the axillary or lateral thoracic artery in 3-5% of cases.^[1]^[2]^[3] Upon entering the latissimus dorsi, the artery bifurcates into a transverse (medial) branch and a descending (lateral) branch, giving off muscular branches to the latissimus dorsi, subscapularis, teres major, and serratus anterior muscles, as well as cutaneous perforators that supply the overlying axillary skin and contribute to anastomoses with intercostal and lumbar arteries.^[1]^[2]^[3] Clinically, the thoracodorsal artery is significant in reconstructive surgery, particularly as the vascular pedicle for the thoracodorsal artery perforator (TDAP) flap, which offers a long pedicle (up to 25 cm) and minimal donor site morbidity for breast, head, neck, and extremity reconstructions due to its reliable size, mobility, and perforator anatomy.^[3]^[2]

Anatomy

Origin

The thoracodorsal artery arises as one of the two terminal branches of the subscapular artery, with the other being the circumflex scapular artery.^[2] The subscapular artery itself originates from the third part of the axillary artery, typically at the point where the axillary artery lies posterior to the subscapularis muscle.^[4] The origin of the thoracodorsal artery occurs within the axilla, specifically at or near the inferior border of the subscapularis muscle, where the subscapular artery divides into its terminal branches. Immediately following its emergence, the artery is accompanied by the thoracodorsal nerve, which arises from the posterior cord of the brachial plexus (roots C6–C8) and travels alongside the vascular pedicle to innervate the latissimus dorsi muscle.^[5]^[1] At its origin, the thoracodorsal artery has a typical diameter of approximately 2–3 mm, which supports its role in delivering substantial blood flow to the musculature of the upper back and shoulder region.^[6]^[7] This caliber reflects its importance as a dominant pedicle for the latissimus dorsi, ensuring adequate perfusion for a large muscle mass.^[8]

Course

The thoracodorsal artery travels inferomedially along the posterior axillary wall, following the lateral border of the scapula toward its inferior angle.^[1] It is accompanied by the thoracodorsal nerve and vein along this shared path.^[6] The vessel passes deep to the latissimus dorsi muscle before entering it near the inferior angle of the scapula.^[2] From its origin to the site of entry into the latissimus dorsi muscle, the thoracodorsal artery measures approximately 8.4 cm in length on average (range: 5.9–14.0 cm), based on cadaveric dissections.^[6] It terminates by dividing into 2–4 branches near the inferior angle of the scapula.^[2] In its course, the artery lies posterior to the subscapularis and teres major muscles while positioned anterior to the serratus anterior muscle along the posterior aspect of the axillary wall.^[3] Upon entering the latissimus dorsi, it courses within the muscle's interfascicular connective tissue.^[2]

Branches

Upon entering the latissimus dorsi muscle, the thoracodorsal artery divides into a horizontal (medial) branch and a vertical (lateral) branch.^[9] The lateral branch runs inferiorly along the lateral border of the latissimus dorsi muscle, providing muscular branches to the serratus anterior and subscapularis muscles.^[3] The medial branch courses medially toward the inferior angle of the scapula, supplying the teres major muscle and additional segments of the latissimus dorsi.^[3] The thoracodorsal artery typically gives rise to 1-2 small cutaneous perforator branches that emerge to supply the overlying skin of the axillary and posterior thoracic regions.^[9] In total, the artery produces 2-4 branches, which form anastomoses with the intercostal arteries.^[2] These branches also connect briefly with the circumflex scapular artery.^[3]

Supply and function

Latissimus dorsi muscle

The thoracodorsal artery provides the dominant arterial supply to the latissimus dorsi muscle, accounting for the majority of its perfusion needs.^[10] This vessel enters the muscle via its hilum at the muscular apex, located on the anterior or deep surface near the upper medial aspect, approximately 6 to 12 cm distal to its origin from the subscapular artery.^[10]90083-4/pdf) Once inside, it delivers oxygenated blood essential for the muscle's metabolic demands across its broad expanse.^[2] Within the latissimus dorsi, the thoracodorsal artery ramifies into primary branches that bifurcate into medial and lateral divisions, forming an interconnected arcade of secondary vessels.^[2] These branches spread throughout the muscle's interfascicular connective tissue, anastomosing to ensure comprehensive coverage from the thoracic vertebral origins to the humeral insertion site.^[11] This vascular architecture supports uniform nutrient distribution, enabling the muscle to maintain integrity during dynamic activities. Minor collateral circulation from posterior intercostal arteries provides supplementary perfusion as a backup mechanism.^[10] The thoracodorsal artery's supply is critical for muscle viability, particularly during contraction when oxygen and nutrient demands peak to sustain forceful movements.^[10] It facilitates the latissimus dorsi's primary functions, including adduction, extension, and medial rotation of the arm at the glenohumeral joint, by ensuring adequate blood flow to meet the elevated metabolic requirements.^[10] Disruption of this supply could compromise these actions, highlighting its physiological importance. Perforator vessels arising from the thoracodorsal artery's intramuscular branches extend beyond the muscle to nourish overlying fasciocutaneous tissues, enabling surgical extensions of the latissimus dorsi flap while preserving core muscular perfusion.^[12] These perforators, often utilized in reconstructive procedures, allow for reliable tissue transfer with minimal donor site morbidity.^[12]

Other structures

The thoracodorsal artery provides secondary vascular supply to the serratus anterior muscle through one or more branches, typically 1–3 vessels of approximately 1 mm in diameter that penetrate the midportion of the muscle along the long thoracic nerve.^[3] These branches contribute to the perfusion of the anterior axillary wall via lateral perforators.^[13] Muscular twigs from the medial and lateral branches of the thoracodorsal artery extend to the subscapularis and teres major muscles, offering supplementary blood flow to these rotator cuff-associated structures.^[14] Specifically, the angular branch of the thoracodorsal artery courses between the serratus anterior and the teres major/subscapularis, delivering periosteal branches that support regional muscular and osseous perfusion.^[15] While not the primary supplier, these contributions aid in the overall vascular network of the posterior shoulder girdle. The artery also furnishes cutaneous supply to the axillary and posterior thoracic skin through small perforating vessels, with a dedicated cutaneous branch present in about 75% of cases arising 0.5–2 cm beyond the subscapular artery bifurcation, and perforators greater than 0.5 mm located within 8 cm distal to the neurovascular hilus.^[3] Through anastomoses, the thoracodorsal artery offers minor contributions to rotator cuff stability, particularly supporting the subscapularis while providing limited collateral flow to the supraspinatus and infraspinatus, though it is not their primary arterial source.^[1] These connections, including those with the dorsal scapular artery, enhance regional collateral circulation in the posterior thoracic area.^[14]

Clinical significance

Reconstructive surgery

The thoracodorsal artery serves as the primary vascular pedicle for the latissimus dorsi musculocutaneous flap, a cornerstone in reconstructive surgery for addressing soft tissue defects, particularly in post-mastectomy breast reconstruction. This flap leverages the artery's robust supply to transfer the latissimus dorsi muscle along with overlying skin and subcutaneous tissue, providing ample volume and reliable perfusion for autologous tissue restoration. The pedicle typically measures 10-15 cm in length with a diameter of 2-3 mm, enabling versatile positioning without excessive tension.^[16]^[17] In breast reconstruction following mastectomy, the use of the latissimus dorsi flap was reported by Bostwick and colleagues in 1977 as a one-stage technique to restore contour and symmetry, building on earlier descriptions such as Iginio Tansini's 1897 introduction of the flap for post-mastectomy defects, revolutionizing options for patients with significant tissue loss. Beyond breast procedures, the flap is employed in head and neck reconstruction to cover complex defects, repair chest wall radiation-induced damage, and provide coverage for extremity wounds, owing to the artery's consistent perforator network that ensures flap viability across diverse anatomical sites.^[18]^[12] Surgical harvest preserves the thoracodorsal artery pedicle by elevating the flap in the lateral decubitus position, allowing identification and protection of the vessel along its course from the subscapular artery origin. For free flap transfers, the pedicle undergoes microsurgical end-to-end or end-to-side anastomosis to recipient vessels, such as the internal mammary artery, to reestablish circulation; in pedicled applications, the artery is rotated into position without division. The accompanying thoracodorsal nerve is often preserved to maintain partial muscle function and neurovascular integrity.^[12]^[19] Flap survival rates exceed 95%, with studies reporting outcomes of 97-98% complete viability when meticulous pedicle dissection avoids twisting or compression. Complications, though infrequent, primarily involve pedicle kinking or thrombosis, which can lead to partial or total flap loss if the artery is inadequately mobilized during harvest.^[20]^[21]

Anatomical variations and procedures

The thoracodorsal artery exhibits several anatomical variations, with the most common involving its origin deviating from the typical subscapular artery. In approximately 12.5% of cases, the subscapular artery is absent, resulting in the thoracodorsal artery arising directly from the axillary artery; rarer origins include a common trunk with the lateral thoracic artery (1-7%).^[22] Cadaveric studies report broader variability in the subscapular-thoracodorsal system, with aberrant origins occurring in up to 12.5% of arterial systems, often requiring surgeons to identify independent branches of the thoracodorsal and circumflex scapular arteries directly from the axillary artery.^[22] Rarer variations include the presence of an accessory thoracodorsal artery originating from the distal axillary artery, which has been documented in isolated case reports and is estimated to occur bilaterally in less than 1% of individuals; such duplicates may provide collateral flow but complicate identification during procedures. High bifurcation of the thoracodorsal artery proximal to its usual site represents even less frequent anomalies.^[23] These variants underscore the need for meticulous intraoperative exploration to prevent inadvertent ligation. Clinically, unrecognized variations pose risks in non-reconstructive procedures, particularly axillary lymph node dissection for breast cancer, where iatrogenic injury to an aberrant thoracodorsal artery can lead to hemorrhage or compromised drainage; preoperative computed tomography angiography is thus recommended to map vessel anatomy and minimize such complications.^[24] Similarly, in shoulder arthroplasty, variations increase the potential for unexpected bleeding if the artery's atypical course intersects the surgical field, as noted in cadaveric analyses emphasizing the artery's proximity to humeral resection sites. During trauma repair involving the axilla or scapular region, failure to account for these deviations heightens the risk of vascular disruption and hematoma formation, potentially exacerbating morbidity in up to 10% of cases with subscapular-thoracodorsal variants.^[22]

References

[1]
Thoracodorsal Artery - Course - Supply - TeachMeAnatomy
Aug 9, 2024 · The thoracodorsal artery is a branch of the subscapular artery that arises in the scapular region of the upper back.
[2]
Thoracodorsal artery: Anatomy, branches, supply - Kenhub
The thoracodorsal artery is one of the two terminal branches of the subscapular artery. It runs inferomedially along the lateral border of the scapula.
[3]
Thoracodorsal Artery - an overview | ScienceDirect Topics
The thoracodorsal artery (TDA) is a terminal branch of the subscapular artery dividing into a transverse and descending branch. The vascular territory of the ...
[4]
Subscapular Artery | Complete Anatomy - Elsevier
Quick Facts. Origin: Axillary artery (third part). Course: From the inferior border of the subscapularis muscle to inferior scapular angle.
[5]
Anatomy, Thorax, Thoracodorsal Nerves - StatPearls - NCBI Bookshelf
Jul 24, 2023 · The thoracodorsal nerve is also referred to as the middle or long subscapular nerve. It arises from the C6 to C8 roots of the brachial plexus.Structure and Function · Embryology · Muscles · Physiologic Variants
[6]
Multidetector computed tomography angiography to evaluate the ...
Sep 24, 2015 · The mean diameter of the thoracodorsal artery origin was 2.29 ± 0.27 mm on the left and 2.31 ± 0.29 mm on the right. Mean length of the ...
[7]
Thoracodorsal artery - e-Anatomy - IMAIOS
The thoracodorsal artery is a branch of the subscapular artery. It travels inferiorly with the thoracodorsal nerve and supplies the latissimus dorsi.
[8]
https://www.imaios.com/en/e-anatomy/anatomical-structures/thoracodorsal-artery-1553672848
[9]
The thoracodorsal artery perforator flap: anatomic basis and clinical ...
The thoracodorsal artery showed a constant bifurcation into a horizontal branch and a lateral branch, located on the deep surface of the latissimus dorsi muscle ...
[10]
Anatomy, Back, Latissimus Dorsi - StatPearls - NCBI Bookshelf
The latissimus dorsi muscle is supplied predominantly by the thoracodorsal artery, a continuation of the subscapular artery, which is a branch of the third part ...
[11]
Latissimus dorsi: Origin, insertion, innervation,function | Kenhub
The thoracodorsal artery (a continuation of the subscapular artery), supplies the latissimus dorsi muscle. It enters the muscle on its costal surface, medial to ...Origin And Insertion · Relations · Blood Supply
[12]
Latissimus Dorsi Flap - StatPearls - NCBI Bookshelf
Apr 1, 2024 · Latissimus Dorsi Myocutaneous Free Flap and Image 4. Latissimus Dorsi ... The thoracodorsal artery, a terminal branch of the subscapular ...
[13]
The anatomy of the subscapular-thoracodorsal arterial system - jpras
This paper describes the anatomy of the subscapular-thoracodorsal arterial system, based on a study of 100 cadaver dissections.
[14]
The Anatomy of the Angular Branch of the Thoracodorsal Artery
Jul 23, 1999 · Normally the angular branch originates in the region where the thoracodorsal nerve meets the vascular pedicle (fig. 2). Type one has its origin ...<|control11|><|separator|>
[15]
Teres Major - Physiopedia
Blood supply of serratus anterior: upper part of the lateral and superior thoracic artery, the lower part of the thoracodorsal artery Innervation of serratus ...
[16]
Thoracodorsal Artery Perforator Flap (TAP Flap) - Microsurgeon.Org
Anatomy. After originating from the subscapular axis, the thoracodorsal vessels course toward the latissimus dorsi. On reaching the deep surface of the muscle, ...
[17]
The vascular basis of the thoracodorsal artery perforator flap - PubMed
The maximum dimensions of the skin that could potentially be supplied by the thoracodorsal artery averaged 600 cm2, with a major axis length of 28 cm and a ...
[18]
Latissimus Flap Breast Reconstruction - Medscape Reference
Feb 21, 2024 · The latissimus muscle flap is a workhorse flap for salvage of failed expander-implant reconstructions. The flap also provides trophic stimulation to the ...Background · History of the Procedure · Indications · Relevant Anatomy
[19]
Latissimus Dorsi Muscle Flap - Microsurgeon.Org
The latissimus muscle is supplied by the thoracodorsal artery, and branch of the subscapular artery. A nerve, the thoracodorsal, and vein accompany the artery.
[20]
The thoracodorsal artery perforator flap: clinical experience and ...
The perforating branches of the thoracodorsal artery offer a robust blood supply to a skin-soft-tissue paddle of 10 to 12 cm x 25 cm, overlying the latissimus ...
[21]
The Thoracodorsal Artery Perforator Flap: A Powerful Tool in Breast ...
The overall complication rate was 16.6 percent. The flap survival rate was 98.3 percent. There was no total flap loss. Three flaps suffered partial-thickness ...
[22]
Anatomic variants of the subscapular-thoracodorsal arterial system
Jan 5, 2022 · Measured SSA lengths on CTA from our cohort were consistent with reported figures from anatomic dissections (mean = 2.5 cm, range = 0.4-6.3 cm).
[23]
Bilateral accessory thoracodorsal artery - PubMed
In the present study, a bilateral accessory thoracodorsal artery, originating on either side of the third part of the axillary artery, is described in a 68-year ...Missing: incidence | Show results with:incidence
[24]
Anatomical variations of the axillary artery and their clinical ... - Hjs.gr
Good knowledge of the axillary artery abnormalities will contribute to less breast surgery complications during lymph node dissections, such as breast cancer- ...