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Superior ulnar collateral artery

The superior ulnar collateral artery (SUCA) is a long, slender branch of the brachial artery in the arm. It typically arises in the middle third of the arm, descends along the medial aspect of the humerus, and accompanies the ulnar nerve posterior to the medial epicondyle of the humerus. It contributes significantly to the arterial anastomosis around the elbow joint, especially on its posterior and medial surfaces.

The SUCA provides blood to the medial head of the triceps brachii, ulnar nerve, and elbow joint capsule, and joins with the posterior ulnar recurrent artery and inferior ulnar collateral artery, maintaining collateral circulation during elbow flexion or brachial artery obstruction.

Synonyms

  • Superior profunda ulnar artery (old terminology)

  • Posterior medial collateral branch of brachial artery

Origin, Course, and Termination

  • Origin: Arises from the brachial artery, usually opposite the origin of the profunda brachii artery, in the middle or lower third of the arm.

  • Course:

    • Descends obliquely downward and medially toward the posterior aspect of the medial epicondyle.

    • Runs posterior to the medial intermuscular septum, accompanying the ulnar nerve.

    • Passes behind the medial epicondyle, superficial to the triceps tendon, to reach the olecranon fossa region.

  • Termination:

    • Ends by anastomosing with the posterior ulnar recurrent artery and small branches of the inferior ulnar collateral artery, forming part of the posterior ulnar anastomosis of the elbow.

Relations

  • Anteriorly: Medial head of triceps and brachialis (proximally)

  • Posteriorly: Medial intermuscular septum and ulnar nerve

  • Medially: Skin and fascia of the posteromedial arm

  • Laterally: Brachial artery (at origin)

  • Inferiorly: Medial epicondyle and posterior elbow joint capsule

Branches

  • Muscular branches: Supply the medial head of triceps brachii and anconeus

  • Articular branches: To the posterior and medial surfaces of the elbow joint

  • Anastomotic branches: Join posterior ulnar recurrent and inferior ulnar collateral arteries

Function

  • Arterial supply: Provides blood to triceps brachii, anconeus, and elbow capsule

  • Collateral pathway: Contributes to the periarticular arterial anastomosis at the posterior aspect of the elbow joint

  • Protective circulation: Maintains distal perfusion during brachial artery compression or ligation

  • Anatomic landmark: Used in vascular flap design and arterial reconstruction in the medial arm

Clinical Significance

  • Collateral importance: A major contributor to the posterior elbow anastomosis

  • Surgical relevance: Must be preserved during medial arm approaches and ulnar nerve transposition procedures

  • Vascular injury: May be damaged in medial humeral fractures or elbow dislocations

  • Aneurysm formation: Rare but may cause compressive neuropathy or pulsatile mass near medial epicondyle

  • Imaging relevance: Assessment via MRA or CTA aids in pre-surgical planning and evaluation of traumatic or ischemic conditions

MRI Appearance

  • T1-weighted images:

    • Normal artery: flow void (dark linear structure) due to rapid blood flow

    • Perivascular fat: bright signal outlining the vessel

    • Thrombus or slow flow: intermediate intraluminal signal intensity

  • T2-weighted images:

    • Flowing blood: dark flow void

    • Vessel wall thickening or thrombus: intermediate-to-bright signal

    • Adjacent muscle and soft tissues well defined

  • STIR:

    • Normal artery: dark flow void

    • Perivascular inflammation or hematoma: bright hyperintense signal

  • Proton Density Fat-Saturated (PD FS):

    • Normal artery: dark linear structure

    • Thrombosis or inflammation: focal or circumferential bright wall signal

  • T1 Fat-Sat Post-Contrast:

    • Normal lumen: brisk homogeneous enhancement

    • Occlusion: segmental non-enhancement with collateral filling

    • Vasculitis or arterial wall inflammation: concentric mural enhancement

MRA (Magnetic Resonance Angiography) Appearance

  • Normal: SUCA appears as a thin enhancing branch arising from the brachial artery in the mid-arm and curving medially to accompany the ulnar nerve behind the medial epicondyle.

  • Technique: Best visualized with contrast-enhanced MRA or 3D Time-of-Flight (TOF) sequences.

  • Pathology:

    • Occlusion or thrombosis: Abrupt loss of luminal signal.

    • Aneurysm: Focal bulbous contrast-filled outpouching.

    • Collateral flow: Tortuous enhancing channels posterior to the elbow.

CT Appearance

Non-Contrast CT:

  • Vessel lumen: not directly visible unless calcified

  • Vessel wall: may appear as soft-tissue strand posterior to the humerus

  • Arterial calcifications: seen as curvilinear high-density lines

Post-Contrast CT (standard):

  • Artery enhances as a tubular contrast-filled structure descending along the medial aspect of the arm

  • Readily distinguished from veins by phase timing

  • Detects aneurysm, wall thickening, or traumatic pseudoaneurysm

CTA (CT Angiography) Appearance

  • Normal:

    • Visualized as a slender, well-opacified vessel branching from the brachial artery in the arm, accompanying the ulnar nerve behind the medial epicondyle.

    • Best demonstrated in arterial-phase CTA with thin-slice multiplanar and 3D reconstructions.

  • Pathology:

    • Stenosis: Focal luminal narrowing with pre- and post-stenotic dilatation.

    • Occlusion: Abrupt cutoff with distal reconstitution via collaterals.

    • Aneurysm: Saccular or fusiform outpouching with uniform contrast filling.

    • Collateral network: Fine serpiginous branches visible posterior to the elbow in chronic occlusion of the brachial artery.

MRI images

Superior ulnar collateral artery axial cross sectional anatomy 3T MRI AI enhanced radiology image -img-00000-00000

MRI images

Superior ulnar collateral artery axial cross sectional anatomy 3T MRI AI enhanced radiology image -img-00000-00000_00001

MRI images

Superior ulnar collateral artery axial cross sectional anatomy 3T MRI AI enhanced radiology image -img-00000-00000_00002