Anatomy of thoracodorsal artery within Latissimus dorsi muscle

Arora L* and Dada R^
Deptt of Anatomy, All India Institute of Medical Sciences

*Dr Latika Arora, Senior Resident, Deptt of Anatomy, AIIMS, Delhi,^ Dr. Rima Dada, Assistant Professor, Deptt of Anatomy, AIIMS, Delhi

Address for Correspondence

Dr Rima Dada,
Assistant Professor,
Deptt of Anatomy, AIIMS,
Ansari Nagar,
Delhi
Email: latika_arora@rediffmail.com

Abstract

Based on dissection of 20 fresh cadaver we have detailed vascular anatomy of thoracodorsal artery.The thoracodorsal artery showed a constant bifurcation into horizontal branch and a lateral branch, located on the deep surface of latissimus dorsi muscle 4cm distal to inferior scapular border and 2.5cm medial to lateral free margin of the muscle. The presented anatomical landmarks are useful for locating the neurovascular hilum. The length of the pedicle and relatively big vessel gauge are good anatomical marker for free transfer of latissimus dorsi flap.

Key Words- Thoracodorsal artery, Latissimus dorsi, reconstructive surgeries

Introduction

The blood supply of latissimus dorsi is particularly important because of it΄s application in plastic reconstructive surgery and cardiac assistance. In the surgical procedures known as cardiomyoplasty [Chagas et al 1989 1 ; Hagege et al 19902 ] the latissimus muscle is mobilized with it΄s neurovascular pedicle intact, transferred into the chest and wrapped around heart . Latissimus dorsi muscle is widely used for other reconstructive surgeries. The tendinous insertion of latissimus dorsi is transferred into greater tuberosity in rotator cuff injuries .Homme MP et al20013 transferred the muscular part of latissimus dorsi into infra and supraspinatous fossawith aim of reactivating infra and supraspinatus muscle. Bostwick J 1979 4 used latissimus dorsi musculocutaneous flap for breast reconstruction . Karanasi Y 5 et al 2002 used latissimus dorsi flap to reconstruct the volume and contour abnormalities that developed when transverse rectus abdominis musculocutaneous flap was used for breast reconstructive surgeries . Although anatomy of primary muscular branches of thoracodorsal artery which run on the deep surface of latissimus muscle is well described [ Schusterman et al 1980 6, Batlett et al 1981 7 and Tobin et al 19818] relatively little literature is available on the vascularization of the latissimus dorsi flap. The present study was undertaken in order to study vascularization of latissimus dorsi more clearly.

Muscle Anatomy

The latissimus dorsi is a superficial flat muscle of an asymmetric triangular form. The muscle fibres originate medially from sixth thoracic down to superior sacral vertebra, distally from posterior outer surface of iliac crest. The thoracolumbar fascia is employed as tendinous mediation. There are accessory origins from distal three or four ribs and regularly from inferior scapular angle. The fan shaped muscle converge to the intertubercular groove of the humerus, wher the spirally rotated tendon inserts ventral to the teres major muscle. Main functions of latissimus dorsi muscle are adduction, inward rotation of the arm and depression of the shoulder girdle. The muscle doesnot work isolated , but as a part of functional unit with other muscles of chest and shoulder. Thus normally the partial loss of latissimus muscle is of no drastic functional consequences for the patient. The dominant vascular supply is the thoracodorsal artery. It derives out of subscapular artery, a branch of axillary artery and is consistently accompanied by the thoracodorsal vein( leading into subclavian vein) and the thoracodorsal nerve ( deriving out of brachial plexus.fig1)

Fig1
Photograph shows circumflex scapular artery [CS] going backward into medial axillary space

Material and Method

The study is based on investigation of 20 latissimus dorsi muscle. Formal alchol fixed corpses were used for the determination of vessel lengths. Cadavers were positioned with ipsilateral arm abducted to 90˚ at the shoulder . An incision was made in axilla following the lateral edge of latissimus dorsi. Our study included examination of subscapular artery and vein, circumflex vessels and thoracodorsal pedicle.

Results

The origin of subscapular artery from acromiothoracic artery varied between 4-6 cm. It divides early about 4-6 cm into two main branches; the circumflex scapular artery that goes backward into medial axillary space and the thoracodorsal artery . The thoracodorsal artery entered the deep surface of latissimus of latissimus dorsi a clearly defined vascular hilus 2.5 cm ( range 1-4 cm) medial to the lateral edge of the latissimus dorsi muscle and approx 4 cm distal to inferior scapular border (fig2 ). At that point the thoracodorsal artery bifurcates .The horizontal branch runs runs parallel to the superior border 3.5 cm [2-5 cm range] from the edge and lateral branch runs parallel to lateral free border of muscle 2cm [range 1-4cm ] from the lateral margin (fig3). Both branches remain basically on the deep surface of latissimus dorsi muscle throughout it΄s course.

Discussion

The latissimus dorsi muscle is one of the largest muscle in human body. It is one of the most versatile and widely used tissue transfer in reconstructive surgery. Previous anatomic studies have elucidated clearly the gross anatomy of latissimus dorsi muscle
[ Bartlett SP 19817 and Friedrich W 1988 9]. Therefore it is known that main vascular supply comes from thoracodorsal vessels, whereas the lower and medial parts of latissimus are supplied by intercostals and paraspinal vessels. In addition constant branching of thoracodorsal vessels in a horizontal and a lateral branch which run on the deep surface of the muscle has been described [ Tobin et al 19818 and Schusterman et al 19816 ]. These anatomic findings led to the clinical redefinement of the split latissimus dorsi flap [ Tobin et al 1981 8]. Some authors proposed to fill the muscle in a horizontal plane with transfer of just the deep segment to reduce bulkiness[ Rowsell et al 1981 10]. We studied the latissimus dorsi muscle to prvide a comprehensive synopsis of it΄s anatomy. The focus was on cutaneous perforator vessels of the thoracodorsal artery and goal was to describe a pattern of how they might be distributed . We found the neurovascular hilus on the deep surface of latissimus dorsi muscle appx 4 cm distal to the inferior free border of latissimus dorsi muscle. At that point there was a constant bifurcation into horizontal branch and a lateral branch. This is in line with the findings of Bartlett SP et al 1981 7 and Friedrich W et al 1988 9.

The result of this study have a direct impact on flap design in which a direct impact on flap designs is used. However the preoperative exploration of the vessel course should be undertaken [ Shesol BF et al 1980 11] so as to not to run in any anomaly and secondly to ensure that planned flap will reach the recipient area without any tension. It is hoped that this anatomic study will expand the flexibility and the use of latissimus dorsi in various reconstructive surgeries.

Legends

Fig2
A fresh cadaver specimen of latissimus dorsi viewed from deep surface showing thoracodorsal artery and vein [TA and TV] entering hilus
 

Fig 3
Photograph shows horizontal [H] and lateral [L] branch of thoracodorsal artery

Fig4 Figure shows anatomy of thoracodorsal artery

References
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(2) Hagege AA, Desnos M and Chachques JC et al 1990 Preliminory report; follow up after dynamic cardiomyoplasty Lancet ;112 2-1124
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(5) Karnas LY, Santoro DT and Shaw WW Use of latissimus dorsi flap for reconstructing and augmentation after TRAM flap breast reconstruction Ann Plastic Surg 2002; 48: 343-347
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