Anterior Interosseous Artery: Anatomy, Course, Function, Imaging

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Anterior interosseous artery

The anterior interosseous artery (AIA) is a major branch of the common interosseous artery, itself derived from the ulnar artery. It descends along the anterior surface of the interosseous membrane in the deep compartment of the forearm, supplying the deep flexor muscles, radius and ulna, and the pronator quadratus muscle. The AIA is accompanied by the anterior interosseous nerve (branch of the median nerve), forming a neurovascular bundle that terminates at the distal forearm, where it contributes to the carpal anastomosis and communicates with the posterior interosseous artery through the dorsal perforating branch.

The artery plays a key role in maintaining perfusion of the deep forearm compartment and provides collateral flow to the wrist and hand, particularly in vascular compromise of the radial or ulnar arteries.

Synonyms

Volar interosseous artery
Deep interosseous artery of the forearm

Origin, Course, and Termination

Origin: Arises from the common interosseous artery, a short branch of the ulnar artery in the proximal forearm.
Course:
- Passes between the oblique cord and the upper border of the interosseous membrane.
- Descends along the anterior surface of the interosseous membrane between the flexor digitorum profundus and flexor pollicis longus muscles.
- Accompanied by the anterior interosseous nerve, it travels distally beneath the pronator quadratus muscle.
Termination:
- Pierces the interosseous membrane near the wrist to join the posterior interosseous artery, contributing to the dorsal carpal network and palmar carpal arch.

Relations

Anteriorly: Flexor digitorum profundus and flexor pollicis longus
Posteriorly: Interosseous membrane
Laterally: Radius
Medially: Ulna
Distally: Pronator quadratus and wrist joint capsule

Branches

Muscular branches: To flexor digitorum profundus, flexor pollicis longus, and pronator quadratus
Nutrient branches: To radius and ulna
Median artery branch: Occasionally arises from AIA to supply the median nerve
Palmar carpal branch: Contributes to the palmar carpal arch
Communicating branch: Joins the posterior interosseous artery near the distal forearm

Function

Arterial supply: Provides oxygenated blood to the deep flexor compartment of the forearm and the interosseous membrane
Collateral flow: Assists in maintaining perfusion to the wrist and hand through the dorsal and palmar carpal networks
Bone perfusion: Sends nutrient branches to the radius and ulna, essential for bone vitality and healing
Clinical importance: Acts as a collateral channel in occlusion of the ulnar or radial arteries

Clinical Significance

Collateral circulation: Plays a critical role in maintaining distal limb perfusion in proximal arterial obstruction
Vascular injury: May be compromised in penetrating forearm trauma or fracture of the radius/ulna
Iatrogenic concern: Vulnerable during orthopedic or reconstructive forearm surgeries
Aneurysm or thrombosis: Rare, but can lead to ischemia of deep forearm muscles
Flap surgery relevance: Often used as a vascular pedicle for anterior interosseous flap in reconstructive hand surgery

MRI Appearance

T1-weighted images:
- Artery shows as a linear flow void (dark signal) against bright fatty background.
- Adjacent muscles show intermediate signal, allowing easy identification of the vessel course.
- Thrombosed segments may demonstrate intermediate intraluminal signal.
T2-weighted images:
- Flowing blood produces a dark signal (flow void).
- Thrombosis or wall inflammation results in bright signal within or around the vessel.
- Relationship with interosseous membrane clearly defined.
STIR:
- Normal artery: dark flow void.
- Perivascular edema or hematoma: Appears bright hyperintense, useful for detecting inflammation or trauma.
Proton Density Fat-Saturated (PD FS):
- Vessel lumen: dark; thrombus or inflammatory wall: bright.
- Enhances visualization of perivascular soft tissue changes.
T1 Fat-Sat Post-Contrast:
- Normal: uniform, brisk enhancement of arterial lumen.
- Occlusion: segmental non-enhancement.
- Wall inflammation: circumferential enhancement of arterial wall.

MRA (Magnetic Resonance Angiography) Appearance

Normal:
- The AIA appears as a thin, enhancing vessel descending anterior to the interosseous membrane between deep flexor muscles.
- Best visualized on 3D Time-of-Flight (TOF) or contrast-enhanced MRA.
Pathology:
- Stenosis: Segmental signal narrowing.
- Occlusion: Absence of signal distal to obstruction.
- Aneurysm: Localized, rounded signal enhancement.
- Collateral formation: Multiple fine enhancing vessels joining the dorsal carpal network.

CT Appearance

Non-Contrast CT:

Artery not directly visible unless wall calcification is present.
Interosseous membrane and adjacent muscles define the expected vascular plane.
Chronic atherosclerotic calcifications appear as linear or punctate high-density foci along the vessel path.
Post-Contrast CT (standard):
AIA enhances as a small, well-defined tubular structure descending along the interosseous membrane.
Demonstrates continuity with the ulnar artery proximally and the dorsal carpal network distally.
Detects aneurysm, wall thickening, or perivascular hematoma.

CTA (CT Angiography) Appearance

Normal:
- The AIA appears as a contrast-filled slender vessel between the radius and ulna, extending distally to the wrist.
- Clearly visualized on arterial-phase CTA with thin-slice or 3D volume-rendered reconstructions.
Pathology:
- Stenosis or occlusion: Narrowing or absence of opacification along its course.
- Aneurysm: Focal saccular dilation with intense contrast filling.
- Dissection: Double-lumen appearance or irregular mural enhancement.
- Collateral flow: Multiple fine enhancing channels connecting with the posterior interosseous and palmar carpal arteries.

MRI images

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