Ulnar artery
Encyclopedia
The ulnar artery is the main blood vessel
Blood vessel
The blood vessels are the part of the circulatory system that transports blood throughout the body. There are three major types of blood vessels: the arteries, which carry the blood away from the heart; the capillaries, which enable the actual exchange of water and chemicals between the blood and...

, with oxygenated blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....

, of the medial aspect of the forearm
Forearm
-See also:*Forearm flexors*Forearm muscles...

. It arises from the brachial artery
Brachial artery
The brachial artery is the major blood vessel of the arm.It is the continuation of the axillary artery beyond the lower margin of teres major muscle. It continues down the ventral surface of the arm until it reaches the cubital fossa at the elbow. It then divides into the radial and ulnar arteries...

 and terminates in the superficial palmar arch, which joins with the superficial branch of the radial artery
Radial artery
In human anatomy, the radial artery is the main blood vessel, with oxygenated blood, of the lateral aspect of the forearm.-Course:The radial artery arises from the bifurcation of the brachial artery in the cubital fossa. It runs distally on the anterior part of the forearm...

. It is palpable on the anterior and medial aspect of the wrist
Wrist
In human anatomy, the wrist is variously defined as 1) the carpus or carpal bones, the complex of eight bones forming the proximal skeletal segment of the hand;...

.

Along its course, it is accompanied by a similarly named vein
Vein
In the circulatory system, veins are blood vessels that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated blood to the heart...

 or veins, the ulnar vein or ulnar veins.

The ulnar artery, the larger of the two terminal branches of the brachial, begins a little below the bend of the elbow in the cubital fossa
Cubital fossa
The cubital fossa is the triangular area on the anterior view of the elbow of a human or other hominid animal. It is colloquially known as the "elbow pit".-Boundaries:...

, and, passing obliquely downward, reaches the ulnar side of the forearm at a point about midway between the elbow and the wrist. It then runs along the ulnar border to the wrist, crosses the transverse carpal ligament on the radial side of the pisiform bone
Pisiform bone
The pisiform bone is a small knobbly, pea-shaped wrist bone.The pisiform bone is found in the proximal row of the carpus. It is located where the ulna joins the carpus...

, and immediately beyond this bone divides into two branches, which enter into the formation of the superficial and deep volar arches.

Forearm

In its upper half, it is deeply seated, being covered by the Pronator teres, Flexor carpi radialis, Palmaris longus, and Flexor digitorum superficialis; it lies upon the Brachialis and Flexor digitorum profundus.

The median nerve
Median nerve
The median nerve is a nerve in humans and other animals. It is in the upper limb. It is one of the five main nerves originating from the brachial plexus....

 is in relation with the medial side of the artery for about 2.5 cm. and then crosses the vessel, being separated from it by the ulnar head of the Pronator teres.

In the lower half of the forearm it lies upon the Flexor digitorum profundus, being covered by the integument and the superficial and deep fasciæ, and placed between the Flexor carpi ulnaris and Flexor digitorum superficialis.

It is accompanied by two venæ comitantes, and is overlapped in its middle third by the Flexor carpi ulnaris; the ulnar nerve
Ulnar nerve
In human anatomy, the ulnar nerve is a nerve which runs near the ulna bone. The ulnar collateral ligament of elbow joint is in relation with the ulnar nerve. The nerve is the largest unprotected nerve in the human body , so injury is common...

 lies on the medial side of the lower two-thirds of the artery, and the palmar cutaneous branch of the nerve descends on the lower part of the vessel to the palm of the hand.

Wrist

At the wrist the ulnar artery is covered by the integument and the volar carpal ligament, and lies upon the Flexor retinaculum of the hand
Flexor retinaculum of the hand
The flexor retinaculum is a strong, fibrous band that arches over the carpus, converting the deep groove on the front of the carpal bones into a tunnel, the carpal tunnel, through which the Flexor tendons of the digits and the median nerve pass.It is attached, medially, to the pisiform and the...

. On its medial side is the pisiform bone
Pisiform bone
The pisiform bone is a small knobbly, pea-shaped wrist bone.The pisiform bone is found in the proximal row of the carpus. It is located where the ulna joins the carpus...

, and, somewhat behind the artery, the ulnar nerve
Ulnar nerve
In human anatomy, the ulnar nerve is a nerve which runs near the ulna bone. The ulnar collateral ligament of elbow joint is in relation with the ulnar nerve. The nerve is the largest unprotected nerve in the human body , so injury is common...

.

Peculiarities

The ulnar artery varies in its origin in the proportion of about one in thirteen cases; it may arise about 5 to 7 cm. below the elbow, but more frequently higher, the brachial being more often the source of origin than the axillary.

Variations in the position of this vessel are more common than in the radial. When its origin is normal, the course of the vessel is rarely changed.

When it arises high up, it is almost invariably superficial to the Flexor muscles in the forearm, lying commonly beneath the fascia, more rarely between the fascia and integument.

In a few cases, its position was subcutaneous in the upper part of the forearm, and subaponeurotic in the lower part.
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