Vessels and nerves of the forearm

Definitions & Key takeaways

The forearm is part of the upper limb between the elbow and the wrist. It contains arteries, veins, and nerves that supply the muscles, bones, and skin of the forearm and hand.

The main arteries of the forearm are the ulnar and the radial arteries, which arise from the bifurcation of the brachial artery. The ulnar artery gives off three major branches immediately distal to the elbow: the anterior ulnar recurrent artery, the posterior ulnar recurrent artery, and the common interosseous artery. In the wrist region, the ulnar artery gives the other two branches, which are the palmar and dorsal carpal branches. Immediately distal to the elbow, the radial artery gives off its first branch called the radial recurrent artery, and then gives the other two branches in the wrist region: the dorsal and palmar carpal branches which anastomose with those of the ulnar artery.

The forearm has superficial and deep veins. The superficial veins are those which can be found in the superficial fascia and are easily accessible. These are the cephalic vein, the basilic vein, and the median cubital vein which connect the cephalic and basilic veins in the area of the cubital fossa. The deep veins are located deep in the muscles, and they commonly accompany major arteries as the venae comitantes �, which is Latin for accompanying veins �. Finally, three important nerves are running in the forearm: the median nerve, the ulnar nerve, and the radial nerve.

Chapters:

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Introduction0:00–0:20

The forearm contains a vast network of vessels and nerves. Most of these originate in the axilla and to get to the forearm, most of them pass through the cubital fossa which is a small triangular fat filled pit on the anterior part of the elbow.

Cubital fossa0:20–1:43

The cubital fossa has three borders. The superior border consists of an imaginary line joining the medial and lateral epicondyles of the humerus.
The lateral border is the medial border of the brachial radialis muscle and the medial border is made up by the lateral border of the pronator teres muscle.
Deep within this region is the floor of the cubital fossa, which is formed by two muscles. The brachialis and supinator superficially.
There is the roof which is formed by the antebrachial fascia and reinforced by the bicipital aponeurosis coming from the biceps brachii as well as the overlying subcutaneous tissue and skin.
The cubital fossa contains some important structures from medial to lateral. There are the median nerve, the brachial artery which bifurcates into the radial artery laterally and the ulnar artery medially.
The accompanying veins to these deep arteries. The tendon of the biceps brachii muscle and radial nerve on the most lateral part found between the brachial radialis and brachialis muscles overlying the brachial artery and median nerve is the bicipital aponeurosis which protects these structures in situations like when blood is drawn from superficial veins, such as the median cubital vein, which lies superficial to the bicipital aponeurosis.
So that's the cubital fossa, short and sweet. Ok.

Ulnar artery1:43–3:14

Now, let's see some details about the arteries of the forearm. The main arteries are the ulnar and radial artery which are the terminal branches of the brachial artery arising in the cubital fossa.
Starting with the ulnar artery. It emerges from the brachial artery in the cubital fossa.
The ulnar artery runs deep to the superficial and intermediate flexor muscle groups to reach the medial side of the forearm, passing superficial to the flexor retinaculum and travels through guyons canal to enter the hand along its course.
The ulnar artery gives off five major direct branches immediately distal to the elbow. The ulnar artery gives its first two branches.
The anterior and posterior ulnar recurrent artery which both contribute to the elbow's periarticular anastomosis. Then it gives off the common interosseous artery which immediately splits into the anterior and the posterior interosseous arteries.
The anterior interosseous artery supplies the deep muscles of the anterior compartment. The posterior interosseous artery then gives off the recurrent interosseous artery that contributes to the arterial anastomosis of the elbow.
After this, it pierces the interosseous membrane to enter the posterior compartment of the forearm to supply those muscles.
Finally, the ulnar artery runs distally to the wrist where it gives off the remaining two branches, the palmar and the dorsal carpal branches which anastomose with the branches of the radial artery to form the palmar and the dorsal carpal arches.
And then there's the radial artery. After emerging from the bifurcation of the brachial artery in the cubital fossa, it runs under the brachial radialis and winds around the lateral aspect of the radius.

Radial artery3:14–4:07

In the distal forearm, it is only covered by skin and fascia making it the ideal place to take the radial pulse. Eventually, it crosses the floor of the anatomical snuffbox and goes on to supply the hand.
During its course, it gives off a few important branches. The first one is the radial recurrent artery which runs backward to participate in the elbow's periarticular anastomosis.
Then the radial artery runs distally to the wrist where it gives off the palmar and the dorsal carpal branches which anastomose with the branches of the ulnar artery to form the palmar and the dorsal carpal arches.
Now feel free to pause for a second and try to remember the five important branches of the ulnar artery and the three important branches of the radial artery.

Quiz4:07–4:21

Periarticular arterial anastomosis4:21–5:37

Now, let's have a look at the periarticular arterial anastomosis around the elbow. There are four major arteries participating in this anastomosis.
The brachial artery, the profunda brachial artery, the radial artery and the ulnar artery having blood supply from different sources allows the elbow joint and its supporting structures to stay perfused.
No matter which position you put your joints in the brachial artery gives two direct branches. First, it gives the superior ulnar collateral artery in the mid arm region.
And then the inferior ulnar collateral artery in the distal arm, these two arteries anastomose with each other. In addition to the superior ulnar collateral artery, anastomosis with the posterior ulnar recurrent artery and the inferior ulnar collateral artery, anastomosis with the anterior ulnar recurrent artery.
Next comes the profunda brachii artery. It also gives two branches as it courses in the distal arm, the middle and the radial collateral arteries.
The middle collateral artery anastomoses with the recurrent interosseous artery. While the radial collateral artery anastomoses with the radial recurrent artery.
The only branch contributed by the radial artery. And now let's switch gears a little bit and talk about major superficial and deep veins of the forearm.

Superficial veins5:37–6:46

The superficial veins are those which can be found in the superficial fascia and are easily accessible. For example, when you need to draw a blood sample, initially, the superficial veins of the upper limbs start as small veins in the subcutaneous tissues from the dorsal venous network of the hand, they converge into bigger venous networks as they progress proximately up along the wrists and the forearm, resulting in big superficial veins called the cephalic vein, the basilic vein and the median cubital vein, the cephalic vein ascends on the anterolateral surface of the forearm and it is often visible through the skin similar to the cephalic vein.
The basilic vein ascends in the subcutaneous tissue on the medial side of the forearm. And as this one enters the arm, it pierces the brachial fascia to run deep to it.
Finally, there's the median cubital vein which is highly variable. It passes between the cephalic vein and the basilic vein along the cubital fossa.
Now, the deep veins are located deep to the muscles and they commonly accompany major arteries as the vena comitantes, which is Latin for accompanying veins.

Deep veins6:46–7:30

The deep veins start as a tiny network from the superficial and deep palmar venous arches on the medial side. This network gives rise to the ulnar veins which ascend alongside the ulnar artery on the medial side of the forearm.
On the lateral side of the hand, the deep palmar venous arch gives rise to the radial veins which climb up the forearm alongside the radial artery.
Both pairs of ulnar and radial veins terminate in the cubital fossa where they join to form the larger brachial veins that accompany the brachial artery in the arm.

Quiz7:30–7:43

If you need a quick break, feel free to pause the video and try to remember the four major arteries that contribute to the elbows, arterial anastomosis.
Now, let's have a look at the important nerves of the forearm which are the median ulnar and radial nerves in the cubital fossa, the median nerve courses medial to the brachial artery and the biceps brachii tendon entering the forearm between the two heads of the pronator teres muscle.

Median nerve7:43–9:02

Then it travels between the flexor digitorum superficialis and profundus. During its course, it gives muscular branches to the muscles of the superficial and intermediate layers of the anterior compartment of the forearm.
With the exception of the flexor carpi ulnaris, with the exception of the flexor carpi ulnaris as it courses distally in the mid forearm, it gives the anterior interosseous nerve which supplies the deep layer of the anterior compartment of the forearm, minus the ulnar half of flexor digitorum profundus.
Before entering the wrist deep to the flexor retinaculum. The median nerve gives the palmar cutaneous branch which passes superficial to the carpal tunnel between the palmaris longus and the flexor carpi radialis to supply the skin of the central palm.
The median nerve itself enters the hand through the carpal tunnel deep to the flexor retinaculum at the wrist. Next, there's the ulnar nerve, it enters the forearm by passing posterior to the medial epicondyle of the humerus from where it descends through the two heads of flexor carpi ulnaris.

Ulnar nerve9:02–9:45

It gives muscular branches that innervate the medial part of the flexor digitorum profundus and the flexor carpi ulnaris and then continues distally coursing over the flexor digitorum profundus at the wrist, the ulnar nerve enters the hand through guyons canal which is a groove between the hook of the hamate and pisiform two carpal bones.
The ulnar nerve also gives off the palmar and dorsal cutaneous branches in the forearm which along with digital branches in the hand supply the skin of the medial hand.

Radial nerve9:45–10:41

And now for the radial nerve before getting to the cubital fossa, the radial nerve has a branch called the posterior cutaneous nerve of the forearm, which supplies the skin of the posterior forearm to the wrist.
The radial nerve itself enters the cubital fossa between the brachial radialis and brachialis anterior to the lateral epicondyle and then branches where it branches into the superficial and deep branch of the radial nerve.
The deep branch pierces the supinator and emerges as the posterior interosseous nerve. The radial nerve, the deep branch of the radial nerve and the posterior interosseous nerve innervate all of the muscles in the posterior compartment of the forearm.
The remaining branch is the superficial branch. This one contributes to the cutaneous innervation of the anatomical snuffbox as well as the dorsal hand and fingers.

Lateral cutaneous nerve of forearm10:41–11:20

The skin over the lateral side of the forearm gets its innervation from. Well, you guessed it the lateral cutaneous nerve of the forearm.
This nerve is a branch of the musculocutaneous nerve. The medial side of the forearm is supplied by the medial cutaneous nerve of the forearm which originates from the medial cord of the brachial plexus.
Initially, this nerve runs with the ulnar nerve before it perforates the deep fascia at approximately the mid arm. It then enters the subcutaneous tissue of the forearm, innervating the skin over the medial side.

Quiz11:20–11:33

One last pause. Before we recap, can you identify the median nerve, the radial nerve and the ulnar nerve in this image as a quick recap, the main arteries of the forearm are the ulnar and the radial arteries which arise from the bifurcation of the brachial artery.

Review11:33–12:38

The ulnar artery gives off three major branches immediately distal to the elbow. The anterior ulnar recurrent artery, the posterior ulnar recurrent artery and the common interosseous artery in the wrist region.
The ulnar artery gives the other two branches which are the palmar and dorsal carpal branches immediately distal to the elbow.
The radial artery gives off its first branch called the radial recurrent artery and then gives the other two branches in the wrist region.
The dorsal and palmar carpal branches which anastomose with those of the ulnar artery. The superficial veins of the forearm are the cephalic vein, the basilic vein and the median cubital vein which connect the cephalic and basilic veins in the area of the cubital fossa.
Finally, there are three important nerves running in the forearm. The median nerve, the ulnar nerve and the radial nerve