Anatomy, Shoulder and Upper Limb, Axillary Artery
Introduction
The axillary artery is the principal arterial supply of the upper limb, commencing as a continuation of the subclavian artery as it emerges from underneath the first rib to enter the axilla. It provides key landmarks for understanding the position of other important structures in the region, in particular the brachial plexus. The axillary artery gives off six branches before terminating at the lower border of teres major by becoming the brachial artery.
Structure and Function
Register For Free And Read The Full Article
- Search engine and full access to all medical articles
- 10 free questions in your specialty
- Free CME/CE Activities
- Free daily question in your email
- Save favorite articles to your dashboard
- Emails offering discounts
Learn more about a Subscription to StatPearls Point-of-Care
Structure and Function
The axillary artery commences from the subclavian artery at the outer border of the first rib and terminates when it becomes the brachial artery at the outer border of the teres major muscle. It is enclosed in the axillary sheath, a continuation of fascia from the prevertebral fascia of the neck, and is anatomically divided into three parts by the pectoralis minor muscle, providing a useful way to conceptualize its course. The first part (proximal to pectoralis minor) has one branch, the second part (beneath pectoralis minor) has two branches, and the third part (distal to pectoralis minor) has three branches.[1] The axillary vein runs medially to the artery along its whole course.
A study of 59 cadavers found the average length of the axillary artery to be 11.22 cm, with each section occurring at roughly equal intervals along its course.[2] The surface marking of the axillary artery in the upper limb can be traced by drawing a line between the midclavicular point to the groove behind the coracobrachialis.
The first part of the axillary artery is defined as being between its commencement distal to the lateral border of the first rib and proximal to the pectoralis minor. It lies on top of the serratus anterior muscle. It has one branch called the superior thoracic artery, which supplies the pectoralis minor and pectoralis major muscles.[3]
The second part of the axillary artery lies directly underneath the pectoralis minor. The first branch of the second part of the artery is the thoracoacromial trunk, which pierces the clavipectoral fascia and divides into four terminal arteries: the acromial artery, pectoral arteries, clavicular artery, and deltoid artery. The second branch of the second part of the axillary artery is the lateral thoracic artery, which follows the lower border of the pectoralis minor and provides blood to the pectoralis and serratus anterior muscles, as well as the mammary gland.[4]
The third part of the axillary artery lies distal to the lower border of the pectoralis minor muscle, anterior to the subscapularis muscle, and teres major muscle.[5] It has three branches that can vary in order: the subscapular trunk, the anterior humeral circumflex artery, and the posterior humeral circumflex artery.[6] The subscapular trunk is typically the largest branch of the axillary artery, running down the posterior wall of the axilla.[7]
It gives rise to the scapular circumflex artery and the thoracodorsal artery. The scapular circumflex artery runs through the triangular space and provides blood to the scapular region. The scapular circumflex artery eventually anastomoses with the suprascapular artery, thus connecting and providing a collateral route between the first and third parts of the axillary artery. The thoracodorsal artery supplies the latissimus dorsi muscle. The two remaining branches of the third part of the axillary artery, the anterior and posterior humeral circumflex artery, supply the head of the humerus and shoulder joint. These arteries anastomose with one another. The anterior humeral circumflex is smaller and runs anterior to the humerus. The posterior humeral circumflex is larger and runs through the quadrilateral space and then posterior to the humerus, accompanied by the axillary nerve and supplying the deltoid muscle.[6]
The axillary artery terminates at the lower border of teres minor muscle, becoming the brachial artery which supplies the distal upper limb.
Embryology
The embryological development of the arterial system of the upper limb is highly complex. It appears to commence with the development at day 29 to 31 of a capillary plexus from the dorsal aorta (Carnegie stage 12). This proceeds during Carnegie stage 13 to develop with the limb and selectively enlarges to give rise to the greater and lesser components of the relevant vasculature. The subclavian and axillary arterial vasculature has generally matured from the capillary plexus by Carnegie stage 15.[8]
Nerves
The brachial plexus is intimately related to the vascular structures of the axilla, as the divisions emerge from beneath the clavicle to form the medial, lateral, and posterior cords around the axillary artery.[9] The first part of the axillary artery has the lateral and posterior cords superolaterally and the medial cord posteriorly[10]. Furthermore, a loop from the medial cord and lateral cord, which joins the medial and lateral pectoral nerves, is situated anteriorly. The second part of the artery is related to the medial, lateral, and posterior cords in the way their names indicate. In general, the subsequent branches from each cord remain in this relation to the third part of the axillary artery.[11][12]
Physiologic Variants
Upper limb arterial variants have been reported as occurring in around 25% of the general population.[13] Specific to the axillary artery, it has been reported that 5 to 10% of people have a bifid axillary artery, which bifurcates in the axilla, and each branch becomes the radial and ulnar artery respectively.[14]
Furthermore, there is a well-recognized physiologic variation in the branching pattern from the axillary artery. This typically manifests as a common origin for the lateral thoracic (LTA) and subscapular arteries (SSA), anterior (ACHA) and posterior (PCHA) circumflex humeral arteries, or thoracoacromial (TAA) and lateral thoracic arteries (LTA).[2]
Surgical Considerations
The axillary artery can be accessed surgically by an infraclavicular or deltopectoral incision in the upper arm.[15]. The pectoralis major and pectoralis minor muscles must be mobilized to access the neurovascular bundle in which the axillary artery forms a part, and careful protection of the cords of the brachial plexus to which it is intimately associated must be ensured. Depending on the specific pathology (aneurysm, blunt trauma, gunshot trauma), injury to the axillary artery may be repaired with autologous venous grafting or synthetic grafting with, for example, polytetrafluoroethylene.[15][16]
Clamping the axillary artery can be accomplished without harming the arm. Surgical procedures concerning the axillary artery require delicacy due to the proximity of the brachial plexus. In cardiac surgery, the right axillary artery is frequently used as an arterial cannulation site, especially in the repair of aortic aneurysm or dissection.[17][18][19]
Clinical Significance
Injuries to the axillary artery are rare but can cause limb loss and most commonly arise from penetrating or blunt trauma to the shoulder. Examples include but are not limited to anterior shoulder dislocation, reduction of anterior shoulder dislocation, and humoral neck fracture.[20][21] These mechanisms of injury may cause axillary artery rupture and subsequent thrombosis. Patients may present with pain, pallor, coldness, absent or delayed capillary refill, numbness or tingling, or lack of radial pulse to the injured limb. However, the collateral blood supply in the shoulder may mask some of these symptoms. Thus, the presentation of axillary artery injury is variable, so a high level of suspicion is essential.
Axillary Artery Aneurysm
Axillary artery aneurysms are one of the injuries that can occur due to penetrating or blunt trauma. However, they may develop from atherosclerotic processes over long periods, but this is exceedingly rare.[22][23] They often are associated with neurological complications due to the close proximity of the axillary artery and the brachial plexus. Aneurysms may arise from the improper use of crutches. Presentation of these patients may include neurological deficits of the upper limb, ischemic fingers, or occlusion of the radial and ulnar arteries due to embolization from an aneurysm. Axillary aneurysms are confirmed by imaging. CT angiography is the most useful diagnostic imaging technique and is currently the gold standard. An alternative imaging modality includes magnetic resonance angiography when intravenous contrast is contraindicated.
Ultrasound is also very useful for detection and diagnosis. An aneurysmectomy and grafting with a saphenous vein is commonly the surgical procedure employed to reverse these complications. Another treatment option for patients is an endovascular aneurysm repair.[24]
Arterial Positional Compression
Axillary artery thrombosis and aneurysm may also be seen, although very rarely, in healthy athletes that perform frequent overhead throwing motions such as pitching a baseball or hitting a volleyball. In the throwing motion, the anterior displacement of the humerus places compression on the third portion of the axillary artery. Intermittent axillary artery compression may cause chronic changes in downstream vascular sufficiency. This could lead to subsequent thrombosis and aneurysms. Medical staff dealing with these athletes should be vigilant for symptoms of ischemic pain, cold intolerance, numbness, or arm fatigue immediately following practice or competition. They should note that symptoms will present later in the disease process because only significant embolization or decreased blood flow causes perceptible changes in temperature or sensation.
CT angiogram and magnetic resonance angiogram can be used to diagnose or screen athletes at risk of symptomatic arterial positional compression. A further example of this is quadrilateral space compression syndrome, a space bordered by the humerus, teres major, long head of triceps, and teres minor, which contains the posterior circumflex humeral artery and axillary nerve, which are vulnerable here to compression.[25]
Media
(Click Image to Enlarge)
Branches of the Aorta. This illustration includes the right common carotid artery, right vertebral artery, right subclavian artery, brachiocephalic artery, ascending aorta, left coronary artery, right coronary artery, left common carotid artery, left vertebral artery, left subclavian artery, left axillary artery, left brachial artery, arch of aorta, and descending aorta.
Contributed by Beckie Palmer
(Click Image to Enlarge)
References
Shi D, Bai J, Zhang L, Wang X. The "Hand as Foot" teaching method in axillary artery anatomy. Asian journal of surgery. 2022 Feb:45(2):800-801. doi: 10.1016/j.asjsur.2021.12.001. Epub 2021 Dec 29 [PubMed PMID: 34973859]
Yang K, Lee H, Choi IJ, Jeong W, Kim HT, Wei Q, Lee JH. Topography and Anatomical Variations of the Axillary Artery. BioMed research international. 2021:2021():6393780. doi: 10.1155/2021/6393780. Epub 2021 May 24 [PubMed PMID: 34124252]
Stowell JT, McComb BL, Mendoza DP, Cahalane AM, Chaturvedi A. Axillary Anatomy and Pathology: Pearls and "Pitfalls" for Thoracic Imagers. Journal of thoracic imaging. 2022 May 1:37(3):W28-W40. doi: 10.1097/RTI.0000000000000639. Epub 2022 Feb 10 [PubMed PMID: 35142752]
Loukas M, du Plessis M, Owens DG, Kinsella CR Jr, Litchfield CR, Nacar A, Lu O, Tubbs RS. The lateral thoracic artery revisited. Surgical and radiologic anatomy : SRA. 2014 Aug:36(6):543-9. doi: 10.1007/s00276-013-1234-x. Epub 2013 Nov 27 [PubMed PMID: 24281130]
Jaiswal LS, Neupane D, Yadav P. Rare variation of the right brachial artery. ANZ journal of surgery. 2022 May:92(5):1281-1282. doi: 10.1111/ans.17291. Epub 2021 Oct 17 [PubMed PMID: 34661957]
Olinger A, Benninger B. Branching patterns of the lateral thoracic, subscapular, and posterior circumflex humeral arteries and their relationship to the posterior cord of the brachial plexus. Clinical anatomy (New York, N.Y.). 2010 May:23(4):407-12. doi: 10.1002/ca.20958. Epub [PubMed PMID: 20235185]
Mills NL, Dupin CL, Everson CT, Leger CL. The subscapular artery: an alternative conduit for coronary bypass. Journal of cardiac surgery. 1993 Jan:8(1):66-71 [PubMed PMID: 8422491]
Level 3 (low-level) evidenceRodríguez-Niedenführ M, Burton GJ, Deu J, Sañudo JR. Development of the arterial pattern in the upper limb of staged human embryos: normal development and anatomic variations. Journal of anatomy. 2001 Oct:199(Pt 4):407-17 [PubMed PMID: 11693301]
Benes M, Kachlik D, Belbl M, Kunc V, Havlikova S, Whitley A, Kunc V. A meta-analysis on the anatomical variability of the brachial plexus: Part I - Roots, trunks, divisions and cords. Annals of anatomy = Anatomischer Anzeiger : official organ of the Anatomische Gesellschaft. 2021 Nov:238():151751. doi: 10.1016/j.aanat.2021.151751. Epub 2021 Apr 30 [PubMed PMID: 33940116]
Level 1 (high-level) evidenceFakoya AOJ, Aguinaldo E, Velasco-Nieves NM, Vandeveer ZT, Morales-Marietti N, Mathew S, Afolabi AG, McCracken T. Unusual Splitting of Medial Cord of the Right Brachial Plexus and Its Relation to the Axillary Artery and Subscapular Artery: A Case Report. Open access Macedonian journal of medical sciences. 2019 Jun 30:7(12):2006-2009. doi: 10.3889/oamjms.2019.561. Epub 2019 Jun 30 [PubMed PMID: 31406546]
Level 3 (low-level) evidenceLeinberry CF, Wehbé MA. Brachial plexus anatomy. Hand clinics. 2004 Feb:20(1):1-5 [PubMed PMID: 15005376]
Gili S, Abreo A, GóMez-Fernández M, Solà R, Morros C, Sala-Blanch X. Patterns of Distribution of the Nerves Around the Axillary Artery Evaluated by Ultrasound and Assessed by Nerve Stimulation During Axillary Block. Clinical anatomy (New York, N.Y.). 2019 Jan:32(1):2-8. doi: 10.1002/ca.23225. Epub 2018 Oct 20 [PubMed PMID: 30341965]
Burzotta F, Brancati MF, Porto I, Saffioti S, Aurigemma C, Niccoli G, Leone AM, Coluccia V, Crea F, Trani C. Comparison of Right and Left Upper Limb Arterial Variants in Patients Undergoing Bilateral Transradial Procedures. Circulation. Cardiovascular interventions. 2015 Dec:8(12):e002863. doi: 10.1161/CIRCINTERVENTIONS.115.002863. Epub [PubMed PMID: 26643739]
Bigeleisen PE. The bifid axillary artery. Journal of clinical anesthesia. 2004 May:16(3):224-5 [PubMed PMID: 15217666]
Rogovskyi VM, Gybalo RV, Lurin IA, Sivash YY, Oklei DV, Taraban IA. A Case of Surgical Treatment of a Gunshot Wound to the Left Scapular Region With Damage to the Distal Axillary and Proximal Brachial Arteries. World journal of surgery. 2022 Jul:46(7):1625-1628. doi: 10.1007/s00268-022-06577-y. Epub 2022 Apr 28 [PubMed PMID: 35484404]
Level 3 (low-level) evidenceTetik O, Yilik L, Besir Y, Can A, Ozbek C, Akcay A, Gurbuz A. Surgical treatment of axillary artery aneurysm. Texas Heart Institute journal. 2005:32(2):186-8; discussion 185 [PubMed PMID: 16107110]
Level 2 (mid-level) evidenceBertoglio L, Grandi A, Melloni A, Kahlberg A, Melissano G, Chiesa R. Percutaneous AXillary Artery (PAXA) Access at the First Segment During Fenestrated and Branched Endovascular Aortic Procedures. European journal of vascular and endovascular surgery : the official journal of the European Society for Vascular Surgery. 2020 Jun:59(6):929-938. doi: 10.1016/j.ejvs.2020.01.027. Epub 2020 Feb 20 [PubMed PMID: 32089506]
Branzan D, Steiner S, Haensig M, Scheinert D, Schmidt A. Percutaneous Axillary Artery Access for Endovascular Treatment of Complex Thoraco-abdominal Aortic Aneurysms. European journal of vascular and endovascular surgery : the official journal of the European Society for Vascular Surgery. 2019 Sep:58(3):344-349. doi: 10.1016/j.ejvs.2019.01.011. Epub 2019 Jul 30 [PubMed PMID: 31375342]
Agrusa CJ, Connolly PH, Ellozy SH, Schneider DB. Safety and Effectiveness of Percutaneous Axillary Artery Access for Complex Aortic Interventions. Annals of vascular surgery. 2019 Nov:61():326-333. doi: 10.1016/j.avsg.2019.05.046. Epub 2019 Aug 5 [PubMed PMID: 31394224]
Stone MA, Ihn HE, Gipsman AM, Iglesias B, Minneti M, Noorzad AS, Omid R. Surgical anatomy of the axillary artery: clinical implications for open shoulder surgery. Journal of shoulder and elbow surgery. 2021 Jun:30(6):1266-1272. doi: 10.1016/j.jse.2020.09.018. Epub 2020 Oct 15 [PubMed PMID: 33069906]
Bucci G, Lucar-López G, Sanchez-Gonzalez J, Malagelada F, Palencia Lopez J, Guevara-Noriega KA. Axillary artery injury and brachial plexus palsy as a complication of proximal humerus fractures. Journal of orthopaedics. 2017 Sep:14(3):340-341. doi: 10.1016/j.jor.2017.06.001. Epub 2017 Jun 24 [PubMed PMID: 28706376]
Michalakis D, Lerais JM, Goffette P, Royer V, Brenot R, Kastler B. [True isolated atherosclerotic aneurysm of the axillary artery]. Journal de radiologie. 2003 Sep:84(9):1016-9 [PubMed PMID: 13679756]
Level 3 (low-level) evidenceSzuchmacher PH, Freed JS. Axillary aneurysms. New York state journal of medicine. 1980 Apr:80(5):795-6 [PubMed PMID: 6930558]
Level 3 (low-level) evidenceBranco BC, Boutrous ML, DuBose JJ, Leake SS, Charlton-Ouw K, Rhee P, Mills JL Sr, Azizzadeh A. Outcome comparison between open and endovascular management of axillosubclavian arterial injuries. Journal of vascular surgery. 2016 Mar:63(3):702-9. doi: 10.1016/j.jvs.2015.08.117. Epub 2015 Oct 23 [PubMed PMID: 26506937]
Charmode S, Mehra S, Kushwaha S. Revisiting the Surgical Approaches to Decompression in Quadrilateral Space Syndrome: A Cadaveric Study. Cureus. 2022 Feb:14(2):e22619. doi: 10.7759/cureus.22619. Epub 2022 Feb 26 [PubMed PMID: 35371758]