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The radial nerve is a continuation of posterior cord of brachial plexus in the axilla. It carries fibres from all the roots (C5, C6, C7, C8, and T1). The Radial nerve is a mixt nerve having both motor and senzitive fibers.
It leaves the axilla by passing through a triangular space bordered as fallows:
Supperiorly is the lower mrgin of teres major;
Inferiorly is the lateral margin of long head of triceps brachii;
Laterarly is the medial margin of the humerus.
After passes through this space the radial nerve descends in the spiral groove on the back of the humerus beeing directed inferior and lateraly. It leaves the spiral groove by piercing the lateral intermuscular septum of the arm. Before entering the spiral groove gives granch to long head of triceps brachii.
Passing through the spiral groove the radial nerve gives the following braches:
Branch to lateral head of triceps brachii;
Branch to medial head of triceps brachii;
Branch to anconeus;
And two sensory branches called the posterior brachial cutaneous and posterior antebrachial cutaneous. Those two sensory branches will pierce the triceps to inervate the skin on the posterior parts of the arm and forearm , respectevely.
In the spiral groove the radial nerve is accompanied by the profunda brachii artery , a branch of the brachial atery.
After passes through lateral intermuscular septum of the arm, the radial nerve descends between brachialis and brachioradialis muscles, thus arriving at the level of the cubital fossa. Above the lateral epicondyle it gives branches to brachioradialis, a small lateral part of brachialis and also to extensor carpi radialis longus.
At the level of lateral epicondyle of humerus, it terminates by dividing into superficial and deep branches in the lateral part of the cubital fossa.
The superficial branch is sensory. It runs downwards deep to brachioradialis muscle emerging from under the tendon of brachioradialis, proximal to the styloid process of radius and then passes over the
tendons of anatomical snuffbox, where it terminates as cutaneous branches which provide sensory innervation to skin over the lateral part of the dorsum of hand and dorsal
surfaces of lateral 3½ digits except nail beds.
#radialnerve #anatomy #brachial