Scapular Anastomosis

Introduction

Introduction to the Scapular Anastomosis

The scapular anastomosis is a rich network of arteries around the scapula, primarily on its posterior (dorsal) surface, within the scapular-deltoid region. It provides collateral circulation to the upper limb when the main axillary or subclavian artery is obstructed (e.g., in aneurysm, thrombosis, or ligation). The anastomosis connects branches of the subclavian artery (first part) with branches of the axillary artery (third part), forming a crucial pathway around the shoulder girdle. Key vessels include the suprascapular artery (from thyrocervical trunk), dorsal scapular artery (transverse cervical artery branch), and circumflex scapular artery (from subscapular artery).

Study

Arterial Contributors to the Scapular Anastomosis

1. Suprascapular artery: Branch of thyrocervical trunk (from first part of subclavian artery). Passes over suprascapular ligament (through scapular notch) to supply supraspinatus and infraspinatus, anastomosing with circumflex scapular artery. 2. Dorsal scapular artery: Usually from transverse cervical artery (thyrocervical trunk). Runs deep along medial border of scapula, supplying levator scapulae and rhomboids, anastomosing with circumflex scapular and suprascapular arteries. 3. Circumflex scapular artery: Branch of subscapular artery (third part of axillary artery). Passes through triangular space (teres major, teres minor, long head of triceps) to reach infraspinous fossa, anastomosing with suprascapular and dorsal scapular arteries. 4. Posterior circumflex humeral artery: Sometimes contributes, passing through quadrangular space. 5. Transverse cervical artery (superficial branch): Less constant, but may supply superficial anastomosis.

Triangular Space & Scapular Notch

The circumflex scapular artery passes through the triangular space (bounded by teres minor superiorly, teres major inferiorly, long head of triceps laterally). The suprascapular artery passes through the scapular notch, below the transverse scapular ligament (suprascapular nerve passes above the ligament). This spatial relationship is clinically important in suprascapular nerve entrapment.

Clinical Significance

The scapular anastomosis provides collateral flow in cases of axillary or subclavian artery occlusion (e.g., from trauma, atherosclerosis, or aneurysm). It is also exploited in surgical flaps – the scapular flap based on circumflex scapular artery is used in reconstructive surgery. Angiography can visualize this network. Rupture of the anastomosis during scapular fracture may cause significant hemorrhage.

Summary

Key Takeaways – Scapular Anastomosis

Three main arteries: suprascapular (subclavian), dorsal scapular (subclavian), circumflex scapular (axillary). They anastomose around scapular spine and infraspinous fossa. Critical for collateral circulation after proximal upper limb artery obstruction. Triangular space transmits circumflex scapular artery. Scapular notch transmits suprascapular artery.