<unk>  may occur secondary to multiple mechanisms:
Thoracic outlet compression from cervical ribs, anomalous fibrous bands, or scalene muscle hypertrophy
Abduction and external rotation of the upper extremity resulting in compression, contusion, and subsequent thrombosis of the artery by the humeral head [such as in baseball pitchers]
Distal embolization, such as from an aneurysmal subclavian artery
The second portion of the artery may be compressed and occluded by the pectoralis minor [“hyperabduction syndrome”]
Sequela of direct arterial injury [such as penetrating injuries, displaced humeral neck fractures, arterial intimal tears]
Rarely, anterior shoulder dislocation may lead to thrombosis
Improper use of crutches may cause axillary artery aneurysm and subsequent thrombosis
Continuation of the subclavian artery
Defined by the lateral border of the first rib to the inferior border of teres major muscle
Continues as the brachial artery
Axillary vein runs medial to the artery
Axillary artery thrombosis
Arterial compression without thrombosis
Subclavian steal syndrome
Thrombosis proximal or distal to the axillary artery
Raynaud’s disease
Arterial dissection
Isolated distal deep venous thrombosis
Vasculitides