Anterior Ulnar Recurrent Artery: Anatomy, Course, Function, MRA & CTA

Topic

Anterior ulnar recurrent artery

The anterior ulnar recurrent artery (AURA) is a small but significant branch of the ulnar artery in the forearm. It arises just distal to the ulnar artery’s origin from the brachial artery (or occasionally from the common interosseous trunk) and ascends proximally toward the anterior aspect of the medial epicondyle of the humerus, where it participates in the rich periarticular anastomosis of the elbow joint.

It supplies blood to the brachialis, pronator teres, and flexor muscles of the forearm, as well as to the anterior aspect of the elbow joint. The AURA is smaller and more anteriorly positioned than the posterior ulnar recurrent artery, and the two together provide an important collateral route in cases of brachial artery obstruction or ligation.

Synonyms

Anterior branch of the ulnar recurrent artery
Superior anterior ulnar collateral branch (older terminology)

Origin, Course, and Termination

Origin: Arises from the ulnar artery approximately 2–4 cm distal to its origin in the cubital fossa.
Course:
- Ascends proximally and medially in front of the flexor digitorum superficialis muscle.
- Passes deep to the pronator teres and anterior to the brachialis muscle.
- Runs toward the medial epicondyle of the humerus and contributes to the elbow’s arterial anastomosis.
Termination:
- Ends by anastomosing with the inferior ulnar collateral artery (from the brachial artery) and small branches around the medial aspect of the elbow joint capsule.

Relations

Anteriorly: Superficial fascia, pronator teres, and skin of the cubital fossa region
Posteriorly: Brachialis muscle and anterior surface of the medial epicondyle
Medially: Ulnar head of pronator teres
Laterally: Brachial artery and median nerve (at origin)
Superiorly: Medial epicondyle and elbow joint capsule

Branches

Muscular branches: To the brachialis, pronator teres, and flexor carpi radialis
Articular branches: Supply anterior and medial aspects of the elbow joint
Anastomotic branches: Join the inferior ulnar collateral artery and small twigs of the radial recurrent artery

Function

Arterial supply: Provides oxygenated blood to the pronator teres, brachialis, and anterior elbow capsule
Collateral circulation: Contributes to the periarticular anastomosis around the elbow, ensuring continuous perfusion during flexion and extension when the main brachial artery flow is temporarily compromised
Clinical role: Serves as a collateral route in brachial artery obstruction, trauma, or surgical ligation

Clinical Significance

Collateral importance: Key component of elbow anastomosis, especially when the brachial artery is injured or occluded
Vascular trauma: Can be affected in elbow fractures or penetrating injuries
Surgical relevance: Important landmark during ulnar artery harvesting, forearm flap surgeries, and bypass grafting
Aneurysm or pseudoaneurysm: Rare, but may present as pulsatile swelling in cubital fossa region
Embolism or thrombosis: Can compromise distal ulnar circulation, especially if other collateral pathways are poor

MRI Appearance

T1-weighted images:
- Artery appears as a flow void (dark signal) due to rapid blood movement.
- Perivascular fat: bright, enhancing contrast with the vessel wall.
- Thrombosis or slow flow: may show intermediate intraluminal signal.
T2-weighted images:
- Flowing blood: dark signal (flow void).
- Wall thickening or thrombus: intermediate-to-bright signal depending on age and composition.
- Surrounding muscle and fat planes clearly delineated.
STIR:
- Normal artery: dark flow void.
- Inflammation or hematoma: bright hyperintense perivascular signal.
Proton Density Fat-Saturated (PD FS):
- Artery: dark linear flow void.
- Thrombosed or inflamed vessel: bright wall enhancement or perivascular signal increase.
T1 Fat-Sat Post-Contrast:
- Normal lumen: shows brisk, homogeneous enhancement.
- Stenosis or occlusion: segmental non-enhancement with collateral visualization.
- Vasculitis or perivascular inflammation: concentric wall enhancement.

MRA (Magnetic Resonance Angiography) Appearance

Normal: The anterior ulnar recurrent artery appears as a small enhancing vessel branching from the ulnar artery near the cubital fossa and curving medially toward the medial epicondyle.
Techniques: Best visualized on 3D TOF (Time-of-Flight) or contrast-enhanced MRA sequences.
Pathology:
- Occlusion or thrombosis: segmental loss of signal.
- Aneurysm: focal bulbous enhancement.
- Collateral flow: visualized as fine serpiginous channels in chronic arterial obstruction.

CT Appearance

Non-Contrast CT:

Vessel lumen not directly visualized unless calcified.
Surrounding soft tissues and muscles provide indirect anatomical context.
Chronic vascular calcification appears as fine curvilinear hyperdensities along artery wall.

Post-Contrast CT (standard):

Artery appears as an enhancing tubular structure ascending anterior to the medial epicondyle.
Distinguishes artery from adjacent veins and tendons based on timing and density.
Detects wall thickening, aneurysm, or perivascular hematoma.

CTA (CT Angiography) Appearance

Normal:
- Clearly shows the artery as a small, contrast-filled vessel arising from the ulnar artery and ascending to join the elbow anastomosis.
- Optimal visualization on arterial-phase CTA with thin-slice reconstructions.
Pathology:
- Occlusion: abrupt tapering or cutoff of contrast flow.
- Aneurysm: focal saccular or fusiform dilation with contrast filling.
- Stenosis: segmental narrowing or irregular wall contour.
- Collateral circulation: multiple fine enhancing channels around the medial epicondyle.