Ulnar artery !

The ulnar artery runs down the little-finger side of the forearm; it feeds the forearm and forms most of the superficial arch of the palm.

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What it is

The larger forearm artery on the little-finger side; it supplies most of the superficial palmar arch and can be damaged by repeated pounding with the palm (hypothenar hammer syndrome).

What it does

Feeds the forearm and most of the superficial palmar arch.

Key facts

Origin: Brachial artery bifurcation
Branches: Anterior and posterior ulnar recurrent, common interosseous, carpal branches, deep palmar branch; ends in the superficial palmar arch
Supplies: Medial forearm, most of the hand

Relations

Course: From the cubital fossa it curves down and medially deep to pronator teres and the FDS, runs straight down on the FDP under the flexor carpi ulnaris, crosses the wrist in the Guyon canal and divides into the superficial palmar arch and a deep palmar branch
Medial: Ulnar nerve; the flexor carpi ulnaris tendon and the pisiform at the wrist
Lateral: Tendons of the FDS in the forearm; the hook of the hamate at the far end of the Guyon canal
Deep: Brachialis, then the FDP, then the flexor retinaculum at the wrist
Superficial: Pronator teres, FCR, palmaris longus and FDS in the upper forearm; the flexor carpi ulnaris overlaps it lower down; the palmar carpal ligament and palmaris brevis at the wrist

How to find it

Surface line: from the middle of the cubital fossa obliquely to the medial border of the forearm at the junction of its upper and middle thirds, then straight down to the lateral side of the pisiform. Ulnar pulse: just above the pisiform, lateral to the flexor carpi ulnaris tendon, with the wrist slightly extended; usually weaker than the radial pulse.

Examination

Allen test with ulnar release: after the palm blanches with both arteries compressed, only the ulnar artery is let go; prompt flushing shows it can perfuse the hand through the arches, which is checked before radial access or harvest

On imaging

Doppler ultrasound follows it from the elbow down the forearm and, at the wrist, beside the ulnar nerve into Guyon's canal. In hypothenar hammer syndrome, repeated blows with the heel of the hand cause thrombosis or aneurysm of its distal part, seen on ultrasound, CT or MR angiography, often with emboli to the fingers. Angiography also maps the arches before radial artery harvest.

Clinical notes

In the Guyon canal the artery and nerve lie together, so a mass, fracture of the hook of the hamate or repeated pounding can cause both cold fingers and ulnar nerve symptoms
A deep cut on the ulnar side of the wrist often divides the artery, the ulnar nerve and the flexor carpi ulnaris tendon together
Transulnar access is an alternative route for angiography when the radial artery is unsuitable
Usually the larger of the two forearm arteries, so loss of the ulnar artery is more likely to threaten the fingers than loss of the radial (not in every hand)

Anatomical variants

Superficial ulnar artery: a rare high-origin artery that runs over the forearm flexors just under the skin and can be mistaken for a vein, with a risk of injection into the artery
Persistent median artery: an embryonic artery that runs with the median nerve, may survive into adult life and can join the superficial palmar arch through the carpal tunnel

Development

Grows out of the brachial part of the axis artery at the same stage as the radial artery; as both enlarge, the embryonic median artery shrinks, although it can survive alongside the median nerve.

Raynaud phenomenon

Test yourself

Think of the answer, then tap the question to see it.

Which structure separates the ulnar artery from the median nerve in the upper forearm?

The deep head of pronator teres: the artery passes deep to it, the median nerve lies in front.

How does the ulnar artery cross the wrist?

Superficial to the flexor retinaculum, lateral to the pisiform, through Guyon's canal with the ulnar nerve on its medial side.

Why can a lesion in Guyon's canal cause both cold fingers and ulnar nerve symptoms?

The ulnar artery and ulnar nerve lie together there; a mass, hook of hamate fracture or repeated pounding affects both.

Which palmar arch does the ulnar artery end in?

The superficial palmar arch, after giving its deep palmar branch.

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Educational information, not medical advice. For any symptom, see a health professional.

Its names

Official Latin (TA2): arteria ulnaris TA2 4655
Official Spanish (DeCS): Arteria ulnar
English (TA2): Ulnar artery

Sources: Terminologia Anatomica (TA2); Anatomy, Shoulder and Upper Limb, Ulnar Artery; Anatomy, Shoulder and Upper Limb, Forearm Arteries; Anatomy of the Human Body (20th ed.): Development of the Vascular System (Lea & Febiger (Gray's Anatomy, 1918), 1918) · adapted, Public domain; Tratado de anatomía humana (9.ª ed.), tomo II, Libro IV Angiología, arterias subclavia, axilar, humeral, radial y cubital, arcos palmares y vías anastomóticas del miembro superior.

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Representative model, for educational purposes only.

Ulnar artery highlighted on the Durgical 3D model