Radial nerve

It originates from the posterior cord of the brachial plexus with roots from C5, C6, C7, C8 & T1.

The radial nerve and its branches supply the dorsal muscles, such as triceps brachii, the extrinsic extensors of the wrist and hands, and the cutaneous nerve supply to most of the back of the hand. (The ulnar nerve cutaneously innervates the back of the little finger and adjacent half of the ring finger).

The radial nerve divides into a deep branch (which becomes the posterior interosseous nerve), and continues as the superficial branch which goes on to innervate the dorsum (back) of the hand.

Course

In arm

The radial nerve enters the arm behind the axillary artery/brachial artery, and it then travels posteriorly on the medial side of the arm.

After giving off branches to the long and medial heads of the triceps brachii, it enters a groove on the humerus, the radial sulcus, where it innervates the lateral head of the triceps.

Along with the deep brachial artery, the radial nerve winds around in the groove (between the medial and lateral heads of the triceps) towards the forearm, running laterally on the posterior aspect of the humerus.

While in the groove, it gives off a branch to the lateral head of the triceps brachii.

The radial nerve emerges from the groove on the lateral aspect of the humerus.

At this point, it pierces the lateral intermuscular septum and enters the anterior compartment of the arm.

It continues its journey inferiorly between the brachialis and brachioradialis muscles.

When the radial nerve reaches the distal part of the humerus, it passes anterior to the lateral epicondyle and continues in the forearm.

In forearm

* The superficial branch of the radial nerve descends in the forearm under the brachioradialis. It eventually pierces the deep fascia near the back of the wrist.

* The deep branch of the radial nerve pierces the supinator muscle, after which it is known as the posterior interosseous nerve.

Branches/Innervations

Cutaneous

*Posterior cutaneous nerve of arm (originates in axilla)

The superficial branch of the radial nerve provides sensory innervation to much of the back of the hand, including the web of skin between the thumb and index finger.

Motor

Deep branch of the radial nerve:

Posterior interosseous nerve (a continuation of the deep branch after the supinator):

The radial nerve (and its deep branch) provides motor innervation to the muscles in the posterior compartment of the arm and forearm, which are mostly extensors. it also enters humerus

Additional images

See also

External links

Category:Nerves of the upper limb